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Sample records for growth mode resulting

  1. Regularity in budding mode and resultant growth morphology of the azooxanthellate colonial scleractinian Tubastraea coccinea

    NASA Astrophysics Data System (ADS)

    Sentoku, A.; Ezaki, Y.

    2012-03-01

    Scleractinia exhibit a variety of growth forms, whether zooxanthellate or azooxanthellate, according to factors that control asexual reproduction and ensuing coral growth. The azooxanthellate branching scleractinian Dendrophyllia arbuscula shows regular modes of budding in terms of the locations of budding sites, the orientations of directive septa, and the inclination angle of budding throughout colonial growth. This study reports that such regularities are also found in the apparently different growth form of the massive dendrophylliid Tubastraea coccinea, which shows the following growth features: (1) the offsets (lateral corallites) always occur near four primary septa, except the two directive primary septa, meaning that the lateral corallites do not appear in the sectors of the two directive septa; (2) the two directive septa in lateral corallites tend to be oriented subperpendicular to the growth direction of the parental corallites; (3) the lateral corallites grow approximately diagonally upwards; and (4) these regularities are seen in the axial and derived lateral corallites among all generations during colony growth. Large differences in growth form are found between the branching D. arbuscula and massive T. coccinea, irrespective of the presence of specific regularities. It is likely that subtle modifications of certain parameters (e.g., budding interval, branch length, corallite size, and inclination angle of lateral corallites) have a strong effect on the overall growth morphology. A precise understanding of such regularities, which occur regardless of generation or taxonomic position, would contribute to understanding the "shape-controlling mechanism" of corals, which are an archetypal modular organism.

  2. Filamentation as primitive growth mode?

    NASA Astrophysics Data System (ADS)

    Bigan, Erwan; Steyaert, Jean-Marc; Douady, Stéphane

    2015-12-01

    Osmotic pressure influences cellular shape. In a growing cell, chemical reactions and dilution induce changes in osmolarity, which in turn influence the cellular shape. Using a protocell model relying upon random conservative chemical reaction networks with arbitrary stoichiometry, we find that when the membrane is so flexible that its shape adjusts itself quasi-instantaneously to balance the osmotic pressure, the protocell either grows filamentous or fails to grow. This behavior is consistent with a mathematical proof. This suggests that filamentation may be a primitive growth mode resulting from the simple physical property of balanced osmotic pressure. We also find that growth is favored if some chemical species are only present inside the protocell, but not in the outside growth medium. Such an insulation requires specific chemical schemes. Modern evolved cells such as E. coli meet these requirements through active transport mechanisms such as the phosphotransferase system.

  3. Filamentation as primitive growth mode?

    PubMed

    Bigan, Erwan; Steyaert, Jean-Marc; Douady, Stéphane

    2015-12-01

    Osmotic pressure influences cellular shape. In a growing cell, chemical reactions and dilution induce changes in osmolarity, which in turn influence the cellular shape. Using a protocell model relying upon random conservative chemical reaction networks with arbitrary stoichiometry, we find that when the membrane is so flexible that its shape adjusts itself quasi-instantaneously to balance the osmotic pressure, the protocell either grows filamentous or fails to grow. This behavior is consistent with a mathematical proof. This suggests that filamentation may be a primitive growth mode resulting from the simple physical property of balanced osmotic pressure. We also find that growth is favored if some chemical species are only present inside the protocell, but not in the outside growth medium. Such an insulation requires specific chemical schemes. Modern evolved cells such as E. coli meet these requirements through active transport mechanisms such as the phosphotransferase system. PMID:26718101

  4. Growth Modes of Nd Deposited on Mo(110) Surface

    NASA Astrophysics Data System (ADS)

    Jo, Sadaharu; Gotoh, Yoshihiko

    1999-12-01

    We have studied the growth modes of Nd deposited on a Mo(110) surface by means of reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). Nd grows on the Mo(110) surface in the Stranski-Krastanov growth mode in the temperature range between 500°C and 750°C, in which a monolayer with a c(5×3) structure grows initially, followed by the growth of Nd islands. On the other hand, Nd grows on the Mo(110) surface in the pseudo Frank-van der Merwe growth mode in the temperature range between room temperature and 500°C. The results of RHEED specular beam intensity oscillations also support the above-mentioned growth modes.

  5. Growth mode of polyethylene single crystals

    SciTech Connect

    Toda, A.; Tanzawa, Y.; Nakagawa, Y.

    1995-12-01

    The growth kinetics and morphology of polyethylene single crystals of narrow molecular weight fractions is reviewed. Single crystals grown from the melt show two types of morphology in the lateral habits; a lenticular shape elongated in the direction of the b-axis (type A) and a truncated lozenge with curved edges of the (100) growth faces (type B). The change in the lateral habits occurs in the vicinity of a transition in the supercooling dependence of growth rate along the b-axis direction. This talk will discuss the mechanism of the change in morphology and growth mode.

  6. Mode of dendrite growth in undercooled alloy melts

    SciTech Connect

    Li, J.; Yang, G.; Zhou, Y.

    1998-01-01

    The mode of dendrite growth in the undercooled Ni-50 at% Cu alloy was investigated. At lower undercoolings, the dendrite growth is mainly controlled by solute diffusion, and the formed dendritic morphologies are similar to those of the conventional as-cast equiaxed crystals, except that here the branches are much denser. At higher undercoolings, however, the severe solutal trapping that results from high dendrite growth velocity weakens the effect of solute diffusion on the dendrite growth. In this case, the dendrites branch in the bunching form. The dendrite spacings were measured, and the results were interpreted with the current dendrite growth theories.

  7. Family Mode Deactivation Therapy Results and Implications

    ERIC Educational Resources Information Center

    Apsche, Jack A.; Bass, Christopher K.

    2006-01-01

    This article highlights the inclusion of Mode Deactivation Therapy as a treatment modality for families in crisis. As an empirically validated treatment, Mode Deactivation Therapy has been effective in treating a wide variety of psychological issues. Mode Deactivation Therapy, (MDT) was developed to treat adolescents with disorders of conduct…

  8. Nonlinear growth of strongly unstable tearing modes

    SciTech Connect

    Waelbroeck, F.L.

    1993-11-01

    Rutherford`s theory of the tearing instability is extended to cases where current nonlinearities are important, such as long wavelength modes in current slabs and the m = 1 instability in tokamaks with moderately large aspect-ratios. Of particular interest is the possibility that the associated magnetic islands, as a result of secondary instabilities, have a singular response to the Ohmic diffusion of the current. A family of islands is used to test this possibility; it is found that the response remains bounded.

  9. Subcritical crack growth in soda-lime glass in combined mode I and mode II loading

    NASA Technical Reports Server (NTRS)

    Singh, Dileep; Shetty, Dinesh K.

    1990-01-01

    Subcritical crack growth under mixed-mode loading was studied in soda-lime glass. Pure mode I, combined mode I and mode II, and pure mode II loadings were achieved in precracked disk specimens by loading in diametral compression at selected angles with respect to the symmetric radial crack. Crack growth was monitored by measuring the resistance changes in a microcircuit grid consisting of parallel, electrically conducting grid lines deposited on the surface of the disk specimens by photolithography. Subcritical crack growth rates in pure mode I, pure mode II, and combined mode I and mode II loading could be described by an exponential relationship between crack growth rate and an effective crack driving force derived from a mode I-mode II fracture toughness envelope. The effective crack driving force was based on an empirical representation of the noncoplanar strain energy release rate. Stress intensities for kinked cracks were assessed using the method of caustics and an initial decrease and a subsequent increase in the subcritical crack growth rates of kinked cracks were shown to correlate with the variations of the mode I and the mode II stress intensities.

  10. Mode 2 fatigue crack growth specimen development

    NASA Technical Reports Server (NTRS)

    Buzzard, R. J.; Gross, B.; Srawley, J. E.

    1983-01-01

    A Mode II test specimen was developed which has potential application in understanding phemonena associated with mixed mode fatigue failures in high performance aircraft engine bearing races. The attributes of the specimen are: it contains one single ended notch, which simplifiers data gathering and reduction; the fatigue crack grous in-line with the direction of load application; a single axis test machine is sufficient to perform testing; and the Mode I component is vanishingly small.

  11. Slow crack growth in glass in combined mode I and mode II loading

    NASA Technical Reports Server (NTRS)

    Shetty, D. K.; Rosenfield, A. R.

    1991-01-01

    Slow crack growth in soda-lime glass under combined mode I and mode II loading was investigated in precracked disk specimens in which pure mode I, pure mode II, and various combinations of mode I and mode II were achieved by loading in diametral compression at selected angles with respect to symmetric radial cracks. It is shown that slow crack growth under these conditions can be described by a simple exponential relationship with elastic strain energy release rate as the effective crack-driving force parameter. It is possible to interpret this equation in terms of theoretical models that treat subcritical crack growth as a thermally activated bond-rupture process with an activation energy dependent on the environment, and the elastic energy release rate as the crack-driving force parameter.

  12. Transport modes during crystal growth in a centrifuge

    NASA Technical Reports Server (NTRS)

    Arnold, William A.; Wilcox, William R.; Carlson, Frederick; Chait, Arnon; Regel', Liia L.

    1992-01-01

    Flow modes arising under average acceleration in centrifugal crystal growth, the gradient of acceleration, and the Coriolis force are investigated using a fully nonlinear three-dimensional numerical model for a centrifugal crystal growth experiment. The analysis focuses on an examination of the quasi-steady state flow modes. The importance of the gradient acceleration is determined by the value of a new nondimensional number, Ad.

  13. Saturation of the f -mode instability in neutron stars. II. Applications and results

    NASA Astrophysics Data System (ADS)

    Pnigouras, Pantelis; Kokkotas, Kostas D.

    2016-07-01

    We present the first results on the saturation of the f -mode instability in neutron stars due to nonlinear mode coupling. Emission of gravitational waves drives the f -mode (fundamental mode) unstable in fast-rotating, newborn neutron stars. The initial growth phase of the mode is followed by its saturation, because of energy leaking to other modes of the star. The saturation point determines the strain of the generated gravitational-wave signal, which can then be used to extract information about the neutron star's equation of state. The parent (unstable) mode couples via parametric resonances with pairs of daughter modes, with the triplets' evolution exhibiting a rich variety of behaviors. We study both supernova- and merger-derived neutron stars, simply modeled as polytropes in a Newtonian context, and show that the parent may couple to many different daughter pairs during the star's evolution through the instability window, with the saturation amplitude changing by orders of magnitude.

  14. Inducible growth mode switches influence Valonia rhizoid differentiation.

    PubMed

    Elvira, Paul Rommel; Sekida, Satoko; Okuda, Kazuo

    2013-02-01

    Cell differentiation and cell type commitment are an integral part of plant growth and development. Investigations on how environmental conditions affect the formation of shoots, roots, and rhizoids can help illustrate how plants determine cell fate and overall morphology. In this study, we evaluated the role of substratum and light on rhizoid differentiation in the coenocytic green alga, Valonia aegagropila. Elongating rhizoids displayed varying growth modes and cell shape upon exposure to different substrata and light conditions. It was found that soft substrata and dark incubation promoted rhizoid elongation via tip growth while subsequent exposure to light prevented tip growth and instead induced swelling in the apical region of rhizoids. Swelling was accompanied by the accumulation of protoplasm in the rhizoid tip through expansion of the cell wall and uninhibited cytoplasmic streaming. Subsequent diffuse growth led to the transformation from slender, rod-shaped rhizoids into spherical thallus-like structures that required photosynthesis. Further manipulation of light regimes caused vacillating cell growth redirections. An elongating V. aegagropila rhizoid cell thus appears capable of growth mode switching that is regulated by immediate environmental conditions thereby influencing ultimate cell shape and function. This is the first description of inducible, multiple growth mode shifts in a single intact plant cell that directly impact its differentiation.

  15. Growth of eccentric modes in disc-planet interactions

    NASA Astrophysics Data System (ADS)

    Teyssandier, Jean; Ogilvie, Gordon I.

    2016-05-01

    We formulate a set of linear equations that describe the behaviour of small eccentricities in a protoplanetary system consisting of a gaseous disc and a planet. Eccentricity propagates through the disc by means of pressure and self-gravity, and is exchanged with the planet via secular interactions. Excitation and damping of eccentricity can occur through Lindblad and corotation resonances, as well as viscosity. We compute normal modes of the coupled disc-planet system in the case of short-period giant planets orbiting inside an inner cavity, possibly carved by the stellar magnetosphere. Three-dimensional effects allow for a mode to be trapped in the inner parts of the disc. This mode can easily grow within the disc's lifetime. An eccentric mode dominated by the planet can also grow, although less rapidly. We compute the structure and growth rates of these modes and their dependence on the assumed properties of the disc.

  16. Experimental Investigation of m=1 Diocotron Mode Growth at Low Electron Densities

    SciTech Connect

    Stephen F. Paul; Kyle Morrison; Ronald C. Davidson

    2003-08-21

    Previous experiments on the Electron Diffusion Gauge showed that the diocotron mode damping increases with higher neutral gas filling pressure. Yet the energy dissipated from a rotating plasma by collisions with neutrals is predicted to excite the mode. To resolve this, experiments have been conducted to examine the coupling between expansion and the m=1 diocotron mode. Results from recent experiments have shown interesting phenomena: (1) The degree and sensitivity of mode growth is observed to be strongly dependent on filament conditions. Mode growth rates of nearly 20 sec{sup -1} have been observed even with negligible resistive drive. Specifically, at low filament bias voltages (and correspondingly low electron densities {approx}1-2 x 10{sup 7} electrons/cm), the mode growth is very sensitive to the heating voltage across the filament, even though changes in filament heating voltage barely affect the plasma expansion, the plasma density profile, the filament emission, or the resulting electron density. (2) At low neutral gas pressure (<10{sup -9} Torr), the diocotron mode growth rate increases with neutral pressure. However, the growth rate is several orders of magnitude larger than theoretical predictions.

  17. Growth modes of ZnO nanostructures from laser ablation

    NASA Astrophysics Data System (ADS)

    Amarilio-Burshtein, I.; Tamir, S.; Lifshitz, Y.

    2010-03-01

    ZnO nanowires (NWs) and other nanostructures were grown by laser ablation of a ZnO containing target onto different substrates with and without the presence of an Au catalyst. The morphology and structure of the NWs were studied using high resolution scanning and transmission electron microscopes [including imaging, selected area electron diffraction (SAED), and energy dispersive x-ray spectroscopy (EDS)]. The different growth modes obtainable could be tuned by varying the Zn concentration in the vapor phase keeping other growth parameters intact. Possible growth mechanisms of these nanowires are suggested and discussed.

  18. Characterization of Mode 1 and Mode 2 delamination growth and thresholds in graphite/peek composites

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.; Murri, Gretchen B.

    1988-01-01

    Composite materials often fail by delamination. The onset and growth of delamination in AS4/PEEK, a tough thermoplastic matrix composite, was characterized for mode 1 and mode 2 loadings, using the Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) test specimens. Delamination growth per fatigue cycle, da/dN, was related to strain energy release rate, G, by means of a power law. However, the exponents of these power laws were too large for them to be adequately used as a life prediction tool. A small error in the estimated applied loads could lead to large errors in the delamination growth rates. Hence strain energy release rate thresholds, G sub th, below which no delamination would occur were also measured. Mode 1 and 2 threshold G values for no delamination growth were found by monitoring the number of cycles to delamination onset in the DCB and ENF specimens. The maximum applied G for which no delamination growth had occurred until at least 1,000,000 cycles was considered the threshold strain energy release rate. Comments are given on how testing effects, facial interference or delamination front damage, may invalidate the experimental determination of the constants in the expression.

  19. Characterization of Mode I and Mode II delamination growth and thresholds in AS4/PEEK composites

    NASA Technical Reports Server (NTRS)

    Martin, Roderick H.; Murri, Gretchen Bostaph

    1990-01-01

    Composite materials often fail by delamination. The onset and growth of delamination in AS4/PEEK, a tough thermoplastic matrix composite, was characterized for mode 1 and mode 2 loadings, using the Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) test specimens. Delamination growth per fatigue cycle, da/dN, was related to strain energy release rate, G, by means of a power law. However, the exponents of these power laws were too large for them to be adequately used as a life prediction tool. A small error in the estimated applied loads could lead to large errors in the delamination growth rates. Hence strain energy release rate thresholds, G sub th, below which no delamination would occur were also measured. Mode 1 and 2 threshold G values for no delamination growth were found by monitoring the number of cycles to delamination onset in the DCB and ENF specimens. The maximum applied G for which no delamination growth had occurred until at least 1,000,000 cycles was considered the threshold strain energy release rate. Comments are given on how testing effects, facial interference or delamination front damage, may invalidate the experimental determination of the constants in the expression.

  20. Growth mode evolution of hafnium oxide by atomic layer deposition

    SciTech Connect

    Nie, Xianglong; Ma, Fei; Ma, Dayan; Xu, Kewei

    2014-01-15

    HfO{sub 2} thin films were deposited using tetrakis-ethylmethylamido hafnium and H{sub 2}O as precursors on silicon by atomic layer deposition (ALD). The morphology and microstructures at different ALD cycles were characterized by atomic force microscopy and high-resolution transmission electron microscopy. Based on the height–height correlation function and power spectral density function, quantitative analysis of surface morphologies was performed. Three characteristic dimensions (ξ{sub 1}, ξ{sub 2}, and ξ{sub 3}) corresponding to three surface structures, islands, local and global fluctuations, were identified. The evolution of ALD growth mode at range of the three critical scales was investigated, respectively. It suggests the transformation of growth mode from quasi two-dimensional layer-by-layer to three-dimensional island for global fluctuations.

  1. Results with a 32-element dual mode imager.

    SciTech Connect

    Cooper, Robert Lee; Gerling, Mark; Brennan, James S.; Mascarenhas, Nicholas; Mrowka, Stanley; Marleau, Peter

    2010-12-01

    We present advances with a 32 element scalable, segmented dual mode imager. Scaling up the number of cells results in a 1.4 increase in efficiency over a system we deployed last year. Variable plane separation has been incorporated which further improves the efficiency of the detector. By using 20 cm diameter cells we demonstrate that we could increase sensitivity by a factor of 6. We further demonstrate gamma ray imaging in from Compton scattering. This feature allows for powerful dual mode imaging. Selected results are presented that demonstrate these new capabilities.

  2. Results with a 32 element dual mode imager.

    SciTech Connect

    Cooper, Robert Lee; Gerling, Mark; Brennan, James S.; Mascarenhas, Nicholas; Mrowka, Stanley; Marleau, Peter

    2010-11-01

    We present advances with a 32 element scalable, segmented dual mode imager. Scaling up the number of cells results in a 1.4 increase in efficiency over a system we deployed last year. Variable plane separation has been incorporated which further improves the efficiency of the detector. By using 20 cm diameter cells we demonstrate that we could increase sensitivity by a factor of 6. We further demonstrate gamma ray imaging in from Compton scattering. This feature allows for powerful dual mode imaging. Selected results are presented that demonstrate these new capabilities.

  3. Single vesicle imaging indicates distinct modes of rapid membrane retrieval during nerve growth

    PubMed Central

    2012-01-01

    Background During nerve growth, cytoplasmic vesicles add new membrane preferentially to the growth cone located at the distal tip of extending axons. Growth cone membrane is also retrieved locally, and asymmetric retrieval facilitates membrane remodeling during growth cone repulsion by a chemorepellent gradient. Moreover, growth inhibitory factors can stimulate bulk membrane retrieval and induce growth cone collapse. Despite these functional insights, the processes mediating local membrane remodeling during axon extension remain poorly defined. Results To investigate the spatial and temporal dynamics of membrane retrieval in actively extending growth cones, we have used a transient labeling and optical recording method that can resolve single vesicle events. Live-cell confocal imaging revealed rapid membrane retrieval by distinct endocytic modes based on spatial distribution in Xenopus spinal neuron growth cones. These modes include endocytic "hot-spots" triggered at the base of filopodia, at the lateral margins of lamellipodia, and along dorsal ridges of the growth cone. Additionally, waves of endocytosis were induced when individual filopodia detached from the substrate and fused with the growth cone dorsal surface or with other filopodia. Vesicle formation at sites of membrane remodeling by self-contact required F-actin polymerization. Moreover, bulk membrane retrieval by macroendocytosis correlated positively with the substrate-dependent rate of axon extension and required the function of Rho-family GTPases. Conclusions This study provides insight into the dynamic membrane remodeling processes essential for nerve growth by identifying several distinct modes of rapid membrane retrieval in the growth cone during axon extension. We found that endocytic membrane retrieval is intensified at specific subdomains and may drive the dynamic membrane ruffling and re-absorption of filopodia and lamellipodia in actively extending growth cones. The findings offer a platform

  4. Designing of a Testing Machine for Shear-Mode Fatigue Crack Growth

    NASA Astrophysics Data System (ADS)

    Kusaba, A.; Okazaki, S.; Endo, M.; Yanase, K.

    As recognized, flaking-type failure is one of the serious problems for railroad tracks and bearings. In essence, flaking-type failure is closely related to the growth of the shear-mode (Mode-II and Mode-III) fatigue crack. In our research group, it is demonstrated that a shear-mode fatigue crack can be reproduced for cylindrical specimens by applying the cyclic torsion in the presence of the static axial compressive stress. However, a biaxial servo-hydraulic fatigue testing machine is quite expensive to purchase and costly to maintain. The low testing speed (about 10Hz) of the testing machine further aggravates the situation. As a result, study on shear-mode fatigue crack growth is still in the nascent stage. To overcome the difficulties mentioned above, in this research activity, we developed a high-performance and cost-effective testing machine to reproduce the shear-mode fatigue crack growth by improving the available resonance-type torsion fatigue testing machine. The primary advantage of using the resonance-type torsion fatigue testing machine is cost-efficiency. In addition, the testing speed effectively can be improved, in comparison with that of a biaxial servo-hydraulic fatigue testing machine. By utilizing the newly-designed testing machine, we have demonstrated that we can successfully reproduce the shear-mode fatigue crack.

  5. Sublimation growth of AlN crystals: Growth mode and structure evolution

    NASA Astrophysics Data System (ADS)

    Yakimova, R.; Kakanakova-Georgieva, A.; Yazdi, G. R.; Gueorguiev, G. K.; Syväjärvi, M.

    2005-07-01

    The aim of this study has been to realize growth conditions suitable for seeded sublimation growth of AlN and to understand the relationship between external growth parameters and the initial stages of growth with respect to growth mode and structure evolution. Close space sublimation growth geometry has been used in a RF-heated furnace employing high-purity graphite coated by TaC with a possibility to change the growth environment from C- to Ta-rich. Influence of certain impurities on the initially formed crystallites with respect to their shape, size and population has been considered. It is shown that some impurity containing vapor molecules may act as transport agents and suppliers of nitrogen for the AlN growth. SiC seeds, both bare and with MOCVD AlN buffer, have been employed. By varying the process conditions we have grown crystals with different habits, e.g. from needles, columnar- and plate-like, to freestanding quasi-bulk material. The growth temperature ranged 1600-2000 °C whereas the optimal external nitrogen pressure varied from 200 to 700 mbar. There is a narrow parameter window in the relationship temperature-pressure for the evolution of different structural forms. Growth modes with respect to process conditions are discussed.

  6. Fatigue crack growth behavior of an 8090 Al-Li alloy under mixed mode 1--mode 3 loading conditions

    SciTech Connect

    Kamat, S.V.; Prasad, N.E.

    1993-11-15

    Aluminum-lithium alloys have evoked considerable interest in recent years because of their high specific strengths and stiffness. An additional advantage of these alloys is their superior fatigue crack growth resistance as compared to the conventional aluminium alloys. However, most of the fatigue crack growth investigations have dealt with crack propagation behavior under mode 1 and loading. A recent study on monotonic fracture behavior of 8090 Al-Li alloys has shown that these alloys possess lower fracture toughness under mode 3 loading as compared to mode 1 loading. The fracture resistance under mixed mode 1 - mode 3 loading was also found to be lower than that under pure mode 1 loading. However, no experimental data is available on the mixed mode 1--mode 3 fatigue crack growth behavior in Al-Li alloys. The objective of the present paper is to study the effect of combined mode 1--mode 3 loading on the fatigue crack growth behavior of an 8090 Al-Li alloy.

  7. Subcritical crack growth under mode I, II, and III loading for Coconino sandstone

    NASA Astrophysics Data System (ADS)

    Ko, Tae Young

    In systems subjected to long-term loading, subcritical crack growth is the principal mechanism causing the time-dependent deformation and failure of rocks. Subcritical crack growth is environmentally-assisted crack growth, which can allow cracks to grow over a long period of time at stresses far smaller than their failure strength and at tectonic strain rates. The characteristics of subcritical crack growth can be described by a relationship between the stress intensity factor and the crack velocity. This study presents the results of studies conducted to validate the constant stress-rate test for determining subcritical crack growth parameters in Coconino sandstone, compared with the conventional testing method, the double torsion test. The results of the constant stress-rate test are in good agreement with the results of double torsion test. More importantly, the stress-rate tests can determine the parameter A with a much smaller standard deviation than the double torsion test. Thus the constant stress-rate test seems to be both a valid and preferred test method for determining the subcritical crack growth parameters in rocks. We investigated statistical aspects of the constant stress-rate test. The effects of the number of tests conducted on the subcritical crack growth parameters were examined and minimum specimen numbers were determined. The mean and standard deviation of the subcritical crack growth parameters were obtained by randomly selecting subsets from the original strength data. In addition, the distribution form of the subcritical crack growth parameters and the relation between the parameter n and A were determined. We extended the constant stress-rate test technique to modes II and III subcritical crack growth in rocks. The experimental results of the modes I, II and III tests show that the values of the subcritical crack growth parameters are similar to each other. The subcritical crack growth parameter n value for Coconino sandstone has the range

  8. Computational comparison of mediated current generation capacity of Chlamydomonas reinhardtii in photosynthetic and respiratory growth modes.

    PubMed

    Mao, Longfei; Verwoerd, Wynand S

    2014-11-01

    Chlamydomonas reinhardtii possesses many potential advantages to be exploited as a biocatalyst in microbial fuel cells (MFCs) for electricity generation. In the present study, we performed computational studies based on flux balance analysis (FBA) to probe the maximum potential of C. reinhardtii for current output and identify the metabolic mechanisms supporting a high current generation in three different cultivation conditions, i.e., heterotrophic, photoautotrophic and mixotrophic growth. The results showed that flux balance limitations allow the highest current output for C. reinhardtii in the mixotrophic growth mode (2.368 A/gDW), followed by heterotrophic growth (1.141 A/gDW) and photoautotrophic growth the lowest (0.7035 A/gDW). The significantly higher mediated electron transfer (MET) rate in the mixotrophic mode is in complete contrast to previous findings for a photosynthetic cyanobacterium, and was attributed to the fact that for C. reinhardtii the photophosphorylation improved the efficiency of converting the acetate into biomass and NADH production. Overall, the cytosolic NADH-dependent current production was mainly associated with five reactions in both mixotrophic and photoautotrophic nutritional modes, whereas four reactions participated in the heterotrophic mode. The mixotrophic and photoautotrophic metabolisms were alike and shared the same set of reactions for maximizing current production, whereas in the heterotrophic mode, the current production was additionally contributed by the metabolic activities in the two organelles: glyoxysome and chloroplast. In conclusion, C. reinhardtii has a potential to be exploited in MFCs of MET mode to produce a high current output. PMID:24875305

  9. Growth of nucleation mode particles in the summertime Arctic: a case study

    NASA Astrophysics Data System (ADS)

    Willis, Megan D.; Burkart, Julia; Thomas, Jennie L.; Köllner, Franziska; Schneider, Johannes; Bozem, Heiko; Hoor, Peter M.; Aliabadi, Amir A.; Schulz, Hannes; Herber, Andreas B.; Leaitch, W. Richard; Abbatt, Jonathan P. D.

    2016-06-01

    The summertime Arctic lower troposphere is a relatively pristine background aerosol environment dominated by nucleation and Aitken mode particles. Understanding the mechanisms that control the formation and growth of aerosol is crucial for our ability to predict cloud properties and therefore radiative balance and climate. We present an analysis of an aerosol growth event observed in the Canadian Arctic Archipelago during summer as part of the NETCARE project. Under stable and clean atmospheric conditions, with low inversion heights, carbon monoxide less than 80 ppbv, and black carbon less than 5 ng m-3, we observe growth of small particles, < 20 nm in diameter, into sizes above 50 nm. Aerosol growth was correlated with the presence of organic species, trimethylamine, and methanesulfonic acid (MSA) in particles ˜ 80 nm and larger, where the organics are similar to those previously observed in marine settings. MSA-to-sulfate ratios as high as 0.15 were observed during aerosol growth, suggesting an important marine influence. The organic-rich aerosol contributes significantly to particles active as cloud condensation nuclei (CCN, supersaturation = 0.6 %), which are elevated in concentration during aerosol growth above background levels of ˜ 100 to ˜ 220 cm-3. Results from this case study highlight the potential importance of secondary organic aerosol formation and its role in growing nucleation mode aerosol into CCN-active sizes in this remote marine environment.

  10. Strain-effect for controlled growth mode and well-ordered structure of quaterrylene thin films

    NASA Astrophysics Data System (ADS)

    Hayakawa, Ryoma; Turak, Ayse; Zhang, XueNa; Hiroshiba, Nobuya; Dosch, Helmut; Chikyow, Toyohiro; Wakayama, Yutaka

    2010-07-01

    We investigated the evolution of quaterrylene thin films on SiO2 and on an octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) to examine the impact of film strains on the growth processes and evolving structure. Surface modification by SAMs allowed tailoring of the growth process from a Stranski-Krastanov (SK) mode (layer-plus-island) on the SiO2 surface to a Frank-van der Merwe mode (layer-by-layer) on the OTS surface. Detailed structural analysis by x-ray diffraction techniques confirmed that the SK mode was driven by lattice strain in the initial wetting layers on the SiO2 surface. On the other hand, strain-free wetting layers were already formed at the beginning of growth on the OTS surface, thereby suppressing three-dimensional island formation. Moreover, the films on the SiO2 surface were found to incorporate high microstrain induced by crystal defects such as dislocations and a mosaic structure. In contrast, few crystal defects were present in the films on OTS surface, demonstrating that OTS treatment enables marked improvement of the molecular alignment. These results clearly indicate that the lattice strain induced by the molecular-substrate interaction is essential for controlling the overall growth process.

  11. Growth mode and structures of magnetic Mn clusters on graphene

    DOE PAGESBeta

    Liu, Xiaojie; Wang, Cai-Zhuang

    2016-06-22

    We present a systematic study of Mn clusters on graphene by first-principles calculations. We show that the growth of Mn on graphene follows a three-dimensional (3D) mode. Both adsorption and attachment energies show that (Mn)3 and (Mn)6 on graphene are energetically favorable in the size range (Mn)1-7. Moreover, larger formation energy for Mn cluster on graphene implies the incoming Mn atoms are likely to nucleate and grow into bigger and bigger Mn clusters on graphene. The magnetic moments of (Mn)1,5,7 on graphene are enhanced by 11%, 186%, and 26% from their values at free-standing clusters, respectively. By contrast, the netmore » magnetic moment of (Mn)2,3,4,6 on graphene is reduced from that of the corresponding free-standing clusters. The origin of the magnetic moment changes can be attributed to the charge transfer within the Mn clusters and between the clusters and graphene upon adsorption.« less

  12. InAs nanowire growth modes on Si (111) by gas source molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Robson, M. T.; LaPierre, R. R.

    2016-02-01

    InAs nanowires (NWs) were grown on silicon substrates by gas source molecular beam epitaxy using five different growth modes: (1) Au-assisted growth, (2) positioned (patterned) Au-assisted growth, (3) Au-free growth, (4) positioned Au-assisted growth using a patterned oxide mask, and (5) Au-free selective-area epitaxy (SAE) using a patterned oxide mask. Optimal growth conditions (temperature, V/III flux ratio) were identified for each growth mode for control of NW morphology and vertical NW yield. The highest yield (72%) was achieved with the SAE method at a growth temperature of 440 °C and a V/III flux ratio of 4. Growth mechanisms are discussed for each of the growth modes.

  13. Effect of adherend thickness and mixed mode loading on debond growth in adhesively bonded composite joints

    NASA Technical Reports Server (NTRS)

    Mangalgiri, P. D.; Johnson, W. S.; Everett, R. A., Jr.

    1986-01-01

    Symmetric and unsymmetric double cantilever beam (DCB) specimens were tested and analyzed to assess the effect of: (1) adherend thickness, and (2) a predominantly mode I mixed mode loading on cyclic debond growth and static fracture toughness. The specimens were made of unidirectional composite (T300/5208) adherends bonded together with EC3445 structural adhesive. The thickness was 8, 16, or 24 plies. The experimental results indicated that the static fracture toughness increases and the cyclic debond growth rate decreases with increasing adherend thickness. This behavior was related to the length of the plastic zone ahead of the debond tip. For the symmetric DCB specimens, it was further found that displacement control tests resulted in higher debond growth rates than did load control tests. While the symmetric DCB tests always resulted in cohesive failures in the bondline, the unsymmetric DCB tests resulted in the debond growing into the thinner adherend and the damage progressing as delamination in that adherend. This behavior resulted in much lower fracture toughness and damage growth rates than found in the symmetric DCB tests.

  14. Onset of nonlinear saturation for Rayleigh-Taylor growth in the presence of a full spectrum of modes

    NASA Astrophysics Data System (ADS)

    Haan, Steven W.

    1989-06-01

    It is generally recognized that a single Rayleigh-Taylor unstable mode grows exponentially, proportional to the initial amplitude, until the amplitude is about (1/10 to (1/5 of the wavelength. The growth then becomes nonlinear, and the mode evolves into spikes and bubbles. This paper considers how this picture of the transition to nonlinearity changes when, instead of there being a single mode, there is a full spectrum of modes. We argue that nonlinear behavior begins whenever the sum of modes over a specified small region of k space becomes comparable to the wavelength. In the case of a single mode, this reduces to the usual comparison of the mode's amplitude with its wavelength λ. But if the modal amplitudes are smooth functions of k, the modes begin to saturate when their amplitude is comparable to λ2/R times a dimensionless scale factor; here, R is the radius in spherical geometry, or the length of the surface in planar geometry. Given this new notion of the amplitude at which nonlinear saturation begins, we construct a simple model to estimate the net perturbation resulting from a broadband initial spectrum. We assume that modes grow exponentially until saturation occurs, and then the growth of the individual modes becomes linear in time. The model predictions in two and three dimensions are compared with Read and Young's experiments [Atomic Weapons Research Establishment Report No. 011/83, Aldermasten, 1983 (unpublished)], and to Youngs's calculations [Physica 12D, 32 (1984)]. The experimental results are used to set the single parameter characterizing the onset of nonlinearity. The model provides a complete description of a weak dependence on initial amplitude. The model can be easily extended to any situation for which one can estimate single-mode growths; results are presented regarding effects on multimode growth of spherical geometry, ablation stabilization, and interface coupling.

  15. The growth of the tearing mode - Boundary and scaling effects

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.; Van Hoven, G.

    1983-01-01

    A numerical model of resistive magnetic tearing is developed in order to verify and relate the results of the principal approximations used in analytic analyses and to investigate the solutions and their growth-rate scalings over a large range of primary parameters which include parametric values applicable to the solar atmosphere. The computations cover the linear behavior for a variety of boundary conditions, emphasizing effects which differentiate magnetic tearing in astrophysical situations from that in laboratory devices. Eigenfunction profiles for long and short wavelengths are computed and the applicability of the 'constant psi' approximation is investigated. The growth rate is computed for values of the magnetic Reynolds number up to a trillion and of the dimensionless wavelength parameter down to 0.001. The analysis predicts significant effects due to differing values of the magnetic Reynolds number.

  16. Development and Application of Benchmark Examples for Mode II Static Delamination Propagation and Fatigue Growth Predictions

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald

    2011-01-01

    The development of benchmark examples for static delamination propagation and cyclic delamination onset and growth prediction is presented and demonstrated for a commercial code. The example is based on a finite element model of an End-Notched Flexure (ENF) specimen. The example is independent of the analysis software used and allows the assessment of the automated delamination propagation, onset and growth prediction capabilities in commercial finite element codes based on the virtual crack closure technique (VCCT). First, static benchmark examples were created for the specimen. Second, based on the static results, benchmark examples for cyclic delamination growth were created. Third, the load-displacement relationship from a propagation analysis and the benchmark results were compared, and good agreement could be achieved by selecting the appropriate input parameters. Fourth, starting from an initially straight front, the delamination was allowed to grow under cyclic loading. The number of cycles to delamination onset and the number of cycles during delamination growth for each growth increment were obtained from the automated analysis and compared to the benchmark examples. Again, good agreement between the results obtained from the growth analysis and the benchmark results could be achieved by selecting the appropriate input parameters. The benchmarking procedure proved valuable by highlighting the issues associated with choosing the input parameters of the particular implementation. Selecting the appropriate input parameters, however, was not straightforward and often required an iterative procedure. Overall the results are encouraging, but further assessment for mixed-mode delamination is required.

  17. HIGH-MODE RAYLEIGH-TAYLOR GROWTH IN NIF IGNITION CAPSULES

    SciTech Connect

    Hammel, B A; Haan, S W; Clark, D; Edwards, M J; Langer, S H; Marinak, M; Patel, M; Salmonson, J; Scott, H A

    2009-08-04

    An assessment of short wavelength hydrodynamic stability is an essential component in the optimization of NIF ignition target designs. Using highly-resolved massively-parallel 2-D Hydra simulations, we routinely evaluate target designs up to mode numbers of 2000 ({lambda} {approx} 2 {micro}m). On the outer ablator surface, mode numbers up to {approx}300 ({lambda} {approx} 20 {micro}m) can have significant growth in CH capsule designs. At the internal fuel:ablator interface mode numbers up to {approx}2000 are important for both CH and Be designs. In addition, 'isolated features' on the capsule, such as the 'fill-tube' ({approx} 5 {micro}m scale-length) and defects, can seed short wavelength growth at the ablation front and the fuel:ablator interface, leading to the injection of {approx} 10's ng of ablator material into the central hot-spot. We are developing methods to measure high-mode mix on NIF implosion experiments. X-ray spectroscopic methods are appealing since mix into the hot-spot will result in x-ray emission from the high-Z dopant (Cu or Ge) in the ablator material (Be or CH).

  18. The propagation and growth of whistler mode waves generated by electron beams in earth's bow shock

    NASA Technical Reports Server (NTRS)

    Tokar, R. L.; Gurnett, D. A.

    1985-01-01

    In this study, the propagation and growth of whistler mode waves generated by electron beams within earth's bow shock is investigated using a planar model for the bow shock and a model electron distribution function. Within the shock, the model electron distribution function possesses a field-aligned T greater than T beam that is directed toward the magnetosheath. Waves with frequencies between about 1 and 100 Hz with a wide range of wave normal angles are generated by the beam via Landau and anomalous cyclotron resonances. However, because the growth rate is small and because the wave packets traverse the shock quickly, these waves do not attain large amplitudes. Waves with frequencies between about 30 and 150 Hz with a wide range of wave normal angles are generated by the beam via the normal cyclotron resonance. The ray paths for most of these waves are directed toward the solar wind although some wave packets, due to plasma convection travel transverse to the shock normal. These wave packets grow to large amplitudes because they spend a long time in the growth region. The results suggest that whistler mode noise within the shock should increase in amplitude with increasing upstream theta sub Bn. The study provides an explanation for the origin of much of the whistler mode turbulence observed at the bow shock.

  19. Phase diagram of growth mode for the SiGe/Si heterostructure system with misfit dislocations

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo; Ujihara, Toru; Usami, Noritaka; Fujiwara, Kozo; Sazaki, Gen; Shishido, Toetsu

    2004-01-01

    The strain, surface and interface energies of the SiGe/Si (SiGe grown on Si) heterostructure system with and without misfit dislocations were calculated for the Frank-van der Merwe (FM), Stranski-Krastanov (SK) and Volmer-Weber (VW) growth modes essentially based on the three kinds of fundamental and simple structures. The free energies for each growth mode were derived from these energies, and it was determined as a function of the composition and layer thickness of SiGe on Si. By comparison of the free energies, the phase diagrams of the FM, SK and VW growth modes for the SiGe/Si system were determined. The (1 1 1) and (1 0 0) reconstructed surfaces were selected for this calculation. From the phase diagrams, it was found for the growth of SiGe on Si that the layer-by-layer growth such as the FM mode was easy to be obtained when the Ge composition is small, and the island growth on a wetting layer such as the SK mode was easy to be obtained when the Ge composition is large. The VW mode is energetically stable in the Ge-rich compositional range, but it is difficult for the VW mode to appear in the actual growth of SiGe on Si because the VW region is right above the SK region. The regions of the SK and VW modes for the (1 1 1) heterostructure are larger than those for the (1 0 0) one because the strain energy of the (1 1 1) face is larger than that of the (1 0 0) face. The regions of the SK and VW modes for the heterostructure with misfit dislocations are narrower than those for the one without misfit dislocations because the strain energy is much released by misfit dislocations. The phase diagrams roughly explain the behavior of the FM and SK growth modes of SiGe on Si.

  20. Influence of Mixed Mode I-Mode II Loading on Fatigue Delamination Growth Characteristics of a Graphite Epoxy Tape Laminate

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Johnston, William M., Jr.

    2014-01-01

    Mixed mode I-mode II interlaminar tests were conducted on IM7/8552 tape laminates using the mixed-mode bending test. Three mixed mode ratios, G(sub II)/G(sub T) = 0.2, 0.5, and 0.8, were considered. Tests were performed at all three mixed-mode ratios under quasi-static and cyclic loading conditions, where the former static tests were used to determine initial loading levels for the latter fatigue tests. Fatigue tests at each mixed-mode ratio were performed at four loading levels, Gmax, equal to 0.5G(sub c), 0.4G(sub c), 0.3G(sub c), and 0.2G(sub c), where G(sub c) is the interlaminar fracture toughness of the corresponding mixed-mode ratio at which a test was performed. All fatigue tests were performed using constant-amplitude load control and delamination growth was automatically documented using compliance solutions obtained from the corresponding quasi-static tests. Static fracture toughness data yielded a mixed-mode delamination criterion that exhibited monotonic increase in Gc with mixed-mode ratio, G(sub II)/G(sub T). Fatigue delamination onset parameters varied monotonically with G(sub II)/G(sub T), which was expected based on the fracture toughness data. Analysis of non-normalized data yielded a monotonic change in Paris law exponent with mode ratio. This was not the case when normalized data were analyzed. Fatigue data normalized by the static R-curve were most affected in specimens tested at G(sub II)/G(sub T)=0.2 (this process has little influence on the other data). In this case, the normalized data yielded a higher delamination growth rate compared to the raw data for a given loading level. Overall, fiber bridging appeared to be the dominant mechanism, affecting delamination growth rates in specimens tested at different load levels and differing mixed-mode ratios.

  1. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    SciTech Connect

    Knauer, J. P.; Verdon, C. P.; Meyerhofer, D. D.; Boehly, T. R.; Bradley, D. K.; Smalyuk, V. A.; Ofer, D.; McKenty, P. W.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.; Gobby, P. L.; Willi, O.; Taylor, R. J.

    1997-04-15

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600-{mu}m-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam.

  2. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    SciTech Connect

    Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.; Boehly, T.R.; Bradley, D.K.; Smalyuk, V.A.; Ofer, D.; McKenty, P.W.; Glendinning, S.G.; Kalantar, D.H.; Watt, R.G.; Gobby, P.L.; Willi, O.; Taylor, R.J.

    1997-04-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5{times}10{sup 14}W/cm{sup 2}. Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4{percent}{endash}7{percent} over a 600-{mu}m-diam region defined by the 90{percent} intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with {ital ORCHID} simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam. {copyright} {ital 1997 American Institute of Physics.}

  3. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Verdon, C. P.; Meyerhofer, D. D.; Boehly, T. R.; Bradley, D. K.; Smalyuk, V. A.; Ofer, D.; McKenty, P. W.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.; Gobby, P. L.; Willi, O.; Taylor, R. J.

    1997-04-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5×1014W/cm2. Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600-μm-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-μm and 60-μm wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-μm-thick polystyrene foam buffer layer resulted in reduced growth of the 31-μm perturbation and essentially unchanged growth for the 60-μm case when compared to targets without foam.

  4. Extending non-fatigue Mode I subcritical crack growth data to subcritical fatigue crack growth: Demonstration of the equivalence of the Charles' law and Paris law exponents

    NASA Astrophysics Data System (ADS)

    Keanini, Russell; Eppes, Martha-Cary

    2016-04-01

    Paris's law connects fatigue-induced subcritical crack growth and fatigue loading. Environmentally-driven subcritical crack growth, while a random process, can be decomposed into a spectrum of cyclic processes, where each spectral component is governed by Paris's law. Unfortunately, almost no data exists concerning the Paris law exponent, m; rather, the great majority of existing sub-critical crack growth measurements on rock have been carried out via Mode I tensile tests, where corresponding data are generally correlated using Charles' law, and where the latter, similar to Paris's law, exposes a power law relationship between crack growth rate and stress intensity. In this study, a statistical argument is used to derive a simple, rigorous relationship between the all-important Paris law and Charles law exponents, m and n. This result has a significant practical implication: subcritical fatigue crack growth in rock, driven by various random environmental weathering processes can now be predicted using available Mode I stress corrosion indices, n.

  5. Mixed-mode fatigue-crack growth thresholds in Ti-6Al-4V at high frequency

    SciTech Connect

    Campbell, J.P.; Ritchie, R.O.

    1999-10-22

    Multiaxial loading conditions exist at fatigue-critical locations within turbine engine components, particularly in association with fretting fatigue in the blade dovetail/disk contact section. For fatigue-crack growth in such situations, the resultant crack-driving force is a combination of the influence of a mode I (tensile opening) stress-intensity range, {Delta}K{sub I}, as well as mode II (in-plane shear) and/or mode III (anti-plane shear) stress-intensity ranges, {Delta}K{sub II} and {Delta}K{sub III}, respectively. For the case of the high-cycle fatigue of turbine-engine alloys, it is critical to quantify such behavior, as the extremely high cyclic loading frequencies ({approximately}1--2 kHz) and correspondingly short times to failure may necessitate a design approached based on the fatigue-crack growth threshold. Moreover, knowledge of such thresholds is required for accurate prediction of fretting fatigue failures. Accordingly, this paper presents the mixed-mode fatigue crack growth thresholds for mode I + II loading (phase angles from 0{degree} to 82{degree}) in a Ti-6Al-4V blade alloy. These results indicate that when fatigue-crack growth in this alloy is characterized in terms of the crack-driving force {Delta}G, which incorporates both the applied tensile and shear loading, the mode 1 fatigue-crack growth threshold is a lower bound (worst case) with respect to mixed-mode (I + II) crack-growth behavior.

  6. The essential features and modes of bacterial polar growth.

    PubMed

    Cameron, Todd A; Zupan, John R; Zambryski, Patricia C

    2015-06-01

    Polar growth represents a surprising departure from the canonical dispersed cell growth model. However, we know relatively little of the underlying mechanisms governing polar growth or the requisite suite of factors that direct polar growth. Underscoring how classic doctrine can be turned on its head, the peptidoglycan layer of polar-growing bacteria features unusual crosslinks and in some species the quintessential cell division proteins FtsA and FtsZ are recruited to the growing poles. Remarkably, numerous medically important pathogens utilize polar growth, accentuating the need for intensive research in this area. Here we review models of polar growth in bacteria based on recent research in the Actinomycetales and Rhizobiales, with emphasis on Mycobacterium and Agrobacterium species.

  7. Heteroepitaxial growth modes with dislocations in a two-dimensional elastic lattice model

    NASA Astrophysics Data System (ADS)

    Katsuno, Hiroyasu; Uwaha, Makio; Saito, Yukio

    2008-11-01

    We study equilibrium shapes of adsorbate crystals by allowing a possibility of dislocations on an elastic substrate in a two-dimensional lattice model. The ground state energy is calculated numerically with the use of an elastic lattice Green's function. From the equilibrium shapes determined for various coverages, we infer the growth mode. As the misfit parameter increases, the growth mode changes from the Frank-van der Merwe (FM) to the Stranski-Krastanov (SK), further to the FM with dislocations for a parameter range of ordinary semiconductor materials. Conceivable growth modes such as the SK with dislocations appear in a parameter range between the SK and the FM with dislocations.

  8. Surface Structure and Growth Mode of Pd Deposited on Mo(110) Surface

    NASA Astrophysics Data System (ADS)

    Maehara, Y.; Kawanowa, H.; Gotoh, Y.

    The surface structure and growth mode of Pd/Mo(110) have been studied using reflection high energy electron diffraction (RHEED). The surface diagram of Pd on the Mo(110) substrate for deposition thickness versus substrate temperature was obtained. Four kinds of surface structures, namely α1, α2, β and γ, were observed. At less than 1 ML, α2 appeared in temperatures ranging from 400 to 1050°C and α1 appeared from RT to 400°C. α2 has a structure intermediate between those of Pd(111) and Mo(110), in which the dense direction of the layer is parallel to the [111]Mo orientation and their atomic row distances are coincident, resulting in formation of a long-period structure with a Mo surface, namely a coincident site lattice. The α1 structure is similar to the 1 × 1 structure. At more than 1.0 ML, β and γ structures appeared simultaneously in the temperature region from 500 to 950°C. However, at a high temperature region from 950 to 1050°C, the α2 structure was observed. β shows a one-dimensional ordered structure, in which Pd atoms line along [111]Mo. γ exhibits a 3 × 1 structure with the same atomic arrangement as the Mo(110) plane rotated at 70.5°. At greater than 2.0 ML, the Pd film grows in the Frank van der Merwe growth mode at a low temperature with accumulation of a Pd(111) layer, and in the Stranski Krastanov growth mode at a high temperature with two-dimensional growth of the γ structure followed by formation of flat crystallites.

  9. Growth mode and structures of silicene on the Ag(1 1 1) surface

    NASA Astrophysics Data System (ADS)

    Lee, Guo-Wei; Chen, Han-De; Lin, Deng-Sung

    2015-11-01

    Low-temperature scanning tunneling microscopy (LT-STM) and ab initio density functional theory (DFT) calculations have been utilized to explore the growth processes and atomic structure of silicene on the Ag(1 1 1) surface. STM images reveal an etching growth mode in the sub-monolayer range. The results confirm the existence of various overlayer structures reported previously and that the lattice parameters of several overlayer structures at sub-monolayer coverages are close to the corresponding substrate supercells. However, detailed analysis of domain boundaries and Moiré-like superstructure in the STM images strongly suggest that the overlayer structures and the substrate lattices have no coincident relationships. Preliminary results of DFT calculations show that the changes in total energy upon translational displacement of the (3 × 3)Si silicene supercells with respect to the Ag(1 1 1) lattice is within a few tens of meV/Si atom.

  10. Horizon instability of extremal Kerr black holes: Nonaxisymmetric modes and enhanced growth rate

    NASA Astrophysics Data System (ADS)

    Casals, Marc; Gralla, Samuel E.; Zimmerman, Peter

    2016-09-01

    We show that the horizon instability of the extremal Kerr black hole is associated with a singular branch point in the Green function at the superradiant bound frequency. We study generic initial data supported away from the horizon and find an enhanced growth rate due to nonaxisymmetric modes. The growth is controlled by the conformal weight h of each mode. We speculate on connections to near-extremal black holes and holographic duality.

  11. Characterization of debond growth mechanism in adhesively bonded composites under mode II static and fatigue loadings

    NASA Technical Reports Server (NTRS)

    Mall, S.; Kochhar, N. K.

    1988-01-01

    An experimental investigation of adhesively bonded composite joint was conducted to characterize the debond growth mechanism under mode II static and fatigue loadings. For this purpose, end-notched flexure specimens of graphite/epoxy (T300/5208) adherends bonded with EC 3445 adhesive were tested. In all specimen tested, the fatigue failure occurred in the form of cyclic debonding. The present study confirmed the result of previous studies that total strain-energy-release rate is the driving parameter for cyclic debonding. Further, the debond growth resistance under cyclic loading with full shear reversal (i.e., stress ratio, R = -1) is drastically reduced in comparison to the case when subjected to cyclic shear loading with no shear reversal (i.e., R = 0.1).

  12. Antibiotic growth promoters in agriculture: history and mode of action.

    PubMed

    Dibner, J J; Richards, J D

    2005-04-01

    This report will review the history of antibiotic growth promoter (AGP) use in the animal industry, concerns about development of antimicrobial resistance, and response in the European Union and United States to these concerns. A brief description of the history of legislation regarding feed use of antimicrobials in Denmark and the experience of animal producers following the 1998 ban will serve to illustrate the consequences on animal performance and health of withdrawing the approval for this use. The biological basis for antibiotic effects on animal growth efficiency will consider effects on intestinal microbiota and effects on the host animal and will use the germ-free animal to illustrate effects of the conventional microflora. The probability that no single compound will replace all of the functions of antimicrobial growth promoters will be considered, and methods to consolidate and analyze the enlarging database will be discussed. PMID:15844822

  13. Growth Mode Transition in Complex Oxide Heteroepitaxy: Atomically Resolved Studies

    DOE PAGESBeta

    Tselev, Alexander; Vasudevan, Rama K.; Gianfrancesco, Anthony G.; Qiao, Liang; Meyer, Tricia L.; Lee, Ho Nyung; Biegalski, Michael D.; Baddorf, Arthur P.; Kalinin, Sergei V.

    2016-04-04

    Here we performed investigations of the atomic-scale surface structure of epitaxial La5/8Ca3/8MnO3 thin films as a model system dependent on growth conditions in pulsed laser deposition with emphasis on film growth kinetics. Postdeposition in situ scanning tunneling microscopy was combined with in operando reflective high-energy electron diffraction to monitor the film growth and ex situ X-ray diffraction for structural analysis. We find a correlation between the out-of-plane lattice parameter and both adspecies mobility and height of the Ehrlich–Schwoebel barrier, with mobility of adatoms greater over the cationically stoichiometric terminations. We find that the data suggest that the out-of-plane lattice parametermore » is dependent on the mechanism of epitaxial strain relaxation, which is controlled by the oxidative power of the deposition environment.« less

  14. Control of growth mode of multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Quang, Nguyen Hong; Kim, Do-Hyung

    2009-09-01

    We have conducted an experimental study to investigate the synthesis of multi-walled carbon nanotubes (CNTs) by a dc plasma-enhanced chemical vapour deposition (PECVD) technique. The synthesis of base and tip-type of CNTs was selectively controlled by changing the catalyst size, catalyst film thickness correlated with altering the NH3 pretreatment plasma current. These types of CNT showed distinctive properties in nanotube structure, growth rate and vertical alignment, which were confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and in situ optical interference measurement. The vertically aligned behaviour of CNT was systematically studied by using a fine-patterned catalyst layer with diverse critical dimensions. Freestanding single CNT was successfully realized by optimum tip-type CNT growth, conventional photolithography and wet-etch process.

  15. Factors influencing the temporal growth rate of the high order TM0n modes in the Ka-band overmoded Cherenkov oscillator

    NASA Astrophysics Data System (ADS)

    Wu, Dapeng; Shu, Ting; Ju, Jinchuan

    2015-06-01

    When the wavelength of overmoded Cherenkov oscillator goes into Ka-band, power handling capacity becomes an essential issue. Using the TM02 mode or higher order TM0n modes as the operating mode is a potential solution. This paper is aimed to find some proper parameters to make the temporal growth rate of the TM02 mode higher in our previously studied Gigawatt (GW)-class Ka band oscillator. An accurate and fast calculation method of the "hot" dispersion equation is derived for rectangular corrugated SWSs, which are widely used in the high frequency Cherenkov devices. Then, factors that affect the temporal growth rate of the high order TM0n modes are analyzed, including the depth of corrugation, the radius of drift tube, and the diode voltage. Results show that, when parameters are chosen properly, the temporal growth rate of the TM02 mode can be as high as 0.3 ns-1.

  16. [Relationship between SO2 exposure mode and Chinese pine growth].

    PubMed

    Tang, Hong-shou; Aoki, Masatoshi; Totsuka, Tsumugu

    2005-01-01

    Chinese pine seedling, which age is 87 days, are exposed to SO2 in three treatments for 60 days from July 1, 2002 to August 29, 2002. In treatment 1 and treatment 2, the concentration of SO2 were 0.1 mg x m(-3) and 0.2 mg x m(-3), respectively. In treatment 3, the concentration of SO2 were 0.5 mg x m(-3) for 6 hours and 0.1 mg x m(-3) for 18 hours per day. In treatment 1, the abnormity of stomata guard cell and leaf colour are not observed. There are no significant difference of chlorophyll content, carotenoid content of leaf, photosynthetic rate, transpiration rate, relative growth rate, and dry weight per plant compare with control, but the sulfur content of leaf increased 17% compare with control, the amount of potassium ion leaching from leaf increased 22% compare with control. In treatment 2, the abnormity of stomata guard cell and leaf colour are not observed. There are no significant difference of chlorophyll content, photosynthetic rate and transpiration rate compare with control. But compare with control, the carotenoid content of leaf decreased 5%, and the sulfur content of leaf increased 92%, the amount of potassium ion leaching from leaf increased 67%, dry weight decreased 4.5% per plant, the relative growth rate decreased 0.6 mg x(gxd)-1. In treatment 3, the abnormity of stomata guard cell and leaf colour are observed. The chlorophyll content were similar with control, but compare with control, the carotenoid content of leaf decreased 21%, and the sulfur content of leaf increased 104%, the amount of potassium ion leaching from leaf increased 89%, photosynthetic rate decreased 5%, transpiration rate increased 8%, the dry weight decreased 7.6% per plant, the relative growth rate decreased 1.3mg x (gxd)-1.

  17. Mixed mode fatigue crack growth in the commercial Al-Li alloys, 8090

    SciTech Connect

    Sinclair, I.; Gregson, P.J. . Dept. of Engineering Materials)

    1994-05-15

    Crystallographic fatigue crack propagation along planar slip bands has been recognized to occur over a particularly wide range of conditions in Al-Li alloys due to the presence of coherent, shearable [delta][prime] (Al[sub 3]Li) precipitates, in conjunction with the strong underlying crystallographic texture often developed in these materials during secondary processing. Such Stage 1 propagation typically produces a highly tortuous crack path during conventional mode 1 fatigue testing. While the net crack growth direction remains parallel to the nominal mode 1 direction, crack tortuosity has been generally recognized as beneficial to fatigue resistance, as both local mixed mode crack-tip loading conditions and roughness induced closure may significantly reduce the driving force for crack extension (i.e. crack shielding'' occurs). Recent investigations of commercial Al-Li plate in the damage tolerant condition have however shown that co-planar Stage 1 crack propagation along preferred [111]-plane orientations may give rise to sustained macroscopic crack deviation from the nominal mode 1 growth direction. Such crack growth raises a number of important questions with regard to conventional, nominally mode 1 based structure lifting and fatigue testing methods when applied to these materials. Work has therefore been carried out to characterized fatigue crack growth during sustained co-planar Stage 1 propagation in a commercial Al-Li alloy, with particular reference to mixed mode loading conditions.

  18. Fracture mode analysis and related surface deformation during dyke intrusion: Results from 2D experimental modelling

    NASA Astrophysics Data System (ADS)

    Abdelmalak, M.; Mourgues, R.; Bureau, D.

    2012-04-01

    The analysis of surface deformation in response to approaching intrusion is important for assessing volcanic hazards. In this paper, we present results from 2D scaled models of magma intrusion, in which we discuss the propagation mode and related surface deformation during dyke growth. Our experiments consist in the injection of analogue magma (Golden syrup) into cohesive fine-grained silica powder, simulating the brittle upper crust. Using an optical image correlation technique (Particle Imaging Velocimetry), we were able to follow the surface deformation, the displacements within the country rock and to calculate strains induced by the magma emplacement. We identified two kinds of intrusion morphologies resulting from different interactions between the dyke and plastic deformations occurring in the country rock near the surface. In both morphologies, the dyke is vertical at depth. Our analysis demonstrates that both hydraulic tensile opening and shear-related propagation operate during this first stage of vertical growth. At the same time, the surface lifted up and formed a smooth symmetrical dome. Both types of morphologies differ in the upper part. During a second stage of evolution, the first type of intrusion inclined at a dip between 45 to 65°. This inclination is not caused by shear deformations and is attributed to stress rotation near the tip. Closer to the surface, the growth of the inclined sheet creates shear bands which conduct the fluid toward the surface. The surface uplift becomes asymmetric. The second type of intrusion does not rotate at depth and continues its vertical propagation by catching vertical tensile cracks. The intrusion of magma in these cracks creates horizontal stresses which are responsible for the closure of fractures and the formation of reverse faults. At the surface the dome remains symmetrical. For both intrusions, the surface uplift accelerates during the second stage and it is strongly influenced by the presence or the

  19. Fuzzy-logic-based hybrid locomotion mode classification for an active pelvis orthosis: Preliminary results.

    PubMed

    Yuan, Kebin; Parri, Andrea; Yan, Tingfang; Wang, Long; Munih, Marko; Vitiello, Nicola; Wang, Qining

    2015-01-01

    In this paper, we present a fuzzy-logic-based hybrid locomotion mode classification method for an active pelvis orthosis. Locomotion information measured by the onboard hip joint angle sensors and the pressure insoles is used to classify five locomotion modes, including two static modes (sitting, standing still), and three dynamic modes (level-ground walking, ascending stairs, and descending stairs). The proposed method classifies these two kinds of modes first by monitoring the variation of the relative hip joint angle between the two legs within a specific period. Static states are then classified by the time-based absolute hip joint angle. As for dynamic modes, a fuzzy-logic based method is proposed for the classification. Preliminary experimental results with three able-bodied subjects achieve an off-line classification accuracy higher than 99.49%.

  20. Fuzzy-logic-based hybrid locomotion mode classification for an active pelvis orthosis: Preliminary results.

    PubMed

    Yuan, Kebin; Parri, Andrea; Yan, Tingfang; Wang, Long; Munih, Marko; Vitiello, Nicola; Wang, Qining

    2015-01-01

    In this paper, we present a fuzzy-logic-based hybrid locomotion mode classification method for an active pelvis orthosis. Locomotion information measured by the onboard hip joint angle sensors and the pressure insoles is used to classify five locomotion modes, including two static modes (sitting, standing still), and three dynamic modes (level-ground walking, ascending stairs, and descending stairs). The proposed method classifies these two kinds of modes first by monitoring the variation of the relative hip joint angle between the two legs within a specific period. Static states are then classified by the time-based absolute hip joint angle. As for dynamic modes, a fuzzy-logic based method is proposed for the classification. Preliminary experimental results with three able-bodied subjects achieve an off-line classification accuracy higher than 99.49%. PMID:26737144

  1. New insights into the generalized Rutherford equation for nonlinear neoclassical tearing mode growth from 2D reduced MHD simulations

    NASA Astrophysics Data System (ADS)

    Westerhof, E.; de Blank, H. J.; Pratt, J.

    2016-03-01

    Two dimensional reduced MHD simulations of neoclassical tearing mode growth and suppression by ECCD are performed. The perturbation of the bootstrap current density and the EC drive current density perturbation are assumed to be functions of the perturbed flux surfaces. In the case of ECCD, this implies that the applied power is flux surface averaged to obtain the EC driven current density distribution. The results are consistent with predictions from the generalized Rutherford equation using common expressions for Δ \\text{bs}\\prime and Δ \\text{ECCD}\\prime . These expressions are commonly perceived to describe only the effect on the tearing mode growth of the helical component of the respective current perturbation acting through the modification of Ohm’s law. Our results show that they describe in addition the effect of the poloidally averaged current density perturbation which acts through modification of the tearing mode stability index. Except for modulated ECCD, the largest contribution to the mode growth comes from this poloidally averaged current density perturbation.

  2. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    SciTech Connect

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.

  3. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5×1014 W/cm2. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile.

  4. Surface structures and growth modes of Ba deposited on Mo(110) surface

    NASA Astrophysics Data System (ADS)

    Jo, S.; Gotoh, Y.

    2000-10-01

    The surface structures and growth modes of barium (Ba) on an Mo(110) surface have been investigated using a molecular beam epitaxy system equipped with a high-energy electron diffraction (RHEED) apparatus. Three kinds of surface structures were observed, c(2×2), (1.6×2) and (1.5×1.8), in regions with low Ba coverage, and their phase diagram was obtained. All Ba atoms which form the c(2×2) structure coincide with Mo atoms, and the (1.6×2) and (1.5×1.8) structures with the regular triangle lattice have line coincidences with the atomic arrangement of the substrate along the [11¯0]Mo and [001]Mo directions, respectively. In the thickness range beyond 1 ML, the growth modes of the Ba-Mo(110) system were different due to the substrate temperature. The growth of the Ba-Mo(110) system is in accordance with the Frank-van der Merwe growth mode at room temperature and the Stranski-Krastanov growth mode at high temperatures.

  5. High-resistance GaN epilayers with low dislocation density via growth mode modification

    NASA Astrophysics Data System (ADS)

    Xu, Z. Y.; Xu, F. J.; Wang, J. M.; Lu, L.; Yang, Z. J.; Wang, X. Q.; Shen, B.

    2016-09-01

    High-resistance GaN with low dislocation density adopting growth mode modification has been investigated by metalorganic chemical vapor deposition. The sheet resistance of the order of 1016 Ω/sq has been achieved at room temperature by diminishing the oxygen impurity level close to the substrate with an AlN blocking layer. Attributed to this method which offers more freedom to tailor the growth mode, a three-dimensional (3D) growth process is introduced by adjusting the growth pressure and temperature at the initial stage of the GaN epitaxy to improve the crystalline quality. The large 3D GaN grains formed during this period roughen the surface, and the following coalescence of the GaN grains causes threading dislocations bending, which finally remarkably reduces the dislocation density.

  6. The growth modes of vapor-deposited Bi on Cu(2 1 0)

    NASA Astrophysics Data System (ADS)

    Blum, B.; Ascolani, H.

    2001-06-01

    This work presents growth modes of vapor-deposited Bi on clean and C contaminated Cu(2 1 0) surfaces, characterized with low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and work-function shifts ( Δeφ). Up to θBi=0.5 ML (monolayer, ML) fractional Bi coverage (equivalent to 0.686×10 15 at. cm -2) a p(1×1) structure is observed, associated with a gradual LEED pattern symmetry change from one mirror plane for clean Cu(2 1 0) to two, for θBi=0.5 ML. The higher symmetry phase is stable up to 723 K, and no appreciable binding-energy shifts are detected by XPS in the Bi (4f 7/2) and Cu (2p 3/2) core lines. Additional Bi results in Stranski-Krastanov growth of a compact Cu(2 1 0)-(6×1)-Bi structure with eight Bi atoms per unit cell, stable up to 628 K. Impurity levels of both either pre or coadsorbed C lower the stability temperature of the (6×1)-Bi phase. However, C does not have any appreciable influence on the p(1×1)-Bi phase. The presence of as little as θC=0.1 ML of preadsorbed C produces Frank-Van der Merwe (layer by layer) growth of the p(1×1) c2mm structure, up till completion of the third layer, and as much as 30% variation in Δeφ values with respect to C-free samples. Carbon appears to have no effect on the growth, at 723 K, of Cu(2 1 0)-p(1×1)-Bi facets from the Cu(1 0 0)-c(2×2)-Bi phase when sufficient defects (vacancies) are present in the selvedge.

  7. Growth of Daphnia magna exposed to mixtures of chemicals with diverse modes of action

    SciTech Connect

    Deneer, J.W.; Seinen, W.; Hermens, J.L.

    1988-02-01

    Concentrations causing inhibition of growth of Daphnia magna after 16 days of exposure were determined for nine chemicals that presumably act through different modes of action. The joint toxic effect of a mixture of these chemicals is found to be nonadditive.

  8. Growth modes in two-dimensional heteroepitaxy on an elastic substrate

    NASA Astrophysics Data System (ADS)

    Katsuno, Hiroyasu; Uemura, Hideaki; Uwaha, Makio; Saito, Yukio

    2005-02-01

    With the use of a two-dimensional harmonic elastic lattice model, in which spontaneous stress caused by the lack of neighboring atoms is incorporated, we determine ground state configuration of adsorbed atoms on a flat elastic substrate. Energy of the system is calculated by direct relaxation dynamics in the epitaxial layer and by using an elastic Green's function method in the substrate. Based on the ground state configurations determined for various coverages, we infer growth mode. As the lattice misfit and the strength of the spontaneous stress increase, the growth mode changes from Frank-van der Merwe (FM) to Stranski-Krastanov (SK) and finally to Volmer-Weber (VW) mode. In a parameter range between the SK and the VW with a large spontaneous stress, the equilibrium configuration changes from a layer to islands in unusual ways as the coverage increases.

  9. Abbreviated epitaxial growth mode (AGM) method for reducing cost and improving quality of LEDs and lasers

    DOEpatents

    Tansu, Nelson; Chan, Helen M; Vinci, Richard P; Ee, Yik-Khoon; Biser, Jeffrey

    2013-09-24

    The use of an abbreviated GaN growth mode on nano-patterned AGOG sapphire substrates, which utilizes a process of using 15 nm low temperature GaN buffer and bypassing etch-back and recovery processes during epitaxy, enables the growth of high-quality GaN template on nano-patterned AGOG sapphire. The GaN template grown on nano-patterned AGOG sapphire by employing abbreviated growth mode has two orders of magnitude lower threading dislocation density than that of conventional GaN template grown on planar sapphire. The use of abbreviated growth mode also leads to significant reduction in cost of the epitaxy. The growths and characteristics of InGaN quantum wells (QWs) light emitting diodes (LEDs) on both templates were compared. The InGaN QWs LEDs grown on the nano-patterned AGOG sapphire demonstrated at least a 24% enhancement of output power enhancement over that of LEDs grown on conventional GaN templates.

  10. Mode growth and competition in the x-ray free-electron laser oscillator start-up from noise.

    SciTech Connect

    Lindberg, R. R.; Kim, K.-J.; Accelerator Systems Division

    2009-07-01

    We describe the radiation properties of an x-ray free-electron laser (FEL) oscillator, beginning with its start-up from noise through saturation. We first decompose the initially chaotic undulator radiation into the growing longitudinal modes of the composite system consisting of the electron beam, the undulator, and the Bragg mirror resonator cavity. Because the radiation initially comprises several modes whose growth rates are comparable, we find that only after many oscillator passes is the output pulse dominantly characterized by the lowest-order Gaussian mode. We verify our analytic results with a novel, reduced one-dimensional FEL code (derived in the text), and with two-dimensional FEL simulations. Understanding the full longitudinal structure during the initial amplification will be critical in assessing the tolerances on the electron beam, undulator, and optical cavity required for robust operation.

  11. Mode growth and competition in the x-ray free-electron laser oscillator start-up from noise.

    SciTech Connect

    Lindberg, R. R.; Kim, K.-J. )

    2009-07-02

    We describe the radiation properties of an x-ray free-electron laser (FEL) oscillator, beginning with its start-up from noise through saturation. We first decompose the initially chaotic undulator radiation into the growing longitudinal modes of the composite system consisting of the electron beam, the undulator, and the Bragg mirror resonator cavity. Because the radiation initially comprises several modes whose growth rates are comparable, we find that only after many oscillator passes is the output pulse dominantly characterized by the lowest-order Gaussian mode. We verify our analytic results with a novel, reduced one-dimensional FEL code (derived in the text), and with two-dimensional FEL simulations. Understanding the full longitudinal structure during the initial amplification will be critical in assessing the tolerances on the electron beam, undulator, and optical cavity required for robust operation.

  12. A plane stress finite element model for elastic-plastic mode I/II crack growth

    NASA Astrophysics Data System (ADS)

    James, Mark Anthony

    A finite element program has been developed to perform quasi-static, elastic-plastic crack growth simulations. The model provides a general framework for mixed-mode I/II elastic-plastic fracture analysis using small strain assumptions and plane stress, plane strain, and axisymmetric finite elements. Cracks are modeled explicitly in the mesh. As the cracks propagate, automatic remeshing algorithms delete the mesh local to the crack tip, extend the crack, and build a new mesh around the new tip. State variable mapping algorithms transfer stresses and displacements from the old mesh to the new mesh. The von Mises material model is implemented in the context of a non-linear Newton solution scheme. The fracture criterion is the critical crack tip opening displacement, and crack direction is predicted by the maximum tensile stress criterion at the crack tip. The implementation can accommodate multiple curving and interacting cracks. An additional fracture algorithm based on nodal release can be used to simulate fracture along a horizontal plane of symmetry. A core of plane strain elements can be used with the nodal release algorithm to simulate the triaxial state of stress near the crack tip. Verification and validation studies compare analysis results with experimental data and published three-dimensional analysis results. Fracture predictions using nodal release for compact tension, middle-crack tension, and multi-site damage test specimens produced accurate results for residual strength and link-up loads. Curving crack predictions using remeshing/mapping were compared with experimental data for an Arcan mixed-mode specimen. Loading angles from 0 degrees to 90 degrees were analyzed. The maximum tensile stress criterion was able to predict the crack direction and path for all loading angles in which the material failed in tension. Residual strength was also accurately predicted for these cases.

  13. Mode Transitions in Glass Cockpit Aircraft: Results of a Field Study

    NASA Technical Reports Server (NTRS)

    Degani, Asaf; Kirlik, Alex; Shafto, Michael (Technical Monitor)

    1995-01-01

    One consequence of increased levels of automation in complex control systems is the presence of modes. A mode is a particular configuration of a control system that defines how human command inputs are interpreted. In complex systems, modes also often determine a specific allocation of control authority between the human and automated systems. Even in simple static devices (e.g., electronic watches, word processors), the presence of modes has been found to cause problems in either-the acquisition or production of skilled performance. Many of these problems arise due to the fact that the selection of a mode causes device behavior to be mediated by hidden internal state information. For these simple systems, many of these interaction problems can be solved by the design of appropriate feedback to communicate internal state information to the human operator. In complex dynamic systems, however, the design issues associated with modes seem to trancend the problem of merely communicating internal state information via displayed feedback. In complex supervisory control systems (e.g., aircraft, spacecraft, military command and control), a key function of modes is the selection of a particular configuration of control authority between the human operator and automated control systems. One mode may result in full manual control, another may result in a mix of manual and automatic control, while a third may result in full automatic control over the entire system. The human operator selects an appropriate mode as a function of current goals, operating conditions, and operating procedures. Thus, the operator is put in a position of essentially trying to control two coupled dynamic systems: the target system itself, and also a highly complex suite of automation controlling the target system. From a historical perspective, it should probably not come as a surprise that very little information is available to guide the design of mode-oriented control systems. The topic of

  14. In situ investigation of growth modes during plasma-assisted molecular beam epitaxy of (0001) GaN

    SciTech Connect

    Koblmueller, G.; Fernandez-Garrido, S.; Calleja, E.; Speck, J. S.

    2007-10-15

    Real-time analysis of the growth modes during homoepitaxial (0001) GaN growth by plasma-assisted molecular beam epitaxy was performed using reflection high energy electron diffraction. A growth mode map was established as a function of Ga/N flux ratio and growth temperature, exhibiting distinct transitions between three-dimensional (3D), layer-by-layer, and step-flow growth modes. The layer-by-layer to step-flow growth transition under Ga-rich growth was surfactant mediated and related to a Ga adlayer coverage of one monolayer. Under N-rich conditions the transition from 3D to layer-by-layer growth was predominantly thermally activated, facilitating two-dimensional growth at temperatures of thermal decomposition.

  15. Time resolved x-ray studies on growth mode changes induced by quantum electronic effect

    NASA Astrophysics Data System (ADS)

    Hong, Hawoong; Basile, Leonardo; Peter, Czoschke; Tai-C., Chiang

    2004-03-01

    Growth of Pb thin films on Si(111)-(7x7) was studied by reflection surface x-ray diffraction in real time. During the deposition of Pb films at low temperatures, not only the reflectivity curves, but also all the rocking curves at every points on the reflectivity curves were continuously measured. In other words, two dimensional k-space mapping around specula reflectivity was obtained instead of conventional time-resolved reflectivity measurement at an anti-Bragg position. The abundance of information from real time 2-D k-space maps reveals very clear changes in the growth mode of ultra thin Pb films. In a temperature range where the quantum size effect is dominant, alternating layer and island growth was observed.[1] At the lower temperatures, layer-by-layer growth proceeds without a break. At the higher temperature, films grow rough. Kinetics leading to the growth mode changes will be discussed. [1] Hawoong Hong, C.-M.Wei, M.Y. Chou, Z.Wu, L. Basile, H. Chen, M. Holt, and T.-C. Chiang, Phys. Rev. Lett., 90, 076104 (2003)

  16. Characterization of Mode I fatigue crack growth in GFRP woven laminates at low temperatures

    SciTech Connect

    Shindo, Yasuhide . E-mail: shindo@material.tohoku.ac.jp; Inamoto, Akihiro; Narita, Fumio

    2005-03-01

    This paper describes an experimental and analytical study on the cryogenic fatigue behavior of glass fiber reinforced polymer woven laminates under Mode I loading. Fatigue crack growth rate tests were performed using compact tension specimens at room temperature, liquid nitrogen temperature (77 K), and liquid helium temperature (4 K). The fracture surfaces were also examined by scanning electron microscopy to correlate with the fatigue properties. A finite element method coupled with fatigue damage was adopted for the extensional analysis. The effects of temperature and loading condition on the fatigue crack growth rates are examined.

  17. Continuous monitoring of bacterial biofilm growth using uncoated Thickness-Shear Mode resonators

    NASA Astrophysics Data System (ADS)

    Castro, P.; Resa, P.; Durán, C.; Maestre, J. R.; Mateo, M.; Elvira, L.

    2012-12-01

    Quartz Crystal Microbalances (QCM) were used to nondestructively monitor in real time the microbial growth of the bacteria Staphylococcus epidermidis (S. epidermidis) in a liquid broth. QCM, sometimes referred to as Thickness-Shear Mode (TSM) resonators, are highly sensitive sensors not only able to measure very small mass, but also non-gravimetric contributions of viscoelastic media. These devices can be used as biosensors for bacterial detection and are employed in many applications including their use in the food industry, water and environment monitoring, pharmaceutical sciences and clinical diagnosis. In this work, three strains of S. epidermidis (which differ in the ability to produce biofilm) have been continuously monitored using an array of piezoelectric TSM resonators, at 37 °C in a selective culturing media. Microbial growth was followed by measuring the changes in the crystal resonant frequency and bandwidth at several harmonics. It was shown that microbial growth can be monitored in real time using multichannel and multiparametric QCM sensors.

  18. Growth modes of thin films of ligand-free metal clusters

    SciTech Connect

    Dollinger, A.; Strobel, C. H.; Bleuel, H.; Marsteller, A.; Gantefoer, G.; Fairbrother, D. H.; Tang, Xin; Bowen, K. H.; Kim, Young Dok

    2015-05-21

    Size-selected Mo{sub n}{sup −}, W{sub n}{sup −}, and Fe{sub n}{sup −} cluster anions are deposited on a weakly interacting substrate (highly oriented pyrolytic graphite) and studied ex-situ using atomic force microscopy. Depending on size, three growth modes can be distinguished. Very small clusters consisting of less than 10–30 atoms behave similar to atoms and coalesce into 3-dimensional bulk-like islands. Medium sized clusters consisting of hundreds of atoms do not coalesce and follow a Stanski-Krastanov growth pattern. At low coverage, an almost perfect monolayer is formed. This is a new finding different from all previous studies on deposited metal clusters. For clusters with several thousands of atoms, the growth pattern again changes. At low coverage, the substrate is dotted with individual clusters, while at high coverage, the surface becomes extremely rough.

  19. Mode-Stirred Method Implementation for HIRF Susceptibility Testing and Results Comparison with Anechoic Method

    NASA Technical Reports Server (NTRS)

    Nguyen, Truong X.; Ely, Jay J.; Koppen, Sandra V.

    2001-01-01

    This paper describes the implementation of mode-stirred method for susceptibility testing according to the current DO-160D standard. Test results on an Engine Data Processor using the implemented procedure and the comparisons with the standard anechoic test results are presented. The comparison experimentally shows that the susceptibility thresholds found in mode-stirred method are consistently higher than anechoic. This is consistent with the recent statistical analysis finding by NIST that the current calibration procedure overstates field strength by a fixed amount. Once the test results are adjusted for this value, the comparisons with the anechoic results are excellent. The results also show that test method has excellent chamber to chamber repeatability. Several areas for improvements to the current procedure are also identified and implemented.

  20. Multimode to single-mode converters: new results on 1-to-61 photonic lanterns

    NASA Astrophysics Data System (ADS)

    Olaya, J.-C.; Ehrlich, K.; Haynes, D. M.; Haynes, R.; Leon-Saval, S. G.; Schirdewahn, D.

    2012-09-01

    Photonic Lanterns are a fibre-based component performing the adiabatic conversion from a multimode fibre to a series of single-mode fibres. This conversion is required for combining fibre-based instruments used in astronomy with complex photonic functions. As any fibre-based system, the optical properties of the Photonic Lanterns need to be fully evaluated. In this paper, we present results on the performance of a 1-to-61 Photonic Lantern in terms of spectral transmission and modal noise characteristics. Firstly, we compare the spectra obtained at the output of two photonic lanterns spliced together in multimode-to-multimode configuration with spectra obtained when transmitting light through step-index single-mode and multimode fibres. We then show that the photonic lantern is generating less modal noise than a step-index multimode fibre of same core diameter, when it is submitted to bending and stretching, and we propose an interpretation of this result based on static mode scrambling performance and single-mode behavior.

  1. Error Field Assessment from Driven Mode Rotation: Results from Extrap-T2R Reversed-Field-Pinch and Perspectives for ITER

    NASA Astrophysics Data System (ADS)

    Volpe, F. A.; Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Olofsson, K. E. J.

    2012-10-01

    A new ITER-relevant non-disruptive error field (EF) assessment technique not restricted to low density and thus low beta was demonstrated at the Extrap-T2R reversed field pinch. Resistive Wall Modes (RWMs) were generated and their rotation sustained by rotating magnetic perturbations. In particular, stable modes of toroidal mode number n=8 and 10 and unstable modes of n=1 were used in this experiment. Due to finite EFs, and in spite of the applied perturbations rotating uniformly and having constant amplitude, the RWMs were observed to rotate non-uniformly and be modulated in amplitude (in the case of unstable modes, the observed oscillation was superimposed to the mode growth). This behavior was used to infer the amplitude and toroidal phase of n=1, 8 and 10 EFs. The method was first tested against known, deliberately applied EFs, and then against actual intrinsic EFs. Applying equal and opposite corrections resulted in longer discharges and more uniform mode rotation, indicating good EF compensation. The results agree with a simple theoretical model. Extensions to tearing modes, to the non-uniform plasma response to rotating perturbations, and to tokamaks, including ITER, will be discussed.

  2. Controlled Growth of one-dimensional zinc oxide nanostructures in the pulsed electrodeposition mode

    SciTech Connect

    Klochko, N. P. Khrypunov, G. S.; Myagchenko, Yu. O.; Melnychuk, E. E.; Kopach, V. R.; Klepikova, E. S.; Lyubov, V. M.; Kopach, A. V.

    2012-06-15

    Zinc oxide nanostructures are objects of study in the field of optoelectronics, solar power engineering, nanosensorics, and catalysis. For the purpose of the controlled growth of one-dimensional submicrometer zinc oxide structures in the pulsed electrodeposition mode, the effect of the pulse electrolysis parameters on the morphology of ZnO layers, their optical properties, and structural and substructural characteristics is determined using X-ray diffraction, optical spectrophotometry, and atomic-force microscopy. The possibility of fabricating arrays of ZnO nanowires with different geometrical shapes, perpendicular to the substrate surface, by varying the frequency of cathode-substrate potential pulses is shown.

  3. Diffractive pion production at COMPASS - First results on 3{pi} final states - neutral mode

    SciTech Connect

    Nerling, Frank

    2010-08-05

    The COMPASS experiment at CERN is designed for light hadron spectroscopy with emphasis on the detection of new states, in particular the search for exotic states and glue-balls. After a short pilot run in 2004 (190 GeV/c negative pion beam, lead target) showing significant production strength for an exotic J{sup PC} = 1{sup -+} state at 1.66 GeV/c{sup 2}, we have collected data with a 190 GeV/c negative charged hadron beam on a proton (liquid hydrogen) and nuclear targets in 2008 and 2009. The spectrometer features good coverage by electromagnetic calorimetry, and our data provide excellent opportunity for simultaneous observation of new states in two different decay modes in the same experiment. The diffractively produced (3{pi}){sup -} system for example can be studied in both modes {pi}{sup -}p{yields}{pi}{sup -{pi}+{pi}-}p and {pi}{sup -}p{yields}{pi}{sup -{pi}0{pi}0}p. Charged and neutral mode rely on completely different parts of the spectrometer. Observing a new state in both modes provides important crosscheck. First results of a preliminary PWA performed on the 2008 data are presented.

  4. Construction and Validation of the Rhodobacter sphaeroides 2.4.1 DNA Microarray: Transcriptome Flexibility at Diverse Growth Modes

    SciTech Connect

    Pappas, Christopher T.; Sram, Jakub; Moskvin, Oleg V.; Ivanov, Pavel S.; Mackenzie, Christopher; Choudhary, Madhusudan; Land, Miriam L; Larimer, Frank W; Kaplan, Samuel; Gomelsky, Mark

    2004-07-01

    A high-density oligonucleotide DNA microarray, a genechip, representing the 4.6-Mb genome of the facultative phototrophic proteobacterium, Rhodobacter sphaeroides 2.4.1, was custom-designed and manufactured by Affymetrix, Santa Clara, Calif. The genechip contains probe sets for 4,292 open reading frames (ORFs), 47 rRNA and tRNA genes, and 394 intergenic regions. The probe set sequences were derived from the genome annotation generated by Oak Ridge National Laboratory after extensive revision, which was based primarily upon codon usage characteristic of this GC-rich bacterium. As a result of the revision, numerous missing ORFs were uncovered, nonexistent ORFs were deleted, and misidentified start codons were corrected. To evaluate R. sphaeroides transcriptome flexibility, expression profiles for three diverse growth modes-aerobic respiration, anaerobic respiration in the dark, and anaerobic photosynthesis-were generated. Expression levels of one-fifth to one-third of the R. sphaeroides ORFs were significantly different in cells under any two growth modes. Pathways involved in energy generation and redox balance maintenance under three growth modes were reconstructed. Expression patterns of genes involved in these pathways mirrored known functional changes, suggesting that massive changes in gene expression are the major means used by R. sphaeroides in adaptation to diverse conditions. Differential expression was observed for genes encoding putative new participants in these pathways (additional photosystem genes, duplicate NADH dehydrogenase, ATP synthases), whose functionality has yet to be investigated. The DNA microarray data correlated well with data derived from quantitative reverse transcription-PCR, as well as with data from the literature, thus validating the R. sphaeroides genechip as a powerful and reliable tool for studying unprecedented metabolic versatility of this bacterium.

  5. In situ growth and activity and modes of penetration of Escherichia coli in unconsolidated porous materials.

    PubMed Central

    Sharma, P K; McInerney, M J; Knapp, R M

    1993-01-01

    Statistically reliable data on the in situ rates of growth, substrate consumption, and product formation are required to test the validity of the mathematical models developed for microbially enhanced oil recovery and in situ bioremediation processes. A simple, replicable porous-core system that could be aseptically divided into sections at various times was developed to follow the kinetics of microbial growth and metabolism in situ. This core system was used to study the kinetics of growth and the mode of penetration of strains of Escherichia coli through anaerobic, nutrient-saturated, fine Ottawa sand (permeability of 7.0 microns2 and porosity of 37%) under static conditions. The in situ rate of growth of a wild-type, motile, chemotactic strain, RW262, was two times slower inside cores than it was in liquid cultures. The mode of metabolism of galactose by strain RW262 was not altered inside cores, as acetate was the only product detected either inside the cores or in liquid cultures. Without applied advective force, strain RW262 grew exponentially and moved through cores at a rate of about 0.1 m/day. The cell population moved through cores in a band-like fashion, as the front of the moving cells consisted of high cell concentrations (greater than 10(5) cells per ml). Until the breakthrough of the cells occurred, galactose consumption and acetate production were observed only in the proximal sections of the core, showing that the cell propagation preceded the complete depletion of the substrate or the accumulation of large amounts of products.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8285677

  6. Effects of experimental conditions on the morphologies, structures and growth modes of pulsed laser-deposited CdS nanoneedles

    PubMed Central

    2014-01-01

    CdS nanoneedles with different morphologies, structures, and growth modes have been grown on Ni-coated Si(100) surface under different experimental conditions by pulsed laser deposition method. The effects of catalyst layer, substrate temperature, and laser pulse energy on the growth of the CdS nanoneedles were studied in detail. It was confirmed that the formation of the molten catalyst spheres is the key to the nucleation of the CdS nanoneedles by observing the morphologies of the Ni catalyst thin films annealed at different substrate temperatures. Both the substrate temperature and laser pulse energy strongly affected the growth modes of the CdS nanoneedles. The secondary growth of the smaller nanoneedles on the top of the main nanoneedles was found at appropriate conditions. A group of more completed pictures of the growth modes of the CdS nanoneedles were presented. PMID:24559455

  7. Comparison of results between the ballooning-modes codes BLOON and BALOON

    SciTech Connect

    Munro, J.K. Jr.

    1981-08-01

    Ballooning mode equation eigenvalues calculated by two different codes, BLOON (written at General Atomic) and BALOON (written at Oak Ridge National Laboratory) have been compared for a sequence of equilibria having a range of ..beta.. values. The results agree for marginal stability only. Differences away from marginal stability may be due to differences in the coordinate systems used for the analysis in the two codes. Equilibria were generated using the ISLAND code of D. Stevens of New York University. Results of various convergence studies made with the codes are presented together with recommendations for their use.

  8. Preliminary results of the ultralong-range sounding of ionospheric irregularities using the ducted mode

    NASA Astrophysics Data System (ADS)

    Ponyatov, A. A.; Uryadov, V. P.; Batukhtin, V. I.; Ivanov, V. A.; Ivanov, D. V.; Ryabova, N. V.; Chernov, A. G.; Shumaev, V. V.; Anderson, S. J.

    1999-12-01

    We present preliminary experimental results concerning transequatorial propagation (TEP) of HF waves upon chirp sounding over the 11950-km path alice Springs (Australia)-Yoshkar-Ola (Russia). The measurements were made in August, 1998. Two anomalous signals with delays of 3.0 and 4.5 ms with respect to the main mode were observed during night time (21:30 23:00 UT). The maximum observed frequencies (MOF) of these signals were 2 3 MHz greater than the main-mode MOF. Simulations allowed us to identify these signals as the ducted signals trapped in the FE interlayer duct due to radiowave refraction on a negative gradient of the electron density and that escaped from the duct due to the scattering by small-scale field-aligned irregularities of the subpolar ionosphere. We discuss radiophysical and geophysical aspects concerning localization of the irregularities responsible for scattering and perspectives of using the ducted mode for over-the-horizon diagnostics of the inhomogeneous structure of the ionosphere with a global network of chirp sounders and HF radars.

  9. On the abrupt growth dynamics of nonlinear resistive tearing mode and the viscosity effects

    SciTech Connect

    Ali, A.; Li, Jiquan; Kishimoto, Y.

    2014-05-15

    The nonlinear evolution of the resistive tearing mode exhibits an abrupt growth after an X-point collapse once the magnetic island exceeds a certain critical width Δ′w{sub c} for large instability parameter Δ′, leading to a current sheet formation [N. F. Loureiro et al., Phys. Rev. Lett. 95, 235003 (2005)]. In this work, we investigate the underlying mechanism of the X-point collapse as well as the current sheet formation including the viscosity effects, based on a secondary instability analysis. The secondary instability is excited due to the quasilinear current modification by the zonal current. In particular, it is identified that the current peaking effect is plausibly responsible for the onset of the X-point collapse and the current sheet formation, leading to the explosive growth of reconnected flux. In the presence of finite viscosity, the Δ′w{sub c} scaling with the resistivity gets modified. A transition behavior is revealed at P{sub r}≈1 for the viscosity dependence of Δ′w{sub c} and the linear tearing instability. However, the explosive growth seems to be independent of the viscosity in the magnetic Prandtl number P{sub r}<1 regime, while large viscosity plays a strong dissipation role.

  10. 45-Day safety screening results for tank 241-U-102, push mode cores 143 and 144

    SciTech Connect

    Steen, F.H.

    1996-06-28

    This document is the 45-day report deliverable for tank 241-U-102 push mode core segments collected between April 16, 1996 and May 6, 1996 and received by the 222-S Laboratory between April 17, 1996 and May 8, 1996. The segments were subsampled and analyzed in accordance, with the Tank 241-U-102 Push Mode Core Sampling and analysis Plan (TSAP) (Hu, 1996) and the Safety Screening Data Quality Objective (DQO) (Dukelow, et al., 1995). The analytical results are included in Table 1. Attachment I is a cross reference to relate the tank farm identification numbers to the 222-S Laboratory LabCore sample numbers. The subsamples generated in the laboratory for analysis are identified in these diagrams with their sources shown. The diagram identifying the hydrostatic head fluid (HHF) blank is also included, Primary safety screening results and the raw data from Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) analyses are included in this report. Two of the samples submitted for DSC analysis exceeded notification limits as stated in the Safety Screening DQO (Dukelow, et al., 1995). Cyanide analysis was requested on these samples and a Reactive System Screening Tool analysis was requested for the sample exhibiting the highest exothenn in accordance with the TSAP (Hu, 1996). The results for these analyses will be reported in a revision to this document.

  11. Molecular mechanisms for the evolution of bacterial morphologies and growth modes

    PubMed Central

    Randich, Amelia M.; Brun, Yves V.

    2015-01-01

    Bacteria exhibit a rich diversity of morphologies. Within this diversity, there is a uniformity of shape for each species that is replicated faithfully each generation, suggesting that bacterial shape is as selectable as any other biochemical adaptation. We describe the spatiotemporal mechanisms that target peptidoglycan synthesis to different subcellular zones to generate the rod-shape of model organisms Escherichia coli and Bacillus subtilis. We then demonstrate, using the related genera Caulobacter and Asticcacaulis as examples, how the modularity of the core components of the peptidoglycan synthesis machinery permits repositioning of the machinery to achieve different growth modes and morphologies. Finally, we highlight cases in which the mechanisms that underlie morphological evolution are beginning to be understood, and how they depend upon the expansion and diversification of the core components of the peptidoglycan synthesis machinery. PMID:26106381

  12. Tuning the growth mode of nanowires via the interaction among seeds, substrates and beam fluxes

    NASA Astrophysics Data System (ADS)

    Zannier, Valentina; Grillo, Vincenzo; Martelli, Faustino; Plaisier, Jasper Rikkert; Lausi, Andrea; Rubini, Silvia

    2014-06-01

    The growth mechanism of semiconductor nanowires is still an argument of high interest, and it is becoming clearer, investigation after investigation, that simple pictures fail to describe the complex behaviors observed under different growth conditions. We report here on the growth of semiconductor nanowires, maintaining control over the chemical composition and the physical state of the metallic seeds, and tuning the growth mechanism by varying the growth conditions. We focused on Au-assisted ZnSe nanowires grown by molecular beam epitaxy on GaAs(111)B substrates. We show that at sufficiently high temperatures, the Au seed is strongly affected by the interaction with the substrate and that nanowire growth can occur through two different mechanisms, which have a strong impact on the nanowire's morphology and crystal quality. In particular, ZnSe NWs may exhibit either a uniformly oriented, straight morphology when the nanoparticle seed is liquid, or a kinked, worm-like shape when the nanoparticle seed is switched to a solid phase. This switch, which tunes the nanowire growth mechanism, is achieved by controlling the Zn-to-Se beam pressure ratio at the Au-seed surface. Our results allow a deeper understanding of particle-assisted nanowire growth, and an accurate control of nanowire morphology via the control of the growth mechanism.The growth mechanism of semiconductor nanowires is still an argument of high interest, and it is becoming clearer, investigation after investigation, that simple pictures fail to describe the complex behaviors observed under different growth conditions. We report here on the growth of semiconductor nanowires, maintaining control over the chemical composition and the physical state of the metallic seeds, and tuning the growth mechanism by varying the growth conditions. We focused on Au-assisted ZnSe nanowires grown by molecular beam epitaxy on GaAs(111)B substrates. We show that at sufficiently high temperatures, the Au seed is strongly

  13. Experimental and Computational Investigation of Biofilm Formation by Rhodopseudomonas palustris Growth under Two Metabolic Modes

    PubMed Central

    Kernan, Chase; Chow, Philicia P.; Christianson, Rebecca J.; Huang, Jean

    2015-01-01

    We examined biofilms formed by the metabolically versatile bacterium Rhodopseudomonas palustris grown via different metabolic modes. R. palustris was grown in flow cell chambers with identical medium conditions either in the presence or absence of light and oxygen. In the absence of oxygen and the presence of light, R. palustris grew and formed biofilms photoheterotrophically, and in the presence of oxygen and the absence of light, R. palustris grew and formed biofilms heterotrophically. We used confocal laser scanning microscopy and image analysis software to quantitatively analyze and compare R. palustris biofilm formation over time in these two metabolic modes. We describe quantifiable differences in structure between the biofilms formed by the bacterium grown heterotrophically and those grown photoheterotrophically. We developed a computational model to explore ways in which biotic and abiotic parameters could drive the observed biofilm architectures, as well as a random-forest machine-learning algorithm based on structural differences that was able to identify growth conditions from the confocal imaging of the biofilms with 87% accuracy. Insight into the structure of phototrophic biofilms and conditions that influence biofilm formation is relevant for understanding the generation of biofilm structures with different properties, and for optimizing applications with phototrophic bacteria growing in the biofilm state. PMID:26087200

  14. [Methods for extraction of exopolymeric complex in plankton and biofilm growth mode of Stenotrophomonas maltophilia 22M].

    PubMed

    Boretskaia, M A; Suslova, O S

    2013-01-01

    The optimal methods for the extraction of exopolymeric complex (EPS) of Stenotrophomonas maltophilia 22M was determined. That EPS was synthesized in plankton and biofilm growth mode on the mild steel surface. It is desirable to use different physical and chemical methods for studying the EPS composition (carbohydrates and proteins) depending on the bacteria growth mode. In this way the interaction with ion exchange resin was the most effective for plankton growth mode to determine the maximum amount of carbohydrates (9.5 microg/ml), and the impact of heating to determine protein (3.9 microg/ml). For EPS biofilm in order to obtain maximum amount of carbohydrate it is desirable to use heating (30 microg/ml) and centrifugation (35 microg/ml). It is recommended to determine protein in the biofilm EPS after treatment with heating (3.75 microg/ml) and centrifugation (3.75 microg/ml).

  15. Scaling Behavior in Economics: I. Empirical Results for Company Growth

    NASA Astrophysics Data System (ADS)

    Nunes Amaral, Luís A.; Buldyrev, Sergey V.; Havlin, Shlomo; Leschhorn, Heiko; Maass, Philipp; Salinger, Michael A.; Stanley, H. Eugene; Stanley, Michael H. R.

    1997-04-01

    We address the question of the growth of firm size. To this end, we analyze the Compustat data base comprising all publicly-traded United States manufacturing firms within the years 1974-1993. We find that the distribution of firm sizes remains stable for the 20 years we study, i.e., the mean value and standard deviation remain approximately constant. We study the distribution of sizes of the “new” companies in each year and find it to be well approximated by a log-normal. We find (i) the distribution of the logarithm of the growth rates, for a fixed growth period of one year, and for companies with approximately the same size S, display an exponential form, and (ii) the fluctuations in the growth rates measured by the width of this distribution σ_1 scale as a power with S, σ_1sim S^{-β}. We find that the exponent β takes the same value, within the error bars, for several measures of the size of a company. In particular, we obtain: β = 0.20± 0.03 for sales, β = 0.18± 0.03 for number of employees, β = 0.18± 0.03 for assets, β = 0.18± 0.03 for cost of goods sold, and β = 0.20± 0.03 for property, plant, and equipment.

  16. Growth Model Comparison Study: A Summary of Results

    ERIC Educational Resources Information Center

    Auty, Bill; Brockmann, Frank

    2012-01-01

    School accountability is subject to considerable scrutiny. It generates sharp political debate, policy challenges, and continuous discussion. Growth models are now a part of that discussion. To many practitioners the sheer volume of "important to know" information is daunting. The members of the Technical Issues in Large Scale Assessment (TILSA)…

  17. Magnetorotational Instability: Nonmodal Growth and the Relationship of Global Modes to the Shearing Box

    SciTech Connect

    J Squire, A Bhattacharjee

    2014-07-01

    We study the magnetorotational instability (MRI) (Balbus & Hawley 1998) using non-modal stability techniques.Despite the spectral instability of many forms of the MRI, this proves to be a natural method of analysis that is well-suited to deal with the non-self-adjoint nature of the linear MRI equations. We find that the fastest growing linear MRI structures on both local and global domains can look very diff erent to the eigenmodes, invariably resembling waves shearing with the background flow (shear waves). In addition, such structures can grow many times faster than the least stable eigenmode over long time periods, and be localized in a completely di fferent region of space. These ideas lead – for both axisymmetric and non-axisymmetric modes – to a natural connection between the global MRI and the local shearing box approximation. By illustrating that the fastest growing global structure is well described by the ordinary diff erential equations (ODEs) governing a single shear wave, we find that the shearing box is a very sensible approximation for the linear MRI, contrary to many previous claims. Since the shear wave ODEs are most naturally understood using non-modal analysis techniques, we conclude by analyzing local MRI growth over finite time-scales using these methods. The strong growth over a wide range of wave-numbers suggests that non-modal linear physics could be of fundamental importance in MRI turbulence (Squire & Bhattacharjee 2014).

  18. Mode of growth of bacterial pathogens in chronic polymicrobial human osteomyelitis.

    PubMed Central

    Marrie, T J; Costerton, J W

    1985-01-01

    Direct examination of material from two cases of persistent (2 and 60 years) osteomyelitis by morphological and culture techniques showed that the pathogens comprised several bacterial species whose cells grew predominantly in discrete exopolysaccharide-enclosed microcolonies made up of a single bacterial morphotype. Bacterial microcolonies were seen between tissue elements in infected connective tissue, and the microcolonies adherent to bone surfaces coalesced to form extensive biofilms that occluded the surfaces of dead bone in sequestrae. Decalcification techniques were required to examine the interior of infected bone, but recognizable remnants were associated with very large amounts of fibrous, ruthenium red-stained material. All bacterial growth in these persistent infections occurred within an intercellular matrix, and some elements of this matrix, which was fibrous in transmission electron microscopy and amorphous in scanning electron microscopy, were associated with the surfaces of bacterial cells in a manner that suggested their production by these organisms. All of the implications of this microcolony mode of bacterial growth in osteomyelitis, and in other chronic bacterial diseases, have yet to be determined. Images PMID:4066923

  19. Results of ASTM round robin testing for mode 1 interlaminar fracture toughness of composite materials

    NASA Technical Reports Server (NTRS)

    Obrien, T. Kevin; Martin, Roderick H.

    1992-01-01

    The results are summarized of several interlaboratory 'round robin' test programs for measuring the mode 1 interlaminar fracture toughness of advanced fiber reinforced composite materials. Double Cantilever Beam (DCB) tests were conducted by participants in ASTM committee D30 on High Modulus Fibers and their Composites and by representatives of the European Group on Fracture (EGF) and the Japanese Industrial Standards Group (JIS). DCB tests were performed on three AS4 carbon fiber reinforced composite materials: AS4/3501-6 with a brittle epoxy matrix; AS4/BP907 with a tough epoxy matrix; and AS4/PEEK with a tough thermoplastic matrix. Difficulties encountered in manufacturing panels, as well as conducting the tests are discussed. Critical issues that developed during the course of the testing are highlighted. Results of the round robin testing used to determine the precision of the ASTM DCB test standard are summarized.

  20. Evaluation of Delamination Growth Characterization Methods Under Mode I Fatigue Loading

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.

    2012-01-01

    Reliable delamination characterization data for laminated composites are needed for input to analytical models of structures to predict delamination. The double-cantilevered beam (DCB) specimen is used with laminated composites to measure fracture toughness, G(sub Ic), delamination onset strain energy release rate, and growth rate data under cyclic loading. In the current study, DCB specimens of IM7/8552 graphite/epoxy supplied by two different manufacturers were tested in static and fatigue to compare the measured characterization data from the two sources, and to evaluate a proposed ASTM standard for generating Paris Law equations. Static results were used to generate compliance calibration constants for the fatigue data, and a delamination resistance curve, G(sub IR), which was used to determine the effects of fiber-bridging on delamination growth. Specimens were tested in fatigue at a cyclic G(sub Imax) level equal to 50, 40 or 30% of G(sub Ic), to determine a delamination onset curve and delamination growth rate. The delamination onset curve equations had similar exponents and the same trends. Delamination growth rate was calculated by fitting a Paris Law to the da/dN versus G(sub Imax) data. Both a 2-point and a 7-point data reduction method were used and the Paris Law equations were compared. To determine the effects of fiber-bridging, growth rate results were normalized by the delamination resistance curve for each material and compared to the non-normalized results. Paris Law exponents were found to decrease by 31% to 37% due to normalizing the growth data. Normalizing the data also greatly reduced the amount of scatter between the different specimens. Visual data records from the fatigue testing were used to calculate individual compliance calibration constants from the fatigue data for some of the specimens. The resulting da/dN versus G(sub Imax) plots showed much improved repeatability between specimens. Gretchen

  1. Nonlinear Spring Finite Elements for Predicting Mode I-Dominated Delamination Growth in Laminated Structure with Through-Thickness reinforcement

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Krueger, Ronald

    2006-01-01

    One particular concern of polymer matrix composite laminates is the relatively low resistance to delamination cracking, in particular when the dominant type of failure is mode I opening. One method proposed for alleviating this problem involves the insertion pultruded carbon pins through the laminate thickness. The pins, known as z-pins, are inserted into the prepreg laminate using an ultrasonic hammer prior to the curing process, resulting in a field of pins embedded normal to the laminate plane as illustrated in Figure. 1. Pin diameters range between 0.28-mm to 0.5-mm and standard areal densities range from 0.5% to 4%. The z-pins are provided by the manufacturer, Aztex(Registered TradeMark) , in a low-density foam preform, which acts to stabilize orientation of the pins during the insertion process [1-3]. Typical pin materials include boron and carbon fibers embedded in a polymer matrix. A number of methods have been developed for predicting delamination growth in laminates reinforced with z-pins. During a study on the effect of z-pin reinforcement on mode I delamination resistance, finite element analyses of z-pin reinforced double cantilever beam (DCB) specimens were performed by Cartie and Partridge [4]. The z-pin bridging stresses were modeled by applying equivalent forces at the pin locations. Single z-pin pull-out tests were performed to characterize the traction law of the pins under mode I loading conditions. Analytical solutions for delamination growth in z-pin reinforced DCB specimens were independently derived by Robinson and Das [5] and Ratcliffe and O'Brien [6]. In the former case, pin bridging stresses were modeled using a distributed load and in the latter example the bridging stresses were discretely modeled by way of grounded springs. Additionally, Robinson and Das developed a data reduction strategy for calculating mode I fracture toughness, G(sub Ic), from a z-pin reinforced DCB specimen test [5]. In both cases a traction law similar to that

  2. Multi-mode spectrographs for small telescopes: design, operation, performances and results

    NASA Astrophysics Data System (ADS)

    Munari, U.; Valisa, P.

    2014-03-01

    We present three generations (Mark.I, II and III) of spectrographs we put into operation with ANS Collaboration 0.61m, 0.70m and 0.84m telescopes. These spectrographs are of the Multi-Mode type, allowing for rapid interchange between Echelle high dispersion and two separate single dispersion modes (low and medium resolution). All three modes are long-slit, rotate to any angle (including parallactic compensation for atmospheric dispersion), allow to select among different comparison lamps, and are auto-guided by TV imaging the slit, which is continuously adjustable in width and by a step decker in height. The latest Mark.III model adds many new features including remote operation, spatial splitting of order overlap in single dispersion modes, interchange between prism and grating cross-dispersion in the Echelle mode, spectropolarimetry, a coronagraphic mode and direct filtered imaging without removing the spectrograph from the Cassegrain focus.

  3. Comparison of sulfur measurements from a regional fine particle network with concurrent acid modes network results

    SciTech Connect

    Bennett, R.L.; Stockburger, L.; Barnes, H.M.

    1994-01-01

    The Fine Particle Network (FPN), a system of fine particle (less than 2.5 micrometers) samplers, was operated at 41 sites selected from the Enviromental Protection Agency Acid MODES program during the two year period in 1988-90. The 24-hour sample results included fine particle mass and the most predominant chemical element concentrations determined by wavelength dispersive x-ray fluorescence analysis. Statistical summaries of the fine mass and sulfur concentrations by site and season were prepared. The availability of simultaneous particulate sulfate measurements from independent collection and analytical procedures provided an opportunity to examine their agreement and provide a more reliable data base for evaluation of regional particulate models and estimation of contribution to urban aerosol concentration.

  4. An approach to the damping of local modes of oscillations resulting from large hydraulic transients

    SciTech Connect

    Dobrijevic, D.M.; Jankovic, M.V.

    1999-09-01

    A new method of damping of local modes of oscillations under large disturbance is presented in this paper. The digital governor controller is used. Controller operates in real time to improve the generating unit transients through the guide vane position and the runner blade position. The developed digital governor controller, whose control signals are adjusted using the on-line measurements, offers better damping effects for the generator oscillations under large disturbances than the conventional controller. Digital simulations of hydroelectric power plant equipped with low-head Kaplan turbine are performed and the comparisons between the digital governor control and the conventional governor control are presented. Simulation results show that the new controller offers better performances, than the conventional controller, when the system is subjected to large disturbances.

  5. Evaluation of Delamination Onset and Growth Characterization Methods under Mode I Fatigue Loading

    NASA Technical Reports Server (NTRS)

    Murri, Gretchen B.

    2013-01-01

    Double-cantilevered beam specimens of IM7/8552 graphite/epoxy from two different manufacturers were tested in static and fatigue to compare the material characterization data and to evaluate a proposed ASTM standard for generating Paris Law equations for delamination growth. Static results were used to generate compliance calibration constants for reducing the fatigue data, and a delamination resistance curve, GIR, for each material. Specimens were tested in fatigue at different initial cyclic GImax levels to determine a delamination onset curve and the delamination growth rate. The delamination onset curve equations were similar for the two sources. Delamination growth rate was calculated by plotting da/dN versus GImax on a log-log scale and fitting a Paris Law. Two different data reduction methods were used to calculate da/dN. To determine the effects of fiber-bridging, growth results were normalized by the delamination resistance curves. Paris Law exponents decreased by 31% to 37% after normalizing the data. Visual data records from the fatigue tests were used to calculate individual compliance constants from the fatigue data. The resulting da/dN versus GImax plots showed improved repeatability for each source, compared to using averaged static data. The Paris Law expressions for the two sources showed the closest agreement using the individually fit compliance data.

  6. Growth and smolting in lower-mode Atlantic Salmon stocked into the Penobscot River, Maine

    USGS Publications Warehouse

    Zydlewski, Joseph; O'Malley, Andrew; Cox, Oliver; Ruksznis, Peter; Trial, Joan G.

    2014-01-01

    Restoration of Atlantic Salmon Salmo salar in Maine has relied on hatchery-produced fry and smolts for critical stocking strategies. Stocking fry minimizes domestication selection, but these fish have poor survival. Conversely, stocked smolts have little freshwater experience but provide higher adult returns. Lower-mode (LM) fish, those not growing fast enough to ensure smolting by the time of stocking, are a by-product of the smolt program and are an intermediate hatchery product. From 2002 to 2009, between 70,000 and 170,000 marked LM Atlantic Salmon were stocked into the Pleasant River (a tributary in the Penobscot River drainage, Maine) in late September to early October. These fish were recaptured as actively migrating smolts (screw trapping), as nonmigrants (electrofishing), and as returning adults to the Penobscot River (Veazie Dam trap). Fork length (FL) was measured and a scale sample was taken to retrospectively estimate FL at winter annulus one (FW1) using the intercept-corrected direct proportion model. The LM fish were observed to migrate as age-1, age-2, and infrequently as age-3 smolts. Those migrating as age-1 smolts had a distinctly larger estimated FL at FW1 (>112 mm) than those that remained in the river for at least one additional year. At the time of migration, age-2 and age-3 smolts were substantially larger than age-1 smolts. Returning adult Atlantic Salmon of LM origin had estimated FLs at FW1 that corresponded to smolt age (greater FL for age 1 than age 2). The LM product produces both age-1 and age-2 smolts that have greater freshwater experience than hatchery smolts and may have growth and fitness advantages. The data from this study will allow managers to better assess the probability of smolting age and manipulate hatchery growth rates to produce a targeted-size LM product.

  7. Enhanced acoustic mode coupling resulting from an internal solitary wave approaching the shelfbreak in the South China Sea.

    PubMed

    Chiu, Linus Y S; Reeder, D Benjamin; Chang, Yuan-Ying; Chen, Chi-Fang; Chiu, Ching-Sang; Lynch, James F

    2013-03-01

    Internal waves and bathymetric variation create time- and space-dependent alterations in the ocean acoustic waveguide, and cause subsequent coupling of acoustic energy between propagating normal modes. In this paper, the criterion for adiabatic invariance is extended to the case of an internal solitary wave (ISW) encountering a sloping bathymetry (i.e., continental shelfbreak). Predictions based on the extended criterion for adiabatic invariance are compared to experimental observations from the Asian Seas International Acoustics Experiment. Using a mode 1 starter field, results demonstrate time-dependent coupling of mode 1 energy to higher adjacent modes, followed by abrupt coupling of mode 5-7 energy to nonadjacent modes 8-20, produces enhanced mode coupling and higher received levels downrange of the oceanographic and bathymetric features. Numerical simulations demonstrate that increasing ISW amplitude and seafloor slope enhance the coupling of energy to adjacent and nonadjacent modes. This enhanced coupling is the direct result of the simultaneous influence of the ISW and its proximity to the shelfbreak, and, compared to the individual effect of the ISW or shelfbreak, has the capacity to scatter 2-4 times the amount of acoustic energy from below the thermocline into the upper water column beyond the shelfbreak in realistic environments.

  8. One-step growth of Si{sub 3}N{sub 4} stem-branch featured nanostructures: Morphology control by VS and VLS mode

    SciTech Connect

    Wang Qiushi; Gao Wei; Shan Lianchen; Zhang Jian; Jin Yunxia; Cong Ridong; Cui Qiliang

    2011-09-15

    We report here one-step synthesis of Si{sub 3}N{sub 4} nanodendrites by selectively applying a vapor-solid (VS) and vapor-liquid-solid (VLS) strategy via direct current arc discharge method. The resultant nanodendrites were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray powder diffraction. The spine-shaped nanodendrites were generated by a noncatalytic growth following a VS mode. The uniform secondary nanowire branches were epitaxial grown from two side surfaces of the nanowire stems. The pine-shaped nanodendrites were obtained through a catalytic growth in a VLS process. These branch nanowires were unsystematically grown from the nanocone-like stems. The photoluminescence spectra of the nanodendrites show a strong white light emission around 400-750 nm, suggesting their potential applications in light and electron emission devices. - Graphical abstract: Spine-shaped and pine-shaped Si{sub 3}N{sub 4} hierarchical nanostructures were synthesized by VS and VLS mode with plasma-assisted dc arc discharge method. Highlights: > Si{sub 3}N{sub 4} stem-branch featured nanostructures have been prepared. > Spine-shaped nanodendrites were generated by a noncatalytic growth following a VS mode. > Pine-shaped nanodendrites were obtained through a catalytic growth in a VLS process.

  9. Mode of utilization of amino acids as growth substrates by Azospirillum brasilense.

    PubMed

    Bhattacharya, Pradip

    2005-12-01

    The study was undertaken to analyze the rate of uptake and utilization of various amino acids by Azospirillum brasilense Sp81 (RG) in a basal mineral salts solution under non-nitrogen fixing condition. These amino acids including other nitrogenous compounds were tested for both N- and C-sources. The kinetic constants (Km and Vmax) of uptake of some amino acids (e.g. lysine, arginine, proline, glutamine and glutamic acid) were exploited using a Hanes-Woolf plot, and discussed in the context of nitrogen starvation or both carbon and nitrogen starvation. To summarize all the kinetic data for these amino acids strongly suggested that the mode of these amino acids utilization in this bacterium followed the same general pattern, although the quantitative differences were there. A single amino acid was able to satisfy the nitrogen needs of this bacterium in basal mineral salts solution, and this possibility could be considered for the cost-effective growth medium for this bacterium in the biotechnological industry.

  10. Improved health and growth of fish fed mannan oligosaccharides: potential mode of action.

    PubMed

    Torrecillas, Silvia; Montero, Daniel; Izquierdo, Marisol

    2014-02-01

    Nowadays, aquaculture industry still confronts several disease-related problems mainly caused by viruses, bacteria and parasites. In the last decade, the use of mannan oligosaccharides (MOS) in fish production has received increased attention due to its beneficial effects on fish performance and disease resistance. This review shows the MOS use in aquaculture with a specific emphasis on the effectiveness of the several MOS forms available in the market related to disease resistance, fish nutrition and the possible mechanisms involved. Among the main beneficial effects attributed to MOS dietary supplementation, enhanced fish performance, feed efficiency and pathogen protection by potentiation of the systemic and local immune system and the reinforcement of the epithelial barrier structure and functionality are some of the most commonly demonstrated benefits. These combined effects suggest that the reinforcement of the intestinal integrity and functionality, together with the stimulation of the innate immune system, are the primary mode of action of MOS in fish. However, the supplementation strategy related to the structure of the MOS added, the correct dose and duration, as well as fish species, size and culture conditions are determinant factors to achieve improvements in health status and growth performance.

  11. Analysis of the Numerical and Geometrical Parameters Influencing the Simulation of Mode I and Mode II Delamination Growth in Unidirectional and Textile Composites

    NASA Astrophysics Data System (ADS)

    Jacques, S.; De Baere, I.; Van Paepegem, W.

    2015-12-01

    The reliability of composite structures depends, among other damage mechanisms, on their ability to withstand delaminations. In order to have a better understanding of the cohesive zone method technique for delamination simulations, a complete analysis of the multiple parameters influencing the results is necessary. In this paper the work is concentrated on the cohesive zone method using cohesive elements. First a summary of the theory of the cohesive zone method is given. A numerical investigation on the multiple parameters influencing the numerical simulation of the mode I and mode II delamination tests has been performed. The parameters such as the stabilization method, the output frequency, the friction and the computational efficiency have been taken into account. The results will be compared to an analytical solution obtained by linear elastic fracture mechanics. Additionally the numerical simulation results will be compared to the experimental results of a glass-fibre reinforced composite material for the mode I Double Cantilever Beam (DCB) and to a carbon fibre 5-harness satin weave reinforced polyphenylene sulphide composite for the mode I DCB and mode II End Notched Flexure (ENF).

  12. Protein crystal growth results from shuttle flight 51-F

    NASA Technical Reports Server (NTRS)

    Bugg, C. E.

    1985-01-01

    The protein crystal growth (PCG) experiments run on 51-F were analyzed. It was found that: (1) sample stability is increased over that observed during the experiments on flight 51-D; (2) the dialysis experiments produced lysozyme crystals that were significantly larger than those obtained in our identical ground-based studies; (3) temperature fluctuations apparently caused problems during the crystallization experiments on 51-F; (4) it is indicated that teflon tape stabilizes droplets on the syringe tips; (5) samples survived during the reentry and landing in glass tips that were not stoppered with plungers; (6) from the ground-based studies, it was expected that equilibration should be complete within 2 to 4 days for all of these vapor-diffusion experiments, thus it appears that the vapor diffusion rates are somewhat slower under microgravity conditions; (7) drop tethering was highly successful, all four of the tethered drops were stable, even though they contained MPD solutions; (8) the PCG experiments on 51-F were done to assess the hardware and experimental procedures that are developed for future flights, when temperature control will be available. Lysozyme crystals obtained by microdialysis are considerably larger than those obtained on the ground, using the identical apparatus and procedures.

  13. Rate-dependent mode I interlaminar crack growth mechanisms in graphite/epoxy and graphite/PEEK

    NASA Technical Reports Server (NTRS)

    Gillespie, J. W., Jr.; Carlsson, L. A.; Smiley, A. J.

    1987-01-01

    In this paper the mode I fracture behavior of graphite/epoxy and graphite/PEEK composites is examined over four decades of crosshead rates (0.25-250 mm/min). Straight-sided double-cantilever-beam specimens consisting of unidirectional laminates were tested at room temperature. For graphite/epoxy the load-deflection response was linear to fracture, and stable slow crack growth initiating at the highest load level was observed for all rates tested. In contrast, mode I crack growth in the graphite/PEEK material was often unstable and showed stick-slip behavior. Subcritical crack growth occurring prior to the onset of fracture was observed at intermediate displacement rates. A mechanism for the fracture behavior of the graphite/PEEK material (based on viscoelastic, plastic, and microcrack coalescence in the process zone) is proposed and related to the observed rate-dependent phenomena.

  14. A Novel Method for Characterizing Fatigue Delamination Growth Under Mode I Using the Double Cantilever Beam Specimen

    NASA Technical Reports Server (NTRS)

    Carvalho, Nelson; Murri, G.

    2014-01-01

    A novel method is proposed to obtain Mode I delamination growth rate from a Double Cantilever Beam (DCB) specimen. In the proposed method, Unidirectional (UD) DCB specimens are tested in fatigue at different initial maximum energy release rates levels. The growth rate data obtained in the first increments of crack growth at each maximum energy release rate level are used to generate a Paris Law equation, which characterizes delamination growth rate without fiber-bridging, and can also be used to determine a delamination onset curve. The remaining delamination growth rate data from each test are used to determine a modified Paris law, which characterizes the delamination growth rate in a DCB specimen, explicitly accounting for fiber-bridging. The proposed expression captures well the scatter in experimental data obtained using the DCB specimens, suggesting its adequacy. The Paris Law characterizing delamination growth rate without fiber-bridging predicts higher delamination growth rates for the same maximum energy release rate applied, leading to a conservative estimate for delamination growth. This is particularly relevant, since in generic ply interfaces, fiber-bridging is less predominant than in UD DCB specimens. Failing to account for fiber-bridging in UD DCB specimens may underestimate the delamination growth rate, yielding non-conservative predictions.

  15. Mirror modes in the Earth's magnetosheath: Results from a global hybrid-Vlasov simulation

    NASA Astrophysics Data System (ADS)

    Hoilijoki, Sanni; Palmroth, Minna; Walsh, Brian M.; Pfau-Kempf, Yann; von Alfthan, Sebastian; Ganse, Urs; Hannuksela, Otto; Vainio, Rami

    2016-05-01

    We investigate mirror mode structures in the Earth's magnetosheath using our global kinetic Vlasiator simulation, which models ion behavior through their distribution function and treats electrons as a charge-neutralizing fluid. We follow the evolution of waves as they advect along velocity streamlines through the magnetosheath. We find that mirror mode waves are observed preferentially in the quasi-perpendicular magnetosheath along velocity streamlines that enter the sheath in the vicinity of the foreshock ULF wave boundary where there are enough initial perturbations in the plasma for the mirror modes to grow, and the plasma properties fulfill the mirror instability condition better than elsewhere in the magnetosheath. We test selection criteria defined by previous studies and show that the spatial extent over which mirror modes occur ranges from much of the magnetosheath on the quasi-perpendicular side of the subsolar point to very small isolated regions depending on the criteria.

  16. Ion surfing: a new mode for cryogenic gas catchers, experimental results

    NASA Astrophysics Data System (ADS)

    Brodeur, Maxime; Bollen, Georg; Gehring, Amanda; Morrissey, David; Pang, Gregory

    2011-10-01

    A new mode of ion-transport and collection for low-energy precision experiments at projectile fragmentation facilities was recently proposed by Bollen. Present beam thermalization methods use gas-filled linear chambers equipped with sets of electrodes that provide an electrostatic gradient and/or alternating electric fields to transport the ions towards an extraction orifice. A new cryogenic linear gas cell of the National Superconducting Cyclotron Laboratory at Michigan State University will transport ions using only electrodynamic RF fields imposed on a series of linear conductive stripes. Traditionally, the ions migrate along a descending electrostatic potential gradient applied on the individual stripes, called the drag field, which requires a large potential difference to be applied in the gas for transport over long distances. The new method to transport the ions, called ``ion surfing,'' replaces the drag field with a traveling wave. The new method can transport ions at greater speed while simplifying the overall system. We will present the results of recent measurements for the transport of 85-Rb ions over distances up to 40 cm with various gas pressures at room temperature. US Department of Energy and the US National Science Foundation.

  17. Experimental and theoretical studies of active control of resistive wall mode growth in the EXTRAP T2R reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Drake, J. R.; Brunsell, P. R.; Yadikin, D.; Cecconello, M.; Malmberg, J. A.; Gregoratto, D.; Paccagnella, R.; Bolzonella, T.; Manduchi, G.; Marrelli, L.; Ortolani, S.; Spizzo, G.; Zanca, P.; Bondeson, A.; Liu, Y. Q.

    2005-07-01

    Active feedback control of resistive wall modes (RWMs) has been demonstrated in the EXTRAP T2R reversed-field pinch experiment. The control system includes a sensor consisting of an array of magnetic coils (measuring mode harmonics) and an actuator consisting of a saddle coil array (producing control harmonics). Closed-loop (feedback) experiments using a digital controller based on a real time Fourier transform of sensor data have been studied for cases where the feedback gain was constant and real for all harmonics (corresponding to an intelligent-shell) and cases where the feedback gain could be set for selected harmonics, with both real and complex values (targeted harmonics). The growth of the dominant RWMs can be reduced by feedback for both the intelligent-shell and targeted-harmonic control systems. Because the number of toroidal positions of the saddle coils in the array is half the number of the sensors, it is predicted and observed experimentally that the control harmonic spectrum has sidebands. Individual unstable harmonics can be controlled with real gains. However if there are two unstable mode harmonics coupled by the sideband effect, control is much less effective with real gains. According to the theory, complex gains give better results for (slowly) rotating RWMs, and experiments support this prediction. In addition, open loop experiments have been used to observe the effects of resonant field errors applied to unstable, marginally stable and robustly stable modes. The observed effects of field errors are consistent with the thin-wall model, where mode growth is proportional to the resonant field error amplitude and the wall penetration time for that mode harmonic.

  18. A Failure Mode in Dense Infrared Detector Arrays Resulting in Increased Dark Current

    NASA Astrophysics Data System (ADS)

    Pinkie, Benjamin; Bellotti, Enrico

    2016-09-01

    In this paper, we investigate a failure mode that arises in dense infrared focal plane detector arrays as a consequence of the interactions of neighboring pixels through the minority carrier profiles in the common absorber layer. We consider the situation in which one pixel in a hexagonal array becomes de-biased relative to its neighbors and show that the dark current in the six neighboring pixels increases exponentially as a function of the difference between the nominal and anomalous biases. Moreover, we show that the current increase in the six nearest-neighbor pixels is in total larger than that by which the current in the affected pixel decreases, causing a net increase in the dark current. The physical origins of this effect are explained as being due to increased lateral diffusion currents that arise as a consequence of breaking the symmetry of the minority carrier profiles. We then perform a parametric study to quantify the magnitude of this effect for a number of detector geometric parameters, operating temperatures, and spectral bands. Particularly, numerical simulations are carried out for short-, mid-, and long-wavelength HgCdTe infrared detectors operating between 77 K and 210 K. We show that this effect is most prevalent in architectures for which the lateral diffusion current is the largest component of the total dark current—high operating temperature devices with narrow epitaxial absorber thicknesses and pitches small compared to the diffusion length of minority carriers. These results could prove significant particularly for short- and mid-wave infrared detectors, which are typically designed to fit these conditions.

  19. Waste compatibility safety issues and final results for tank 241-T-110 push mode samples

    SciTech Connect

    Nuzum, J.L.

    1997-05-15

    This document is the final laboratory report for Tank 241-T-110. Push mode core segments were removed from risers 2 and 6 between January 29, 1997, and February 7, 1997. Segments were received and extruded at 222-S Laboratory. Analyses were performed in accordance with Tank 241-T-110 Push Mode Core Sampling and analysis Plan (TSAP) and Safety Screening Data Quality Objective (DQO). None of the subsamples submitted for total alpha activity (AT) or differential scanning calorimetry (DSC) analyses exceeded the notification limits stated in DQO.

  20. Ponderomotive stabilization of flute modes in mirrors Feedback control and numerical results

    NASA Technical Reports Server (NTRS)

    Similon, P. L.

    1987-01-01

    Ponderomotive stabilization of rigid plasma flute modes is numerically investigated by use of a variational principle, for a simple geometry, without eikonal approximation. While the near field of the studied antenna can be stabilizing, the far field has a small contribution only, because of large cancellation by quasi mode-coupling terms. The field energy for stabilization is evaluated and is a nonnegligible fraction of the plasma thermal energy. A new antenna design is proposed, and feedback stabilization is investigated. Their use drastically reduces power requirements.

  1. Influence of modes of metal transfer on grain structure and direction of grain growth in low nickel austenitic stainless steel weld metals

    SciTech Connect

    Mukherjee, Manidipto; Saha, Saptarshi; Pal, Tapan Kumar; Kanjilal, Prasanta

    2015-04-15

    The present study elaborately discussed the effect of different modes of metal transfer (i.e., short circuit mode, spray mode and pulse mode) on grain structure and direction of grain growth in low nickel austenitic stainless steel weld metals. Electron backscattered diffraction (EBSD) analysis was used to study the grain growth direction and grain structure in weld metals. The changes in grain structure and grain growth direction were found to be essentially varied with the weld pool shape and acting forces induced by modes of metal transfer at a constant welding speed. Short circuit mode of metal transfer owing to higher Marangoni force (M{sub a}) and low electromagnetic force (R{sub m}) promotes the lower weld pool volume (Γ) and higher weld pool maximum radius (r{sub m}). Short circuit mode also shows curved and tapered columnar grain structures and the grain growth preferentially occurred in <001> direction. In contrast, spray mode of metal transfer increases the Γ and reduces the r{sub m} values due to very high R{sub m} and typically reveals straight and broad columnar grain structures with preferential growth direction in <111>. In the pulse mode of metal transfer relatively high M{sub a} and R{sub m} simultaneously increase the weld pool width and the primary penetration which might encourage relatively complex grain growth directions in the weld pool and cause a shift of major intensity from <001> to <111> direction. It can also be concluded that the fusion zone grain structure and direction of grain growth are solely dependent on modes of metal transfer and remain constant for a particular mode of metal transfer irrespective of filler wire used. - Highlights: • Welded joints of LNiASS were prepared by varying modes of metal transfer. • Weld pool shape, grain structure and grain growth direction were studied. • Short circuit mode shows curved and tapered grain growth in <001> direction. • Spray mode shows straight and broad columnar grain growth

  2. Evaluation in femoral neck fracture scintimetry: modes of region of interest selection and influence on results

    SciTech Connect

    Holmberg, S.; Mesko, L.; Stroemqvist, B.; Thorngren, K.G.

    1985-04-01

    Different sized ROIs within the femoral head and different modes of calculation were used in (/sup 99m/Tc)MDP scintimetry after femoral neck fracture. In preoperative scintimetry, correction for increased trochanteric uptake gave the best discrimination, whereas in postoperative scintimetry the direct ratio fractured/intact femoral head was superior. The change in ROI size had little influence.

  3. Controlling cell growth on titanium by surface functionalization of heptylamine using a novel combined plasma polymerization mode.

    PubMed

    Zhao, Jing H; Michalski, Wojtek P; Williams, Catherine; Li, Li; Xu, Hong-Sheng; Lamb, Peter R; Jones, Scott; Zhou, Yan M; Dai, Xiujuan J

    2011-05-01

    A novel bio-interface, produced by a combined plasma polymerization mode on a titanium (Ti) surface, was shown to enhance osteoblast growth and reduce fibroblast cell growth. This new method can securely attach a tailored interface to difficult materials such as Ti or ceramics. Here a more stable and higher density of NH₂ functional groups is able to withstand sterilization in ethanol. The biocompatibility, in terms of cell attachment and actin cytoskeleton development, was markedly improved in vitro, compared with untreated Ti surfaces and samples treated by other plasma modes. It gave a boosted (approximately six times higher) cellular response of osteoblasts in their initial adhesion stage. These factors should increase the formation of new bone around implants (reducing healing time), promoting osseointegration and thereby increasing implantation success rates. PMID:21370442

  4. Hidden modes in open disordered media: analytical, numerical, and experimental results

    NASA Astrophysics Data System (ADS)

    Bliokh, Yury P.; Freilikher, Valentin; Shi, Z.; Genack, A. Z.; Nori, Franco

    2015-11-01

    We explore numerically, analytically, and experimentally the relationship between quasi-normal modes (QNMs) and transmission resonance (TR) peaks in the transmission spectrum of one-dimensional (1D) and quasi-1D open disordered systems. It is shown that for weak disorder there exist two types of the eigenstates: ordinary QNMs which are associated with a TR, and hidden QNMs which do not exhibit peaks in transmission or within the sample. The distinctive feature of the hidden modes is that unlike ordinary ones, their lifetimes remain constant in a wide range of the strength of disorder. In this range, the averaged ratio of the number of transmission peaks {N}{{res}} to the number of QNMs {N}{{mod}}, {N}{{res}}/{N}{{mod}}, is insensitive to the type and degree of disorder and is close to the value \\sqrt{2/5}, which we derive analytically in the weak-scattering approximation. The physical nature of the hidden modes is illustrated in simple examples with a few scatterers. The analogy between ordinary and hidden QNMs and the segregation of superradiant states and trapped modes is discussed. When the coupling to the environment is tuned by an external edge reflectors, the superradiance transition is reproduced. Hidden modes have been also found in microwave measurements in quasi-1D open disordered samples. The microwave measurements and modal analysis of transmission in the crossover to localization in quasi-1D systems give a ratio of {N}{{res}}/{N}{{mod}} close to \\sqrt{2/5}. In diffusive quasi-1D samples, however, {N}{{res}}/{N}{{mod}} falls as the effective number of transmission eigenchannels M increases. Once {N}{{mod}} is divided by M, however, the ratio {N}{{res}}/{N}{{mod}} is close to the ratio found in 1D.

  5. Quantitative analysis of tissue deformation dynamics reveals three characteristic growth modes and globally aligned anisotropic tissue deformation during chick limb development

    PubMed Central

    Morishita, Yoshihiro; Kuroiwa, Atsushi; Suzuki, Takayuki

    2015-01-01

    Tissue-level characterization of deformation dynamics is crucial for understanding organ morphogenetic mechanisms, especially the interhierarchical links among molecular activities, cellular behaviors and tissue/organ morphogenetic processes. Limb development is a well-studied topic in vertebrate organogenesis. Nevertheless, there is still little understanding of tissue-level deformation relative to molecular and cellular dynamics. This is mainly because live recording of detailed cell behaviors in whole tissues is technically difficult. To overcome this limitation, by applying a recently developed Bayesian approach, we here constructed tissue deformation maps for chick limb development with high precision, based on snapshot lineage tracing using dye injection. The precision of the constructed maps was validated with a clear statistical criterion. From the geometrical analysis of the map, we identified three characteristic tissue growth modes in the limb and showed that they are consistent with local growth factor activity and cell cycle length. In particular, we report that SHH signaling activity changes dynamically with developmental stage and strongly correlates with the dynamic shift in the tissue growth mode. We also found anisotropic tissue deformation along the proximal-distal axis. Morphogenetic simulation and experimental studies suggested that this directional tissue elongation, and not local growth, has the greatest impact on limb shaping. This result was supported by the novel finding that anisotropic tissue elongation along the proximal-distal axis occurs independently of cell proliferation. Our study marks a pivotal point for multi-scale system understanding in vertebrate development. PMID:25858459

  6. Step-Edge-Guided Nucleation and Growth of Aligned WSe2 on Sapphire via a Layer-over-Layer Growth Mode.

    PubMed

    Chen, Liang; Liu, Bilu; Ge, Mingyuan; Ma, Yuqiang; Abbas, Ahmad N; Zhou, Chongwu

    2015-08-25

    Two-dimensional (2D) materials beyond graphene have drawn a lot of attention recently. Among the large family of 2D materials, transitional metal dichalcogenides (TMDCs), for example, molybdenum disulfides (MoS2) and tungsten diselenides (WSe2), have been demonstrated to be good candidates for advanced electronics, optoelectronics, and other applications. Growth of large single-crystalline domains and continuous films of monolayer TMDCs has been achieved recently. Usually, these TMDC flakes nucleate randomly on substrates, and their orientation cannot be controlled. Nucleation control and orientation control are important steps in 2D material growth, because randomly nucleated and orientated flakes will form grain boundaries when adjacent flakes merge together, and the formation of grain boundaries may degrade mechanical and electrical properties of as-grown materials. The use of single crystalline substrates enables the alignment of as-grown TMDC flakes via a substrate-flake epitaxial interaction, as demonstrated recently. Here we report a step-edge-guided nucleation and growth approach for the aligned growth of 2D WSe2 by a chemical vapor deposition method using C-plane sapphire as substrates. We found that at temperatures above 950 °C the growth is strongly guided by the atomic steps on the sapphire surface, which leads to the aligned growth of WSe2 along the step edges on the sapphire substrate. In addition, such atomic steps facilitate a layer-over-layer overlapping process to form few-layer WSe2 structures, which is different from the classical layer-by-layer mode for thin-film growth. This work introduces an efficient way to achieve oriented growth of 2D WSe2 and adds fresh knowledge on the growth mechanism of WSe2 and potentially other 2D materials. PMID:26221865

  7. Step-Edge-Guided Nucleation and Growth of Aligned WSe2 on Sapphire via a Layer-over-Layer Growth Mode.

    PubMed

    Chen, Liang; Liu, Bilu; Ge, Mingyuan; Ma, Yuqiang; Abbas, Ahmad N; Zhou, Chongwu

    2015-08-25

    Two-dimensional (2D) materials beyond graphene have drawn a lot of attention recently. Among the large family of 2D materials, transitional metal dichalcogenides (TMDCs), for example, molybdenum disulfides (MoS2) and tungsten diselenides (WSe2), have been demonstrated to be good candidates for advanced electronics, optoelectronics, and other applications. Growth of large single-crystalline domains and continuous films of monolayer TMDCs has been achieved recently. Usually, these TMDC flakes nucleate randomly on substrates, and their orientation cannot be controlled. Nucleation control and orientation control are important steps in 2D material growth, because randomly nucleated and orientated flakes will form grain boundaries when adjacent flakes merge together, and the formation of grain boundaries may degrade mechanical and electrical properties of as-grown materials. The use of single crystalline substrates enables the alignment of as-grown TMDC flakes via a substrate-flake epitaxial interaction, as demonstrated recently. Here we report a step-edge-guided nucleation and growth approach for the aligned growth of 2D WSe2 by a chemical vapor deposition method using C-plane sapphire as substrates. We found that at temperatures above 950 °C the growth is strongly guided by the atomic steps on the sapphire surface, which leads to the aligned growth of WSe2 along the step edges on the sapphire substrate. In addition, such atomic steps facilitate a layer-over-layer overlapping process to form few-layer WSe2 structures, which is different from the classical layer-by-layer mode for thin-film growth. This work introduces an efficient way to achieve oriented growth of 2D WSe2 and adds fresh knowledge on the growth mechanism of WSe2 and potentially other 2D materials.

  8. Biochar Treatment Resulted in a Combined Effect on Soybean Growth Promotion and a Shift in Plant Growth Promoting Rhizobacteria

    PubMed Central

    Egamberdieva, Dilfuza; Wirth, Stephan; Behrendt, Undine; Abd_Allah, Elsayed F.; Berg, Gabriele

    2016-01-01

    The application of biochar to soil is considered to have the potential for long-term soil carbon sequestration, as well as for improving plant growth and suppressing soil pathogens. In our study we evaluated the effect of biochar on the plant growth of soybeans, as well as on the community composition of root-associated bacteria with plant growth promoting traits. Two types of biochar, namely, maize biochar (MBC), wood biochar (WBC), and hydrochar (HTC) were used for pot experiments to monitor plant growth. Soybean plants grown in soil amended with HTC char (2%) showed the best performance and were collected for isolation and further characterization of root-associated bacteria for multiple plant growth promoting traits. Only HTC char amendment resulted in a statistically significant increase in the root and shoot dry weight of soybeans. Interestingly, rhizosphere isolates from HTC char amended soil showed higher diversity than the rhizosphere isolates from the control soil. In addition, a higher proportion of isolates from HTC char amended soil compared with control soil was found to express plant growth promoting properties and showed antagonistic activity against one or more phytopathogenic fungi. Our study provided evidence that improved plant growth by biochar incorporation into soil results from the combination of a direct effect that is dependent on the type of char and a microbiome shift in root-associated beneficial bacteria. PMID:26941730

  9. Use of anomolous thermal imaging effects for multi-mode systems control during crystal growth

    NASA Technical Reports Server (NTRS)

    Wargo, Michael J.

    1989-01-01

    Real time image processing techniques, combined with multitasking computational capabilities are used to establish thermal imaging as a multimode sensor for systems control during crystal growth. Whereas certain regions of the high temperature scene are presently unusable for quantitative determination of temperature, the anomalous information thus obtained is found to serve as a potentially low noise source of other important systems control output. Using this approach, the light emission/reflection characteristics of the crystal, meniscus and melt system are used to infer the crystal diameter and a linear regression algorithm is employed to determine the local diameter trend. This data is utilized as input for closed loop control of crystal shape. No performance penalty in thermal imaging speed is paid for this added functionality. Approach to secondary (diameter) sensor design and systems control structure is discussed. Preliminary experimental results are presented.

  10. High-resolution simulations and modeling of reshocked single-mode Richtmyer-Meshkov instability. I. Comparison to experimental data and to amplitude growth model predictions

    SciTech Connect

    Latini, M; Schilling, O; Don, W

    2006-05-15

    The reshocked single-mode Richtmyer-Meshkov instability is simulated in two spatial dimensions using the fifth- and ninth-order weighted essentially non-oscillatory shock-capturing method with uniform spatial resolution of 256 points per initial perturbation wavelength. The initial conditions and computational domain are modeled after the single-mode, Mach 1.21 air(acetone)/SF{sub 6} shock tube experiment of Collins and Jacobs [J. Fluid Mech. 464, 113 (2002)]. The simulation densities are shown to be in very good agreement with the corrected experimental planar laser-induced fluorescence images at selected times before reshock of the evolving interface. Analytical, semianalytical and phenomenological linear and nonlinear, impulsive, perturbation and potential flow models for single-mode Richtmyer-Meshkov unstable perturbation growth are summarized. The simulation amplitudes are shown to be in very good agreement with the experimental data and with the predictions of linear amplitude growth models for small times and with those of nonlinear amplitude growth models at later times up to the time at which the driver-based expansion in the experiment (but not present in the simulations or models) expands the layer before reshock. The qualitative and quantitative differences between the fifth- and ninth-order simulation results are discussed. Using a local and global quantitative metric, the prediction of the Zhang and Sohn [Phys. Fluids 9, 1106 (1997)] nonlinear Pade model is shown to be in best overall agreement with the simulation amplitudes before reshock. The sensitivity of the amplitude growth model predictions to the initial growth rate from linear instability theory, the post-shock Atwood number and amplitude, and the velocity jump due to the passage of the shock through the interface is also investigated numerically. In Part II [Phys. Fluids (2006)], a comprehensive investigation of mixing induced by the reshocked single-mode Richtmyer-Meshkov instability is

  11. Overexpression of the Tomato Pollen Receptor Kinase LePRK1 Rewires Pollen Tube Growth to a Blebbing Mode[W][OPEN

    PubMed Central

    Gui, Cai-Ping; Dong, Xin; Liu, Hai-Kuan; Huang, Wei-Jie; Zhang, Dong; Wang, Shu-Jie; Barberini, María Laura; Gao, Xiao-Yan; Muschietti, Jorge; McCormick, Sheila

    2014-01-01

    The tubular growth of a pollen tube cell is crucial for the sexual reproduction of flowering plants. LePRK1 is a pollen-specific and plasma membrane–localized receptor-like kinase from tomato (Solanum lycopersicum). LePRK1 interacts with another receptor, LePRK2, and with KINASE PARTNER PROTEIN (KPP), a Rop guanine nucleotide exchange factor. Here, we show that pollen tubes overexpressing LePRK1 or a truncated LePRK1 lacking its extracellular domain (LePRK1ΔECD) have enlarged tips but also extend their leading edges by producing “blebs.” Coexpression of LePRK1 and tomato PLIM2a, an actin bundling protein that interacts with KPP in a Ca2+-responsive manner, suppressed these LePRK1 overexpression phenotypes, whereas pollen tubes coexpressing KPP, LePRK1, and PLIM2a resumed the blebbing growth mode. We conclude that overexpression of LePRK1 or LePRK1ΔECD rewires pollen tube growth to a blebbing mode, through KPP- and PLIM2a-mediated bundling of actin filaments from tip plasma membranes. Arabidopsis thaliana pollen tubes expressing LePRK1ΔECD also grew by blebbing. Our results exposed a hidden capability of the pollen tube cell: upon overexpression of a single membrane-localized molecule, LePRK1 or LePRK1ΔECD, it can switch to an alternative mechanism for extension of the leading edge that is analogous to the blebbing growth mode reported for Dictyostelium and for Drosophila melanogaster stem cells. PMID:25194029

  12. Mode of action: developmental thyroid hormone insufficiency--neurological abnormalities resulting from exposure to propylthiouracil.

    PubMed

    Zoeller, R Thomas; Crofton, Kevin M

    2005-01-01

    Because thyroid hormone is essential for normal brain development before and after birth, environmental chemicals that interfere with thyroid hormone signaling can adversely affect brain development. Adverse consequences of thyroid hormone insufficiency depend both on severity and developmental timing, indicating that environmental antithyroid factors may produce different effects at different developmental windows of exposure. Mechanistic studies can provide important insight into the potential impact of chemicals on human thyroid function, but relevance to humans must be systematically evaluated. This kind of analysis depends on data sets that include information about animals and humans. The drug 6-n-propyl-2-thiouracil (PTU) is used in animals to experimentally manipulate serum thyroid hormone levels, and in humans to treat patients, including pregnant women, with Graves' disease. A systematic analysis of the mode of action (MOA) of PTU in rats and in humans discloses similar modes of action. While the analysis predicts that PTU doses that produce thyroid hormone insufficiency in humans would adversely affect the developing brain, careful monitoring of PTU administration in pregnant and lactating humans keeps infant serum thyroid hormone levels within the normal range.

  13. Interfacial wave theory of dendrite growth - Global mode solution and quantum condition

    NASA Technical Reports Server (NTRS)

    Xu, Jian-Jun

    1990-01-01

    The signal feedback process at the edge of the dendrite tip is investigated, and the global instability mechanism of the system is derived. A mechanism is developed to describe a discrete set of unstable global modes for the system. Called WEASR, the method considers the wave emission at the turning point and signal reflections between the turning point and the front edge of the tip. It is shown that the method can obtain the asymptotic solutions for the unstable global modes and the quantum condition for the corresponding eigenvalues. A turning point called the pattern formation condition is shown to be crucial in the formation of dendritic structure and the choice of the final tip velocity. The wave emission process is outlined, and the importance of a signal feedback process at the edge of the dendrite tip is demonstrated. Parameters such as stability and surface tension can be analyzed in terms of their effects on WEASR modes.

  14. [Effects of different water-saving irrigation modes on chestnut growth and fruiting in drought hilly land].

    PubMed

    Tian, Shou-Le; Shen, Guang-Ning; Xu, Lin; Sun, Xiao-Li

    2012-03-01

    Taking the chestnut trees in a semi-arid and semi-humid hilly orchard of Tai' an, Shandong Province of East China as test objects, a field experiment was conducted to study the effects of different water-saving irrigation modes (pottery jar storing water, small hole storing water, and border irrigation with covering) on the soil moisture characteristics and the growth, fruiting, and development of chestnut roots. Comparing with the control (border irrigation), all the three water-saving irrigation modes could prolong the period of soil keeping moist, and the best effect came from pottery, jar treatment, with the soil keeping moist for 32 days, 13 days longer than the control. Under water-saving irrigations, the bearing branches length and number, leaf area and mass, and shoot mixed buds all increased obviously. Both pottery jar storing water and small hole storing water could irrigate deeper roots and induce root growth in deeper soil layers, and thus, relieve the drought stress on superficial roots. The three water-saving irrigation modes could increase chestnut yield markedly, with an increment of 18.8%, 16.5%, and 14.2%, respectively, as compared with the control.

  15. Measurements of sideband mode-coupling effects and linear MHD growth rates associated with the ponderomotive force

    SciTech Connect

    Meassick, S.

    1988-01-01

    Measurements of the interactions of rf waves in the ion cyclotron range of frequencies (ICRF) with flute interchange modes are presented. Interactions between the applied l = +1 rf wave and an m = {minus}1 flute mode give rise to sidebands above and below the rf frequency with mode numbers of l = 0 and l = +2 respectively. The contribution of the sideband terms to perturbed energy are shown to cancel 40% of the direct ponderomotive contribution for w/w{sub ci} = 1.25. This is less then the 90% predicted by self-consistent theories of the ponderomotive force for an applied l = +1 rf wave above the ion cyclotron frequency with a large separation between the plasma and the vacuum vessel. Measurements of the linear growth and decay rate of the flute instability in the presence of rf are presented. These measurements allow a determination of the net stabilizing force on the plasma. The measured growth rate is in good agreement with that calculated by considering only the curvature driven instability and the ponderomotive force.

  16. Summary of Mode Deactivation Therapy, Cognitive Behavior Therapy and Social Skills Training with Two Year Post Treatment Results

    ERIC Educational Resources Information Center

    Apsche, Jack A.; Bass, Christopher K.; Siv, Alexander M.

    2006-01-01

    This study summarized two treatment research studies and included recidivism data for two years post discharge for group therapy. The study compared Mode deactivation Therapy (MDT), Cognitive Behavior Therapy (CBT), and Social Skills training (SST), results of the MDT series of studies and the two year post-study recidivism data. The data from the…

  17. Growth curves for Turkish Girls with Turner Syndrome: Results of the Turkish Turner Syndrome Study Group

    PubMed Central

    Darendeliler, Feyza; Yeşilkaya, Ediz; Bereket, Abdullah; Baş, Firdevs; Bundak, Rüveyde; Sarı, Erkan; Küçükemre Aydın, Banu; Darcan, Şükran; Dündar, Bumin; Büyükinan, Muammer; Kara, Cengiz; Mazıcıoğlu, Mümtaz M.; Adal, Erdal; Akıncı, Ayşehan; Atabek, Mehmet Emre; Demirel, Fatma; Çelik, Nurullah; Özkan, Behzat; Özhan, Bayram; Orbak, Zerrin; Ersoy, Betül; Doğan, Murat; Ataş, Ali; Turan, Serap; Gökşen, Damla; Tarım, Ömer; Yüksel, Bilgin; Ercan, Oya; Hatun, Şükrü; Şimşek, Enver; Ökten, Ayşenur; Abacı, Ayhan; Döneray, Hakan; Özbek, Mehmet Nuri; Keskin, Mehmet; Önal, Hasan; Akyürek, Nesibe; Bulan, Kezban; Tepe, Derya; Emeksiz, Hamdi Cihan; Demir, Korcan; Kızılay, Deniz; Topaloğlu, Ali Kemal; Eren, Erdal; Özen, Samim; Demirbilek, Hüseyin; Abalı, Saygın; Akın, Leyla; Eklioğlu, Beray Selver; Kaba, Sultan; Anık, Ahmet; Baş, Serpil; Ünüvar, Tolga; Sağlam, Halil; Bolu, Semih; Özgen, Tolga; Doğan, Durmuş; Çakır, Esra Deniz; Şen, Yaşar; Andıran, Nesibe; Çizmecioğlu, Filiz; Evliyaoğlu, Olcay; Karagüzel, Gülay; Pirgon, Özgür; Çatlı, Gönül; Can, Hatice Dilek; Gürbüz, Fatih; Binay, Çiğdem; Baş, Veysel Nijat; Sağlam, Celal; Gül, Davut; Polat, Adem; Açıkel, Cengizhan; Cinaz, Peyami

    2015-01-01

    Objective: Children with Turner syndrome (TS) have a specific growth pattern that is quite different from that of healthy children. Many countries have population-specific growth charts for TS. Considering national and ethnic differences, we undertook this multicenter collaborative study to construct growth charts and reference values for height, weight and body mass index (BMI) from 3 years of age to adulthood for spontaneous growth of Turkish girls with TS. Methods: Cross-sectional height and weight data of 842 patients with TS, younger than 18 years of age and before starting any therapy, were evaluated. Results: The data were processed to calculate the 3rd, 10th, 25th, 50th, 75th, 90th and 97th percentile values for defined ages and to construct growth curves for height-for-age, weight-for-age and BMI-for-age of girls with TS. The growth pattern of TS girls in this series resembled the growth pattern of TS girls in other reports, but there were differences in height between our series and the others. Conclusion: This study provides disease-specific growth charts for Turkish girls with TS. These disease-specific national growth charts will serve to improve the evaluation of growth and its management with growth-promoting therapeutic agents in TS patients. PMID:26831551

  18. Water and lysozyme: Some results from the bending and stretching vibrational modes

    NASA Astrophysics Data System (ADS)

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Cirino; Cicero, Nicola; Stanley, H. Eugene

    2015-10-01

    The dynamic or glass transition in biomolecules is important to their functioning. Also essential is the transition between the protein native state and the unfolding process. To better understand these transitions, we use Fourier transform infrared spectroscopy to study the vibrational bending and stretching modes of hydrated lysozymes across a wide temperature range. We find that these transitions are triggered by the strong hydrogen bond coupling between the protein and hydration water. More precisely, we demonstrate that in both cases the water properties dominate the evolution of the system. We find that two characteristic temperatures are relevant: in the supercooled regime of confined water, the fragile-to-strong dynamic transition occurs at T L , and in the stable liquid phase, T* ≈ 315 ± 5 K characterizes the behavior of both isothermal compressibility K T ( T, P) and the coefficient of thermal expansion a P ( T, P).

  19. Pistillate flower development and pollen tube growth mode during the delayed fertilization stage in Corylus heterophylla Fisch.

    PubMed

    Liu, Jianfeng; Zhang, Huidi; Cheng, Yunqing; Kafkas, Salih; Güney, Murat

    2014-09-01

    Unlike most angiosperms, in which fertilization occurs within several days after pollination, fertilization in hazel (Corylus Spp.) is delayed by two to three and a half months. However, the female inflorescences or young fruits are too hard or lignified to be dissected according to regular paraffin sectioning technique. So, what the nature of development during the extended progamic phases of hazel remains unknown. The female inflorescence development and pollen tube growth mode during the delayed fertilization stage in hazel were investigated by improved paraffin sectioning and aniline blue staining of pollen tubes. The results showed ovaries and ovules of hazel were invisible at the time of blooming. Early ovary and ovule primordium began to form from 15 to 20 days after blooming, respectively. Integument and mature embryo sacs differentiated from the nucellus on 40th and 55th day after blooming, respectively. Pollen tubes were retarded in the bottom of the style or the pollen tube cavity (PTC, a specifical lignified cavity structure at the bottom of style for pollen tube to rest during progamic phase) for about 26 days. Then, the pollen tubes were observed to leave the PTC and began to enter the ovary. After that, a single pollen tube passed through the vicinity of the micropyle. Finally, pollen tubes turned a corner and penetrated the embryo sac through the tissue of the chalaza instead of micropyle on 52 and 55 days after blooming, respectively. The results of more in-depth information will be beneficial to better understanding of the delayed fertilization process in hazel.

  20. The lack of synchronization between iron uptake and cell growth leads to iron overload in Saccharomyces cerevisiae during post-exponential growth modes.

    PubMed

    Park, Jinkyu; McCormick, Sean P; Chakrabarti, Mrinmoy; Lindahl, Paul A

    2013-12-31

    Fermenting cells growing exponentially on rich (YPAD) medium underwent a transition to a slow-growing state as glucose levels declined and their metabolism shifted to respiration. During exponential growth, Fe import and cell-growth rates were matched, affording an approximately invariant cellular Fe concentration. During the transition period, the high-affinity Fe import rate declined slower than the cell-growth rate declined, causing Fe to accumulate, initially as Fe(III) oxyhydroxide nanoparticles but eventually as mitochondrial and vacuolar Fe. Once the cells had reached slow-growth mode, Fe import and cell-growth rates were again matched, and the cellular Fe concentration was again approximately invariant. Fermenting cells grown on minimal medium (MM) grew more slowly during the exponential phase and underwent a transition to a true stationary state as glucose levels declined. The Fe concentration of MM cells that just entered the stationary state was similar to that of YPAD cells, but MM cells continued to accumulate Fe in the stationary state. Fe initially accumulated as nanoparticles and high-spin Fe(II) species, but vacuolar Fe(III) also eventually accumulated. Surprisingly, Fe-packed 5-day-old MM cells suffered no more reactive oxygen species (ROS) damage than younger cells, suggesting that the Fe concentration alone does not accurately predict the extent of ROS damage. The mode and rate of growth at the time of harvesting dramatically affected cellular Fe content. A mathematical model of Fe metabolism in a growing cell was developed. The model included the import of Fe via a regulated high-affinity pathway and an unregulated low-affinity pathway. The import of Fe from the cytosol to vacuoles and mitochondria and nanoparticle formation were also included. The model captured essential trafficking behavior, demonstrating that cells regulate Fe import in accordance with their overall growth rate and that they misregulate Fe import when nanoparticles

  1. First results on double {beta}-decay modes of Cd, Te, and Zn Isotopes

    SciTech Connect

    Bloxham, T.; Freer, M.; Boston, A.; Nolan, P.; Dawson, J.; Reeve, C.; Wilson, J. R.; Zuber, K.; Dobos, D.; Goessling, C.; Kiel, H.; Muenstermann, D.; Oehl, S.; Fox, S. P.; Fulton, B. R.; McGrath, J.; Wadsworth, R.; Harrison, P. F.; Morgan, B.; Ramachers, Y.

    2007-08-15

    Four 1-cm{sup 3} CdZnTe semiconductor detectors were operated in the Gran Sasso National Laboratory to explore the feasibility of such devices for double {beta}-decay searches as proposed for the COBRA experiment. The research involved background studies accompanied by measurements of energy resolution performed at the surface. Energy resolutions sufficient to reduce the contribution of two-neutrino double {beta}-decay events to a negligible level for a large-scale experiment have already been achieved and further improvements are expected. Using activity measurements of contaminants in all construction materials a background model was developed with the help of Monte Carlo simulations and major background sources were identified. A total exposure of 4.34 kg{center_dot}days of underground data have been accumulated allowing a search for neutrinoless double {beta}-decay modes of seven isotopes found in CdZnTe. Half-life limits (90% C.L.) are presented for decays to ground and excited states. Four improved lower limits have been obtained, including zero neutrino double electron capture transitions of {sup 64}Zn and {sup 120}Te to the ground state, which are 1.19x10{sup 17} years and 2.68x10{sup 15} years, respectively.

  2. Mode of Filamentous Growth of Leucothrix mucor in Pure Culture and in Nature, as Studied by Tritiated Thymidine Autoradiography

    PubMed Central

    Brock, Thomas D.

    1967-01-01

    Mode of growth of Leucothrix mucor filaments was measured by autoradiography with tritiated thymidine. Studies were performed on L. mucor in pure cultures in free suspension, as an epiphyte of pure cultures of the red alga Antithamnion sarniense, and as an epiphyte of red algae in the sea. Statistical analyses of the distribution of growing cells was done by use of the nonparametric One-Sample Runs Test and a Cluster analysis adapted from quadrat analyses of plant ecologists. No evidence of preferential growth at base or tip of L. mucor filaments was obtained in any of these studies. However, in nature, but not in the laboratory, there were regions of L. mucor filaments which were nongrowing or dormant. Such nongrowing regions could incorporate tritiated glucose. Images PMID:6025435

  3. Effects of dietary fructooligosaccharide levels and feeding modes on growth, immune responses, antioxidant capability and disease resistance of blunt snout bream (Megalobrama amblycephala).

    PubMed

    Zhang, Chun-Nuan; Li, Xiang-Fei; Jiang, Guang-Zhen; Zhang, Ding-Dong; Tian, Hong-Yan; Li, Jun-Yi; Liu, Wen-Bin

    2014-12-01

    This study aimed to determine the effects of fructooligosaccharide (FOS) levels and its feeding modes on growth, immune response, antioxidant capability and disease resistance of blunt snout bream (Megalobrama amblycephala). Fish (12.5 ± 0.5 g) were subjected to three FOS levels (0, 0.4% and 0.8%) and two feeding modes (supplementing FOS continuously and supplementing FOS two days interval 5 days) according to a 3 × 2 factorial design. At the end of 8-week feeding trial, fish were challenged by Aeromonas hydrophila with concentration of 1 × 10(5) CFU mL(-1) and mortality was recorded for the next 96 h. Fish fed 0.4% FOS continuously (D2) and fish fed the basal diet for 5 days followed by 0.8% FOS for 2 days (D5) showed admirable growth performance. The highest plasma lysozyme, acid phosphatase and myeloperoxidase activities as well as complement component 3, total protein and immunoglobulin M (IgM) levels were all observed in fish fed D5. They were significantly higher (P < 0.05) than those of the control group and/or fish fed 0.8% FOS continuously, but exhibited no statistical difference (P > 0.05) with that of fish fed D2. A similar trend was also observed in antioxidant capability as well as the expression of Leap-I and Leap-Ⅱ. Mortality showed an opposite trend with the immune response with the lowest rate observed in fish fed D5. The results indicated that diet supplementing FOS in appropriate levels and feeding modes could improve the growth, immune response and antioxidant capability of fish, as might consequently lead to enhanced disease resistance. It can be speculated that the basal diet for 5 days followed by 0.8% FOS for 2 days was most suitable for blunt snout bream.

  4. SPA-LEED study of the morphology and nucleation of a novel growth mode and the "devil's staircase" on lead/silicon(111)

    NASA Astrophysics Data System (ADS)

    Yeh, Wang-Chi Vincent

    In this thesis we describe two intriguing and unexpected discoveries we made in the Pb/Si(111). A novel growth mode was discovered on Pb thin film grown on Si(111)-7 x 7 reconstructed surface: nano-scale islands of uniform 7-layer height with steep edges and flat tops can form below room temperature. This growth mode is different from the three common modes: Frank-van der Merwe, Volmer-Weber, and Stranski-Krastanov modes. The three common modes could be explained by thermodynamic considerations on the surface free energy and do not lead to the type of self-organization we have discovered. This novel mode is explained by quantum size effects (QSE), which states that the confinement of electrons inside a well requires that the dimensions of the well meet the requirements of energy quantization: the electron wavefunctions have to form standing waves within the confining well. Further study showed that different stable heights that differ by two-layer difference could be selected by changing deposition temperature, total coverage, annealing temperature, or initial interface. Oxygen covered structures are found to retain their selected height up to almost room temperature. In addition, a novel "devil's staircase" was discovered in Pb/Si(111) between coverage 6/5 ML and 4/3 ML. Experimentally it has been an outstanding challenge to show a "devil's staircase" since physical phenomena are not expected to be described by non-differentiable functions, i.e., the stability curve Deltamu vs. theta of a "devil's staircase". This novel staircase differs from conventional ones in the difference between their two generating phases: their [11¯0] dimensions differ by two lattice constants instead of one. It was found unexpectedly that such a staircase can form with macroscopic spatial extent (˜0.5 mm) even at low temperature (T ˜ 120K) where atoms are not expected to mobile! This unusual result suggests that a high degree of self-organization is possible in the system of Pb/Si(111).

  5. Multi-stacked InAs/GaAs quantum dots grown with different growth modes for quantum dot solar cells

    SciTech Connect

    Kim, Yeongho; Ban, Keun-Yong Honsberg, Christiana B.

    2015-06-01

    We have studied the material properties and device performance of InAs/GaAs quantum dot solar cells (QDSCs) made using three different QD growth modes: Stranski-Krastanov (S-K), quasi-monolayer (QML), and sub-monolayer (SML) growth modes. All QDSCs show an extended external quantum efficiency (EQE) at near infrared wavelengths of 950–1070 nm from the QD absorption. Compared to the S-K and SML QDSCs, the QML QDSC with a higher strain exhibits a poor EQE response in the wavelength region of 300–880 nm due to increased non-radiative recombination. The conversion efficiency of the S-K and SML QDSCs exceeds that of the reference cell (13.4%) without QDs due to an enhanced photocurrent (>16% increase) produced by the silicon doped QD stacks. However, as expected from the EQE of the QML QDSC, the increase of strain-induced crystalline defects greatly degrades the photocurrent and open-circuit voltage, leading to the lowest conversion efficiency (8.9%)

  6. 45-Day safety screen results for tank 241-U-202, push mode, cores 75 and 78

    SciTech Connect

    Jo, J.

    1995-05-05

    This document is a report of the analytical results for samples collected from the radioactive wastes in Tank 241-U-202 at the Hanford Reservation. Core samples were collected from the solid wastes in the tank and underwent safety screening analyses including differential scanning calorimetry, thermogravimetric analysis, and total alpha analysis. Results indicate that no safety screening notification limits were exceeded.

  7. Comparison of the spiral growth modes of silicon-face and carbon-face silicon carbide crystals

    NASA Astrophysics Data System (ADS)

    Seiss, M.; Ouisse, T.; Chaussende, D.

    2013-12-01

    We have studied the dependence of the terrace width of growth spirals on local supersaturation during the growth of on-axis silicon carbide (SiC) crystals. Local supersaturation is adjusted by changing the residual argon gas pressure inside the sublimation growth chamber. Whereas Si-face crystals seem to partly verify the model of Burton, Cabrera and Frank, we found that on C-face crystals, the terrace width is independent of supersaturation. In contrast to previously reported data obtained from KDP crystals, we cannot ascribe our result to hollow-core dislocations or micropipes, as the observed growth spirals arose from independent and closed, unit or double-unit screw dislocations. Besides, we checked that neither the finite growth area nor the influence of the stress field of the dislocation can explain our data.

  8. 45-Day safety screen results for tank 241-C-105, push mode, cores 72 and 76

    SciTech Connect

    Sasaki, L.M.

    1995-05-03

    This document is a report of the analytical results for samples collected between March 14 and March 22, 1995 from the radioactive wastes in Tank 241-C-105 at the Hanford Reservation. Core samples were collected from the solid wastes in the tank and underwent safety screening analyses including differential scanning calorimetry, thermogravimetric analysis, and total alpha analysis.

  9. Ratios between acute aquatic toxicity and effects on population growth rates in relation to toxicant mode of action

    SciTech Connect

    Roex, E.W.M.; Gestel, C.A.M. Van; Wezel, A.P. Van; Straalen, N.M. Van

    2000-03-01

    Environmental risk assessment of chemicals is mostly based on the results of standardized toxicity tests. To obtain environmental quality criteria, extrapolation factors are used that depend on the amount and quality of available data. These extrapolation factors do not, however, take into account the mode of action of the compound tested or the life history of the test organism. In this study, the authors analyzed the variability in acute-to-chronic ratios (ACRs) for various chemicals in relation to their mode of action. Chemicals were classified as nonpolar narcotics, polar narcotics, specifically acting compounds, and heavy metals. As an acute endpoint, the LC50 was used; as a chronic endpoint, the lowest test concentration at which the natural rate of population increase (r) is affected, or LOEC(r), was used. Data were derived from the on-line literature. Nonpolar narcotic chemicals demonstrate the smallest variation in ACRs, and acute tests can be used to derive chronic endpoints for this class. For the other classes, the variation in ACRs is larger. Fish species especially show a relatively large ACR. For heavy metals, differences in the mode of action may play an important role in explaining differences in ACRs. For the other three classes, however, it is less reliable to predict chronic toxicity using the results of acute tests. In general, differences in species sensitivity rather than in mode of action for the chemical seem to determine differences in ACRs.

  10. The Mode of Cell Wall Growth in Selected Archaea Is Similar to the General Mode of Cell Wall Growth in Bacteria as Revealed by Fluorescent Dye Analysis ▿ †

    PubMed Central

    Wirth, Reinhard; Bellack, Annett; Bertl, Markus; Bilek, Yvonne; Heimerl, Thomas; Herzog, Bastian; Leisner, Madeleine; Probst, Alexander; Rachel, Reinhard; Sarbu, Christina; Schopf, Simone; Wanner, Gerhard

    2011-01-01

    The surfaces of 8 bacterial and 23 archaeal species, including many hyperthermophilic Archaea, could be stained using succinimidyl esters of fluorescent dyes. This allowed us for the first time to analyze the mode of cell wall growth in Archaea by subculturing stained cells. The data obtained show that incorporation of new cell wall material in Archaea follows the pattern observed for Bacteria: in the coccoid species Pyrococcus furiosus incorporation was in the region of septum formation while for the rod-shaped species Methanopyrus kandleri and Methanothermus sociabilis, a diffuse incorporation of cell wall material over the cell length was observed. Cell surface appendages like fimbriae/pili, fibers, or flagella were detectable by fluorescence staining only in a very few cases although their presence was proven by electron microscopy. Our data in addition prove that Alexa Fluor dyes can be used for in situ analyses at temperatures up to 100°C. PMID:21169435

  11. Accelerated fatigue crack growth behavior of PWA 1480 single crystal alloy and its dependence on the deformation mode

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Ghosn, Louis J.

    1988-01-01

    An investigation of the fatigue crack growth (FCG) behavior of PWA 1480 single crystal nickel base superalloy was conducted. Typical Paris region behavior was observed above a delta K of 8 MPa sq rt of m. However, below that stress intensity range, the alloy exhibited highly unusual behavior. This behavior consisted of a region where the crack growth rate became essentially independent of the applied stress intensity. The transition in the FCG behavior was related to a change in the observed crack growth mechanisms. In the Paris region, fatigue failure occurred along (111) facets; however, at the lower stress intensities, (001) fatigue failure was observed. A mechanism was proposed, based on barriers to dislocation motion, to explain the changes in the observed FCG behavior. The FCG data were also evaluated in terms of a recently proposed stress intensity parameter, K sub rss. This parameter, based on the resolved shear stresses on the slip planes, quantified the crack driving force as well as the mode I delta K, and at the same time was also able to predict the microscopic crack path under different stress states.

  12. Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma.

    PubMed

    Nishiokada, Takuya; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Muramatsu, Masayuki; Sato, Fuminobu; Kitagawa, Atsushi; Kato, Yushi

    2016-02-01

    Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF. PMID:26931932

  13. Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma

    NASA Astrophysics Data System (ADS)

    Nishiokada, Takuya; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Muramatsu, Masayuki; Sato, Fuminobu; Kitagawa, Atsushi; Kato, Yushi

    2016-02-01

    Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.

  14. Experimental results of superimposing 9.9 GHz extraordinary mode microwaves on 2.45 GHz ECRIS plasma.

    PubMed

    Nishiokada, Takuya; Nagaya, Tomoki; Hagino, Shogo; Otsuka, Takuro; Muramatsu, Masayuki; Sato, Fuminobu; Kitagawa, Atsushi; Kato, Yushi

    2016-02-01

    Efficient production of multicharged ions has been investigated on the tandem-type ECRIS in Osaka University. According to the consideration of the accessibility conditions of microwaves to resonance and cutoff regions, it was suggested that the upper hybrid resonance (UHR) heating contributed to enhancement of ion beam intensity. In order to enhance multicharged ion beams efficiently, injecting higher frequency microwave with extraordinary (X-mode) toward UHR region has been tried. In this study, 2.45 GHz frequency microwaves are used for conventional ECR discharge, and 9.9 GHz frequency microwaves with X-mode are superimposed for UHR heating. The effects of additive microwave injection are investigated experimentally in terms of plasma parameters and electron energy distribution function (EEDF) measured by Langmuir probe and ion beam current. As the results show, it is confirmed that the electrons in the high energy region are affected by 9.9 GHz X-mode microwave injection from the detailed analysis of EEDF.

  15. Use of mode subspace projections for depth discrimination with a horizontal line array: theory and experimental results.

    PubMed

    Premus, Vincent E; Helfrick, Mark N

    2013-06-01

    A solution to the problem of acoustic source depth discrimination in a downward refracting, shallow-water ocean waveguide is presented for the case of a horizontal line array at endfire. The approach exploits the phenomenon of mode trapping, wherein a shallow acoustic source cannot excite the lowest order waveguide modes due to its evanescent amplitude dependence near the surface. The important implication of this "trapping" behavior is that, given sufficient spatial aperture, it provides a mechanism for differentiating a shallow acoustic noise source from one at depth. The method does not require array cant, or physical vertical aperture of any kind, but instead relies only on the sensitivity of a line array at endfire to differences in horizontal wave number to resolve low and high order mode subspace excitations. The only inputs to the algorithm are an approximate sound speed profile, water depth, and bottom type. The theoretical basis for the test statistic is first reviewed, followed by discussion of key requirements, and illustration of the concept using results from a RAM PE simulation for a downward refracting environment. Finally, the algorithm is experimentally demonstrated using data from a bottom-mounted HLA deployed in the moderately cluttered continental shelf environment of the Florida Straits.

  16. Band Engineering by Controlling vdW Epitaxy Growth Mode in 2D Gallium Chalcogenides.

    PubMed

    Cai, Hui; Soignard, Emmanuel; Ataca, Can; Chen, Bin; Ko, Changhyun; Aoki, Toshihiro; Pant, Anupum; Meng, Xiuqing; Yang, Shengxue; Grossman, Jeffrey; Ogletree, Frank D; Tongay, Sefaattin

    2016-09-01

    Atomically thin quasi-2D GaSe flakes are synthesized via van der Waals (vdW) epitaxy on a polar Si (111) surface. The bandgap is continuously tuned from its commonly accepted value at 620 down to the 700 nm range, only attained previously by alloying Te into GaSe (GaSex Te1- x ). This is accomplished by manipulating various vdW epitaxy kinetic factors, which allows the choice bet ween screw-dislocation-driven and layer-bylayer growth, and the design of different morphologies with different material-substrate interaction (strain) energies. PMID:27271214

  17. Development of a numerical procedure for mixed mode K-solutions and fatigue crack growth in FCC single crystal superalloys

    NASA Astrophysics Data System (ADS)

    Ranjan, Srikant

    2005-11-01

    Fatigue-induced failures in aircraft gas turbine and rocket engine turbopump blades and vanes are a pervasive problem. Turbine blades and vanes represent perhaps the most demanding structural applications due to the combination of high operating temperature, corrosive environment, high monotonic and cyclic stresses, long expected component lifetimes and the enormous consequence of structural failure. Single crystal nickel-base superalloy turbine blades are being utilized in rocket engine turbopumps and jet engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. These materials have orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Computation of stress intensity factors (SIFs) and the ability to model fatigue crack growth rate at single crystal cracks subject to mixed-mode loading conditions are important parts of developing a mechanistically based life prediction for these complex alloys. A general numerical procedure has been developed to calculate SIFs for a crack in a general anisotropic linear elastic material subject to mixed-mode loading conditions, using three-dimensional finite element analysis (FEA). The procedure does not require an a priori assumption of plane stress or plane strain conditions. The SIFs KI, KII, and KIII are shown to be a complex function of the coupled 3D crack tip displacement field. A comprehensive study of variation of SIFs as a function of crystallographic orientation, crack length, and mode-mixity ratios is presented, based on the 3D elastic orthotropic finite element modeling of tensile and Brazilian Disc (BD) specimens in specific crystal orientations. Variation of SIF through the thickness of the specimens is also analyzed. The resolved shear stress intensity coefficient or effective SIF, Krss, can be computed as a function of crack tip SIFs and the

  18. Atomic Resolution in Situ Imaging of a Double-Bilayer Multistep Growth Mode in Gallium Nitride Nanowires

    DOE PAGESBeta

    Gamalski, A. D.; Tersoff, J.; Stach, E. A.

    2016-04-13

    We study the growth of GaN nanowires from liquid Au–Ga catalysts using environmental transmission electron microscopy. GaN wires grow in either (11¯20) or (11¯00) directions, by the addition of {11¯00} double bilayers via step flow with multiple steps. Step-train growth is not typically seen with liquid catalysts, and we suggest that it results from low step mobility related to the unusual double-height step structure. Finally, the results here illustrate the surprising dynamics of catalytic GaN wire growth at the nanoscale and highlight striking differences between the growth of GaN and other III–V semiconductor nanowires.

  19. Atomic Resolution in Situ Imaging of a Double-Bilayer Multistep Growth Mode in Gallium Nitride Nanowires.

    PubMed

    Gamalski, A D; Tersoff, J; Stach, E A

    2016-04-13

    We study the growth of GaN nanowires from liquid Au-Ga catalysts using environmental transmission electron microscopy. GaN wires grow in either ⟨112̅0⟩ or ⟨11̅00⟩ directions, by the addition of {11̅00} double bilayers via step flow with multiple steps. Step-train growth is not typically seen with liquid catalysts, and we suggest that it results from low step mobility related to the unusual double-height step structure. The results here illustrate the surprising dynamics of catalytic GaN wire growth at the nanoscale and highlight striking differences between the growth of GaN and other III-V semiconductor nanowires. PMID:26990711

  20. Magnetorotational instability: nonmodal growth and the relationship of global modes to the shearing box

    SciTech Connect

    Squire, J.; Bhattacharjee, A.

    2014-12-10

    We study magnetorotational instability (MRI) using nonmodal stability techniques. Despite the spectral instability of many forms of MRI, this proves to be a natural method of analysis that is well-suited to deal with the non-self-adjoint nature of the linear MRI equations. We find that the fastest growing linear MRI structures on both local and global domains can look very different from the eigenmodes, invariably resembling waves shearing with the background flow (shear waves). In addition, such structures can grow many times faster than the least stable eigenmode over long time periods, and be localized in a completely different region of space. These ideas lead—for both axisymmetric and non-axisymmetric modes—to a natural connection between the global MRI and the local shearing box approximation. By illustrating that the fastest growing global structure is well described by the ordinary differential equations (ODEs) governing a single shear wave, we find that the shearing box is a very sensible approximation for the linear MRI, contrary to many previous claims. Since the shear wave ODEs are most naturally understood using nonmodal analysis techniques, we conclude by analyzing local MRI growth over finite timescales using these methods. The strong growth over a wide range of wave-numbers suggests that nonmodal linear physics could be of fundamental importance in MRI turbulence.

  1. Magnetorotational Instability: Nonmodal Growth and the Relationship of Global Modes to the Shearing Box

    NASA Astrophysics Data System (ADS)

    Squire, J.; Bhattacharjee, A.

    2014-12-01

    We study magnetorotational instability (MRI) using nonmodal stability techniques. Despite the spectral instability of many forms of MRI, this proves to be a natural method of analysis that is well-suited to deal with the non-self-adjoint nature of the linear MRI equations. We find that the fastest growing linear MRI structures on both local and global domains can look very different from the eigenmodes, invariably resembling waves shearing with the background flow (shear waves). In addition, such structures can grow many times faster than the least stable eigenmode over long time periods, and be localized in a completely different region of space. These ideas lead—for both axisymmetric and non-axisymmetric modes—to a natural connection between the global MRI and the local shearing box approximation. By illustrating that the fastest growing global structure is well described by the ordinary differential equations (ODEs) governing a single shear wave, we find that the shearing box is a very sensible approximation for the linear MRI, contrary to many previous claims. Since the shear wave ODEs are most naturally understood using nonmodal analysis techniques, we conclude by analyzing local MRI growth over finite timescales using these methods. The strong growth over a wide range of wave-numbers suggests that nonmodal linear physics could be of fundamental importance in MRI turbulence.

  2. Continental Margin of Kamchatka Peninsula, Russia: the Mode and Nature of Crustal Growth in the Accretionary Orogen

    NASA Astrophysics Data System (ADS)

    Konstantinovskaya, E. A.; Bindeman, I. N.

    2001-12-01

    Tectonic accretion of island arc terranes is the process widely developed in Pacific Rim in the present and in the past. The mode and nature of crustal growth of continental margins during arc accretion are various and essentially determined by deformation of the margin. The Cenozoic Kamchatka orogen formed by the accretion of two island arc terranes: Achaivayam-Valaginskaya arc (A-V, Eocene) (2) and Kronotskaya arc (terminal Miocene) to the continental margin of Asia. During the Early Eocene, the southern segment of the A-V arc collided with the Sredinny metamorphic massif, which was the frontal part of the Asian continental margin (3). New results from SHRIMP dating of zircons (1) from metamorphic rocks of Sredinny massif (Kolpakovskaya series) show that the massif contains an abundance of Archean, Proterozoic and Phanerozoic detrital zircon cores, and ubiquitous 77 Ma rims. The youngest ages are from four 47-53 Ma unzoned zircon cores, with dull cathodoluminescence, and irregular morphology. We regard the 47-53 Ma episode of zircon growth in the Sredinny massif as evidence for superimposed metamorphism induced by continental margin subduction at the beginning of its collision with the A-V arc in the early Eocene. Physical modeling experiments of arc-continent collision suggest that deformation at continental margin is controlled by strength of the subducting crust. Failure, accretion and erosion-activated extrusion/exhumation of the subducted crust occur in the continental margin in the case when the margin is weakened by pre-existing faulting, extension, or heating. At the beginning of the continental margin subduction, crust of the margin fails along the continent-vergent thrust. The subducted crustal slice is, then, completely scraped from the mantle base and accreted to the fore-arc block. Subsequent thrusting and thickening of the subducting crust within the continental margin lead to formation of the accretionary orogen composed of crustal slices in front

  3. Synthesis, growth and characterization of ZnO microtubes using a traveling-wave mode microwave system

    SciTech Connect

    Al-Naser, Qusay A.H.; Zhou, Jian; Wang, Han; Liu, Guizhen; Wang, Lin

    2015-06-15

    Highlights: • ZnO microtubes were successfully synthesized within 15 min. • Introducing a design of a traveling-wave mode microwave system. • Growth temperature of ZnO microtubes becomes predominant between 1350 °C and 1400 °C. • ZnO microtube showed a strong ultraviolet and a weak and broad green emission. • ZnO microtube is composed only of ZnO with high crystallinity. - Abstract: Field emission scanning electron microscopy (FESEM) investigation reveals that zinc oxide (ZnO) microtubes have been successfully synthesized via a traveling-wave mode microwave system. These products are hexagonal tubular crystals with an average diameter of 60 μm and 250 μm in length, having a well faceted end and side surfaces. The wall thickness of the ZnO tubes is about 3–5 μm. The influence of reaction temperature on the formation of crystalline ZnO hexagonal tubes is studied. Room temperature photoluminescence (PL) spectra have also been examined to explore the optical property which exhibits strong ultraviolet emission at 377.422 nm and a weak and broad green emission band at 587.548 nm. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) show that the product is composed only of ZnO with high crystallinity. The presented synthesis method possesses several advantages, which would be significant to the deeper study and wide applications of ZnO tubes in the future.

  4. C-di-GMP regulates Pseudomonas aeruginosa stress response to tellurite during both planktonic and biofilm modes of growth

    PubMed Central

    Chua, Song Lin; Sivakumar, Krishnakumar; Rybtke, Morten; Yuan, Mingjun; Andersen, Jens Bo; Nielsen, Thomas E.; Givskov, Michael; Tolker-Nielsen, Tim; Cao, Bin; Kjelleberg, Staffan; Yang, Liang

    2015-01-01

    Stress response plays an important role on microbial adaptation under hostile environmental conditions. It is generally unclear how the signaling transduction pathway mediates a stress response in planktonic and biofilm modes of microbial communities simultaneously. Here, we showed that metalloid tellurite (TeO32–) exposure induced the intracellular content of the secondary messenger cyclic di-GMP (c-di-GMP) of Pseudomonas aeruginosa. Two diguanylate cyclases (DGCs), SadC and SiaD, were responsible for the increased intracellular content of c-di-GMP. Enhanced c-di-GMP levels by TeO32– further increased P. aeruginosa biofilm formation and resistance to TeO32–. P. aeruginosa ΔsadCΔsiaD and PAO1/plac-yhjH mutants with low intracellular c-di-GMP content were more sensitive to TeO32– exposure and had low relative fitness compared to the wild-type PAO1 planktonic and biofilm cultures exposed to TeO32–. Our study provided evidence that c-di-GMP level can play an important role in mediating stress response in microbial communities during both planktonic and biofilm modes of growth. PMID:25992876

  5. C-di-GMP regulates Pseudomonas aeruginosa stress response to tellurite during both planktonic and biofilm modes of growth.

    PubMed

    Chua, Song Lin; Sivakumar, Krishnakumar; Rybtke, Morten; Yuan, Mingjun; Andersen, Jens Bo; Nielsen, Thomas E; Givskov, Michael; Tolker-Nielsen, Tim; Cao, Bin; Kjelleberg, Staffan; Yang, Liang

    2015-01-01

    Stress response plays an important role on microbial adaptation under hostile environmental conditions. It is generally unclear how the signaling transduction pathway mediates a stress response in planktonic and biofilm modes of microbial communities simultaneously. Here, we showed that metalloid tellurite (TeO3(2-)) exposure induced the intracellular content of the secondary messenger cyclic di-GMP (c-di-GMP) of Pseudomonas aeruginosa. Two diguanylate cyclases (DGCs), SadC and SiaD, were responsible for the increased intracellular content of c-di-GMP. Enhanced c-di-GMP levels by TeO3(2-) further increased P. aeruginosa biofilm formation and resistance to TeO3(2-). P. aeruginosa ΔsadCΔsiaD and PAO1/p(lac)-yhjH mutants with low intracellular c-di-GMP content were more sensitive to TeO3(2-) exposure and had low relative fitness compared to the wild-type PAO1 planktonic and biofilm cultures exposed to TeO3(2-). Our study provided evidence that c-di-GMP level can play an important role in mediating stress response in microbial communities during both planktonic and biofilm modes of growth.

  6. How Stand Productivity Results from Size- and Competition-Dependent Growth and Mortality

    PubMed Central

    Caspersen, John P.; Vanderwel, Mark C.; Cole, William G.; Purves, Drew W.

    2011-01-01

    Background A better understanding of the relationship between stand structure and productivity is required for the development of: a) scalable models that can accurately predict growth and yield dynamics for the world's forests; and b) stand management regimes that maximize wood and/or timber yield, while maintaining structural and species diversity. Methods We develop a cohort-based canopy competition model (“CAIN”), parameterized with inventory data from Ontario, Canada, to examine the relationship between stand structure and productivity. Tree growth, mortality and recruitment are quantified as functions of diameter and asymmetric competition, using a competition index (CAIh) defined as the total projected area of tree crowns at a given tree's mid-crown height. Stand growth, mortality, and yield are simulated for inventoried stands, and also for hypothetical stands differing in total volume and tree size distribution. Results For a given diameter, tree growth decreases as CAIh increases, whereas the probability of mortality increases. For a given CAIh, diameter growth exhibits a humped pattern with respect to diameter, whereas mortality exhibits a U-shaped pattern reflecting senescence of large trees. For a fixed size distribution, stand growth increases asymptotically with total density, whereas mortality increases monotonically. Thus, net productivity peaks at an intermediate volume of 100–150 m3/ha, and approaches zero at 250 m3/ha. However, for a fixed stand volume, mortality due to senescence decreases if the proportion of large trees decreases as overall density increases. This size-related reduction in mortality offsets the density-related increase in mortality, resulting in a 40% increase in yield. Conclusions Size-related variation in growth and mortality exerts a profound influence on the relationship between stand structure and productivity. Dense stands dominated by small trees yield more wood than stands dominated by fewer large trees, because

  7. Quantum stabilities and growth modes of thin metal films: Unsupported and NiAl-supported Ag(1 1 0) and Ag(1 0 0)

    NASA Astrophysics Data System (ADS)

    Han, Yong; Evans, J. W.; Liu, Da-Jiang

    2008-07-01

    We present density functional theory (DFT) analyses of the stability of Ag thin films versus film thicknesses for various surface orientations. We include benchmark results for freestanding films, but consider in detail Ag(1 1 0) films supported on a NiAl(1 1 0) substrate, and Ag(1 0 0) films supported on a NiAl(1 0 0) substrate. The supported films exhibit an almost perfect lattice-match between film and substrate surface unit cells, so one can assess film stability in the absence of significant lateral mismatch strain. We also provide a characterization of film growth modes for these NiAl-supported Ag films based on DFT results for the relevant energetics.

  8. Non-canonical signaling mode of the epidermal growth factor receptor family

    PubMed Central

    Lee, Heng-Huan; Wang, Ying-Nai; Hung, Mien-Chie

    2015-01-01

    Epidermal growth factor receptor (EGFR) and its family members are key players in both physiological and pathological settings for which they are well recognized as models for investigating the functions and regulations of other membrane receptor tyrosine kinases (RTKs) and serve as therapeutic targets critical to clinical need and fundamental research. The canonical view of the pivotal functions in the EGFR family has been well documented as being an initiator of signaling amplification cascades from the plasma membrane to different subcellular compartments via receptor endocytic trafficking, intermolecular interaction, and kinase-substrate reaction in a temporalspatial manner. However, several lines of evidence have identified non-canonical roles of the EGFR family, acting as a transcriptional factor and a chromatin regulator in the nucleus to regulate gene expression, DNA replication, and DNA damage repair. Moreover, the EGFR family can even exert its impact outside the host cell through exosomal vesicle secretion. The emerging concept of the non-canonical roles of the EGFR family reveals an astonishing and elaborate scheme on the molecular functions of membrane RTKs, offering new insights into the receptor biology as well as the development of comprehensive therapeutic strategies in the future. PMID:26693051

  9. Nanostructured oxide-based powders: investigation of the growth mode of the CeO2 clusters on the YSZ surface.

    PubMed

    Natile, Marta M; Glisenti, Antonella

    2006-02-16

    CeO(2)/YSZ nanocomposite powders, characterized by increasing Ce/Zr atomic ratio, were obtained by depositing, by wet impregnation, different amounts of CeO(2) on the yttria-stabilized zirconia (YSZ) surface. These powders were characterized by means of X-ray photoelectron spectroscopy, transmission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Experimental results allow us to obtain interesting information concerning the growth mode, the morphology, and the dimensions of the CeO(2) clusters on the YSZ supporting surface. A 3-D growing mechanism was observed for the CeO(2) nanoparticles. With increasing Ce/Zr atomic ratio the CeO(2) clusters become more and more spherical. Moreover, XPS data also show the presence of Ce(III) and Ce(IV) ions at the interface supported/supporting oxides.

  10. 45-Day safety screen results for Tank 241-U-201, push mode, cores 70, 73 and 74

    SciTech Connect

    Sathyanarayana, P.

    1995-05-04

    Three core samples, each having two segments, from Tank 241-U-201 (U-201) were received by the 222-S Laboratories. Safety screening analysis, such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and total alpha activity were conducted on Core 70, Segment 1 and 2 and on Core 73, Segment 1 and 2. Core 74, Segment 1 and 2 were taken to test rotary bit in push mode sampling. No analysis was requested on Core 74, Segment 1 and 2. Analytical results for the TGA analyses for Core 70, Segment 1, Upper half solid sample was less than the safety screening notification limit of 17 percent water. Notification was made on April 27, 1995. No exotherm was associated with this sample. Analytical results are presented in Tables 1 to 4, with the applicable notification limits shaded.

  11. [Effects of different fertilization modes on vegetable growth, fertilizer nitrogen utilization, and nitrogen loss from vegetable field].

    PubMed

    Huang, Dong-feng; Wang, Guo; Li, Wei-hua; Qiu, Xiao-xuan

    2009-03-01

    A field experiment with Chinese cabbage, water spinach, and three-colored amaranth cropped three times in one year was conducted to study the effects of seven fertilization modes, i.e., none fertilization, basal application of chemical fertilizers, 1/2 basal application and 1/2 top-dressing of chemical fertilizers, basal application of chemical fertilizers and dicyandiamide, 1/2 basal application and 1/2 top-dressing of chemical fertilizers and dicyandiamide, 1/2 basal application and 1/2 top-dressing of chemical fertilizers and organic manure, and basal application of organic manure, on the plant height, yield, nitrogen accumulation, and fertilizer nitrogen utilization of the vegetables, and the loss of NO3- -N and NH4+ -N from vegetable field under natural rainfall condition. The results showed that comparing with none fertilization, the fertilization modes '1/2 basal application and 1/2 top-dressing of chemical fertilizers and organic manure' and 'basal application of chemical fertilizers and dicyandiamide' improved the agronomic properties of test vegetables, increased their yields by 103%-219% and 93%-226%, and nitrogen accumulation by 153% -216% and 231%-320%, respectively, and enhanced fertilizer nitrogen utilization rate. They also decreased the surface runoff loss of NO3- -N and NH4+ -N by 48.1% and 46.5%, respectively, compared with the mode 'basal application of chemical fertilizers', and hence, reduced the risk of agricultural non-point pollution. Therefore, these two fertilization modes could be popularized in vegetable production.

  12. Mode I, Mode II, and mixed mode interlaminar fracture of woven fabric carbon/epoxy

    SciTech Connect

    Alif, N.; Carlsson, L.A.; Gillespie, J.W. Jr.

    1997-12-31

    Interlaminar fracture behavior of a five-harness satin orthogonal woven fabric carbon/epoxy composite laminate loaded in Mode I, Mode II, and mixed mode has been investigated. Fracture testing employed the DCB, ENF, and MMB specimens. Special emphasis was put on microscopic details of crack growth and their relation to fracture resistance. For all fracture mode combinations it was found that crack growth occurred in a nonplanar region of topology determined by the weave pattern and relative positioning of the plies adjacent to the crack plane. The woven fabric structure constrains fiber bridging, but partial debonding of transversely oriented fiber bundles led to occasional crack branching, stick-slip behavior leading to variations in the Mode I fracture resistance. Slow stable crack growth occurred in the ENF and MMB specimens prior to unstable fracture and resulted in nonlinear load-displacement response.. A linear relation between the critical values of G{sub I} and G{sub II} was observed.

  13. Comparison of High Rate Laser Ablation and Resulting Structures Using Continuous and Pulsed Single Mode Fiber Lasers

    NASA Astrophysics Data System (ADS)

    Knebel, T.; Streek, A.; Exner, H.

    This paper compares high rate laser ablation and resulting structures of aluminum by using both a continuous wave and a ns-pulsed single mode fiber laser of high average laser power. Two different scan technologies were applied for fast deflection of the laser beams. In this work, 2.5D laser processing was studied by using a high aperture galvanometer scanner with a maximum scan speed of 18 m/s. By contrast, considerably higher scan speeds up to 1,000 m/s were achieved by using the in-house developed polygon scanner system. The ablation rates and the processing rates per unit area were analyzed by means of the depths of line-scan ablation tracks and laser processed cavities. In addition, SEM photograph of the machining samples will be presented in order to evaluate the machining quality. Finally the feasibility of this high rate technology for industrial application is demonstrated by machining examples.

  14. Investigations with the Sentinel-1 Interferometric Wide Swath mode: first results and comparison with in-situ geodetic data

    NASA Astrophysics Data System (ADS)

    Borgstrom, Sven; Del Gaudio, Carlo; De Martino, Prospero; Ricciardi, Giovanni P.; Ricco, Ciro; Siniscalchi, Valeria; Prats-Iraola, Pau; Nannini, Matteo; Costantini, Mario; Minati, Federico; Walter, Thomas

    2015-04-01

    The contribution focuses on the current status of the ESA study entitled "INSARAP: Sentinel-1 InSAR Performance study with TOPS Data". The study investigates the performance of the interferometric wide swath (IW) mode of Sentinel-1, which is implemented using the terrain observation by progressive scans (TOPS) mode. In this regard, first analyses with Sentinel-1 time series will be shown, with a comparison with in-situ geodetic measurements on different test sites identified in the framework of the study, namely, Campi Flegrei/Vesuvius area in Italy, Istanbul city in Turkey, and Mexico City. The evaluation of the results will be performed by exploiting mainly continuous GPS stations located on the different sites, besides leveling measurements when also available. Also in a recent past, the comparison between InSAR and continuous GPS data, the latter projected into the radar LOS, has proven to be very effective for a cross comparison, besides InSAR Cal/Val activities, as it was for instance in the case of the recent inflation events occurred in Campi Flegrei area, marked by the well know bradyseismic phenomenon. Although continuous GPS networks are characterized by a poor space coverage in comparison with InSAR results, continuous GPS data recording allows to complement the geodetic information from InSAR sensors, limited by their revisiting time. The issue to be faced in this study is the possibility to deal with very low deformation rates in comparison with the Sentinel-1 C-band data, although the Sentinel-1 time series we expect to get from October 2014 to date should allow the identification of ground deformation in the areas of interest.

  15. Biofilm growth mode promotes maximum carrying capacity and community stability during product inhibition syntrophy

    PubMed Central

    Brileya, Kristen A.; Camilleri, Laura B.; Zane, Grant M.; Wall, Judy D.; Fields, Matthew W.

    2014-01-01

    Sulfate-reducing bacteria (SRB) can interact syntrophically with other community members in the absence of sulfate, and interactions with hydrogen-consuming methanogens are beneficial when these archaea consume potentially inhibitory H2 produced by the SRB. A dual continuous culture approach was used to characterize population structure within a syntrophic biofilm formed by the SRB Desulfovibrio vulgaris Hildenborough and the methanogenic archaeum Methanococcus maripaludis. Under the tested conditions, monocultures of D. vulgaris formed thin, stable biofilms, but monoculture M. maripaludis did not. Microscopy of intact syntrophic biofilm confirmed that D. vulgaris formed a scaffold for the biofilm, while intermediate and steady-state images revealed that M. maripaludis joined the biofilm later, likely in response to H2 produced by the SRB. Close interactions in structured biofilm allowed efficient transfer of H2 to M. maripaludis, and H2 was only detected in cocultures with a mutant SRB that was deficient in biofilm formation (ΔpilA). M. maripaludis produced more carbohydrate (uronic acid, hexose, and pentose) as a monoculture compared to total coculture biofilm, and this suggested an altered carbon flux during syntrophy. The syntrophic biofilm was structured into ridges (∼300 × 50 μm) and models predicted lactate limitation at ∼50 μm biofilm depth. The biofilm had structure that likely facilitated mass transfer of H2 and lactate, yet maximized biomass with a more even population composition (number of each organism) when compared to the bulk-phase community. Total biomass protein was equivalent in lactate-limited and lactate-excess conditions when a biofilm was present, but in the absence of biofilm, total biomass protein was significantly reduced. The results suggest that multispecies biofilms create an environment conducive to resource sharing, resulting in increased biomass retention, or carrying capacity, for cooperative populations. PMID:25566209

  16. Protein crystal growth results from the United States Microgravity Laboratory-1 mission

    NASA Technical Reports Server (NTRS)

    Delucas, Lawrence J.; Moore, K. M.; Vanderwoerd, M.; Bray, T. L.; Smith, C.; Carson, M.; Narayana, S. V. L.; Rosenblum, W. M.; Carter, D.; Clark, A. D, Jr.

    1994-01-01

    Protein crystal growth experiments have been performed by this laboratory on 18 Space Shuttle missions since April, 1985. In addition, a number of microgravity experiments also have been performed and reported by other investigators. These Space Shuttle missions have been used to grow crystals of a variety of proteins using vapor diffusion, liquid diffusion, and temperature-induced crystallization techniques. The United States Microgravity Laboratory - 1 mission (USML-1, June 25 - July 9, 1992) was a Spacelab mission dedicated to experiments involved in materials processing. New protein crystal growth hardware was developed to allow in orbit examination of initial crystal growth results, the knowledge from which was used on subsequent days to prepare new crystal growth experiments. In addition, new seeding hardware and techniques were tested as well as techniques that would prepare crystals for analysis by x-ray diffraction, a capability projected for the planned Space Station. Hardware that was specifically developed for the USML-1 mission will be discussed along with the experimental results from this mission.

  17. The Membrane-anchoring Domain of Epidermal Growth Factor Receptor Ligands Dictates Their Ability to Operate in Juxtacrine Mode

    SciTech Connect

    Dong, Jianying; Opresko, Lee; Chrisler, William B.; Orr, Galya; Quesenberry, Ryan D.; Lauffenburger, Douglas A.; Wiley, H S.

    2005-06-01

    All ligands of the epidermal growth factor receptor (EGFR) are synthesized as membrane-anchored precursors. Previous work has suggested that some ligands, such as EGF, must be proteolytically released to be active, whereas others, such as heparin binding EGF-like growth factor (HB-EGF) can function while still anchored to the membrane (i.e., juxtacrine signaling). To explore the structural basis for these differences in ligand activity, we engineered a series of membrane-anchored ligands in which the core, receptor-binding domain of EGF was combined with different domains of both EGF and HB-EGF. We found that ligands having the N-terminal extension of EGF could not bind to the EGFR, even when released from the membrane. Ligands lacking an N-terminal extension, but possessing the membrane-anchoring domain of EGF still required proteolytic release for activity, whereas ligands with the membrane anchoring domain of HB-EGF could elicit full biological activity while still membrane anchored. Ligands containing the HB-EGF membrane anchor, but lacking an N-terminal extension, activated EGFR during their transit through the Golgi apparatus . However, cell-mixing experiments and fluorescence resonance energy transfer (FRET) studies showed that juxtacrine signaling typically occurred in trans at the cell surface, at points of cell-cell contact. Our data suggest that the membrane-anchoring domain of ligands selectively controls their ability to participate in juxtacrine signaling and thus, only a subclass of EGFR ligands can act in a juxtacrine mode.

  18. Haloxyfop mode of action in liquid cultures of proso millet: An analysis of haloxyfop sensitivity changes during growth

    SciTech Connect

    Irzyk, G.P.

    1989-01-01

    Haloxyfop is a grass-selective herbicide that inhibits acetyl-CoA carboxylase in species that are not tolerant to the herbicide. Liquid cultures of proso millet (Panicum miliaceum) cells treated with haloxyfop at different phases of growth exhibited different levels of sensitivity to the herbicide. Treatment of 1-d cultures with 1 {mu}M haloxyfop completely inhibited growth within 48 h. In contrast, 1 mM haloxyfop was required to elicit a similar response in 4-, 7-, or 10-d cultures. Calculated IC{sub 50} values indicated a 300-fold decrease in haloxyfop sensitivity during the period from 1 to 4 d. This period of growth coincided with the greatest increase in cell number during culture growth and suggested that dividing cells are most sensitive to haloxyfop. Uptake and metabolism of {sup 14}C-haloxyfop in 1-d and 4-d cultures were compared. In both cultures, amounts of radiolabel uptake were similar. Almost all radioactivity extracted from 1- and 4-d cells was present as the parent compound. These results suggested that the sensitivity change was related to other factors. Acetyl-CoA carboxylase activity of proso millet cells, measured in vitro by the acetyl-CoA-dependent incorporation of {sup 14} C-bicarbonate into an acid-stable product, was essentially constant during culture growth. Micromolar concentrations of haloxyfop significantly inhibited acetyl-CoA carboxylase activity from both sensitive and insensitive cultures. Thus, the change in the sensitivity of cultures to haloxyfop was not correlated with changes in acetyl-CoA carboxylase abundance, activity, or sensitivity to haloxyfop during culture growth. In vivo incorporation of {sup 14}C-acetate into lipids was decreased by 1 {mu}M haloxyfop in both 1-d and 4-d cultures at the earliest sampling times but the amount of inhibition was significantly greater in the sensitive cultures.

  19. Energy of auroral electrons and Z mode generation

    NASA Technical Reports Server (NTRS)

    Krauss-Varban, D.; Wong, H. K.

    1990-01-01

    The present consideration of Z-mode radiation generation, in light of observational results indicating that the O mode and second-harmonic X-mode emissions can prevail over the X-mode fundamental radiation when suprathermal electron energy is low, gives attention to whether the thermal effect on the Z-mode dispersion can be equally important, and whether the Z-mode can compete for the available free-energy source. It is found that, under suitable circumstances, the growth rate of the Z-mode can be substantial even for low suprathermal auroral electron energies. Growth is generally maximized for propagation perpendicular to the magnetic field.

  20. Analyzing Exercise Behaviors during the College Years: Results from Latent Growth Curve Analysis

    PubMed Central

    Wittman, Werner

    2016-01-01

    The objective of this study is to analyze changes in the predictors of physical activity behavior among college students. The Theory of Planned Behavior served as its theoretical framework. Methods: Among an initial sample of 417 college students, 195 participants completed a validated questionnaire measuring attitudes, subjective norms, perceived control, intentions and self-reported physical activity, at the beginning and end of each of 3 college semesters. Latent growth curve modeling analyses were conducted to examine the relationships between the trajectories of changes in PA, intentions, attitudes, subjective norms, and perceived control. Results: Good fit indices supported the validity of the proposed longitudinal model (CFI > .97, RMSEA < .05). Changes in perceived control (γ = 0.57) were significantly linked with changes in intentions (p < .05). Perceived control (γ = 0.28) and intention growth (γ = 0.36) predicted behavior changes (p < .05). No gender differences were observed on attitudes, subjective norms and perceived control (p > .10). However, girls tend to have higher growth parameters on intentions and physical activity (p < .05). In summary, intentions and physical activity has significantly increased over 3 college semesters (growth parameters significant at p < .05). Conclusions: This study demonstrated that attitudes and perceived control are key determinants regarding the intentions of being active. On a longer term perspective, future physical activity interventions should focus on the enhancement of students’ perceived control. Such educational context should help in promoting the adoption of an active lifestyle during college. PMID:27124179

  1. Neoproterozoic to Paleozoic Geological Evolution of Mongolia: Constraints on Modes of "Crustal Growth" in the Central Asian Orogenic Belt

    NASA Astrophysics Data System (ADS)

    Macdonald, F. A.; Bold, U.; Smith, E.; Olin, P. H.; Crowley, J. L.; Schmitz, M. D.

    2012-12-01

    The Central Asian Orogenic Belt (CAOB) is widely considered the largest area of Phanerozoic juvenile crustal growth on Earth. However, the timing and nature of the orogenic events in the core of the CAOB in Mongolia has remained poorly constrained due to a dearth of detailed geological and geochronological studies. To bridge this gap and test models of crustal growth, here we refine the sequencing of geological events by focusing on the formation and destruction of Neoproterozoic and Paleozoic tectonic basins. Mongolia's basins record a complete Neoproterozoic to Cambrian Wilson cycle with rifting of the Mongolian continent at ca. 700 Ma, the development of a Cryogenian to Ediacaran thermally subsiding passive margin, an arc-continent collision at ca. 520 Ma, and a continent-arc-continent collision at ca. 500 Ma. During this collisional orogeny, that is the Cambrian Altaids, crustal growth occurred largely through the obduction of ophiolites. Rifting of the southern margin occurred during the Ordovician Period, with the development of a Silurian passive margin. Oblique northwest-dipping subduction was initiated during the Devonian and resulted in a transpressional accretionary orogen. The CAOB culminated with a continent-arc-continent collision and the accretion of the North China and Tarim Blocks in the latest Permian. The Devonian to early Permian accretionary orogen is associated not only with voluminous plutonism, but also, major translational structures oblique to the margin resulting in the appearance of many accreted terranes. These data are consistent with existing coarse Hf and Nd isotopic data, but also provide a framework for future detailed studies. Although our geological constraints suggest distinct periods of apparent crustal growth through either collisional or accretionary orogenies, net crustal growth after accounting for recycling is equivocal.

  2. Growth mode and self-organization of LuPc2 on Si(001)-2×1 vicinal surfaces: An optical investigation

    NASA Astrophysics Data System (ADS)

    Boudet, S.; Bidermane, I.; Lacaze, E.; Gallas, B.; Bouvet, M.; Brunet, J.; Pauly, A.; Borensztein, Y.; Witkowski, N.

    2012-09-01

    We report an investigation of the initial growth and of the self-organization of lutetium biphthalocyanine LuPc2 on Si(001)-2×1 vicinal surfaces. Using surface-sensitive optical spectroscopies, namely, surface-difference-reflectance spectroscopy (SDRS) and reflectance-anisotropy spectroscopy (RAS), together with local-probe microscopies, we are able to propose a scenario for the growth mode up to about 20 nm. We demonstrate that the growth mode initially proceeds through the formation of a wetting layer, followed by the formation of clusters whose sizes increase while keeping a constant shape in which the molecules are inclined. Moreover, the LuPc2 molecules are self-organized along the step edges, and we are able to estimate that about 30% to 100% of the molecules are aligned when considering that the molecules are tilted by 45∘ to 63∘ with respect to the surface normal.

  3. Observation of growth mode dependence on over-potential values: a combination of in-situ optical monitoring and ex-situ atomic force microscopy characterization.

    NASA Astrophysics Data System (ADS)

    O'Toole, M. K.; Gray, J.; Moffat, T.; Orme, C.; Schwarzacher, W.; Zhu, X. D.

    2005-03-01

    We study the over-potential electrodeposition of Pb on Cu(100) using a combination of an in-situ oblique-incidence reflectivity difference technique and ex-situ atomic force microscopy. We identified two distinctly different over-potential growth modes that depend on the values of the overpotential. We have characterized the morphology corresponding to the two growth modes using AFM. At a high over-potential there is even growth of small clusters across the monolayer thick under-potential deposited (UPD) Pb covered Cu(100) surface. At lower over-potentials (a fraction of a volt from the value for UPD), we observed much larger 3-D clusters, more than 400 nm in height and separated by an averaged distance of one micron.

  4. Exponential growth of an unstable [ital l]=1 diocotron mode for a hollow electron column in a warm-fluid model

    SciTech Connect

    Rasband, S.N.; Spencer, R.L.; Vanfleet, R.R. )

    1993-03-01

    Numerical investigations of a warm-fluid model with an isothermal equation of state for the perpendicular dynamics of an axisymmetric, magnetically confined pure electron plasma predict an exponentially unstable, [ital l]=1, diocotron mode for hollow density profiles. The unstable mode can be identified with a stable, nonsmooth mode that exists in cold drift models but which is destabilized by finite temperature effects. The unstable mode has many properties similar to the experimental results reported by Driscoll [Phys. Rev. Lett. [bold 64], 645 (1990)].

  5. Effects of proof loads and combined mode loadings on fracture and flaw growth characteristics of aerospace alloys

    NASA Technical Reports Server (NTRS)

    Shah, R. C.

    1974-01-01

    This experimental program was undertaken to determine the effects of (1) combined tensile and bending loadings, (2) combined tensile and shear loadings, and (3) proof overloads on fracture and flaw growth characteristics of aerospace alloys. Tests were performed on four alloys: 2219-T87 aluminum, 5Al-2.5Sn (ELl) titanium, 6Al-4V beta STA titanium and high strength 4340 steel. Tests were conducted in room air, gaseous nitrogen at -200F (144K), liquid nitrogen and liquid hydrogen. Flat center cracked and surface flawed specimens, cracked tube specimens, circumferentially notched round bar and surface flawed cylindrical specimens were tested. The three-dimensional photoelastic technique of stress freezing and slicing was used to determine stress intensity factors for surface flawed cylindrical specimens subjected to tension or torsion. Results showed that proof load/temperature histories used in the tests have a small beneficial effect or no effect on subsequent fracture strength and flaw growth rates.

  6. Impact of interfacial misfit dislocation growth mode on highly lattice-mismatched InxGa1-xSb epilayer grown on GaAs substrate by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Huynh, Sa Hoang; Ha, Minh Thien Huu; Do, Huy Binh; Luc, Quang Ho; Yu, Hung Wei; Chang, Edward Yi

    2016-09-01

    Highly lattice-mismatch (over 8%) ternary InxGa1-xSb alloy directly grown on GaAs substrates was demonstrated by metalorganic chemical vapor deposition (MOCVD). The influence of growth parameters, such as growth temperature, indium vapor composition, and V/III ratio, on the film properties was investigated, and it was found that the growth temperature has the strongest effect on the surface morphology and the crystal quality of the InxGa1-xSb epilayer. An optimized growth temperature of ˜590 °C and a V/III ratio of 2.5 were used for the growth of the InxGa1-xSb epilayer on GaAs that displays a lower surface roughness. High-resolution transmission electron microscopy micrographs exhibit that InxGa1-xSb epilayer growth on GaAs was governed by the interfacial misfit dislocation growth mode. Furthermore, the variation of the intermixing layer thickness at the InxGa1-xSb/GaAs heterointerface was observed. These results provide an information of growing highly lattice-mismatched epitaxial material systems by MOCVD growth process.

  7. Modes of Action and Functions of ERECTA-family Receptor-like Kinases in Plant Organ Growth and Development

    SciTech Connect

    TORII, Keiko U.

    2012-05-01

    Higher plants constitute the central resource for renewable lignocellulose biomass that can supplement for the world's depleting stores of fossil fuels. As such, understanding the molecular and genetic mechanisms of plant organ growth will provide key knowledge and genetic resources that enables manipulation of plant biomass feedstock for better growth and productivity. The goal of this proposal is to understand how cell proliferation and growth are coordinated during aboveground organ morphogenesis, and how cell-cell signaling mediated by a family of receptor kinases coordinates plant organogenesis. The well-established model plant Arabidopsis thaliana is used for our research to facilitate rapid progress. Specifically, we focus on how ERECTA-family leucine-rich repeat receptor kinases (LRR-RLKs) interact in a synergistic manner to promote organogenesis and pattern formation in Arabidopsis. This project was highly successful, resulted in fourteen publications including nine peer-reviewed original research articles. One provisional US patent has been filed through this DOE funding. We have addressed the critical roles for a family of receptor kinases in coordinating proliferation and differentiation of plants, and we successfully elucidated the downstream targets of this signaling pathway in specifying stomatal patterning.

  8. Characterization and optimization of 2-step MOVPE growth for single-mode DFB or DBR laser diodes

    NASA Astrophysics Data System (ADS)

    Bugge, F.; Mogilatenko, A.; Zeimer, U.; Brox, O.; Neumann, W.; Erbert, G.; Weyers, M.

    2011-01-01

    We have studied the MOVPE regrowth of AlGaAs over a grating for GaAs-based laser diodes with an internal wavelength stabilisation. Growth temperature and aluminium concentration in the regrown layers considerably affect the oxygen incorporation. Structural characterisation by transmission electron microscopy of the grating after regrowth shows the formation of quaternary InGaAsP regions due to the diffusion of indium atoms from the top InGaP layer and As-P exchange processes during the heating-up procedure. Additionally, the growth over such gratings with different facets leads to self-organisation of the aluminium content in the regrown AlGaAs layer, resulting in an additional AlGaAs grating, which has to be taken into account for the estimation of the coupling coefficient. With optimized growth conditions complete distributed feedback laser structures have been grown for different emission wavelengths. At 1062 nm a very high single-frequency output power of nearly 400 mW with a slope efficiency of 0.95 W/A for a 4 μm ridge-waveguide was obtained.

  9. Effects of misfit dislocations and AlN buffer layer on the GaInN/GaN phase diagram of the growth mode

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo; Ujihara, Toru; Miyashita, Satoru; Sazaki, Gen

    2001-01-01

    The thickness-composition phase diagrams of the growth modes were determined for the GaInN-on-GaN (GaInN/GaN) and the GaInN-on-AlN-on-GaN (GaInN/AlN/GaN) structures. For this determination, the strain energy was calculated by considering the stress relaxation due to introduction of misfit dislocations, the surface energy was estimated from bonding enthalpy of the nearest-neighbor bonds on the surface, and the interface energy was estimated by considering both effects of the dangling bonds due to lattice misfit and the abrupt transition of bonding species at the heterointerface. From these phase diagrams, it was found that the layer-by-layer growth such as the Frank-van der Merwe mode was very difficult to obtain for the epitaxial growth of GaInN on GaN when the InN fraction is large. The Volmer-Weber mode is dominant in the phase diagram of the GaInN/GaN structures. The influence of an AlN buffer layer with a larger surface energy was studied by introducing an AlN layer between the GaInN layer and the GaN substrate. It was known that the layer-by-layer growth could be more easily obtained if misfit dislocations were introduced and an AlN layer was used as a buffer.

  10. Tissue-specific alternative splicing of Shaker potassium channel transcripts results from distinct modes of regulating 3' splice choice.

    PubMed

    Iverson, L E; Mottes, J R; Yeager, S A; Germeraad, S E

    1997-05-01

    Alternative splicing of precursor RNA enables a single gene to encode multiple protein isoforms with different functional characteristics and tissue distributions. Differential splicing of Drosophila Shaker (Sh) gene transcripts regulates the tissue-specific expression of kinetically distinct potassium ion channels throughout development. Regulation of Sh alternative splicing is being examined in germline transformants using lacZ as a reporter gene. P-element constructs were generated in which one or both of the two mutually exclusive Sh 3' acceptor sites were positioned in the same translational reading frame as the lacZ coding sequences. The constructs were introduced into the germline and the transgenic animals examined for tissue-specific beta-galactosidase expression patterns. Some tissues exhibit "promiscuous" splicing; these tissues are competent to splice to either 3' acceptor even when both are present on the same pre-mRNA. In other tissues splice choice results from competition between the two 3' sites; these tissues can splice to either site when it is the only available 3' acceptor, but when given a choice will splice to only one of the two 3' acceptors. In some tissues, splicing occurs exclusively at only one of the 3' acceptor sites; these tissues are not competent to splice to one of the sites even if it is the only 3' acceptor present on the pre-mRNA. These results suggests that multiple, distinct regulatory modes are operating to control tissue-specific alternative splicing of Sh 3' domains and are discussed in terms of potential underlying mechanisms for regulating the tissue-specific expression of alternatively spliced genes.

  11. Recent results and new hardware developments for protein crystal growth in microactivity

    NASA Technical Reports Server (NTRS)

    Delucas, L. J.; Long, M. M.; Moore, K. M.; Smith, C.; Carson, M.; Narayana, S. V. L.; Carter, D.; Clark, A. D., Jr.; Nanni, R. G.; Ding, J.

    1993-01-01

    Protein crystal growth experiments have been performed on 16 space shuttle missions since April, 1985. The initial experiments utilized vapor diffusion crystallization techniques similar to those used in laboratories for earth-based experiments. More recent experiments have utilized temperature induced crystallization as an alternative method for growing high quality protein crystals in microgravity. Results from both vapor diffusion and temperature induced crystallization experiments indicate that proteins grown in microgravity may be larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions than the best crystals of these proteins grown on earth.

  12. A chemical energy approach of avascular tumor growth: multiscale modeling and qualitative results.

    PubMed

    Ampatzoglou, Pantelis; Dassios, George; Hadjinicolaou, Maria; Kourea, Helen P; Vrahatis, Michael N

    2015-01-01

    In the present manuscript we propose a lattice free multiscale model for avascular tumor growth that takes into account the biochemical environment, mitosis, necrosis, cellular signaling and cellular mechanics. This model extends analogous approaches by assuming a function that incorporates the biochemical energy level of the tumor cells and a mechanism that simulates the behavior of cancer stem cells. Numerical simulations of the model are used to investigate the morphology of the tumor at the avascular phase. The obtained results show similar characteristics with those observed in clinical data in the case of the Ductal Carcinoma In Situ (DCIS) of the breast. PMID:26558163

  13. The TRPC channel blocker SKF 96365 inhibits glioblastoma cell growth by enhancing reverse mode of the Na+/Ca2+ exchanger and increasing intracellular Ca2+

    PubMed Central

    Song, M; Chen, D; Yu, S P

    2014-01-01

    BACKGROUND AND PURPOSE SKF 96365 is well known for its suppressing effect on human glioblastoma growth by inhibiting pre-activated transient receptor potential canonical (TRPC) channels and Ca2+ influx. The effect of SKF 96363 on glioblastoma cells, however, may be multifaceted and this possibility has been largely ignored. EXPERIMENTAL APPROACH The effects of SKF 96365 on cell cycle and cell viability of cultured human glioblastoma cells were characterized. Western blot, Ca2+ imaging and patch clamp recordings were used to delineate cell death mechanisms. siRNA gene knockdown provided additional evidence. KEY RESULTS SKF 96365 repressed glioblastoma cell growth via increasing intracellular Ca2+ ([Ca2+]i) irrespective of whether TRPC channels were blocked or not. The effect of SKF 96365 primarily resulted from enhanced reverse operation of the Na+/Ca2+ exchanger (NCX) with an EC50 of 9.79 μM. SKF 96365 arrested the glioblastoma cells in the S and G2 phases and activated p38-MAPK and JNK, which were all prevented by the Ca2+ chelator BAPTA-AM or EGTA. The expression of NCX in glioblastoma cells was significantly higher than in normal human astrocytes. Knockdown of the NCX1 isoforms diminished the effect of SKF 96365 on glioblastoma cells. CONCLUSIONS AND IMPLICATIONS At the same concentration, SKF 96365 blocks TRPC channels and enhances the reverse mode of the NCX causing [Ca2+]i accumulation and cytotoxicity. This finding suggests an alternative pharmacological mechanism of SKF 96365. It also indicates that modulation of the NCX is an effective method to disrupt Ca2+ homeostasis and suppress human glioblastoma cells. PMID:24641279

  14. Silencing of Doublecortin-Like (DCL) Results in Decreased Mitochondrial Activity and Delayed Neuroblastoma Tumor Growth

    PubMed Central

    Verissimo, Carla S.; Elands, Rachel; Cheng, Sou; Saaltink, Dirk-Jan; ter Horst, Judith P.; Alme, Maria N.; Pont, Chantal; van de Water, Bob; Håvik, Bjarte; Fitzsimons, Carlos P.; Vreugdenhil, Erno

    2013-01-01

    Doublecortin-like (DCL) is a microtubule-binding protein crucial for neuroblastoma (NB) cell proliferation. We have investigated whether the anti-proliferative effect of DCL knockdown is linked to reduced mitochondrial activity. We found a delay in tumor development after DCL knockdown in vivo in doxycycline-inducible NB tumor xenografts. To understand the mechanisms underlying this tumor growth retardation we performed a series of in vitro experiments in NB cell lines. DCL colocalizes with mitochondria, interacts with the mitochondrial outer membrane protein OMP25/ SYNJ2BP and DCL knockdown results in decreased expression of genes involved in oxidative phosphorylation. Moreover, DCL knockdown decreases cytochrome c oxidase activity and ATP synthesis. We identified the C-terminal Serine/Proline-rich domain and the second microtubule-binding area as crucial DCL domains for the regulation of cytochrome c oxidase activity and ATP synthesis. Furthermore, DCL knockdown causes a significant reduction in the proliferation rate of NB cells under an energetic challenge induced by low glucose availability. Together with our previous studies, our results corroborate DCL as a key player in NB tumor growth in which DCL controls not only mitotic spindle formation and the stabilization of the microtubule cytoskeleton, but also regulates mitochondrial activity and energy availability, which makes DCL a promising molecular target for NB therapy. PMID:24086625

  15. TNF Neutralization Results in the Delay of Transplantable Tumor Growth and Reduced MDSC Accumulation

    PubMed Central

    Atretkhany, Kamar-Sulu N.; Nosenko, Maxim A.; Gogoleva, Violetta S.; Zvartsev, Ruslan V.; Qin, Zhihai; Nedospasov, Sergei A.; Drutskaya, Marina S.

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells (IMCs) that, under normal conditions, may differentiate into mature macrophages, granulocytes, and dendritic cells. However, under pathological conditions associated with inflammation, cancer, or infection, such differentiation is inhibited leading to IMC expansion. Under the influence of inflammatory cytokines, these cells become MDSCs, acquire immunosuppressive phenotype, and accumulate in the affected tissue, as well as in the periphery. Immune suppressive activity of MDSCs is partly due to upregulation of arginase 1, inducible nitric oxide synthase, and anti-inflammatory cytokines, such as IL-10 and TGF-β. These suppressive factors can enhance tumor growth by repressing T-cell-mediated anti-tumor responses. TNF is a critical factor for the induction, expansion, and suppressive activity of MDSCs. In this study, we evaluated the effects of systemic TNF ablation on tumor-induced expansion of MDSCs in vivo using TNF humanized (hTNF KI) mice. Both etanercept and infliximab treatments resulted in a delayed growth of MCA 205 fibrosarcoma in hTNF KI mice, significantly reduced tumor volume, and also resulted in less accumulated MDSCs in the blood 3 weeks after tumor cell inoculation. Thus, our study uncovers anti-tumor effects of systemic TNF ablation in vivo. PMID:27148266

  16. Delivery Mode, Duration of Labor, and Cord Blood Adiponectin, Leptin, and C-Reactive Protein: Results of the Population-Based Ulm Birth Cohort Studies

    PubMed Central

    Logan, Chad A.; Thiel, Larissa; Bornemann, Rebecca; Koenig, Wolfgang; Reister, Frank; Brenner, Hermann; Rothenbacher, Dietrich; Genuneit, Jon

    2016-01-01

    Background Numerous studies have reported associations between delivery mode and health outcomes in infancy and later life. Previous smaller studies indicated a relationship between delivery mode and newborn inflammation potentially constituting a mediating factor. We aimed to determine the influence of delivery mode and duration of labor on cord blood concentrations of adiponectin, leptin, and high-sensitivity C-reactive protein (hs-CRP). Methods In the Ulm SPATZ Health Study, 934 singleton newborns and their mothers were recruited during their hospital stay in the University Medical Center Ulm, Southern Germany, from 04/2012-05/2013. Inflammatory biomarkers were measured by ELISAs (n = 836). Delivery mode was analyzed categorically (elective cesarean (reference), active labor delivery: emergency cesarean, assisted vaginal, and spontaneous vaginal); duration of labor continuously. Following log-transformation, linear regression was used to estimate geometric means ratios (GMR) adjusted for potential confounders for the effects of delivery mode and duration of labor on each biomarker separately. Independent replication was sought in the similarly conducted Ulm Birth Cohort Study recruited from 11/2000-11/2001. Results Individually, active labor delivery modes as well as increasing duration of labor were associated with higher leptin and hs-CRP concentrations. After mutual adjustment, the associations with delivery modes were attenuated but those for duration of labor remained statistically significant (GMR (95%CI) 1.10 (1.00; 1.21) and 1.15 (1.04; 1.27) for leptin and hs-CRP per hour of labor, respectively). No significant adjusted associations were observed between delivery modes and adiponectin concentrations. These findings were replicated in an independent birth cohort study. Conclusions Cord blood leptin and hs-CRP concentrations were associated with duration of labor rather than delivery mode. Further research is warranted to investigate these associations

  17. Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation

    PubMed Central

    Ojovan, Silviya M.; McDonald, Mathew; Rabieh, Noha; Shmuel, Nava; Erez, Hadas; Nesladek, Milos; Spira, Micha E.

    2014-01-01

    Using a variety of proliferating cell types, it was shown that the surface of nanocrystalline diamond (NCD) provides a permissive substrate for cell adhesion and development without the need of complex chemical functionalization prior to cell seeding. In an extensive series of experiments we found that, unlike proliferating cells, post-mitotic primary neurons do not adhere to bare NCD surfaces when cultured in defined medium. These observations raise questions on the potential use of bare NCD as an interfacing layer for neuronal devices. Nevertheless, we also found that classical chemical functionalization methods render the “hostile” bare NCD surfaces with adhesive properties that match those of classically functionalized substrates used extensively in biomedical research and applications. Based on the results, we propose a mechanism that accounts for the conflicting results; which on one hand claim that un-functionalized NCD provides a permissive substrate for cell adhesion and growth, while other reports demonstrate the opposite. PMID:24966832

  18. MODE OF ACTION: NEUROTOXICITY INDUCED BY THYROID HORMONE DISRUPTION DURING DEVELOPMENT - HEARING LOSS RESULTING FROM EXPOSURE TO PHAHS.

    EPA Science Inventory

    A manuscript summarizes a workshop aimed at developing a framework to determine the relevancy of animal modes-of-action for extrapolation to humans. This specific report used animal data on the neurodevelopmental effects of hypothyroidism to test the framework. Propylthiouracil,...

  19. MODE OF ACTION: NEUROTOXICITY INDUCED BY DEVELOPMENTAL THYROID HORMONE INSUFFICIENCY -- NEUROLOGICAL ABNORMALITIES RESULTING FROM EXPOSURE TO PROPYLTHIOURACIL.

    EPA Science Inventory

    A manuscript summarizes a workshop aimed at developing a framework to determine the relevancy of animal modes-of-action for extrapolation to humans. This specific report used animal data on neurodevelopmental effects of thyroid hormone disruption to test the framework. Polyhaloge...

  20. Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.

    PubMed

    Xie, Liqiang; Yan, Wei; Li, Jing; Yu, Liqin; Wang, Jianghua; Li, Guangyu; Chen, Nan; Steinman, Alan D

    2015-07-01

    Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae. PMID:25897773

  1. Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.

    PubMed

    Xie, Liqiang; Yan, Wei; Li, Jing; Yu, Liqin; Wang, Jianghua; Li, Guangyu; Chen, Nan; Steinman, Alan D

    2015-07-01

    Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae.

  2. Mitochondrial dysfunction mediated by cytoplasmic acidification results in pollen tube growth cessation in Pyrus pyrifolia.

    PubMed

    Gao, Yongbin; Zhou, Hongsheng; Chen, Jianqing; Jiang, Xueting; Tao, Shutian; Wu, Juyou; Zhang, Shaoling

    2015-04-01

    The length of pollen tubes grown in synthetic media is normally shorter than those grown in vivo. However, the mechanism(s) underlying the cessation of pollen tube growth under culture conditions remain(s) largely unknown. Here, we report a previously unknown correlation between vacuolar function and the cell's ability to sustain mitochondrial functions in pear pollen tubes. The pear pollen tubes in vitro grew slowly after 15 hours post-cultured (HPC) and nearly ceased growth at 18 HPC. There was increased malondialdehyde content and membrane ion leakage at 15 HPC compared with 12 HPC. Furthermore, cytoplasmic acidification mainly mediated by decreased vacuolar H(+)-ATPase [V-ATPase, Enzyme Commission (EC) 3.6.1.3] activity was observed in pollen tubes after 15 HPC, and this further resulted in mitochondrial dysfunction, including mitochondrial structure disruption, mitochondrial membrane potential collapse and decreases in both oxygen consumption and ATP production. Our findings suggest that vacuoles and mitochondria intimately linked in regulating pollen tube elongation.

  3. The Herschel view of the dominant mode of galaxy growth from z = 4 to the present day

    NASA Astrophysics Data System (ADS)

    Schreiber, C.; Pannella, M.; Elbaz, D.; Béthermin, M.; Inami, H.; Dickinson, M.; Magnelli, B.; Wang, T.; Aussel, H.; Daddi, E.; Juneau, S.; Shu, X.; Sargent, M. T.; Buat, V.; Faber, S. M.; Ferguson, H. C.; Giavalisco, M.; Koekemoer, A. M.; Magdis, G.; Morrison, G. E.; Papovich, C.; Santini, P.; Scott, D.

    2015-03-01

    We present an analysis of the deepest Herschel images in four major extragalactic fields GOODS-North, GOODS-South, UDS, and COSMOS obtained within the GOODS-Herschel and CANDELS-Herschel key programs. The star formation picture provided by a total of 10 497 individual far-infrared detections is supplemented by the stacking analysis of a mass complete sample of 62 361 star-forming galaxies from the Hubble Space Telescope (HST) H band-selected catalogs of the CANDELS survey and from two deep ground-based Ks band-selected catalogs in the GOODS-North and the COSMOS-wide field to obtain one of the most accurate and unbiased understanding to date of the stellar mass growth over the cosmic history. We show, for the first time, that stacking also provides a powerful tool to determine the dispersion of a physical correlation and describe our method called "scatter stacking", which may be easily generalized to other experiments. The combination of direct UV and far-infrared UV-reprocessed light provides a complete census on the star formation rates (SFRs), allowing us to demonstrate that galaxies at z = 4 to 0 of all stellar masses (M∗) follow a universal scaling law, the so-called main sequence of star-forming galaxies. We find a universal close-to-linear slope of the log 10(SFR)-log 10(M∗) relation, with evidence for a flattening of the main sequence at high masses (log 10(M∗/M⊙) > 10.5) that becomesless prominent with increasing redshift and almost vanishes by z ≃ 2. This flattening may be due to the parallel stellar growth of quiescent bulges in star-forming galaxies, which mostly happens over the same redshift range. Within the main sequence, we measure a nonvarying SFR dispersion of 0.3 dex: at a fixed redshift and stellar mass, about 68% of star-forming galaxies form stars at a universal rate within a factor 2. The specific SFR (sSFR = SFR/M∗) of star-forming galaxies is found to continuously increase from z = 0 to 4. Finally we discuss the implications of

  4. Experimental results of H-mode power threshold with lower hybrid wave heating on the EAST tokamak

    NASA Astrophysics Data System (ADS)

    Huang, Canbin; Gao, Xiang; Liu, Zixi; Han, Xiang; Zhang, Tao; Wang, Yumin; Zang, Shoubiao; Kong, Defeng; the EAST Team

    2016-07-01

    The density roll-over dependence on H-mode power threshold is observed on EAST for the first time. In campaign 2014 and 2015 shots with a toroidal field of 2.25 T have observed roll-over dependence with lower hybrid wave as the only auxiliary heating method, while shots with a toroidal field of 1.79 T and 1.9 T exhibit linear dependence consistent with scaling law. The density of minimum power for accessing H-mode on EAST has different plasma current values of 400 kA and 500 kA, and is better described in the normalized Greenwald fraction {{\\widehat{n}}\\text{e,min}}/{{n}\\text{G}}~≈ ~0.4 at {{B}\\text{T}}=2.35 \\text{T} . The absence of {{\\widehat{n}}\\text{e,min}} in 1.7 T and 1.8 T may be attributed to the positive dependence with toroidal field. Besides, correlation analysis of H-mode power threshold and divertor geometry in scanning X-point is summarized and compared. Outer leg length (distance from X-point to outer strike point) has the highest correlation coefficient with H-mode power threshold, which explains the data scattering within the same plasma parameters. A new equation of scaling law is proposed: {{P}\\text{th \\_\\text{EAST}}}=4.27\\text{OL}{{\\text{L}}1.4}× {{P}\\text{th \\_\\text{08}}}.~ Neutral particles are believed to be the hidden factor in different divertor geometry, and play a negative role in L-H transition via charge exchange damping.

  5. No evidence for consistent long-term growth stimulation of 13 tropical tree species: results from tree-ring analysis.

    PubMed

    Groenendijk, Peter; van der Sleen, Peter; Vlam, Mart; Bunyavejchewin, Sarayudh; Bongers, Frans; Zuidema, Pieter A

    2015-10-01

    The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate-vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2 -fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest-stand level, but insights into species-specific growth changes - that ultimately determine community-level responses - are lacking. Here, we analyse species-specific growth changes on a centennial scale, using growth data from tree-ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size-class isolation) growth-trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8-10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large-scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous

  6. No evidence for consistent long-term growth stimulation of 13 tropical tree species: results from tree-ring analysis.

    PubMed

    Groenendijk, Peter; van der Sleen, Peter; Vlam, Mart; Bunyavejchewin, Sarayudh; Bongers, Frans; Zuidema, Pieter A

    2015-10-01

    The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate-vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2 -fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest-stand level, but insights into species-specific growth changes - that ultimately determine community-level responses - are lacking. Here, we analyse species-specific growth changes on a centennial scale, using growth data from tree-ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size-class isolation) growth-trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8-10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large-scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous

  7. Determination of growth modes of Cu on O/Ni( 1 0 0 ) and NiO( 1 0 0 ) surfaces by SIMS and secondary electron emission measurements

    NASA Astrophysics Data System (ADS)

    Karolewski, M. A.

    2002-10-01

    The growth modes of Cu overlayers deposited on oxygen-predosed Ni(1 0 0) surfaces in the Cu coverage range 0-8 monolayers (ML) have been studied using secondary ion mass spectrometry (SIMS) and ion-induced secondary electron emission measurements. On a c(2×2)-O/Ni(1 0 0) surface prepared by 40 L O 2 exposure of Ni(1 0 0), Cu grows according to the Frank-van der Merwe (FVDM, or layer-by-layer) mode up to at least 2 ML Cu coverage. In contrast, Cu grows by the Volmer-Weber mode on a NiO(1 0 0) surface prepared by 400 L O 2 exposure of Ni(1 0 0) up to at least 8 ML Cu coverage; three-dimensional growth of Cu clusters commences at about 0.2 ML Cu coverage. The characterisation of Cu overlayer growth modes from the measurement of SIMS intensity variations hinges largely on the behaviour of the Ni 2+ and Cu 2+ cluster ions which mainly originate from the surface layer of the sample. For example, the deposition of 1 ML Cu on c(2×2)-O/Ni(1 0 0) completely quenches Ni 2+ emission, whereas on NiO(1 0 0) this process is not complete even after deposition of 8 ML Cu. This behaviour can be formally described with a simple analytical model. On the basis of comparisons between the secondary ion and secondary electron emission properties of O/Cu/Ni(1 0 0) and Cu/O/Ni(1 0 0) surfaces, it is concluded that the Cu layers deposited on the c(2×2)-O/Ni(1 0 0) substrate are covered by an adsorbed layer of oxygen.

  8. Strong Destabilization of Stable Modes with a Half-Frequency Associated with Chirping Geodesic Acoustic Modes in the Large Helical Device

    NASA Astrophysics Data System (ADS)

    Ido, T.; Itoh, K.; Osakabe, M.; Lesur, M.; Shimizu, A.; Ogawa, K.; Toi, K.; Nishiura, M.; Kato, S.; Sasaki, M.; Ida, K.; Inagaki, S.; Itoh, S.-I.

    2016-01-01

    Abrupt and strong excitation of a mode has been observed when the frequency of a chirping energetic-particle driven geodesic acoustic mode (EGAM) reaches twice the geodesic acoustic mode (GAM) frequency. The frequency of the secondary mode is the GAM frequency, which is a half-frequency of the primary EGAM. Based on the analysis of spatial structures, the secondary mode is identified as a GAM. The phase relation between the secondary mode and the primary EGAM is locked, and the evolution of the growth rate of the secondary mode indicates nonlinear excitation. The results suggest that the primary mode (EGAM) contributes to nonlinear destabilization of a subcritical mode.

  9. Root Growth Inhibition in Boron-Deficient or Aluminum-Stressed Squash May Be a Result of Impaired Ascorbate Metabolism.

    PubMed Central

    Lukaszewski, K. M.; Blevins, D. G.

    1996-01-01

    Although cessation of growth is the most apparent symptom of boron deficiency, the biochemical function of boron in growth processes is not well understood. We propose that the action of boron in root meristems is associated with ascorbate metabolism. Total inhibition of root growth in squash (Cucurbita pepo L.) plants transferred to boron-free medium coincided with a major decrease (up to 98%) in the ascorbate concentration of root apices. Under low-boron conditions, in which root growth was partially inhibited, ascorbate concentration declined in proportion to growth rate. The decline in ascorbate concentration in boron-deficient root tips was not related to ascorbate oxidation. Ascorbate added to the medium improved root growth in plants supplied with insufficient boron. Increasing concentrations of aluminum in the nutrient medium caused progressive inhibition of root growth and a parallel reduction in ascorbate concentration of root apices. Elevated boron levels improved root growth under toxic aluminum conditions and produced root apices with higher ascorbate concentrations. To our knowledge, this is the first report of a correlation between boron nutrition, ascorbate concentration in root apices, and growth. These findings show that root growth inhibition resulting from either boron deficiency or aluminum toxicity may be a consequence of disrupted ascorbate metabolism. PMID:12226437

  10. Rapid loss of the plasma sheet energetic electrons associated with the growth of whistler mode waves inside the bursty bulk flows

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Yu, J.; Cao, J. B.

    During the interval 07:45:36- 07:54:24 UT on 24 August 2005, Cluster satellites (C1 and C3) observed an obvious loss of energetic electrons (3.2- 95keV) associated with the growth of whistler mode waves inside some bursty bulk flows (BBFs) in the midtail plasma sheet (X _{GSM}= -17.25 R _{E}). However, the fluxes of the higher-energy electrons (>128keV) and energetic ions (10- 160 keV) were relatively stable in the BBF-impacted regions. The energy-dependent electron loss inside the BBFs is mainly due to the energy-selective pitch angle scatterings by whistler mode waves within the time scales from several seconds to several minutes, and the electron scatterings in different pitch angle distributions are different in the wave growth regions. The plasma sheet energetic electrons have mainly a quasi-perpendicular pitch angle distribution (30(°) growth regions inside the BBFs. Unlike the energetic electrons, the low-energy electrons (0.073- 2.1keV) have initially a field-aligned pitch angle distribution (0(°) mode waves, and their loss in field-aligned directions is accompanied by their increase in quasi-perpendicular directions in the wave growth regions, but the loss of the low-energy electrons inside the BBFs is not obvious in the presence of their large background fluxes. These observations indicate that the resonant electrons in an anisotropic pitch angle distribution mainly undergo the rapid pitch angle scattering loss during the wave-particle resonances.

  11. Formation and growth of indoor air aerosol particles as a result of D-limonene oxidation

    NASA Astrophysics Data System (ADS)

    Vartiainen, E.; Kulmala, M.; Ruuskanen, T. M.; Taipale, R.; Rinne, J.; Vehkamäki, H.

    Oxidation of D-limonene, which is a common monoterpene, can lead to new aerosol particle formation in indoor environments. Thus, products containing D-limonene, such as citrus fruits, air refresheners, household cleaning agents, and waxes, can act as indoor air aerosol particle sources. We released D-limonene into the room air by peeling oranges and measured the concentration of aerosol particles of three different size ranges. In addition, we measured the concentration of D-limonene, the oxidant, and the concentration of ozone, the oxidizing gas. Based on the measurements we calculated the growth rate of the small aerosol particles, which were 3-10 nm in diameter, to be about 6300nmh-1, and the losses of the aerosol particles that were due to the coagulation and condensation processes. From these, we further approximated the concentration of the condensable vapour and its source rate and then calculated the formation rate of the small aerosol particles. For the final result, we calculated the nucleation rate and the maximum number of molecules in a critical cluster. The nucleation rate was in the order of 105cm-3s-1 and the number of molecules in a critical-sized cluster became 1.2. The results were in agreement with the activation theory.

  12. Some results from studies on the effects of weightlessness on the growth of epiphytic orchids

    NASA Technical Reports Server (NTRS)

    Cherevchenko, T. M.; Mayko, T. K.

    1983-01-01

    Epidendrum orchids were placed in a Malakhit-2 micro-greenhouse aboard the Soyuz-36-Salyut-6 space station to test their growth under weightless conditions. Growth occurred but was less than in control plants left on Earth; cells were smaller and parenchymal development slowed in all tissues. Stems, roots, and leaves were smaller. The number of stomas on the leaves was about the same as in the controls, but, because of the smaller leaf size, there were more per unit area. A modeling experiment using a clinostat revealed a large decrease in gibberellin activity and auxin activity. It was assumed that weightlessness primarily affects gibberellin biosynthesis, inhibiting cell growth. Reestablishment of growth compound activity upon return of the plants to Earth was indicated by the fact that the orchids resumed growth thereafter.

  13. Prenatal Exposure to Organophosphorous Pesticides and Fetal Growth: Pooled Results from Four Longitudinal Birth Cohort Studies

    PubMed Central

    Harley, Kim G.; Engel, Stephanie M.; Vedar, Michelle G.; Eskenazi, Brenda; Whyatt, Robin M.; Lanphear, Bruce P.; Bradman, Asa; Rauh, Virginia A.; Yolton, Kimberly; Hornung, Richard W.; Wetmur, James G.; Chen, Jia; Holland, Nina T.; Barr, Dana Boyd; Perera, Frederica P.; Wolff, Mary S.

    2015-01-01

    Background: Organophosphorous (OP) pesticides are associated with reduced fetal growth in animals, but human studies are inconsistent. Objectives: We pooled data from four cohorts to examine associations of prenatal OP exposure with birth weight (n = 1,169), length (n = 1,152), and head circumference (n = 1,143). Methods: Data were from the CHAMACOS, HOME, Columbia, and Mount Sinai birth cohorts. Concentrations of three diethyl phosphate (ΣDEP) and three dimethyl phosphate (ΣDMP) metabolites of OP pesticides [summed to six dialkyl phosphates (ΣDAPs)] were measured in maternal urine. Linear regression and mixed-effects models were used to examine associations with birth outcomes. Results: We found no significant associations of ΣDEP, ΣDMP, or ΣDAPs with birth weight, length, or head circumference overall. However, among non-Hispanic black women, increasing urinary ΣDAP and ΣDMP concentrations were associated with decreased birth length (β = –0.4 cm; 95% CI: –0.9, 0.0 and β = –0.4 cm; 95% CI: –0.8, 0.0, respectively, for each 10-fold increase in metabolite concentration). Among infants with the PON1192RR genotype, ΣDAP and ΣDMP were negatively associated with length (β = –0.4 cm; 95% CI: –0.9, 0.0 and β = –0.5 cm; 95% CI: –0.9, –0.1). Conclusions: This study confirms previously reported associations of prenatal OP exposure among black women with decreased infant size at birth, but finds no evidence of smaller birth weight, length, or head circumference among whites or Hispanics. Contrary to our hypothesis, we found stronger inverse associations of DAPs and birth outcome in infants with the less susceptible PON1192RR genotype. The large pooled data set facilitated exploration of interactions by race/ethnicity and PON1 genotype, but was limited by differences in study populations. Citation: Harley KG, Engel SM, Vedar MG, Eskenazi B, Whyatt RM, Lanphear BP, Bradman A, Rauh VA, Yolton K, Hornung RW, Wetmur JG, Chen J, Holland NT, Barr DB

  14. Label-free Growth Receptor-2 Detection and Dissociation Constant Assessment in Diluted Human Serum Using a Longitudinal Extension Mode of a Piezoelectric Microcantilever Sensor.

    PubMed

    Capobianco, Joseph A; Shih, Wan Y; Adams, Gregory P; Shih, Wei-Heng

    2011-12-15

    We have investigated real-time, label-free, in-situ detection of human epidermal growth factor receptor 2 (Her2) in diluted serum using the first longitudinal extension mode of a lead zirconate-lead titanate (PZT)/glass piezoelectric microcantilever sensor (PEMS) with H3 single-chain variable fragment (scFv) immobilized on the 3-mercaptopropyltrimethoxysilane (MPS) insulation layer of the PEMS surface. We showed that with the longitudinal extension mode, the PZT/glass PEMS consisting of a 1 mm long and 127 μm thick PZT layer bonded with a 75 μm thick glass layer with a 1.8 mm long glass tip could detect Her2 at a concentration of 6-60 ng/ml (or 0.06-0.6 nM) in diluted human serum, about 100 times lower than the concentration limit obtained using the lower-frequency flexural mode of a similar PZT/glass PEMS. We further showed that with the longitudinal mode, the PZT/glass PEMS determined the equilibrium H3-Her2 dissociation constant K(d) to be 3.3±0.3 × 10(-8) M consistent with the value, 3.2±0.28 ×10(-8) M deduced by the surface plasmon resonance method (BIAcore).

  15. Genomic Alterations Are Enhanced in Placentas from Pregnancies with Fetal Growth Restriction and Preeclampsia: Preliminary Results

    PubMed Central

    Biron-Shental, Tal; Sharony, Reuven; Shtorch-Asor, Atalia; Keiser, Meirav; Sadeh-Mestechkin, Dana; Laish, Ido; Amiel, Aliza

    2016-01-01

    Fetal growth restriction (FGR) secondary to placental insufficiency and preeclampsia (PE) are associated with substantially increased childhood and adult morbidity and mortality. The long-term outcomes are related to placental aberrations and intrauterine programming. Advances in microarray technology allow high-resolution, genome-wide evaluation for DNA copy number variations - deletions and duplications. The aim of our study was to demonstrate the usefulness of microarray testing in FGR placentas. Using Affymetrix GeneChip for chromosomal microarray (CMA), we analyzed 10 placentas from pregnancies with FGR attributed to placental insufficiency; 5 with FGR below the 5th percentile and 5 from the 5th to <10th percentiles. All fetuses had normal anomaly scans and karyotypes. We also analyzed 5 third-trimester placentas from pregnancies complicated by PE with severe features and 5 from PE without severe features, all with appropriately grown fetuses. The results were compared to 10 placentas from uncomplicated pregnancies with healthy neonates. CMA analysis identified more genomic alterations in FGR (p < 0.05) and in PE (p < 0.05) placentas than in healthy controls. There was a correlation to the severity of FGR and PE. The genomic alterations were below the resolution of normal karyotyping. The altered genes are related to adult human height, stress reactions and to cellular migration, differentiation and adhesion. Though very preliminary, our data support evaluating FGR and PE placentas using CMA. Larger data sets are needed for further evaluation of the findings and their clinical implications. PMID:27022328

  16. Monolithic integration of a single quantum well laser diode and a mode-size convertor using shadow-masked metalorganic vapour phase epitaxial growth

    NASA Astrophysics Data System (ADS)

    Vermeire, G.; Vermaerke, F.; Moerman, I.; Haes, J.; Baets, R.; Van Daele, P.; Demeester, P.; Gustafsson, A.; Samuelson, L.

    1994-12-01

    In this paper we propose the monolithic integration of quantum well InGaAs/GaAs 0.98 μm lasers with passive mode-size convertors using the shadow-masked growth technique. The full width at half maximum (FWHM) of the far-field in the transverse direction could be reduced from 47° to 30° without a significant increase of Ith and even a slight increase of ν d. Values down to 21° could be reached although a small penalty in threshold current had to be paid. Along the tapered sections, a bandgap increase up to 130 meV has been measured providing transparent windows near the laser facets. Adjusting the nominal layer structure of the laser should allow the realization of reliable 0.98 μm pump lasers for erbium-doped fibre amplifiers showing an improved coupling efficiency in single mode fibres and an enhanced reliability.

  17. Growth

    NASA Astrophysics Data System (ADS)

    Waag, Andreas

    This chapter is devoted to the growth of ZnO. It starts with various techniques to grow bulk samples and presents in some detail the growth of epitaxial layers by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and pulsed laser deposition (PLD). The last section is devoted to the growth of nanorods. Some properties of the resulting samples are also presented. If a comparison between GaN and ZnO is made, very often the huge variety of different growth techniques available to fabricate ZnO is said to be an advantage of this material system. Indeed, growth techniques range from low cost wet chemical growth at almost room temperature to high quality MOCVD growth at temperatures above 1, 000∘C. In most cases, there is a very strong tendency of c-axis oriented growth, with a much higher growth rate in c-direction as compared to other crystal directions. This often leads to columnar structures, even at relatively low temperatures. However, it is, in general, not straight forward to fabricate smooth ZnO thin films with flat surfaces. Another advantage of a potential ZnO technology is said to be the possibility to grow thin films homoepitaxially on ZnO substrates. ZnO substrates are mostly fabricated by vapor phase transport (VPT) or hydrothermal growth. These techniques are enabling high volume manufacturing at reasonable cost, at least in principle. The availability of homoepitaxial substrates should be beneficial to the development of ZnO technology and devices and is in contrast to the situation of GaN. However, even though a number of companies are developing ZnO substrates, only recently good quality substrates have been demonstrated. However, these substrates are not yet widely available. Still, the situation concerning ZnO substrates seems to be far from low-cost, high-volume production. The fabrication of dense, single crystal thin films is, in general, surprisingly difficult, even when ZnO is grown on a ZnO substrate. However

  18. Preliminary results of Physiological plant growth modelling for human life support in space

    NASA Astrophysics Data System (ADS)

    Sasidharan L, Swathy; Dussap, Claude-Gilles; Hezard, Pauline

    2012-07-01

    Human life support is fundamental and crucial in any kind of space explorations. MELiSSA project of European Space Agency aims at developing a closed, artificial ecological life support system involving human, plants and micro organisms. Consuming carbon dioxide and water from the life support system, plants grow in one of the chambers and convert it into food and oxygen along with potable water. The environmental conditions, nutrient availability and its consumption of plants should be studied and necessarily modeled to predict the amount of food, oxygen and water with respect to the environmental changes and limitations. The reliability of a completely closed system mainly depends on the control laws and strategies used. An efficient control can occur, only if the system to control is itself well known, described and ideally if the responses of the system to environmental changes are predictable. In this aspect, the general structure of plant growth model has been designed together with physiological modelling.The physiological model consists of metabolic models of leaves, stem and roots, of which concern specific metabolisms of the associated plant parts. On the basis of the carbon source transport (eg. sucrose) through stem, the metabolic models (leaf and root) can be interconnected to each other and finally coupled to obtain the entire plant model. For the first step, leaf metabolic model network was built using stoichiometric, mass and energy balanced metabolic equations under steady state approach considering all necessary plant pathways for growth and maintenance of leaves. As the experimental data for lettuce plants grown in closed and controlled environmental chambers were available, the leaf metabolic model has been established for lettuce leaves. The constructed metabolic network is analyzed using known stoichiometric metabolic technique called metabolic flux analysis (MFA). Though, the leaf metabolic model alone is not sufficient to achieve the

  19. Alternative Binding Modes Identified for Growth and Differentiation Factor-associated Serum Protein (GASP) Family Antagonism of Myostatin*

    PubMed Central

    Walker, Ryan G.; Angerman, Elizabeth B.; Kattamuri, Chandramohan; Lee, Yun-Sil; Lee, Se-Jin; Thompson, Thomas B.

    2015-01-01

    Myostatin, a member of the TGF-β family of ligands, is a strong negative regulator of muscle growth. As such, it is a prime therapeutic target for muscle wasting disorders. Similar to other TGF-β family ligands, myostatin is neutralized by binding one of a number of structurally diverse antagonists. Included are the antagonists GASP-1 and GASP-2, which are unique in that they specifically antagonize myostatin. However, little is known from a structural standpoint describing the interactions of GASP antagonists with myostatin. Here, we present the First low resolution solution structure of myostatin-free and myostatin-bound states of GASP-1 and GASP-2. Our studies have revealed GASP-1, which is 100 times more potent than GASP-2, preferentially binds myostatin in an asymmetrical 1:1 complex, whereas GASP-2 binds in a symmetrical 2:1 complex. Additionally, C-terminal truncations of GASP-1 result in less potent myostatin inhibitors that form a 2:1 complex, suggesting that the C-terminal domains of GASP-1 are the primary mediators for asymmetric complex formation. Overall, this study provides a new perspective on TGF-β antagonism, where closely related antagonists can utilize different ligand-binding strategies. PMID:25657005

  20. Alternative binding modes identified for growth and differentiation factor-associated serum protein (GASP) family antagonism of myostatin.

    PubMed

    Walker, Ryan G; Angerman, Elizabeth B; Kattamuri, Chandramohan; Lee, Yun-Sil; Lee, Se-Jin; Thompson, Thomas B

    2015-03-20

    Myostatin, a member of the TGF-β family of ligands, is a strong negative regulator of muscle growth. As such, it is a prime therapeutic target for muscle wasting disorders. Similar to other TGF-β family ligands, myostatin is neutralized by binding one of a number of structurally diverse antagonists. Included are the antagonists GASP-1 and GASP-2, which are unique in that they specifically antagonize myostatin. However, little is known from a structural standpoint describing the interactions of GASP antagonists with myostatin. Here, we present the First low resolution solution structure of myostatin-free and myostatin-bound states of GASP-1 and GASP-2. Our studies have revealed GASP-1, which is 100 times more potent than GASP-2, preferentially binds myostatin in an asymmetrical 1:1 complex, whereas GASP-2 binds in a symmetrical 2:1 complex. Additionally, C-terminal truncations of GASP-1 result in less potent myostatin inhibitors that form a 2:1 complex, suggesting that the C-terminal domains of GASP-1 are the primary mediators for asymmetric complex formation. Overall, this study provides a new perspective on TGF-β antagonism, where closely related antagonists can utilize different ligand-binding strategies. PMID:25657005

  1. Size-dependent standard deviation for growth rates: empirical results and theoretical modeling.

    PubMed

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H Eugene; Grosse, I

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation sigma(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation sigma(R) on the average value of the wages with a scaling exponent beta approximately 0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation sigma(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of sigma(R) on the average payroll with a scaling exponent beta approximately -0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable. PMID:18643131

  2. Size-dependent standard deviation for growth rates: Empirical results and theoretical modeling

    NASA Astrophysics Data System (ADS)

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H. Eugene; Grosse, I.

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation σ(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation σ(R) on the average value of the wages with a scaling exponent β≈0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation σ(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of σ(R) on the average payroll with a scaling exponent β≈-0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

  3. Regularity Results for a Class of Functionals with Non-Standard Growth

    NASA Astrophysics Data System (ADS)

    Acerbi, Emilio; Mingione, Giuseppe

    We consider the integral functional under non-standard growth assumptions that we call p(x) type: namely, we assume that a relevant model case being the functional Under sharp assumptions on the continuous function p(x)>1 we prove regularity of minimizers. Energies exhibiting this growth appear in several models from mathematical physics.

  4. Reconstructing skeletal fiber arrangement and growth mode in the coral Porites lutea (Cnidaria, Scleractinia): a confocal Raman microscopy study

    NASA Astrophysics Data System (ADS)

    Wall, M.; Nehrke, G.

    2012-11-01

    Confocal Raman microscopy (CRM) mapping was used to investigate the microstructural arrangement and organic matrix distribution within the skeleton of the coral Porites lutea. Relative changes in the crystallographic orientation of crystals within the fibrous fan-system could be mapped, without the need to prepare thin sections, as required if this information is obtained by polarized light microscopy. Simultaneously, incremental growth lines can be visualized without the necessity of etching and hence alteration of sample surface. Using these methods two types of growth lines could be identified: one corresponds to the well-known incremental growth layers, whereas the second type of growth lines resemble denticle finger-like structures (most likely traces of former spines or skeletal surfaces). We hypothesize that these lines represent the outer skeletal surface before another growth cycle of elongation, infilling and thickening of skeletal areas continues. We show that CRM mapping with high spatial resolution can significantly improve our understanding of the micro-structural arrangement and growth patterns in coral skeletons.

  5. Global Modeling of Nebulae with Particle Growth, Drift, and Evaporation Fronts. I. Methodology and Typical Results

    NASA Astrophysics Data System (ADS)

    Estrada, Paul R.; Cuzzi, Jeffrey N.; Morgan, Demitri A.

    2016-02-01

    We model particle growth in a turbulent, viscously evolving protoplanetary nebula, incorporating sticking, bouncing, fragmentation, and mass transfer at high speeds. We treat small particles using a moments method and large particles using a traditional histogram binning, including a probability distribution function of collisional velocities. The fragmentation strength of the particles depends on their composition (icy aggregates are stronger than silicate aggregates). The particle opacity, which controls the nebula thermal structure, evolves as particles grow and mass redistributes. While growing, particles drift radially due to nebula headwind drag. Particles of different compositions evaporate at “evaporation fronts” (EFs) where the midplane temperature exceeds their respective evaporation temperatures. We track the vapor and solid phases of each component, accounting for advection and radial and vertical diffusion. We present characteristic results in evolutions lasting 2 × 105 years. In general, (1) mass is transferred from the outer to the inner nebula in significant amounts, creating radial concentrations of solids at EFs; (2) particle sizes are limited by a combination of fragmentation, bouncing, and drift; (3) “lucky” large particles never represent a significant amount of mass; and (4) restricted radial zones just outside each EF become compositionally enriched in the associated volatiles. We point out implications for millimeter to submillimeter SEDs and the inference of nebula mass, radial banding, the role of opacity on new mechanisms for generating turbulence, the enrichment of meteorites in heavy oxygen isotopes, variable and nonsolar redox conditions, the primary accretion of silicate and icy planetesimals, and the makeup of Jupiter’s core.

  6. Modification of the high latitude F region of the ionosphere by X-mode powerful HF radio waves: Experimental results from multi-instrument diagnostics

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskaya, Nataly; Rietveld, Michael; Haggstrom, Ingemar; Borisova, Tatiana; Yeoman, Tim

    We present the experimental results for strong plasma modifications induced by the X-mode powerful HF radio waves injected towards the magnetic zenith into the high latitude F region of the ionosphere. A large number of experiments in the course of Russian EISCAT heating campaigns were conducted in 2009 - 2013 under different background conditions in a wide heater frequency range from 4 to 8 MHz. The EISCAT UHF incoherent scatter radar at Tromsø, the CUTLASS (SuperDARN) HF coherent radar in Finland, SEE receiver at Tromsø, the HF Doppler equipment near St. Petersburg, and the EISCAT ionosonde (dynasonde) were used as diagnostic instruments. The results show that the X-mode HF pump wave can generate: (1) strong small-scale artificial field aligned irregularities (AFAIs); (2) HF-induced plasma and HF-enhanced ion lines (HFPLs and HFILs) from UHF radar spectra; (3) strong electron density enhancements along magnetic field line in a wide altitude range; (4) spectral components (few tens of Hz) in the Doppler spectra of the heater signal measured at a distance of 1200 km from the Tromsø HF heating facility. The experimental results obtained points to the strong magnetic zenith effect due to self-focusing powerful HF radio wave with X-mode polarization. For heater frequencies in the range of about 4 - 6 MHz the mentioned above phenomena are generated when the heater frequency is equal or above the ordinary-mode critical frequency (foF2). Under high background electron density and the heater frequencies used of 6.5 - 8.0 MHz, the strong X-mode HF-induced phenomena were observed both when the heater frequency is equal or above the foF2 and the heater frequency is below the foF2.

  7. Modification of the high latitude ionosphere F region by X-mode powerful HF radio waves: Experimental results from multi-instrument diagnostics

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Yeoman, T. K.; Häggström, I.; Kalishin, A. S.

    2015-12-01

    We present experimental results concentrating on a variety of phenomena in the high latitude ionosphere F2 layer induced by an extraordinary (X-mode) HF pump wave at high heater frequencies (fH=6.2-8.0 MHz), depending on the pump frequency proximity to the ordinary and extraordinary mode critical frequencies, foF2 and fxF2. The experiments were carried out at the EISCAT HF heating facility with an effective radiated power of 450-650 MW in October 2012 and October-November 2013. Their distinctive feature is a wide diapason of critical frequency changes, when the fH/foF2 ratio was varied through a wide range from 0.9 to 1.35. It provides both a proper comparison of X-mode HF-induced phenomena excited under different ratios of fH/foF2 and an estimation of the frequency range above foF2 in which such X-mode phenomena are still possible. It was shown that the HF-enhanced ion and plasma lines are excited above foF2 when the HF pump frequency is lying in range between the foF2 and fxF2, foF2≤fH≤fxF2, whereas small-scale field-aligned irregularities continued to be generated even when fH exceeded fxF2 by up to 1 MHz and an X-polarized pump wave cannot be reflected from the ionosphere. Another parameter of importance is the magnetic zenith effect (HF beam/radar angle direction) which is typical for X-mode phenomena under fH/foF2 >1 as well as fH/foF2 ≤1. We have shown for the first time that an X-mode HF pump wave is able to generate strong narrowband spectral components in the SEE spectra (within 1 kHz of pump frequency) in the ionosphere F region, which were recorded at distance of 1200 km from the HF heating facility. The observed spectral lines can be associated with the ion acoustic, electrostatic ion cyclotron, and electrostatic ion cyclotron harmonic waves (otherwise known as neutralized ion Bernstein waves). The comparison between the O- and X-mode SEE spectra recorded at distance far from HF heating facility clearly demonstrated that variety of the narrowband

  8. Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

    PubMed Central

    2012-01-01

    Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM) [Gilbert et al., Journal of the American Chemical Society 2008, 130

  9. RORα switches transcriptional mode of ERRγ that results in transcriptional repression of CYP2E1 under ethanol-exposure

    PubMed Central

    Han, Yong-Hyun; Kim, Don-Kyu; Na, Tae-Young; Ka, Na-Lee; Choi, Hueng-Sik; Lee, Mi-Ock

    2016-01-01

    Increased cytochrome P450 2E1 (CYP2E1) expression is the main cause of oxidative stress, which exacerbates alcoholic liver diseases (ALDs). Estrogen-related receptor gamma (ERRγ) induces CYP2E1 expression and contributes to enhancing alcohol-induced liver injury. Retinoic acid-related orphan receptor alpha (RORα) has antioxidative functions; however, potential cross-talk between ERRγ and RORα in the regulation of CYP2E1 has not been studied. We report that RORα suppressed ERRγ-mediated CYP2E1 expression. A physical interaction of RORα with ERRγ at the ERRγ−response element in the CYP2E1 promoter was critical in this suppression. At this site, coregulator recruitment of ERRγ was switched from coactivator p300 to the nuclear receptor corepressor 1 in the presence of RORα. Cross-talk between ERRγ and RORα was demonstrated in vivo, in that administration of JC1–40, a RORα activator, significantly decreased both CYP2E1 expression and the signs of liver injury in ethanol-fed mice, and this was accompanied by coregulator switching. Thus, this non-classical RORα pathway switched the transcriptional mode of ERRγ, leading to repression of alcohol-induced CYP2E1 expression, and this finding may provide a new therapeutic strategy against ALDs. PMID:26464440

  10. Real-time monitoring of hypertrophy in HL-1 cardiomyocytes by impedance measurements reveals different modes of growth.

    PubMed

    Bloch, Laura; Ndongson-Dongmo, Bernadin; Kusch, Angelika; Dragun, Duska; Heller, Regine; Huber, Otmar

    2016-10-01

    Hypertrophic growth is a response of the heart to increased mechanical load or physiological stress. Thereby, cardiomyocytes grow in length and/or width to maintain cardiac pump function. Major signaling pathways involved in cardiomyocyte growth and remodeling have been identified during recent years including calcineurin-NFAT and PI3K-Akt signaling. Modulation of these pathways is of certain interest for therapeutic treatment of cardiac hypertrophy. However, quantification and characterization of hypertrophy in response to different stimuli or modulators is difficult. This study aims to test different read-out systems for detection and quantification of differences in hypertrophic growth in response to prohypertrophic stimuli. Real-time impedance measurements allowed the detection of distinct differences in hypertrophic growth in response to endothelin, norepinephrine, phenylephrine or BIO, which were not observable by other methods such as flow cytometry. Endothelin treatment induced a rapid and strong peak in the impedance signal concomitant with a massive reorientation of the actin cytoskeleton. Changes in expression of hypertrophy-associated genes were detected and stabilization of β-catenin was identified as a common response to all hypertrophic stimuli used in this study. Hypertrophic growth was blocked by the PI3K/mTOR inhibitor PI-103.

  11. Defective minor spliceosome mRNA processing results in isolated familial growth hormone deficiency

    PubMed Central

    Argente, Jesús; Flores, Raquel; Gutiérrez-Arumí, Armand; Verma, Bhupendra; Martos-Moreno, Gabriel Á; Cuscó, Ivon; Oghabian, Ali; Chowen, Julie A; Frilander, Mikko J; Pérez-Jurado, Luis A

    2014-01-01

    The molecular basis of a significant number of cases of isolated growth hormone deficiency remains unknown. We describe three sisters affected with severe isolated growth hormone deficiency and pituitary hypoplasia caused by biallelic mutations in the RNPC3 gene, which codes for a minor spliceosome protein required for U11/U12 small nuclear ribonucleoprotein (snRNP) formation and splicing of U12-type introns. We found anomalies in U11/U12 di-snRNP formation and in splicing of multiple U12-type introns in patient cells. Defective transcripts include preprohormone convertases SPCS2 and SPCS3 and actin-related ARPC5L genes, which are candidates for the somatotroph-restricted dysfunction. The reported novel mechanism for familial growth hormone deficiency demonstrates that general mRNA processing defects of the minor spliceosome can lead to very narrow tissue-specific consequences. Subject Categories Genetics, Gene Therapy ' Genetic Disease; Metabolism PMID:24480542

  12. Stable Isotope Biogeochemistry of Seabird Guano Fertilization: Results from Growth Chamber Studies with Maize (Zea Mays)

    PubMed Central

    Szpak, Paul; Longstaffe, Fred J.; Millaire, Jean-François; White, Christine D.

    2012-01-01

    Background Stable isotope analysis is being utilized with increasing regularity to examine a wide range of issues (diet, habitat use, migration) in ecology, geology, archaeology, and related disciplines. A crucial component to these studies is a thorough understanding of the range and causes of baseline isotopic variation, which is relatively poorly understood for nitrogen (δ15N). Animal excrement is known to impact plant δ15N values, but the effects of seabird guano have not been systematically studied from an agricultural or horticultural standpoint. Methodology/Principal Findings This paper presents isotopic (δ13C and δ15N) and vital data for maize (Zea mays) fertilized with Peruvian seabird guano under controlled conditions. The level of 15N enrichment in fertilized plants is very large, with δ15N values ranging between 25.5 and 44.7‰ depending on the tissue and amount of fertilizer applied; comparatively, control plant δ15N values ranged between −0.3 and 5.7‰. Intraplant and temporal variability in δ15N values were large, particularly for the guano-fertilized plants, which can be attributed to changes in the availability of guano-derived N over time, and the reliance of stored vs. absorbed N. Plant δ13C values were not significantly impacted by guano fertilization. High concentrations of seabird guano inhibited maize germination and maize growth. Moreover, high levels of seabird guano greatly impacted the N metabolism of the plants, resulting in significantly higher tissue N content, particularly in the stalk. Conclusions/Significance The results presented in this study demonstrate the very large impact of seabird guano on maize δ15N values. The use of seabird guano as a fertilizer can thus be traced using stable isotope analysis in food chemistry applications (certification of organic inputs). Furthermore, the fertilization of maize with seabird guano creates an isotopic signature very similar to a high-trophic level marine resource, which must

  13. Potentiostatic controlled nucleation and growth modes of electrodeposited cobalt thin films on n-Si(1 1 1)

    NASA Astrophysics Data System (ADS)

    Mechehoud, Fayçal; Khelil, Abdelbacet; Eddine Hakiki, Nour; Bubendorff, Jean-Luc

    2016-08-01

    The nucleation and growth of Co electrodeposits on n-Si(1 1 1) substrate have been investigated as a function of the applied potential in a large potential range using electrochemical techniques (voltammetry and chrono-amperometry) and surface imaging by atomic force microscopy (AFM). The surface preparation of the sample is crucial and we achieve a controlled n-Si(1 1 1) surface with mono-atomic steps and flat terraces. Using Scharifker-Hills models for fitting the current-time transients, we show that a transition from an instantaneous nucleation process to a progressive one occurs when the overpotential increases. A good agreement between the nucleation and growth parameters extracted from the models and the AFM data's is observed. The growth is of the Volmer-Weber type with a roughness and a spatial extension in the substrate plane of the deposited islands that increase with thickness.

  14. Orbital- versus glacial-mode forcing of tropical African climate: Results of scientific drilling in Lake Malawi, East Africa

    NASA Astrophysics Data System (ADS)

    Scholz, C. A.; Cohen, A. S.; Johnson, T. C.; King, J. W.; Brown, E. T.; Lyons, R. P.; Stone, J. R.; Beuning, K. R.

    2007-12-01

    Lake Malawi extends from 9-14 degrees S within the East African Rift Valley, and at 700 m deep, contains more than 20 percent of the surface water on the African continent. In 2005 the Lake Malawi Scientific Drilling Project drilled 7 holes at two sites in the lake, recovering a continuous sediment record that samples much of the Quaternary. Detailed studies completed to date on sediments deposited during the past 145 ka indicate periods of severe aridity at precessional frequency between 135 and 75 ka, when the lake's water volume was periodically reduced by at least 95 percent. These dramatic drops in lake level (more than 550 m), signifying markedly arid conditions in the catchment, are documented in sediment lithology (decreased organic carbon content and increased authigenic carbonate content during severe lowstands), aquatic microfossils (appearance of a littoral ostracode fauna, and saline/alkaline lake diatom flora during extreme low lake stages), as well as in dramatic reductions in catchment pollen production. These intervals of pronounced tropical African aridity in the early late-Pleistocene were much more severe than the Last Glacial Maximum, and are consistent with sediment records from Lakes Tanganyika (East Africa) and Bosumtwi (West Africa). In all three lakes a major rise in water levels and a shift to more humid conditions is observed after ~70 ka. The transition to wetter, more stable conditions coincides with the relaxation of orbital eccentricity and a reduction in the amplitude of precession. The observed climate mode switch to decreased environmental variability is consistent with terrestrial and marine records from in and around tropical Africa, but these new drill cores provide evidence for dramatically drier conditions prior to 70 ka that have not as yet been detected in marine sediment records. Such climate change may have stimulated the expansion and migrations of early modern human populations.

  15. Overexpression of the tomato pollen receptor kinase LePRK1 rewires pollen tube growth to a blebbling mode

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The tubular growth of a pollen tube cell is crucial for the sexual reproduction of flowering plants. LePRK1 is a pollen-specific and plasma membrane–localized receptor-like kinase from tomato (Solanum lycopersicum). LePRK1 interacts with another receptor, LePRK2, and with KINASE PARTNER PROTEIN (KPP...

  16. Impact of E × B flow shear on turbulence and resulting power fall-off width in H-mode plasmas in experimental advanced superconducting tokamak

    SciTech Connect

    Yang, Q. Q. Zhong, F. C. E-mail: fczhong@dhu.edu.cn; Jia, M. N.; Xu, G. S. E-mail: fczhong@dhu.edu.cn; Wang, L.; Wang, H. Q.; Chen, R.; Yan, N.; Liu, S. C.; Chen, L.; Li, Y. L.; Liu, J. B.

    2015-06-15

    The power fall-off width in the H-mode scrape-off layer (SOL) in tokamaks shows a strong inverse dependence on the plasma current, which was noticed by both previous multi-machine scaling work [T. Eich et al., Nucl. Fusion 53, 093031 (2013)] and more recent work [L. Wang et al., Nucl. Fusion 54, 114002 (2014)] on the Experimental Advanced Superconducting Tokamak. To understand the underlying physics, probe measurements of three H-mode discharges with different plasma currents have been studied in this work. The results suggest that a higher plasma current is accompanied by a stronger E×B shear and a shorter radial correlation length of turbulence in the SOL, thus resulting in a narrower power fall-off width. A simple model has also been applied to demonstrate the suppression effect of E×B shear on turbulence in the SOL and shows relatively good agreement with the experimental observations.

  17. Impact of E × B flow shear on turbulence and resulting power fall-off width in H-mode plasmas in experimental advanced superconducting tokamak

    NASA Astrophysics Data System (ADS)

    Yang, Q. Q.; Xu, G. S.; Zhong, F. C.; Wang, L.; Wang, H. Q.; Chen, R.; Yan, N.; Liu, S. C.; Chen, L.; Jia, M. N.; Li, Y. L.; Liu, J. B.

    2015-06-01

    The power fall-off width in the H-mode scrape-off layer (SOL) in tokamaks shows a strong inverse dependence on the plasma current, which was noticed by both previous multi-machine scaling work [T. Eich et al., Nucl. Fusion 53, 093031 (2013)] and more recent work [L. Wang et al., Nucl. Fusion 54, 114002 (2014)] on the Experimental Advanced Superconducting Tokamak. To understand the underlying physics, probe measurements of three H-mode discharges with different plasma currents have been studied in this work. The results suggest that a higher plasma current is accompanied by a stronger E × B shear and a shorter radial correlation length of turbulence in the SOL, thus resulting in a narrower power fall-off width. A simple model has also been applied to demonstrate the suppression effect of E × B shear on turbulence in the SOL and shows relatively good agreement with the experimental observations.

  18. Effect of Estimated Daily Global Solar Radiation Data on the Results of Crop Growth Models

    PubMed Central

    Trnka, Miroslav; Eitzinger, Josef; Kapler, Pavel; Dubrovský, Martin; Semerádová, Daniela; Žalud, Zden ěk; Formayer, Herbert

    2007-01-01

    The results of previous studies have suggested that estimated daily global radiation (RG) values contain an error that could compromise the precision of subsequent crop model applications. The following study presents a detailed site and spatial analysis of the RG error propagation in CERES and WOFOST crop growth models in Central European climate conditions. The research was conducted i) at the eight individual sites in Austria and the Czech Republic where measured daily RG values were available as a reference, with seven methods for RG estimation being tested, and ii) for the agricultural areas of the Czech Republic using daily data from 52 weather stations, with five RG estimation methods. In the latter case the RG values estimated from the hours of sunshine using the Ångström-Prescott formula were used as the standard method because of the lack of measured RG data. At the site level we found that even the use of methods based on hours of sunshine, which showed the lowest bias in RG estimates, led to a significant distortion of the key crop model outputs. When the Ångström-Prescott method was used to estimate RG, for example, deviations greater than ±10 per cent in winter wheat and spring barley yields were noted in 5 to 6 per cent of cases. The precision of the yield estimates and other crop model outputs was lower when RG estimates based on the diurnal temperature range and cloud cover were used (mean bias error 2.0 to 4.1 per cent). The methods for estimating RG from the diurnal temperature range produced a wheat yield bias of more than 25 per cent in 12 to 16 per cent of the seasons. Such uncertainty in the crop model outputs makes the reliability of any seasonal yield forecasts or climate change impact assessments questionable if they are based on this type of data. The spatial assessment of the RG data uncertainty propagation over the winter wheat yields also revealed significant differences within the study area. We found that RG estimates based on

  19. Results.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

  20. Effect of dosage and application mode of L-carnitine on plasma lipid and egg-yolk cholesterol of turkeys, hatchability of eggs and post-hatch growth of their offsprings.

    PubMed

    Oso, A O; Fafiolu, A O; Adeleke, M A; Ladokun, O A; Sobayo, R A; Jegede, A V; Peters, S O; Oyebamiji, O A; Akinsola, J

    2014-08-01

    The effect of dosage and application mode of L-carnitine on plasma lipid and egg-yolk cholesterol of breeder turkeys, hatchability of eggs and post-hatch growth response was investigated using 180 breeder hens. The hens were assigned to six dietary treatments in a 2 × 3 factorial arrangements of two application modes of L-carnitine (diet and drinking water) supplemented at 0, 50 and 100 ppm (mg/kg or mg/l) levels, respectively. Each treatment was replicated five times with six hens per replicate. Dietary inclusion of 50 ppm L-carnitine showed the lowest (p < 0.01) plasma total cholesterol (TC) and low-density lipoprotein concentration (LDL). Breeder hens offered 50 ppm L-carnitine with no regard to application mode recorded the highest (p < 0.01) plasma high-density lipoprotein (HDL). Hens offered 50 and 100 ppm L-carnitine irrespective of application mode also showed reduced (p < 0.01) egg-yolk TC concentration at 32 weeks of age. Dietary supplementation of 50 ppm L-carnitine for breeder turkeys recorded the lowest (p < 0.01) egg-yolk triglyceride (TG) at 40 weeks of age. Hens offered 50 ppm L-carnitine irrespective of application mode recorded the highest (p < 0.05) hen-day egg production. Incidence of dead-in-shell also reduced (p < 0.05) with increasing dosage of L-carnitine. Dietary supplementation of 50 ppm and oral application in drinking water of 100 ppm L-carnitine for breeder turkeys resulted in highest (p < 0.05) egg fertility. Offsprings from breeder hens fed diets supplemented with L-carnitine recorded no post-hatch mortality. Highest (p < 0.05) post-hatch final live weight and weight gain was obtained with poults obtained from hens fed diet supplemented with 50 ppm L-carnitine. In conclusion, dietary supplementation of 50 ppm L-carnitine for turkey hens showed improved serum lipid profile, egg fertility, reduced dead-in-shell, egg-yolk cholesterol and resulted in improved post-hatch growth performance.

  1. Postweaning Exposure to Aflatoxin Results in Impaired Child Growth: A Longitudinal Study in Benin, West Africa

    PubMed Central

    Gong, Yunyun; Hounsa, Assomption; Egal, Sharif; Turner, Paul C.; Sutcliffe, Anne E.; Hall, Andrew J.; Cardwell, Kitty; Wild, Christopher P.

    2004-01-01

    Aflatoxins are dietary contaminants that are hepatocarcinogenic and immunotoxic and cause growth retardation in animals, but there is little evidence concerning the latter two parameters in exposed human populations. Aflatoxin exposure of West African children is known to be high, so we conducted a longitudinal study over an 8-month period in Benin to assess the effects of exposure on growth. Two hundred children 16–37 months of age were recruited from four villages, two with high and two with low aflatoxin exposure (50 children per village). Serum aflatoxin–albumin (AF-alb) adducts, anthropometric parameters, information on food consumption, and various demographic data were measured at recruitment (February) and at two subsequent time points (June and October). Plasma levels of vitamin A and zinc were also measured. AF-alb adducts increased markedly between February and October in three of the four villages, with the largest increases in the villages with higher exposures. Children who were fully weaned at recruitment had higher AF-alb than did those still partially breast-fed (p < 0.0001); the major weaning food was a maize-based porridge. There was no association between AF-alb and micronutrient levels, suggesting that aflatoxin exposure was not accompanied by a general nutritional deficiency. There was, however, a strong negative correlation (p < 0.0001) between AF-alb and height increase over the 8-month follow-up after adjustment for age, sex, height at recruitment, socioeconomic status, village, and weaning status; the highest quartile of AF-alb was associated with a mean 1.7 cm reduction in growth over 8 months compared with the lowest quartile. This study emphasizes the association between aflatoxin and stunting, although the underlying mechanisms remain unclear. Aflatoxin exposure during the weaning period may be critical in terms of adverse health effects in West African children, and intervention measures to reduce exposure merit investigation

  2. Langmuir wave growth and electron bunching: Results from a wave-particle correlator

    SciTech Connect

    Ergun, R.E.; Carlson, C.W.; McFadden, J.P.; Clemmons, J.H. ); Boehm, M.H. )

    1991-01-01

    Recent measurements of auroral electrons and intense Langmuir waves on a high-altitude sounding rocket show that these waves were produced by dispersive bursts of low-energy electrons. The sounding rocket was launched northward into the evening auroral zone during a substorm expansion and crossed several discrete auroral arcs having electron energy peaks greater than 25 keV. The large-amplitude Langmuir waves, which appeared in {approximately}100-ms bursts and had amplitudes greater than 200 mV/m, were seen only during periods of enhanced low-energy (0.3-3.0 keV), field-aligned electron precipitation. The enhanced electron flux displayed a dispersive signature in which the higher-energy electrons arrived before the lower-energy electrons. A wave-particle correlator, a new instrument that performed a direct correlation of the arrival times of electrons with the phase of the high-frequency wave field, detected electron bunching at the wave frequency during the bursts of intense Langmuir waves. The electron bunching events, which had amplitudes of a few percent, provided a direct identification of the energy (velocity) of the resonant electrons and therefore established the parallel wavelength ({approximately}15 m). The electron bunching events were detected at or near the energy at which a positive slope in the electron distribution function was seen. During a dispersive burst, the phase velocity (or wavelength) of the Langmuir waves changed in response to the changing velocity at which the positive slope occured. The authors conclude that the velocity dispersion in the low-energy, field-aligned electrons created the unstable electron distribution that was responsible for Langmuir wave growth. The proposed growth mechanism is similar to that suggested for Langmuir wave growth during solar type III radio bursts.

  3. Growth and form of planetary seedlings: results from a microgravity aggregation experiment.

    PubMed

    Blum, J; Wurm, G; Kempf, S; Poppe, T; Klahr, H; Kozasa, T; Rott, M; Henning, T; Dorschner, J; Schräpler, R; Keller, H U; Markiewicz, W J; Mann, I; Gustafson, B A; Giovane, F; Neuhaus, D; Fechtig, H; Grün, E; Feuerbacher, B; Kochan, H; Ratke, L; El Goresy, A; Morfill, G; Weidenschilling, S J; Schwehm, G; Metzler, K; Ip, W H

    2000-09-18

    The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.

  4. Serotonin accumulation in transgenic rice by over-expressing tryptophan decarboxylase results in a dark brown phenotype and stunted growth.

    PubMed

    Kanjanaphachoat, Parawee; Wei, Bi-Yin; Lo, Shuen-Fang; Wang, I-Wen; Wang, Chang-Sheng; Yu, Su-May; Yen, Ming-Liang; Chiu, Sheng-Hsien; Lai, Chien-Chen; Chen, Liang-Jwu

    2012-04-01

    A mutant M47286 with a stunted growth, low fertility and dark-brown phenotype was identified from a T-DNA-tagged rice mutant library. This mutant contained a copy of the T-DNA tag inserted at the location where the expression of two putative tryptophan decarboxylase genes, TDC-1 and TDC-3, were activated. Enzymatic assays of both recombinant proteins showed tryptophan decarboxylase activities that converted tryptophan to tryptamine, which could be converted to serotonin by a constitutively expressed tryptamine 5' hydroxylase (T5H) in rice plants. Over-expression of TDC-1 and TDC-3 in transgenic rice recapitulated the stunted growth, darkbrown phenotype and resulted in a low fertility similar to M47286. The degree of stunted growth and dark-brown color was proportional to the expression levels of TDC-1 and TDC-3. The levels of tryptamine and serotonin accumulation in these transgenic rice lines were also directly correlated with the expression levels of TDC-1 and TDC-3. A mass spectrometry assay demonstrated that the darkbrown leaves and hulls in the TDC-overexpressing transgenic rice were caused by the accumulation of serotonin dimer and that the stunted growth and low fertility were also caused by the accumulation of serotonin and serotonin dimer, but not tryptamine. These results represent the first evidence that over-expression of TDC results in stunted growth, low fertility and the accumulation of serotonin, which when converted to serotonin dimer, leads to a dark brown plant color.

  5. Alterations in the upper facial growth of Macaca mulatta resulting from high-pull headgear.

    PubMed

    Meldrum, R J

    1975-04-01

    Four prepubertal Macaca mulatta monkeys, ranging in age from 13 to 24 months, were used in an investigation of the effects of high-pull headgear (to a face-bow) therapy on the growth of the upper facial skeleton. Amalgam bone implants were placed across the frontomaxillary, frontozygomatic, zygomaticomaxillary, and zygomaticotemporal sutures in each animal. Three of the monkeys wore appliances consisting of a maxillary dental spling, a face-bow, two coil springs, and an acrylic helmet. The fourth monkey (control) wore only a dental splint and a face-bow. A continuous high-pull headgear force of 300 grams per side was applied to the three monkeys for 81, 87 and 89 days, respectively, before death. Procion brilliant red 8-HBS vital stain was administered to all four animals at the start of and 3 days before the end of the treatment period. The facial growth patterns were determined from lateral cephalograms taken before and after treatment, from direct measurement of implant separation at the sutures, and from histologic sections of the four mentioned facial sutures.

  6. Holistic microstructural techniques reveal synchronous and alternating andalusite and staurolite growth during three tectonic events resulted from shifting partitioning of growth vs deformation

    NASA Astrophysics Data System (ADS)

    Bell, T. H.; Fay, C.

    2016-10-01

    Excellent inclusion trails in a sample containing both staurolite and andalusite porphyroblasts are used to demonstrate techniques that allow the intimate relationships between deformation and porphyroblast growth to be recognized, described in detail and understood. This approach reveals three main phases of growth of both mineral phases, some of which was demonstrably synchronous, during three tectonic events. Each main period of growth occurred during the early stages of three deformations that were successively near orthogonal. However, extra periods are distinguishable in andalusite in some of these events because this phase occurs as clusters of large crystals that vary in orientation by 2° to > 10°. All foliations defined by all inclusion trails within every porphyroblast inflect/intersect about an axis trending at 025° (called a FIA). This indicates that the direction of the horizontal component of bulk shortening was identical for the first and third of the three deformations recorded by porphyroblast growth. Portions of sigmoidal to slightly spiral-shaped inclusion trails in most porphyroblast clusters locally diverge in opposite directions due to overprinting orthogonal bulk shortening typical of that which forms millipede geometries. These microstructures confirm the role of coaxial bulk shortening in initiating porphyroblast growth in an environment that locally becomes strongly non-coaxial as the deformation intensifies in the same event. In this sample, increasing non-coaxiality as the deformation intensified resulted in the same asymmetry for each of the three events and thus an overall spiral-like shape. Differing stages in the development of these bulk-shortening geometries preserved in adjacent or touching phases negate any role for porphyroblast rotation during ductile deformation. Andalusite and staurolite grew without any inter-reaction in locations where they lie in contact. This multiply repeated growth behaviour initiated within zones of

  7. Continental Crust Growth as a Result of Continental Collision: Ocean Crust Melting and Melt Preservation

    NASA Astrophysics Data System (ADS)

    Niu, Y.; Zhao, Z.; Zhou, S.; Zhu, D.; Dong, G.; Mo, X.; Xie, G.; Dong, X.

    2010-12-01

    The significance of the continental crust (CC) on which we live is self-evident. However, our knowledge remains limited on its origin, its way and rate of growth, and how it has acquired the “andesitic” composition from mantle derived magmas. Compared to rocks formed from mantle derived magmas in all tectonic settings, volcanic arc rocks associated with oceanic lithosphere subduction share some common features with the CC; both are relatively depleted in “fluid-insoluble” elements (e.g., Nb, Ta and Ti), but enriched in “fluid-soluble” elements (e.g., U, K and Pb). These chemical characteristics are referred to as the “arc-like signature”, and point to a genetic link between subduction-zone magmatism and CC formation, thus leading to the “island-arc” model widely accepted for the origin of the CC over the past 40 years. However, it has been recognized also that this “island-arc” model has several difficulties. These include (1) bulk arc crust (AC) is basaltic, whereas the bulk CC is andesitic [1]; (2) AC has a variably large Sr excess whereas the CC is Sr deficient [2]; and (3) AC production is mass-balanced by subduction-erosion and sediment recycling, thus contributing no new mass to CC growth, at least in the Phanerozoic [3,4]. Our data on magmatic rocks (both volcanic and intrusive) formed during the India-Asia continental collision (~65 - ~45Ma) [5] show a remarkable compositional similarity to the bulk CC with the typical “arc-like signature” [6]. Also, these syncollisional felsic rocks exhibit strong mantle isotopic signatures, implying that they were recently derived from a mantle source. The petrology and geochemistry of these syncollisional felsic rocks is most consistent with an origin via partial melting of upper oceanic crust (i.e., last fragments of underthrusting oceanic crust) under amphibolite facies conditions, adding net mantle-derived materials to form juvenile CC mass. This leads to the logical and testable hypothesis

  8. Effect of current mode on PEO treatment of magnesium in Ca- and P-containing electrolyte and resulting coatings

    NASA Astrophysics Data System (ADS)

    Gao, Yonghao; Yerokhin, Aleksey; Matthews, Allan

    2014-10-01

    Plasma electrolytic oxidation (PEO) coatings were produced on commercially pure magnesium in a biologically friendly electrolyte composed of 2 g L-1 Ca(OH)2 and 12 g L-1 Na3PO4·12H2O using pulsed unipolar and bipolar current regimes with negative biasing varying from 0 to 20 mA cm-2. Analysis of voltage transients was performed to characterise the PEO processes. The coating morphology and phase composition were studied by scanning electron microscopy and X-ray diffraction technique, respectively. In vitro corrosion performance of the coatings was evaluated in a simulated body fluid at 37 ± 1 °C, using electrochemical techniques including open circuit potential monitoring, electrochemical impedance spectroscopy and potentiodynamic polarisation scans. The influence of the negative biasing on the PEO process and resulting coating characteristics is discussed. Unlike generally recognised beneficial effects of the negative biasing in PEO treatments of some other metal-electrolyte systems, it was found that detrimental effects are induced to the coatings on cp-Mg produced in the studied electrolyte when the negative current amplitude increases, which may be attributed to hydrogen liberation at the coating/substrate interface during the negative biasing cycles. As a result, a deterioration of vitro corrosion performance was observed for the pulsed bipolar PEO coatings compared to those produced using the pulsed unipolar regime which provides better quality coatings.

  9. Bleomycin in Octaarginine-modified Fusogenic Liposomes Results in Improved Tumor Growth Inhibition

    PubMed Central

    Koshkaryev, Alexander; Piroyan, Aleksandr; Torchilin, Vladimir P.

    2012-01-01

    Bleomycin (BLM) is an example of an anticancer drug that should be delivered into cytosol for its efficient therapeutic action. With this in mind, we developed octaarginine (R8)-modified fusogenic DOPE-liposomes (R8-DOPE-BLM). R8-modification dramatically increased (up to 50-fold) the cell-liposome interaction. R8-DOPE-liposomes were internalized via macropinocytosis and did not end up in the lysosomes. R8-DOPE-BLM led to a significantly stronger cell death and DNA damage in vitro relative to all controls. R8-DOPE-BLM demonstrated a prominent anticancer effect in the BALB/c mice bearing 4T1 tumors. Thus, R8-DOPE-BLM provided efficient intracellular delivery of BLM leading to strong tumor growth inhibition in vivo. PMID:22743614

  10. Bleomycin in octaarginine-modified fusogenic liposomes results in improved tumor growth inhibition.

    PubMed

    Koshkaryev, Alexander; Piroyan, Aleksandr; Torchilin, Vladimir P

    2013-07-01

    Bleomycin (BLM) is an example of an anticancer drug that should be delivered into cytosol for its efficient therapeutic action. With this in mind, we developed octaarginine (R8)-modified fusogenic DOPE-liposomes (R8-DOPE-BLM). R8-modification dramatically increased (up to 50-fold) the cell-liposome interaction. R8-DOPE-liposomes were internalized via macropinocytosis and did not end up in the lysosomes. R8-DOPE-BLM led to a significantly stronger cell death and DNA damage in vitro relative to all controls. R8-DOPE-BLM demonstrated a prominent anticancer effect in the BALB/c mice bearing 4T1 tumors. Thus, R8-DOPE-BLM provided efficient intracellular delivery of BLM leading to strong tumor growth inhibition in vivo. PMID:22743614

  11. Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases.

    PubMed

    Running, Mark P; Lavy, Meirav; Sternberg, Hasana; Galichet, Arnaud; Gruissem, Wilhelm; Hake, Sarah; Ori, Naomi; Yalovsky, Shaul

    2004-05-18

    Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the alpha-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the beta-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes.

  12. Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases

    PubMed Central

    Running, Mark P.; Lavy, Meirav; Sternberg, Hasana; Galichet, Arnaud; Gruissem, Wilhelm; Hake, Sarah; Ori, Naomi; Yalovsky, Shaul

    2004-01-01

    Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the α-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the β-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes. PMID:15128936

  13. Association between intimate partner violence and poor child growth: results from 42 demographic and health surveys

    PubMed Central

    Fink, Günther; Kaaya, Sylvia; Danaei, Goodarz; Fawzi, Wafaie; Ezzati, Majid; Lienert, Jeffrey; Smith Fawzi, Mary C

    2016-01-01

    Abstract Objective To determine the impact of intimate partner violence against women on children’s growth and nutritional status in low- and middle-income countries. Methods We pooled records from 42 demographic and health surveys in 29 countries. Data on maternal lifetime exposure to physical or sexual violence by an intimate partner, socioeconomic and demographic characteristics were collected. We used logistic regression models to determine the association between intimate partner violence and child stunting and wasting. Findings Prior exposure to intimate partner violence was reported by 69 652 (34.1%) of the 204 159 ever-married women included in our analysis. After adjusting for a range of characteristics, stunting in children was found to be positively associated with maternal lifetime exposure to only physical (adjusted odds ratio, aOR: 1.11; 95% confidence interval, CI: 1.09–1.14) or sexual intimate partner violence (aOR: 1.09; 95% CI: 1.05–1.13) and to both forms of such violence (aOR: 1.10; 95% CI: 1.05–1.14). The associations between stunting and intimate partner violence were stronger in urban areas than in rural ones, for mothers who had low levels of education than for women with higher levels of education, and in middle-income countries than in low-income countries. We also found a small negative association between wasting and intimate partner violence (aOR: 0.94; 95%CI: 0.90–0.98). Conclusion Intimate partner violence against women remains common in low- and middle-income countries and is highly detrimental to women and to the growth of the affected women’s children. Policy and programme efforts are needed to reduce the prevalence and impact of such violence. PMID:27147763

  14. Global atmospheric response to specific linear combinations of the main SST modes.. Part I: numerical experiments and preliminary results

    NASA Astrophysics Data System (ADS)

    Trzaska, S.; Moron, V.; Fontaine, B.

    1996-10-01

    This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST) patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP) climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder) than the long-term mean in the southern hemisphere (northern hemisphere)]. Atlantic SSTAs may also play a significant role. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->

  15. Transition from planar to island growth mode in SiGe structures fabricated on SiGe/Si(001) strain-relaxed buffers

    NASA Astrophysics Data System (ADS)

    Shaleev, M. V.; Novikov, A. V.; Yurasov, D. V.; Hartmann, J. M.; Kuznetsov, O. A.; Lobanov, D. N.; Krasilnik, Z. F.

    2012-10-01

    The specifics of the two-to-three dimensional growth mode transition of pure Ge on SiGe/Si(001) strain-relaxed buffers (SRBs) were investigated. It was shown that the critical thickness for elastic relaxation is influenced not only by the lattice mismatch between the substrate and the film but also by Ge segregation and surface roughness dependent on parameters of strained layers. Critical thickness was found to be smaller for Ge grown on SiGe strain-relaxed buffers than on pure Si(001) substrates, in spite of the lesser lattice mismatch. Insertion of thin tensile-strained Si layers between Ge and SiGe strain-relaxed buffers increased the critical thickness.

  16. Ground Based Experiments in Support of Microgravity Research Results-Vapor Growth of Organic Nonlinear Optical Thin Film

    NASA Technical Reports Server (NTRS)

    Zugrav, M. Ittu; Carswell, William E.; Haulenbeek, Glen B.; Wessling, Francis C.

    2001-01-01

    This work is specifically focused on explaining previous results obtained for the crystal growth of an organic material in a reduced gravity environment. On STS-59, in April 1994, two experiments were conducted with N,N-dimethyl-p-(2,2-dicyanovinyl) aniline (DCVA), a promising nonlinear optical (NLO) material. The space experiments were set to reproduce laboratory experiments that yielded small, bulk crystals of DCVA. The results of the flight experiment, however, were surprising. Rather than producing a bulk single crystal, the result was the production of two high quality, single crystalline thin films. This result was even more intriguing when it is considered that thin films are more desirable for NLO applications than are bulk single crystals. Repeated attempts on the ground to reproduce these results were fruitless. A second set of flight experiments was conducted on STS-69 in September 1995. This time eight DCVA experiments were flown, with each of seven experiments containing a slight change from the first reference experiment. The reference experiment was programmed with growth conditions identical to those of the STS-59 mission. The slight variations in each of the other seven were an attempt to understand what particular parameter was responsible for the preference of thin film growth over bulk crystal growth in microgravity. Once again the results were surprising. In all eight cases thin films were grown again, albeit with varying quality. So now we were faced with a phenomenon that not only takes place in microgravity, but also is very robust, resisting all attempts to force the growth of bulk single crystals.

  17. Growth of Sr(0.61)Ba(0.39)Nb2O6 fibers - New results regarding orientation

    NASA Technical Reports Server (NTRS)

    Wilde, Jeffrey P.; Jundt, Dieter H.; Galambos, Ludwig; Hesselink, Lambertus

    1991-01-01

    The paper describes stable growth of Sr(0.61)Ba(0.39)Nb2O6 (SBN) single-crystal optical fibers (grown by the laser-heated pedestal growth method) along the 100-line and 110-line crystallographic axes. The orientation of SBN fibers was investigated using transmission holograms recorded by focusing two separate, but mutually coherent, optical wavefronts into one end of the fiber. Results showed that the crystal quality of 100-line and 110-line SBN fibers grown at a given pull velocity strongly depended on the fiber diameter; generally, the quality improves with decreasing diameter.

  18. Modeling delta growth and channel geometry on Wax Lake Delta, Louisiana. Preliminary results

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Czapiga, M. J.; Li, C.; Shaw, J. B.; Parker, G.

    2013-12-01

    A numerical model of delta growth, in which the distributary channels are assumed to have self-constructed their cross sections, is validated on Wax Lake Delta, Louisiana. As in previous laterally averaged models of delta growth, the delta is divided in a low slope delta top, a steep delta front and a low slope basement. The flow on the delta top is assumed steady, and a backwater formulation is implemented. Since one or more channels can actively transport water and sediment on the delta top during floods, we simplify the problem by assuming that the bed material is transported in one rectangular channel, with width and depth roughly equal to the sum of the active channel widths, and to the average depth of the active channels. The problem is characterized by one equation (i.e. the backwater equation) in two unknowns, the channel width and depth. Another equation is thus needed to close the problem. Under the assumptions that 1) the system is at bankfull flow, and 2) the Shields number in the channels is equal to its channel formative value, our closure relation is a channel-formative criterion. In particular, a recently derived relation to estimate the formative (bankfull) Shields number as a function of the friction slope is implemented. Recent field work on Wax Lake Delta shows that the distributary channels are incising into a relatively stiff basement. In our model we do not attempt to directly model channel incision, but we implicitly account for it with a modified formulation to compute the shoreline migration rate. In this formulation the bed material at the shoreline is trapped in the non-channelized portion of the delta front only. Measured and numerical shoreline migration rates, longitudinal profiles of delta elevation, and channel geometry, i.e. width and depth, are compared. In the relatively near future we plan to 1) use our model to estimate land-building potential of engineered diversions of the Mississippi River, and 2) couple the present model

  19. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth.

    PubMed

    Winkler, Claudia; De Munter, Sofie; Van Dessel, Nele; Lesage, Bart; Heroes, Ewald; Boens, Shannah; Beullens, Monique; Van Eynde, Aleyde; Bollen, Mathieu

    2015-12-15

    The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe. PMID:26542020

  20. The selective inhibition of protein phosphatase-1 results in mitotic catastrophe and impaired tumor growth.

    PubMed

    Winkler, Claudia; De Munter, Sofie; Van Dessel, Nele; Lesage, Bart; Heroes, Ewald; Boens, Shannah; Beullens, Monique; Van Eynde, Aleyde; Bollen, Mathieu

    2015-12-15

    The serine/threonine protein phosphatase-1 (PP1) complex is a key regulator of the cell cycle. However, the redundancy of PP1 isoforms and the lack of specific inhibitors have hampered studies on the global role of PP1 in cell cycle progression in vertebrates. Here, we show that the overexpression of nuclear inhibitor of PP1 (NIPP1; also known as PPP1R8) in HeLa cells culminated in a prometaphase arrest, associated with severe spindle-formation and chromosome-congression defects. In addition, the spindle assembly checkpoint was activated and checkpoint silencing was hampered. Eventually, most cells either died by apoptosis or formed binucleated cells. The NIPP1-induced mitotic arrest could be explained by the inhibition of PP1 that was titrated away from other mitotic PP1 interactors. Consistent with this notion, the mitotic-arrest phenotype could be rescued by the overexpression of PP1 or the inhibition of the Aurora B kinase, which acts antagonistically to PP1. Finally, we demonstrate that the overexpression of NIPP1 also hampered colony formation and tumor growth in xenograft assays in a PP1-dependent manner. Our data show that the selective inhibition of PP1 can be used to induce cancer cell death through mitotic catastrophe.

  1. Observations of vortex merger and growth reduction in a dual-mode, supersonic Kelvin-Helmholtz instability experiment

    NASA Astrophysics Data System (ADS)

    Wan, Willow; Malamud, Guy; Shimony, Assaf; Trantham, Matt; Klein, Sallee; Shvarts, Dov; Kuranz, Carolyn; Drake, R. Paul

    2015-11-01

    The Kelvin-Helmholtz instability (KHI) generates vortical structures and turbulence at an interface with shear flow. This instability is ubiquitous in natural and engineering systems including astrophysical environments and laboratory plasmas. Detailed measurements of modulation amplitude growth reduction and vortex merger evolving from well-defined initial conditions can benchmark hydrodynamic models and theories. This experiment provides the first measurements of the vortex merger rate of well-characterized seed perturbations evolving under the influence of the KHI in a supersonic flow. These data were obtained by utilizing a sustained laser pulse to drive a steady shockwave into low-density carbon foam, introducing shear along a precision-machined plastic interface. The evolution and merger of the modulations was measured with x-ray radiography and reproduced with 2D hydrodynamic simulations. This work is funded by the U.S. Department of Energy, through the NNSA-DS and SC-OFES Joint Program in High-Energy-Density Laboratory Plasmas, grant number DE-NA0001840, and the National Laser User Facility Program, grant number DE-NA0002032, and through the Laboratory for Laser Energetics, University of Rochester by the NNSA/OICF under Cooperative Agreement No. DE-FC52-08NA28302.

  2. Molecular insights into the klotho-dependent, endocrine mode of action of fibroblast growth factor 19 subfamily members.

    PubMed

    Goetz, Regina; Beenken, Andrew; Ibrahimi, Omar A; Kalinina, Juliya; Olsen, Shaun K; Eliseenkova, Anna V; Xu, ChongFeng; Neubert, Thomas A; Zhang, Fuming; Linhardt, Robert J; Yu, Xijie; White, Kenneth E; Inagaki, Takeshi; Kliewer, Steven A; Yamamoto, Masaya; Kurosu, Hiroshi; Ogawa, Yasushi; Kuro-o, Makoto; Lanske, Beate; Razzaque, Mohammed S; Mohammadi, Moosa

    2007-05-01

    Unique among fibroblast growth factors (FGFs), FGF19, -21, and -23 act in an endocrine fashion to regulate energy, bile acid, glucose, lipid, phosphate, and vitamin D homeostasis. These FGFs require the presence of Klotho/betaKlotho in their target tissues. Here, we present the crystal structures of FGF19 alone and FGF23 in complex with sucrose octasulfate, a disaccharide chemically related to heparin. The conformation of the heparin-binding region between beta strands 10 and 12 in FGF19 and FGF23 diverges completely from the common conformation adopted by paracrine-acting FGFs. A cleft between this region and the beta1-beta2 loop, the other heparin-binding region, precludes direct interaction between heparin/heparan sulfate and backbone atoms of FGF19/23. This reduces the heparin-binding affinity of these ligands and confers endocrine function. Klotho/betaKlotho have evolved as a compensatory mechanism for the poor ability of heparin/heparan sulfate to promote binding of FGF19, -21, and -23 to their cognate receptors. PMID:17339340

  3. Molecular Insights into the Klotho-Dependent, Endocrine Mode of Action of Fibroblast Growth Factor 19 Subfamily Members

    SciTech Connect

    Goetz,R.; Beenken, A.; Ibrahimi, O.; Kalinina, J.; Olsen, S.; Eliseenkova, A.; Xu, C.; Neubert, T.; Zhang, F.; et al.

    2007-01-01

    Unique among fibroblast growth factors (FGFs), FGF19, -21, and -23 act in an endocrine fashion to regulate energy, bile acid, glucose, lipid, phosphate, and vitamin D homeostasis. These FGFs require the presence of Klotho/{beta}Klotho in their target tissues. Here, we present the crystal structures of FGF19 alone and FGF23 in complex with sucrose octasulfate, a disaccharide chemically related to heparin. The conformation of the heparin-binding region between {beta} strands 10 and 12 in FGF19 and FGF23 diverges completely from the common conformation adopted by paracrine-acting FGFs. A cleft between this region and the {beta}1-{beta}2 loop, the other heparin-binding region, precludes direct interaction between heparin/heparan sulfate and backbone atoms of FGF19/23. This reduces the heparin-binding affinity of these ligands and confers endocrine function. Klotho/{beta}Klotho have evolved as a compensatory mechanism for the poor ability of heparin/heparan sulfate to promote binding of FGF19, -21, and -23 to their cognate receptors.

  4. Growth modes and epitaxy of FeAl thin films on a-cut sapphire prepared by pulsed laser and ion beam assisted deposition

    SciTech Connect

    Yao, Xiang; Trautvetter, Moritz; Ziemann, Paul; Wiedwald, Ulf

    2014-01-14

    FeAl films around equiatomic composition are grown on a-cut (112{sup ¯}0) sapphire substrates by ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD) at ambient temperature. Subsequent successive annealing is used to establish chemical order and crystallographic orientation of the films with respect to the substrate. We find a strongly [110]-textured growth for both deposition techniques. Pole figures prove the successful preparation of high quality epitaxial films by PLD with a single in-plane orientation. IBAD-grown films, however, exhibit three in-plane orientations, all of them with broad angular distributions. The difference of the two growth modes is attributed to the existence of a metastable intermediate crystalline orientation as concluded from nonassisted sputter depositions at different substrate temperatures. The formation of the chemically ordered crystalline B2 phase is accompanied by the expected transition from ferromagnetic to paramagnetic behavior of the films. In accordance with the different thermally induced structural recovery, we find a step-like magnetic transition to paramagnetic behavior after annealing for 1 h at T{sub A} = 300 °C for IBAD deposition, while PLD-grown films show a gradual decrease of ferromagnetic signals with rising annealing temperatures.

  5. Damage mechanics - failure modes

    SciTech Connect

    Krajcinovic, D.; Vujosevic, M.

    1996-12-31

    The present study summarizes the results of the DOE sponsored research program focused on the brittle failure of solids with disordered microstructure. The failure is related to the stochastic processes on the microstructural scale; namely, the nucleation and growth of microcracks. The intrinsic failure modes, such as the percolation, localization and creep rupture, are studied by emphasizing the effect of the micro-structural disorder. A rich spectrum of physical phenomena and new concepts that emerges from this research demonstrates the reasons behind the limitations of traditional, deterministic, and local continuum models.

  6. Empowering a mesophilic inoculum for thermophilic nitrification: Growth mode and temperature pattern as critical proliferation factors for archaeal ammonia oxidizers.

    PubMed

    Courtens, Emilie N P; Vandekerckhove, Tom; Prat, Delphine; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Meerbergen, Ken; Lievens, Bart; Boon, Nico; Vlaeminck, Siegfried E

    2016-04-01

    Cost-efficient biological treatment of warm nitrogenous wastewaters requires the development of thermophilic nitrogen removal processes. Only one thermophilic nitrifying bioreactor was described so far, achieving 200 mg N L(-1) d(-1) after more than 300 days of enrichment from compost samples. From the practical point of view in which existing plants would be upgraded, however, a more time-efficient development strategy based on mesophilic nitrifying sludge is preferred. This study evaluated the adaptive capacities of mesophilic nitrifying sludge for two linear temperature increase patterns (non-oscillating vs. oscillating), two different slopes (0.25 vs. 0.08 °C d(-1)) and two different reactor types (floc vs. biofilm growth). The oscillating temperature pattern (0.25 °C d(-1)) and the moving bed biofilm reactor (0.08 °C d(-1)) could not reach nitrification at temperatures higher than 46 °C. However, nitrification rates up to 800 mg N L(-1) d(-1) and 150 mg N g(-1) volatile suspended solids d(-1) were achieved at a temperature as high as 49 °C by imposing the slowest linear temperature increase to floccular sludge. Microbial community analysis revealed that this successful transition was related with a shift in ammonium oxidizing archaea dominating ammonia oxidizing bacteria, while for nitrite oxidation Nitrospira spp. was constantly more abundant than Nitrobacter spp.. This observation was accompanied with an increase in observed sludge yield and a shift in maximal optimum temperature, determined with ex-situ temperature sensitivity measurements, predicting an upcoming reactor failure at higher temperature. Overall, this study achieved nitrification at 49 °C within 150 days by gradual adaptation of mesophilic sludge, and showed that ex-situ temperature sensitivity screening can be used to monitor and steer the transition process. PMID:26841233

  7. Influence of exercise contraction mode and protein supplementation on human skeletal muscle satellite cell content and muscle fiber growth

    PubMed Central

    Farup, Jean; Rahbek, Stine Klejs; Riis, Simon; Vendelbo, Mikkel Holm; de Paoli, Frank

    2014-01-01

    Skeletal muscle satellite cells (SCs) are involved in remodeling and hypertrophy processes of skeletal muscle. However, little knowledge exists on extrinsic factors that influence the content of SCs in skeletal muscle. In a comparative human study, we investigated the muscle fiber type-specific association between emergence of satellite cells (SCs), muscle growth, and remodeling in response to 12 wk unilateral resistance training performed as eccentric (Ecc) or concentric (Conc) resistance training ± whey protein (Whey, 19.5 g protein + 19.5 g glucose) or placebo (Placebo, 39 g glucose) supplementation. Muscle biopsies (vastus lateralis) were analyzed for fiber type-specific SCs, myonuclei, and fiber cross-sectional area (CSA). Following training, SCs increased with Conc in both type I and type II fibers (P < 0.01) and exhibited a group difference from Ecc (P < 0.05), which did not increase. Myonuclei content in type I fibers increased in all groups (P < 0.01), while a specific accretion of myonuclei in type II fibers was observed in the Whey-Conc (P < 0.01) and Placebo-Ecc (P < 0.01) groups. Similarly, whereas type I fiber CSA increased independently of intervention (P < 0.001), type II fiber CSA increased exclusively with Whey-Conc (P < 0.01) and type II fiber hypertrophy correlated with whole muscle hypertrophy exclusively following Conc training (P < 0.01). In conclusion, isolated concentric knee extensor resistance training appears to constitute a stronger driver of SC content than eccentric resistance training while type II fiber hypertrophy was accentuated when combining concentric resistance training with whey protein supplementation. PMID:25103976

  8. Empowering a mesophilic inoculum for thermophilic nitrification: Growth mode and temperature pattern as critical proliferation factors for archaeal ammonia oxidizers.

    PubMed

    Courtens, Emilie N P; Vandekerckhove, Tom; Prat, Delphine; Vilchez-Vargas, Ramiro; Vital, Marius; Pieper, Dietmar H; Meerbergen, Ken; Lievens, Bart; Boon, Nico; Vlaeminck, Siegfried E

    2016-04-01

    Cost-efficient biological treatment of warm nitrogenous wastewaters requires the development of thermophilic nitrogen removal processes. Only one thermophilic nitrifying bioreactor was described so far, achieving 200 mg N L(-1) d(-1) after more than 300 days of enrichment from compost samples. From the practical point of view in which existing plants would be upgraded, however, a more time-efficient development strategy based on mesophilic nitrifying sludge is preferred. This study evaluated the adaptive capacities of mesophilic nitrifying sludge for two linear temperature increase patterns (non-oscillating vs. oscillating), two different slopes (0.25 vs. 0.08 °C d(-1)) and two different reactor types (floc vs. biofilm growth). The oscillating temperature pattern (0.25 °C d(-1)) and the moving bed biofilm reactor (0.08 °C d(-1)) could not reach nitrification at temperatures higher than 46 °C. However, nitrification rates up to 800 mg N L(-1) d(-1) and 150 mg N g(-1) volatile suspended solids d(-1) were achieved at a temperature as high as 49 °C by imposing the slowest linear temperature increase to floccular sludge. Microbial community analysis revealed that this successful transition was related with a shift in ammonium oxidizing archaea dominating ammonia oxidizing bacteria, while for nitrite oxidation Nitrospira spp. was constantly more abundant than Nitrobacter spp.. This observation was accompanied with an increase in observed sludge yield and a shift in maximal optimum temperature, determined with ex-situ temperature sensitivity measurements, predicting an upcoming reactor failure at higher temperature. Overall, this study achieved nitrification at 49 °C within 150 days by gradual adaptation of mesophilic sludge, and showed that ex-situ temperature sensitivity screening can be used to monitor and steer the transition process.

  9. Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

    PubMed

    Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

    2016-02-10

    Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C.

  10. Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

    PubMed

    Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

    2016-02-10

    Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C. PMID:26761590

  11. Changes in Maternal Plasma Adiponectin from Late Pregnancy to the Postpartum Period According to the Mode of Delivery: Results from a Prospective Cohort in Rio de Janeiro, Brazil

    PubMed Central

    Rebelo, Fernanda; Franco-Sena, Ana Beatriz; Struchiner, Claudio Jose; Kac, Gilberto

    2016-01-01

    Introduction Maternal plasma adiponectin is inversely related to insulin resistance, atherosclerosis and child health. However, little is known about its concentrations in the perinatal period, especially according to mode of delivery. Our aim is to evaluate the association between mode of delivery and changes in maternal plasma adiponectin from 3rd trimester of pregnancy to 30–45 days postpartum. Methods A cohort was recruited in Rio de Janeiro, Brazil, with four waves of follow-up: 5-13th, 22-26th, 30-36th gestational weeks and 30–45 days postpartum. Eligible subjects should be between 20–40 years of age, be free of chronic and infectious diseases and presenting with a singleton pregnancy. The mode of delivery was classified as vaginal (VD) or cesarean (CS). Plasma adiponectin concentration (μg/mL) was measured using commercial ELISA kits. Statistical analyses included the Wilcoxon rank-sum test and the multiple linear mixed effects model. Results A total of 159 participated in the study. Median adiponectin concentrations were higher for the VD group (n = 99; 8.25, IQR: 5.85–11.90) than for the CS group (n = 60; 7.34, IQR: 4.36–9.76; p = 0.040) in the postpartum samples but were not different between the two groups in the 3rd trimester. Women who underwent CS had a lower rate of increase in adiponectin concentration from the 3rd trimester to 30–45 days postpartum compared to those who underwent VD (β = -.15, 95% CI: -.28-.02, p = 0.030). Conclusion The CS procedure was associated with lower maternal circulating concentrations of adiponectin at 30–45 days postpartum, compared to the VD. PMID:27391647

  12. The effect of potential upon the high-temperature fatigue crack growth response of low-alloy steels. Part 1: Crack growth results

    SciTech Connect

    James, L.A.; Moshier, W.C.

    1997-04-01

    Corrosion-fatigue crack propagation experiments were conducted on several low-alloy steels in elevated temperature aqueous environments, and experimental parameters included temperature, sulfur content of the steel, applied potential level, and dissolved hydrogen (and in one case, dissolved oxygen) concentration in the water. Specimen potentials were controlled potentiostatically, and the observation (or non-observation) of accelerated fatigue crack growth rates was a complex function of the above parameters. Electrochemical results and the postulated explanation for the complex behavior are given in Part II.

  13. Early Blood Pressure Lowering Does Not Reduce Growth of Intraventricular Hemorrhage following Acute Intracerebral Hemorrhage: Results of the INTERACT Studies

    PubMed Central

    Chan, Edward; Anderson, Craig S.; Wang, Xia; Arima, Hisatomi; Saxena, Anubhav; Moullaali, Tom J.; Delcourt, Candice; Wu, Guojun; Wang, Jinchao; Chen, Guofang; Lavados, Pablo M.; Stapf, Christian; Robinson, Thompson; Chalmers, John

    2016-01-01

    Background Intraventricular hemorrhage (IVH) extension is common following acute intracerebral hemorrhage (ICH) and is associated with poor prognosis. Aim To determine whether intensive blood pressure (BP)-lowering therapy reduces IVH growth. Methods Pooled analyses of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trials (INTERACT1 and INTERACT2) computed tomography (CT) substudies; multicenter, open, controlled, randomized trials of patients with acute spontaneous ICH and elevated systolic BP, randomly assigned to intensive (<140 mm Hg) or guideline-based (<180 mm Hg) BP management. Participants had blinded central analyses of baseline and 24-hour CT. Association of BP lowering to IVH growth was assessed in analysis of covariance. Results There was no significant difference in adjusted mean IVH growth following intensive (n = 228) compared to guideline-recommended (n = 228) BP treatment (1.6 versus 2.2 ml, respectively; p = 0.56). Adjusted mean IVH growth was nonsignificantly greater in patients with a mean achieved systolic BP ≥160 mm Hg over 24 h (3.94 ml; p trend = 0.26). Conclusions Early intensive BP-lowering treatment had no clear effect on IVH in acute ICH. PMID:27603933

  14. Plasma rich in growth factors: preliminary results of use in the preparation of future sites for implants.

    PubMed

    Anitua, E

    1999-01-01

    This article presents preliminary clinical evidence of the beneficial effect of the use of plasma rich in growth factors of autologous origin. The plasma is obtained from the individual patient by plasmapheresis. The macroscopic and microscopic results obtained with bone regeneration using this technique, which uses no membrane or barrier, can be observed. The incorporation of these concepts can introduce several advantages, including the enhancement and acceleration of bone regeneration and more rapid and predictable soft tissue healing.

  15. Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation.

    PubMed

    Soltys, Dorota; Rudzińska-Langwald, Anna; Kurek, Wojciech; Gniazdowska, Agnieszka; Sliwinska, Elwira; Bogatek, Renata

    2011-09-01

    Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2-10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2-6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement.

  16. Modelling the Impact of Life on Continental Growth - Mechanisms and Results

    NASA Astrophysics Data System (ADS)

    Höning, D.; Spohn, T.

    2013-12-01

    The complexity of planetary evolution increases with the number of interacting reservoirs. On Earth, even the biosphere is speculated to interact with the interior. It has been argued (e.g., Rosing et al. 2006; Sleep et al, 2012) that the formation of continents could be a consequence of bioactivity harvesting solar energy through photosynthesis to help build the continents and that the mantle should carry a chemical biosignature. Through plate tectonics, the surface biosphere can impact deep subduction zone processes and the interior of the Earth. Subducted sediments are particularly important, because they influence the Earth's interior in several ways, and in turn are strongly influenced by the Earth's biosphere. In our model, we use the assumption that a thick sedimentary layer of low permeability on top of the subducting oceanic crust, caused by a biologically enhanced weathering rate, can suppress shallow dewatering. This in turn leads to greater availability of water in the source region of andesitic partial melt, resulting in an enhanced rate of continental production and regassing rate into the mantle. Our model includes (i) mantle convection, (ii) continental erosion and production, and (iii) mantle water degassing at mid-ocean ridges and regassing at subduction zones. The mantle viscosity of our model depends on (i) the mantle water concentration and (ii) the mantle temperature, whose time dependency is given by radioactive decay of isotopes in the Earth's mantle. Boundary layer theory yields the speed of convection and the water outgassing rate of the Earth's mantle. Our results indicate that present day values of continental surface area and water content of the Earth's mantle represent an attractor in a phase plane spanned by both parameters. We show that the biologic enhancement of the continental erosion rate is important for the system to reach this fixed point. An abiotic Earth tends to reach an alternative stable fixed point with a smaller

  17. Stimulated bacterial growth under elevated p CO₂: results from an off-shore mesocosm study.

    PubMed

    Endres, Sonja; Galgani, Luisa; Riebesell, Ulf; Schulz, Kai-Georg; Engel, Anja

    2014-01-01

    Marine bacteria are the main consumers of freshly produced organic matter. Many enzymatic processes involved in the bacterial digestion of organic compounds were shown to be pH sensitive in previous studies. Due to the continuous rise in atmospheric CO2 concentration, seawater pH is presently decreasing at a rate unprecedented during the last 300 million years but the consequences for microbial physiology, organic matter cycling and marine biogeochemistry are still unresolved. We studied the effects of elevated seawater pCO2 on a natural plankton community during a large-scale mesocosm study in a Norwegian fjord. Nine Kiel Off-Shore Mesocosms for Future Ocean Simulations (KOSMOS) were adjusted to different pCO2 levels ranging initially from ca. 280 to 3000 µatm and sampled every second day for 34 days. The first phytoplankton bloom developed around day 5. On day 14, inorganic nutrients were added to the enclosed, nutrient-poor waters to stimulate a second phytoplankton bloom, which occurred around day 20. Our results indicate that marine bacteria benefit directly and indirectly from decreasing seawater pH. During the first phytoplankton bloom, 5-10% more transparent exopolymer particles were formed in the high pCO2 mesocosms. Simultaneously, the efficiency of the protein-degrading enzyme leucine aminopeptidase increased with decreasing pH resulting in up to three times higher values in the highest pCO2/lowest pH mesocosm compared to the controls. In general, total and cell-specific aminopeptidase activities were elevated under low pH conditions. The combination of enhanced enzymatic hydrolysis of organic matter and increased availability of gel particles as substrate supported up to 28% higher bacterial abundance in the high pCO2 treatments. We conclude that ocean acidification has the potential to stimulate the bacterial community and facilitate the microbial recycling of freshly produced organic matter, thus strengthening the role of the microbial loop in the

  18. Expression of metallothionein-human growth hormone fusion genes in transgenic mice results in disproportionate skeletal gigantism.

    PubMed

    Wolf, E; Rapp, K; Brem, G

    1991-01-01

    Transgenic mice harbouring mouse metallothionein I-human growth hormone (MT-hGH) fusion genes were produced using the microinjection technique. The bones of adult MT-hGH transgenic mice, which continuously expressed high levels of hGH in their serum, and age-matched controls lacking detectable concentrations of hGH were measured microscopically. In addition to analyzing absolute skeletal dimensions, measurements were related to the cube root of the maximum body weight of the same animal. Absolute values obtained from transgenic mice were significantly higher than those obtained from controls for most of the defined measurements. However, the increase in skeletal dimensions was mostly not as pronounced as the increase in body weight and all bones were not affected to the same extent. There was no significant correlation between the serum GH concentration in individual mice and their degree of bony overgrowth. A disproportionate skeletal gigantism in MT-hGH transgenic mice may result from time differences in epiphyseal union of various bones of both sexes as well as differences in mechanical bone loading due to a drastically increased body weight. Individual concentrations of locally produced tissue insulin-like growth factor I (IGF I) might also play a role. Possible effects of these factors are discussed. The results presented in this study show that MT-hGH transgenic mice provide a powerful tool for the investigation of hormonal regulation of bone growth. PMID:1938045

  19. Vapor transport growth of organic solids in microgravity and unit gravity: some comparisons and results to date

    NASA Technical Reports Server (NTRS)

    Zugrav, Maria Ittu; Carswell, William E.; Haulenbeek, Glen B.; Sanghadasa, Mohan; O'Brien, Sue K.; Ghita, Bogdan C.; Gathings, William E.

    2002-01-01

    Thin films of an organic nonlinear optical (NLO) material, N, N-dimethyl-p-(2,2-dicyanovinyl) aniline (DCVA), have been grown in space and on the ground by physical vapor transport in an effusive ampoule arrangement. The thin film growth technique developed on the ground is a direct result of information gleaned from experiments in microgravity. This paper covers the results of our experimental investigations for establishing "ideal" terrestrial conditions for deposition of a DCVA film. The active control during the deposition process was exercised by three deposition variables: the material source temperature, the background pressure external to the growth ampoule and the substrate temperature. Successful growth occurred when the difference in temperature between the source material and the copper substrate was 14 degrees C and the background nitrogen pressure was such that the transport was either diffusive or convective. A qualitative diffusion limited boundary was estimated to occur at a pressure of approximately 20 torr. We have probed the DCVA thin films with visible-near infrared reflection absorption spectroscopy, polarized Fourier transform infrared spectrometry, differential interference contrast optical microscopy, and stylus profilometry.

  20. Scientific Growth and Identity Development during a Postbaccalaureate Program: Results from a Multisite Qualitative Study

    PubMed Central

    Remich, Robin; Naffziger-Hirsch, Michelle E.; Gazley, J. Lynn; McGee, Richard

    2016-01-01

    This report builds upon our previous study, which described five patterns of why college graduates join National Institutes of Health (NIH)-funded diversity-focused Postbaccalaureate Research Education Programs (PREP). A 2015 report from the NIH showed that a high fraction of PREP participants matriculate into PhD and MD/PhD programs. This current study reveals how participants change during PREP, the program elements that facilitate change, and how identity as a graduate student and future scientist develops. Data come from in-depth interviews done at the beginning and end of PREP with 48 individuals from seven PREP programs. Results reveal three domains of development: academics, research, and presentation of oneself; each domain contains a developmental continuum. Key attributes of PREP enabling development include opportunities to attend graduate-level classes and seminars; time to practice reading literature; extended lab time with one’s own project; high and explicit expectations from mentors; and multiple opportunities to talk about science and improve communication skills. PREP enabled participants to develop their identities as graduate students and to anticipate being seen by others as highly prepared for PhD training. After PREP, 85% (n = 41) started the PhD or MD/PhD, making PREP an intervention approach with great potential to broaden participation in biomedical PhD programs. PMID:27496357

  1. Scientific Growth and Identity Development during a Postbaccalaureate Program: Results from a Multisite Qualitative Study.

    PubMed

    Remich, Robin; Naffziger-Hirsch, Michelle E; Gazley, J Lynn; McGee, Richard

    2016-01-01

    This report builds upon our previous study, which described five patterns of why college graduates join National Institutes of Health (NIH)-funded diversity-focused Postbaccalaureate Research Education Programs (PREP). A 2015 report from the NIH showed that a high fraction of PREP participants matriculate into PhD and MD/PhD programs. This current study reveals how participants change during PREP, the program elements that facilitate change, and how identity as a graduate student and future scientist develops. Data come from in-depth interviews done at the beginning and end of PREP with 48 individuals from seven PREP programs. Results reveal three domains of development: academics, research, and presentation of oneself; each domain contains a developmental continuum. Key attributes of PREP enabling development include opportunities to attend graduate-level classes and seminars; time to practice reading literature; extended lab time with one's own project; high and explicit expectations from mentors; and multiple opportunities to talk about science and improve communication skills. PREP enabled participants to develop their identities as graduate students and to anticipate being seen by others as highly prepared for PhD training. After PREP, 85% (n = 41) started the PhD or MD/PhD, making PREP an intervention approach with great potential to broaden participation in biomedical PhD programs.

  2. Scientific Growth and Identity Development during a Postbaccalaureate Program: Results from a Multisite Qualitative Study.

    PubMed

    Remich, Robin; Naffziger-Hirsch, Michelle E; Gazley, J Lynn; McGee, Richard

    2016-01-01

    This report builds upon our previous study, which described five patterns of why college graduates join National Institutes of Health (NIH)-funded diversity-focused Postbaccalaureate Research Education Programs (PREP). A 2015 report from the NIH showed that a high fraction of PREP participants matriculate into PhD and MD/PhD programs. This current study reveals how participants change during PREP, the program elements that facilitate change, and how identity as a graduate student and future scientist develops. Data come from in-depth interviews done at the beginning and end of PREP with 48 individuals from seven PREP programs. Results reveal three domains of development: academics, research, and presentation of oneself; each domain contains a developmental continuum. Key attributes of PREP enabling development include opportunities to attend graduate-level classes and seminars; time to practice reading literature; extended lab time with one's own project; high and explicit expectations from mentors; and multiple opportunities to talk about science and improve communication skills. PREP enabled participants to develop their identities as graduate students and to anticipate being seen by others as highly prepared for PhD training. After PREP, 85% (n = 41) started the PhD or MD/PhD, making PREP an intervention approach with great potential to broaden participation in biomedical PhD programs. PMID:27496357

  3. 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.

  4. Persistent-mode high-temperature superconductor shim coils: A design concept and experimental results of a prototype Z1 high-temperature superconductor shim.

    PubMed

    Iwasa, Yukikazu; Hahn, Seungyong; Voccio, John; Keun Park, Dong; Kim, Youngjae; Bascuñán, Juan

    2013-07-29

    Design, fabrication, and test results of a type persistent-mode high-temperature superconductor (HTS) shim coil are presented. A prototype Z1 rectangle-loop shim, cut from 46-mm wide Y-Ba-Cu-O tape manufactured by AMSC, was fabricated and tested at 77 K. The HTS shim, much thinner than the conventional NbTi shim, is placed inside the main magnet and immune to its diamagnetic wall effects. Combined with the >12-T and >10-K operation capability, the HTS shim offers a versatile design option for nuclear magnetic resonance (NMR) magnets, liquid-helium-free as well as conventional, and is particularly attractive in the next generation NMR magnets.

  5. Persistent-mode high-temperature superconductor shim coils: A design concept and experimental results of a prototype Z1 high-temperature superconductor shim

    PubMed Central

    Iwasa, Yukikazu; Hahn, Seungyong; Voccio, John; Keun Park, Dong; Kim, Youngjae; Bascuñán, Juan

    2013-01-01

    Design, fabrication, and test results of a type persistent-mode high-temperature superconductor (HTS) shim coil are presented. A prototype Z1 rectangle-loop shim, cut from 46-mm wide Y-Ba-Cu-O tape manufactured by AMSC, was fabricated and tested at 77 K. The HTS shim, much thinner than the conventional NbTi shim, is placed inside the main magnet and immune to its diamagnetic wall effects. Combined with the >12-T and >10-K operation capability, the HTS shim offers a versatile design option for nuclear magnetic resonance (NMR) magnets, liquid-helium-free as well as conventional, and is particularly attractive in the next generation NMR magnets. PMID:23983275

  6. The evaluation of flap growth and long-term results of pediatric mandible reconstructions using free fibular flaps.

    PubMed

    Temiz, Gökhan; Bilkay, Ufuk; Tiftikçioğlu, Yiğit Özer; Mezili, Candan Tevfik; Songür, Ecmel

    2015-05-01

    Currently, the free fibular flap is well accepted as the first choice for mandibular reconstruction. Achieving functional results in pediatric patients requires a different approach than that employed for mature patients. Because the pediatric craniofacial skeleton continues to grow, reconstruction is more challenging, and the long-term results can be different from those of adult patients. In this study, we sought to measure flap growth objectively in our series. Ten pediatric patients who underwent reconstruction with free fibular flaps were retrospectively reviewed. Flap growth was evaluated by comparing the intraoperative photographs with photographs of the control panoramic mandibular radiographs taken using photo-anthropometric techniques. The measurements were converted to proportionality indices (PI), and these indices were compared. Subsequent complications and functional results were also evaluated. The mean patient age was 11.8 years, and the mean follow up was 57.7 months. The mean preoperative PI value was 10.74  ±  2.47. The mean postoperative PI value was 12.52  ±  2.34. The mean difference between the preoperative and postoperative PI values was -1.78 ± 0.53. These photo-anthropometric data clearly illustrated the growth of the fibular flaps (P = 0.001). None of these patients exhibited nonunion of the fractures; however, one patient experienced a delayed union, one had chronic temporomandibular joint pain, and one had chronic temporomandibular joint luxation. In two patients, the inter-incisive measurements were below the third percentile, and two additional patients had grade 2 eating abilities, which can be regarded as poor. All of the patients had symmetric mandibular contours. Free fibular flaps continue to grow in pediatric patients. This flap is a "workhorse" flap in children because it adapts to the craniofacial skeleton via its ability to grow, and this ability results in subsequent good cosmetic and functional results. PMID

  7. Transient-mode liquid phase epitaxial growth of GaAs on GaAs-coated Si substrates prepared by migration-enhanced molecular beam epitaxy

    NASA Technical Reports Server (NTRS)

    Nakamura, Shuji; Sakai, Shiro; Chang, Shi S.; Ramaswamy, Ramu V.; Kim, Jae-Hoon; Radhakrishnan, Gouri; Liu, John K.; Katz, Joseph

    1989-01-01

    Planar oxide-maskless growth of GaAs was demonstrated by transient-mode liquid phase epitaxy (TMLPE) on GaAs-coated Si substrates that were prepared by migration-enhanced molecular beam epitaxy (MEMBE). In TMLPE, the cool substrate was brought into contact with hot melts for a short time. A GaAs layer as thick as 30 microns was grown in 10 sec. The etch pits observed in TMLPE-grown layers became longer in one direction and decreased in density with increasing the TMLPE epilayer thickness. The density of etch pits in a 20 micron-thick layer was approximately 5 x 10 the 6th/sq cm. Strong bandgap emission elliptically polarized with a major axis perpendicular to the surface was observed at about 910 nm, while deep-level emission from the TMLPE/MEMBE GaAs interface was detected at 980 nm. The photoluminescence intensity divided by the carrier concentration of the TMLPE-grown layer was about 270 times larger than that of the MEMBE-grown layer used as a substrate.

  8. Larval growth of Diaprepes abbreviatus (Coleoptera: Curculionidae) and resulting root injury to three citrus varieties in two soil types.

    PubMed

    Rogers, S; Mccoy, C W; Graham, J H

    2000-04-01

    Larval growth and intraspecific competition of Diaprepes abbreviatus (L.) larvae and consequent root injury in container-grown citrus in the greenhouse were evaluated. Roots of Carrizo citrange, Citrus sinesis L. Osbeck x Poncirus trifoliata (L.) Raf.; Cleopatra mandarin, C. reticulata Blanco, and Swingle citrumelo, C. paradisi Macf. x P. trifoliata (L.) Raf. rootstock seedlings grown in Candler fine sand and potting soil were colonized with different populations of D. abbreviatus larvae. Larvae were exposed to the seedlings for 79 d. Larval growth and development increased steadily for approximately 70 d on all rootstock-soil combinations, at which time most larvae were instars 6-8. Most feeding injury occurred to roots when larvae were between instars 3 and 6. Larval weight reached a plateau at approximately 70 d, but often declined between 70 and 79 d. When larvae were small, injury to seedlings developed slowly, primarily on fibrous roots, then feeding increased rapidly, often resulting in total consumption of both fibrous root and bark tissue. Although not statistically significant, root injury developed slightly slower on Swingle citrumelo compared with Carrizo and Cleopatra rootstocks, but damage was comparable by 79 d. Little or no difference in consumptive benefit to the larvae was found between the rootstocks. Based on larval weight days, little feeding injury occurred during the first 21 d, but increased rapidly between 21 and 60 d. Soil type affected the rate of larval growth and development, with potting soil contributing to greater growth rates. Detritus in potting soil provided little or no nutritional resource, suggesting that the effect of potting soil on larval development was primarily physical. In addition, fewer inoculated larvae per seedling exhibited greater weight gains than higher infestation densities, suggesting that intraspecific competition for nutritional resources influenced larval development.

  9. Low-threshold mode instability in Yb3+-doped few-mode fiber amplifiers.

    PubMed

    Kuznetsov, Maxim; Vershinin, Oleg; Tyrtyshnyy, Valentin; Antipov, Oleg

    2014-12-01

    Spatio-temporal instability of the fundamental mode in Yb(3+)-doped few-mode PM fiber amplifiers with a core diameter of 8.5 μm was registered at 2-30 Watts pump power. Both experimental and theoretical analysis revealed the nonlinear power transformation of the LP(01) fundamental mode into high-order modes. Numerical simulation revealed self-consistent growth of the higher-order mode and traveling electronic index grating accompanying the population grating induced by the mode interference field (due to different polarizability of the excited and unexcited Yb(3+) ions). Experimental results and numerical calculations showed the increase of the instability threshold along with an increase of the signal frequency bandwidth.

  10. Improvement in Growth After 1 Year of Growth Hormone Therapy in Well-Nourished Infants with Growth Retardation Secondary to Chronic Renal Failure: Results of a Multicenter, Controlled, Randomized, Open Clinical Trial

    PubMed Central

    Moreno, M. Llanos; Neto, Arlete; Ariceta, Gema; Vara, Julia; Alonso, Angel; Bueno, Alberto; Afonso, Alberto Caldas; Correia, António Jorge; Muley, Rafael; Barrios, Vicente; Gómez, Carlos; Argente, Jesús

    2010-01-01

    Background and objectives: Our aim was to evaluate the growth-promoting effect of growth hormone (GH) treatment in infants with chronic renal failure (CRF) and persistent growth retardation despite adequate nutritional and metabolic management. Design, setting, participants, & measurements: The study design included randomized, parallel groups in an open, multicenter trial comparing GH (0.33 mg/kg per wk) with nontreatment with GH during 12 months. Sixteen infants who had growth retardation, were aged 12 ± 3 months, had CRF (GFR ≤60 ml/min per 1.73 m2), and had adequate nutritional intake and good metabolic control were recruited from eight pediatric nephrology departments from Spain and Portugal. Main outcome measures were body length, body weight, bone age, biochemical and hormonal analyses, renal function, bone mass, and adverse effects. Results: Length gain in infants who were treated with GH was statistically greater (P < 0.05) than that of nontreated children (14.5 versus 9.5 cm/yr; SD score 1.43 versus −0.11). The GH-induced stimulation of growth was associated with no undesirable effects on bone maturation, renal failure progression, or metabolic control. In addition, GH treatment improved forearm bone mass and increased serum concentrations of total and free IGF-I and IGF-binding protein 3 (IGFBP-3), whereas IGF-II, IGFBP-1, IGFBP-2, GH-binding protein, ghrelin, and leptin were not modified. Conclusions: Infants with CRF and growth retardation despite good metabolic and nutritional control benefit from GH treatment without adverse effects during 12 months of therapy. PMID:20522533

  11. Potential lipid accumulation and growth characteristic of the green alga Chlorella with combination cultivation mode of nitrogen (N) and phosphorus (P).

    PubMed

    Li, Yuqin; Han, Fangxin; Xu, Hua; Mu, Jinxiu; Chen, Di; Feng, Bo; Zeng, Hongyan

    2014-12-01

    This study aimed to evaluate the potential lipid accumulation of an oleaginous Chlorella protothecoides by combination cultivation mode of nitrogen (N) and phosphorus (P). Under co-deficiency of N and P, the largest lipid content (55.8%) was accomplished in C. protothecoides, which was higher than either sole P-deficiency (32.77%) or N-deficiency (52.5%), or co-repletion of N and P (control) (22.17%). However, the highest lipid productivity (224.14mg/L/day) with combination mode of N-deficiency and P-repletion represented 1.19-3.70-fold more than that of control, P-deficiency/limitation, and co-deficiency of N and P, respectively. This indicating N-deficiency plus P-repletion was a promising lipid trigger to motivate lipid accumulation in C. protothecoides cells. Further, difference gel electrophoresis (DIGE)-based proteomics was employed to reveal the molecular pathways associated with lipid biosynthesis. These results provide the foundation to develop engineering strategies targeting lipid productivity for industrial production of microalgae-based biodiesel.

  12. Human epidermal growth factor receptor 2 positive (HER2+) metastatic breast cancer: how the latest results are improving therapeutic options

    PubMed Central

    Jiang, Hanfang; Rugo, Hope S.

    2015-01-01

    Human epidermal growth factor receptor 2 positive (HER2+) metastatic breast cancer (MBC) remains an incurable disease, and approximately 25% of patients with HER2+ early breast cancer still relapse after adjuvant trastuzumab-based treatment. HER2 is a validated therapeutic target that remains relevant throughout the disease process. Recently, a number of novel HER2 targeted agents have become available, including lapatinib (a small molecule tyrosine kinase inhibitor of both HER2 and the epidermal growth factor receptor), pertuzumab (a new anti-HER2 monoclonal antibody) and ado-trastuzumab emtansine (T-DM1, a novel antibody–drug conjugate), which provide additional treatment options for patients with HER2+ MBC. The latest clinical trials have demonstrated improved outcome with treatment including pertuzumab or T-DM1 compared with standard HER2 targeted therapy. Here we review the clinical development of approved and investigational targeted agents for the treatment of HER2+ MBC, summarize the latest results of important clinical trials supporting use of these agents in the treatment of HER2+ MBC, and discuss how these results impact therapeutic options in clinical practice. PMID:26557900

  13. Mode III fatigue crack propagation in low alloy steel

    NASA Astrophysics Data System (ADS)

    Ritchie, R. O.; McClintock, F. A.; Nayeb-Hashemi, H.; Ritter, M. A.

    1982-01-01

    To provide a basis for estimating fatigue life in large rotating generator shafts subjected to transient oscillations, a study is made of fatigue crack propagation in Mode III (anti-plane shear) in torsionally-loaded spheroidized AISI4340 steel, and results compared to analogous behavior in Mode I. Torsional S/N curves, determined on smooth bars containing surface defects, showed results surprisingly close to expected unnotched Mode I data, with lifetime increasing from 104 cycles at nominal yield to 106 cycles at half yield. Fatigue crack growth rates in Mode III, measured on circumferentially-notched samples, were found to be slower than in Mode I, although still power-law related to the alternating stress intensity (△K III) for small-scale yielding. Mode III growth rates were only a small fraction (0.002 to 0.0005) of cyclic crack tip displacements (△CTD III) per cycle, in contrast to Mode I where the fraction was much larger (0.1 to 0.01). A micromechanical model for Mode III growth is proposed, where crack advance is considered to take place by a Mode II coalescence of cracks, initiated at inclusions ahead of the main crack front. This mechanism is consistent with the crack increment being a small fraction of △CTDIII per cycle.

  14. Real-time x-ray studies of crystal growth modes during metal-organic vapor phase epitaxy of GaN on c- and m-plane single crystals

    NASA Astrophysics Data System (ADS)

    Perret, Edith; Highland, M. J.; Stephenson, G. B.; Streiffer, S. K.; Zapol, P.; Fuoss, P. H.; Munkholm, A.; Thompson, Carol

    2014-08-01

    Non-polar orientations of III-nitride semiconductors have attracted significant interest due to their potential application in optoelectronic devices with enhanced efficiency. Using in situ surface x-ray scattering during metal-organic vapor phase epitaxy (MOVPE) of GaN on non-polar (m-plane) and polar (c-plane) orientations of single crystal substrates, we have observed the homoepitaxial growth modes as a function of temperature and growth rate. On the m-plane surface, we observe all three growth modes (step-flow, layer-by-layer, and three-dimensional) as conditions are varied. In contrast, the +c-plane surface exhibits a direct crossover between step-flow and 3D growth, with no layer-by-layer regime. The apparent activation energy of 2.8 ± 0.2 eV observed for the growth rate at the layer-by-layer to step-flow boundary on the m-plane surface is consistent with those observed for MOVPE growth of other III-V compounds, indicating a large critical nucleus size for islands.

  15. Influence of aeration-homogenization system in stirred tank bioreactors, dissolved oxygen concentration and pH control mode on BHK-21 cell growth and metabolism.

    PubMed

    Núñez, Eutimio Gustavo Fernández; Leme, Jaci; de Almeida Parizotto, Letícia; Chagas, Wagner Antonio; de Rezende, Alexandre Gonçalves; da Costa, Bruno Labate Vale; Monteiro, Daniela Cristina Ventini; Boldorini, Vera Lucia Lopes; Jorge, Soraia Attie Calil; Astray, Renato Mancini; Pereira, Carlos Augusto; Caricati, Celso Pereira; Tonso, Aldo

    2014-08-01

    This work focused on determining the effect of dissolved oxygen concentration (DO) on growth and metabolism of BHK-21 cell line (host cell for recombinant proteins manufacturing and viral vaccines) cultured in two stirred tank bioreactors with different aeration-homogenization systems, as well as pH control mode. BHK-21 cell line adapted to single-cell suspension was cultured in Celligen without aeration cage (rotating gas-sparger) and Bioflo 110, at 10, 30 and 50 % air saturation (impeller for gas dispersion from sparger-ring). The pH was controlled at 7.2 as far as it was possible with gas mixtures. In other runs, at 30 and 50 % (DO) in Bioflo 110, the cells grew at pH controlled with CO2 and NaHCO3 solution. Glucose, lactate, glutamine, and ammonium were quantified by enzymatic methods. Cell concentration, size and specific oxygen consumption were also determined. When NaHCO3 solution was not used, the optimal DOs were 10 and 50 % air saturation for Celligen and Bioflo 110, respectively. In this condition maximum cell concentrations were higher than 4 × 10(6) cell/mL. An increase in maximum cell concentration of 36 % was observed in batch carried out at 30 % air saturation in a classical stirred tank bioreactor (Bioflo 110) with base solution addition. The optimal parameters defined in this work allow for bioprocess developing of viral vaccines, transient protein expression and viral vector for gene therapy based on BHK-21 cell line in two stirred tank bioreactors with different agitation-aeration systems.

  16. Stenotrophomonas maltophilia interferes via the DSF-mediated quorum sensing system with Candida albicans filamentation and its planktonic and biofilm modes of growth.

    PubMed

    de Rossi, Beatriz Passerini; García, Carlos; Alcaraz, Eliana; Franco, Mirta

    2014-01-01

    Stenotrophomonas maltophilia is a nosocomial pathogen of increasing importance. S. maltophilia K279a genome encodes a diffusible signal factor (DSF) dependent quorum sensing (QS) system that was first identified in Xanthomonas campestris pv. campestris. DSF from X. campestris is a homologue of farnesoic acid, a Candida albicans QS signal which inhibits the yeast-to-hyphal shift. Here we describe the antagonistic effects of S. maltophilia on C. albicans on filamentation as well as on its planktonic and biofilm modes of growth. To determine the role of the DSF-mediated quorum sensing system in these effects, C. albicans ATCC 10231 and C. albicans tup1 mutant, locked in the filamentous form, were grown with K279a or with its rpfF deletion mutant (DSF-). A significant reduction in viable counts of C. albicans was observed in planktonic cocultures with K279a as well as in mixed biofilms. Furthermore, no viable cells of C. albicans tup1 were recovered from K279a mixed biofilms. Fungal viability was also assessed by labeling biofilms with SYTO 9 and propidium iodide. Confocal images showed that K279a can kill hyphae and also yeast cells. Light microscopic analysis showed that K279a severely affects hyphae integrity. On the other hand, the presence of K279a rpfF did not affect fungal morphology or viability. In conclusion, we report for the first time that S. maltophilia interferes with two key virulence factors of C. albicans, the yeast-to-hyphal transition and biofilm formation. DSF could be directly responsible for these effects or may induce the gene expression involved in antifungal activity.

  17. Effects of Atmospheric Pollutants on Plant Growth and on Soil Magnetic Properties: Preliminary Results from Controlled Experiments

    NASA Astrophysics Data System (ADS)

    Sapkota, B.; Cioppa, M. T.

    2009-05-01

    The effects of an iron pollutant (magnetite, <5µm) on both tomato plants and their growth media (soil) in garden pots have been examined in this study. Morphological differences in the plants subjected to different concentrations (0.04 mg/kg and 0.4mg/kg) of the pollutant have been monitored at different ontogenic stages by measuring plant height and leaf colour, using a reflectance spectrometer (USB 4000). The surface magnetic susceptibility (MS) of the growth media has been measured using the Bartington MS2 system on a weekly basis. The changes in soil magnetic properties and some trace element concentrations of elements potentially associated with Fe have been determined through magnetic and chemical methods. The preliminary results in the control samples and a few of the contaminated samples show that exposure to iron contaminant can affect plant growth significantly, and can change the magnetic susceptibility of the growth media. Distinct morphological differences are observed in plants subjected to different treatments. The control plants are much taller (30-40cm, measured to date) compared to low-contamination (20-30cm) and high- contamination plants (10-15cm). In contrast, the mean brightness and saturation values of the leaves did not vary substantially. These colour parameters were hypothesized to vary significantly; however an explanation for their similarity is still being researched. The average decrease in MS is about 23% in the control soil. From a theoretical perspective, with the decrease in MS, there should be a corresponding decrease in iron minerals, which should be observable by chemical methods. However the MS values increased in most of the samples with contaminated soils but the mechanism by which this occurs is unclear. We would expect that, in such a controlled environment, any changes in soil magnetic properties and trace element concentrations must be due to the plant growth and its effects on the surrounding soil. The background values

  18. On the relative role of processes whose sequence results in crack growth in the cladding of LMFBR fuel pins

    NASA Astrophysics Data System (ADS)

    Mikhlin, E. Ya.

    1991-08-01

    Processes are discussed the joint effect of which results in crack development in austenitic steel-clad oxide fuel pins. Such processes include generation of Te which is considered as the main embrittling agent, its transport and accumulation at the cladding inner surface, where together with Cs it forms a liquid surface-acting medium, and finally, development of intergranular cracks in the cladding caused by the contact with this medium. As the process of crack growth in itself proceeds faster than accumulation of liquid surfactants at the cladding, the cracks will be able to reach the critical length only after the necessary amount of Te has been accumulated. Its accumulation is determined and therefore, controlled by the process of Te transport in the fuel grains. It is shown that the main contribution to the accumulation of Te at the cladding surface is provided by the hottest internal zones of the fuel pellet. On the basis of the analysis given, means are discussed, for inhibiting or blocking the crack growth.

  19. HerMES: a search for high-redshift dusty galaxies in the HerMES Large Mode Survey - catalogue, number counts and early results

    NASA Astrophysics Data System (ADS)

    Asboth, V.; Conley, A.; Sayers, J.; Béthermin, M.; Chapman, S. C.; Clements, D. L.; Cooray, A.; Dannerbauer, H.; Farrah, D.; Glenn, J.; Golwala, S. R.; Halpern, M.; Ibar, E.; Ivison, R. J.; Maloney, P. R.; Marques-Chaves, R.; Martinez-Navajas, P. I.; Oliver, S. J.; Pérez-Fournon, I.; Riechers, D. A.; Rowan-Robinson, M.; Scott, Douglas; Siegel, S. R.; Vieira, J. D.; Viero, M.; Wang, L.; Wardlow, J.; Wheeler, J.

    2016-10-01

    Selecting sources with rising flux densities towards longer wavelengths from Herschel/Spectral and Photometric Imaging Receiver (SPIRE) maps is an efficient way to produce a catalogue rich in high-redshift (z > 4) dusty star-forming galaxies. The effectiveness of this approach has already been confirmed by spectroscopic follow-up observations, but the previously available catalogues made this way are limited by small survey areas. Here we apply a map-based search method to 274 deg2 of the Herschel Multi-tiered Extragalactic Survey (HerMES) Large Mode Survey and create a catalogue of 477 objects with SPIRE flux densities S500 > S350 > S250 and a 5σ cut-off S500 > 52 mJy. From this catalogue we determine that the total number of these `red' sources is at least an order of magnitude higher than predicted by galaxy evolution models. These results are in agreement with previous findings in smaller HerMES fields; however, due to our significantly larger sample size we are also able to investigate the shape of the red source counts for the first time. We have obtained spectroscopic redshift measurements for two of our sources using the Atacama Large Millimeter/submillimeter Array. The redshifts z = 5.1 and 3.8 confirm that with our selection method we can indeed find high-redshift dusty star-forming galaxies.

  20. Large mode radius resonators

    NASA Technical Reports Server (NTRS)

    Harris, Michael R.

    1987-01-01

    Resonator configurations permitting operation with large mode radius while maintaining good transverse mode discrimination are considered. Stable resonators incorporating an intracavity telescope and unstable resonator geometries utilizing an output coupler with a Gaussian reflectivity profile are shown to enable large radius single mode laser operation. Results of heterodyne studies of pulsed CO2 lasers with large (11mm e sup-2 radius) fundamental mode sizes are presented demonstrating minimal frequency sweeping in accordance with the theory of laser-induced medium perturbations.

  1. Microbial Growth and Air Pollutants in the Corrosion of Carbonate Rocks: Results from Laboratory and Outdoor Experimental Tests

    NASA Astrophysics Data System (ADS)

    Moroni, B.; Poli, G.; Pitzurra, L.

    2003-04-01

    Microorganisms and atmospheric pollution are primary causes of deterioration of materials exposed to open air. Due to the variety of chemical-mineralogical compositions and textures, stone represents a variegated substrate that interacts with environmental fluids and particulate, and is a selective environment for biological proliferation. Carbonate rocks, in particular, are highly exposed to environmental decay and extremely susceptible to acid attack caused by atmospheric pollutants and metabolic acid production. The aim of this work is to study the combined effect of microbial contamination and atmospheric pollutants in the weathering of carbonate rocks by means of laboratory and outdoor exposure tests. Laboratory experiments performed on carbonate rocks allowed evaluation of the influence of the gas mixture in the chemical modifications of the lithic substrate, and formulation of a kinetic model of sulphation. The obtained results suggest that nucleation alternates with growth as leading processes in the development of sulphation. In particular, nucleation of the reaction products is the leading process in the initial period of sulphation, which is characterized by a marked slowdown of the reaction progress, whereas growth of the products is the leading process in the subsequent period of resumption of sulphation. In situ experiments performed by exposing limestone specimens at two air monitoring stations in Perugia with different degrees of urban air pollution showed high levels of fungal colonization at early times and the presence of weathering products (i.e. gypsum) in the longer term. Results point to a combined effect of microbial colonization and atmospheric pollutants in promoting the weathering of stone through acid attack within the film of water present on the surface of the exposed material, and through the oxidation of metal sulphide particulate pollutant to sulphate. Laboratory tests assaying the extent of fungal colonization and/or chemical

  2. Strong growth orientation dependence of strain relaxation in epitaxial (Ba,Sr)TiO{sub 3} films and the resulting dielectric properties

    SciTech Connect

    Yamada, Tomoaki; Kamo, Takafumi; Funakubo, Hiroshi; Su Dong; Iijima, Takashi

    2011-05-01

    The growth orientation dependence of strain relaxation and the dielectric properties were investigated for (001)- and (111)-epitaxial (Ba,Sr)TiO{sub 3} films. The films were deposited on SrRuO{sub 3}/SrTiO{sub 3} and SrTiO{sub 3} substrates using rf magnetron sputtering. The residual strain was found to be remarkably different between the two orientations, although these lattice mismatches are identical; the strain relaxation of the (001)-epitaxial films is significantly slower than that of the (111)-epitaxial films and is promoted only when the growth rate is very low ({<=}5 nm/h). The observed orientation dependence is discussed with the surface energy for both growth orientations, which influences the growth mode of the films. Due to the large contrast of the strain in the (001)- and (111)-epitaxial films, the paraelectric to ferroelectric phase transition temperature of the (001)-epitaxial films is much higher than that of unstrained bulks, while the (111)-epitaxial films show a phase transition temperature corresponding to that of unstrained bulks regardless of the growth rates.

  3. Early life exposure to PCB126 results in delayed mortality and growth impairment in the zebrafish larvae.

    PubMed

    Di Paolo, Carolina; Groh, Ksenia J; Zennegg, Markus; Vermeirssen, Etiënne L M; Murk, Albertinka J; Eggen, Rik I L; Hollert, Henner; Werner, Inge; Schirmer, Kristin

    2015-12-01

    The occurrence of chronic or delayed toxicity resulting from the exposure to sublethal chemical concentrations is an increasing concern in environmental risk assessment. The Fish Embryo Toxicity (FET) test with zebrafish provides a reliable prediction of acute toxicity in adult fish, but it cannot yet be applied to predict the occurrence of chronic or delayed toxicity. Identification of sublethal FET endpoints that can assist in predicting the occurrence of chronic or delayed toxicity would be advantageous. The present study characterized the occurrence of delayed toxicity in zebrafish larvae following early exposure to PCB126, previously described to cause delayed effects in the common sole. The first aim was to investigate the occurrence and temporal profiles of delayed toxicity during zebrafish larval development and compare them to those previously described for sole to evaluate the suitability of zebrafish as a model fish species for delayed toxicity assessment. The second aim was to examine the correlation between the sublethal endpoints assessed during embryonal and early larval development and the delayed effects observed during later larval development. After exposure to PCB126 (3-3000ng/L) until 5 days post fertilization (dpf), larvae were reared in clean water until 14 or 28 dpf. Mortality and sublethal morphological and behavioural endpoints were recorded daily, and growth was assessed at 28 dpf. Early life exposure to PCB126 caused delayed mortality (300 ng/L and 3000 ng/L) as well as growth impairment and delayed development (100 ng/L) during the clean water period. Effects on swim bladder inflation and cartilaginous tissues within 5 dpf were the most promising for predicting delayed mortality and sublethal effects, such as decreased standard length, delayed metamorphosis, reduced inflation of swim bladder and column malformations. The EC50 value for swim bladder inflation at 5 dpf (169 ng/L) was similar to the LC50 value at 8 dpf (188 and 202 ng/L in

  4. Pulsed-laser excitation of acoustic modes in open high-Q photoacoustic resonators for trace gas monitoring: results for C2H4

    NASA Astrophysics Data System (ADS)

    Brand, Christian; Winkler, Andreas; Hess, Peter; Miklós, András; Bozóki, Zoltán; Sneider, János

    1995-06-01

    The pulsed excitation of acoustic resonances was studied with a continuously monitoring photoacoustic detector system. Acoustic waves were generated in C2H4/N 2 gas mixtures by light absorption of the pulses from a transversely excited atmospheric CO2 laser. The photoacoustic part consisted of high-Q cylindrical resonators (Q factor 820 for the first radial mode in N2) and two adjoining variable acoustic filter systems. The time-resolved signal was Fourier transformed to a frequency spectrum of high resolution. For the first radial mode a Lorentzian profile was fitted to the measured data. The outside noise suppression and the signal-to-noise ratio were investigated in a normal laboratory environment in the flow-through mode. The acoustic and electric filter system combined with the

  5. The effect of a dominant initial single mode on the Kelvin–Helmholtz instability evolution: New insights on previous experimental results

    DOE PAGESBeta

    Shimony, Assaf; Shvarts, Dov; Malamud, Guy; Di Stefano, Carlos A.; Kuranz, Carolyn C.; Drake, R. P.

    2016-04-12

    This paper brings new insights on an experiment, measuring the Kelvin–Helmholtz (KH) instability evolution, performed on the OMEGA-60 laser facility. Experimental radiographs show that the initial seed perturbations in the experiment are of multimode spectrum with a dominant single-mode of 16 μm wavelength. In single-mode-dominated KH instability flows, the mixing zone (MZ) width saturates to a constant value comparable to the wavelength. However, the experimental MZ width at late times has exceeded 100 μm, an order of magnitude larger. In this work, we use numerical simulations and a statistical model in order to investigate the vortex dynamics of the KHmore » instability for the experimental initial spectrum. Here, we conclude that the KH instability evolution in the experiment is dominated by multimode, vortex-merger dynamics, overcoming the dominant initial mode.« less

  6. Selection Indices and Multivariate Analysis Show Similar Results in the Evaluation of Growth and Carcass Traits in Beef Cattle

    PubMed Central

    Brito Lopes, Fernando; da Silva, Marcelo Corrêa; Magnabosco, Cláudio Ulhôa; Goncalves Narciso, Marcelo; Sainz, Roberto Daniel

    2016-01-01

    This research evaluated a multivariate approach as an alternative tool for the purpose of selection regarding expected progeny differences (EPDs). Data were fitted using a multi-trait model and consisted of growth traits (birth weight and weights at 120, 210, 365 and 450 days of age) and carcass traits (longissimus muscle area (LMA), back-fat thickness (BF), and rump fat thickness (RF)), registered over 21 years in extensive breeding systems of Polled Nellore cattle in Brazil. Multivariate analyses were performed using standardized (zero mean and unit variance) EPDs. The k mean method revealed that the best fit of data occurred using three clusters (k = 3) (P < 0.001). Estimates of genetic correlation among growth and carcass traits and the estimates of heritability were moderate to high, suggesting that a correlated response approach is suitable for practical decision making. Estimates of correlation between selection indices and the multivariate index (LD1) were moderate to high, ranging from 0.48 to 0.97. This reveals that both types of indices give similar results and that the multivariate approach is reliable for the purpose of selection. The alternative tool seems very handy when economic weights are not available or in cases where more rapid identification of the best animals is desired. Interestingly, multivariate analysis allowed forecasting information based on the relationships among breeding values (EPDs). Also, it enabled fine discrimination, rapid data summarization after genetic evaluation, and permitted accounting for maternal ability and the genetic direct potential of the animals. In addition, we recommend the use of longissimus muscle area and subcutaneous fat thickness as selection criteria, to allow estimation of breeding values before the first mating season in order to accelerate the response to individual selection. PMID:26789008

  7. Effects of development mode, contaminated sediments, and maternal characteristics on growth and reproduction in the polychaetes Streblospio benedicti (Spionidae) and Capitella sp. I (Capitellidae)

    SciTech Connect

    Bridges, T.S.

    1992-01-01

    Experiments were conducted to examine the effects of contaminated sediments (sewage, blue-green algae and hydrocarbons) and maternal characteristics on reproduction, and offspring success in S. benedicti (lecithotrophic) and Capitella sp. I. For S. benedicti, contaminated sediments had a negative effect on growth and age and size at first reproduction. Per brood fecundity was positively related to female size and negatively related to female age. Treatments did not have an effect on reproductive output. Per offspring C and N investment increased with female age. This increase in per offspring investment resulted in enhanced survivorship and juvenile growth in offspring of older females. For Capitella sp. I, growth was increased, age at first reproduction was accelerated, and per brood fecundity was 3--4 [times] higher in the algae and sewage treatments. Treatments did not have an effect on reproductive output. Fecundity was positively related to female size. Per brood and per offspring C and N investment decreased with female age, but not in all treatments. The C:N ratio of offspring increased with female age. Offspring from mothers in the sewage treatment were larger two weeks after release. Offspring in size two weeks after release decreased with female age in the sewage treatment. Differences in the response of S. benedicti and Capitella sp. I to contaminated sediments may be due to differences in feeding behavior, digestive physiology, nutritional requirements and their sensitivity to hydrocarbons, metals and low oxygen concentrations. Differences in the effect of female age between the two species appear related to development and ecological differences in the two species.

  8. Simultaneous blockade of the epidermal growth factor receptor/mammalian target of rapamycin pathway by epidermal growth factor receptor inhibitors and rapamycin results in reduced cell growth and survival in biliary tract cancer cells.

    PubMed

    Herberger, Beata; Berger, Walter; Puhalla, Harald; Schmid, Katharina; Novak, Sabine; Brandstetter, Anita; Pirker, Christine; Gruenberger, Thomas; Filipits, Martin

    2009-06-01

    The prognosis of patients with biliary tract adenocarcinomas (BTA) is still poor due to lack of effective systemic treatment options. Knowledge of the molecular mechanisms involved in the pathogenesis of this disease is of importance for the development of new treatment strategies. We determined the expression of epidermal growth factor receptor (EGFR) and activated mammalian target of rapamycin (p-mTOR) in paraffin-embedded surgical specimens of BTA (n = 89) by immunohistochemistry. Overall survival was analyzed with Cox models adjusted for clinical and pathologic factors. Combined EGFR/p-mTOR expression was significantly associated with relapse-free survival [adjusted hazard ratio for relapse, 2.20; 95% confidence interval (95% CI), 1.45-3.33; P < 0.001] and overall survival (adjusted hazard ratio for death, 2.32; 95% CI, 1.50-3.58; P < 0.001) of the patients. The effect of the EGFR inhibitors erlotinib or cetuximab and the mTOR inhibitor rapamycin on growth and survival of five BTA cell lines was tested in short-term 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays and long-term colony formation assays. Simultaneous blockade of EGFR and mTOR in biliary tract cancer cell lines results in a synergistic inhibition of both phosphatidylinositol-3-kinase and mitogen-activated protein kinase pathways, leading to reduced cell growth and survival. These results suggest that combined targeted therapy with EGFR and mTOR inhibitors may potentially benefit patients with BTAs and should be further evaluated in clinical trials.

  9. Double tearing modes in the presence of internal transport barrier

    SciTech Connect

    Zhao, X. M.; Tang, C. J.; Peng, X. D.; Qiu, X. M.

    2011-07-15

    The linear characteristics of double tearing modes (DTMs) in the presence of internal transport barrier (ITB) are investigated in a cylindrical tokamak plasma. A simple model describing density profile of ITB is suggested. Combining the safety factor profile given by Bierwage et al.[Phys. Plasmas 12, 082504 (2005); 14, 022107 (2007)], the DTMs spectra, scaling laws, and relationships between growth rate and density profile factor in the presence of ITB are studied, respectively. The results show that the resistive drift instability occurs in the case of high poloidal mode numbers. A transition from DTMs to the resistive drift instability is observed, and the dependence of DTMs growth rate on the magnetic Reynolds number has changed greatly due to the presence of ITB. In addition, the linear growth rates of the modes including those with low and high poloidal mode number increase when the plasma density profile steepens in the presence of ITB whatever the inter-resonant distance is smaller or larger.

  10. Overexpression of transforming growth factor-beta1 in fetal monkey lung results in prenatal pulmonary fibrosis.

    PubMed

    Tarantal, A F; Chen, H; Shi, T T; Lu, C-H; Fang, A B; Buckley, S; Kolb, M; Gauldie, J; Warburton, D; Shi, W

    2010-10-01

    Altered transforming growth factor (TGF)-β expression levels have been linked to a variety of human respiratory diseases, including bronchopulmonary dysplasia and pulmonary fibrosis. However, a causative role for aberrant TGF-β in neonatal lung diseases has not been defined in primates. Exogenous and transient TGF-β1 overexpression in fetal monkey lung was achieved by transabdominal ultrasound-guided fetal intrapulmonary injection of adenoviral vector expressing TGF-β1 at the second or third trimester of pregnancy. The lungs were then harvested near term, and fixed for histology and immunohistochemistry. Lung hypoplasia was observed where TGF-β1 was overexpressed during the second trimester. The most clearly marked phenotype consisted of severe pulmonary and pleural fibrosis, which was independent of the gestational time point when TGF-β1 was overexpressed. Increased cell proliferation, particularly in α-smooth muscle actin-positive myofibroblasts, was detected within the fibrotic foci. But epithelium to mesenchyme transdifferentiation was not detected. Massive collagen fibres were deposited on the inner and outer sides of the pleural membrane, with an intact elastin layer in the middle. This induced fibrotic pathology persisted even after adenoviral-mediated TGF-β1 overexpression was no longer evident. Therefore, overexpression of TGF-β1 within developing fetal monkey lung results in severe and progressive fibrosis in lung parenchyma and pleural membrane, in addition to pulmonary hypoplasia.

  11. Growth on ethanol results in co-ordinated Saccharomyces cerevisiae response to inactivation of genes encoding superoxide dismutases.

    PubMed

    Lushchak, Oleh V; Semchyshyn, Halyna M; Lushchak, Volodymyr I

    2007-01-01

    Superoxide dismutase (SOD) is an essential enzyme protecting cells against oxidative stress. However, its specific role under different conditions is not clear. To study the possible role of SOD in the cell during respiration, Saccharomyces cerevisiae single and double mutants with inactivated SOD1 and/or SOD2 genes growing on ethanol as an energy and carbon source were used. Activities of antioxidant and associated enzymes as well as the level of protein carbonyls were measured. SOD activity was significantly higher in a Mn-SOD deficient strain than that in the wild-type parental strain, but significantly lower in a Cu, Zn-SOD mutant. A strong positive correlation between SOD and catalase activities (R(2) = 0.99) shows possible protection of catalase by SOD from inactivation in vivo and/or decrease in catalase activity because of lower H(2)O(2) formation in the mutant cells. SOD deficiency resulted in a malate dehydrogenase activity increase, whereas glucose-6-phosphate dehydrogenase (G6PDH) activity was lower in SOD-deficient strains. Linear and non-linear positive correlations between SOD and isocitrate dehydrogenase activities are discussed. No changes in the activity of glutathione reductase and protein carbonyl levels support the idea that SOD-deficient cells are not exposed to strong oxidative stress during exponential growth of yeast cultures on ethanol.

  12. Analysis of laser speckle contrast images variability using a novel empirical mode decomposition: comparison of results with laser Doppler flowmetry signals variability.

    PubMed

    Humeau-Heurtier, Anne; Abraham, Pierre; Mahe, Guillaume

    2015-02-01

    Laser Doppler flowmetry (LDF) and laser speckle contrast imaging (LSCI) have emerged as noninvasive optical modalities to monitor microvascular blood flow. Many studies proposed to extract physiological information from LDF by analyzing signals variability. By opposition, such analyses for LSCI data have not been conducted yet. We propose to analyze LSCI variability using a novel data-driven method: the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN). CEEMDAN is suitable for nonlinear and nonstationary data and leads to intrinsic mode functions (IMFs). It is based on the ensemble empirical mode decomposition (EEMD) which relies on empirical mode decomposition (EMD). In our work the average frequencies of LSCI IMFs given by CEEMDAN are compared with the ones given by EMD and EEMD. Moreover, LDF signals acquired simultaneously to LSCI data are also processed with CEEMDAN, EMD and EEMD. We show that the average frequencies of IMFs given by CEEMDAN depend on the signal-to-noise ratio (SNR) used in the computation but, for a given SNR, the average frequencies found for LSCI are close to the ones obtained for LDF. By opposition, EEMD leads to IMFs with frequencies that do not vary much when the SNR level is higher than a threshold. The new CEEMDAN algorithm has the advantage of achieving a complete decomposition with no error in the reconstruction but our study suggests that further work is needed to gain knowledge in the adjustment of the added noise level. CEEMDAN, EMD and EEMD are data-driven methods that can provide a better knowledge of LSCI.

  13. Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

    NASA Astrophysics Data System (ADS)

    Böning, Guido; Todica, Andrei; Vai, Alessandro; Lehner, Sebastian; Xiong, Guoming; Mille, Erik; Ilhan, Harun; la Fougère, Christian; Bartenstein, Peter; Hacker, Marcus

    2013-11-01

    The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [18F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [18F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group, we

  14. Exclusive breastfeeding and its effect on growth of Malawian infants: results from a cross-sectional study

    PubMed Central

    Kuchenbecker, J; Jordan, I; Reinbott, A; Herrmann, J; Jeremias, T; Kennedy, G; Muehlhoff, E; Mtimuni, B; Krawinkel, M B

    2015-01-01

    Background: For the optimal nutrition of children under 2 years of age, it is considered important that they be exclusively breastfed for the first 6 months before being given complementary food. Aims and Objectives: A cross-sectional nutritional baseline survey was undertaken in 2011 in the Kasungu and Mzimba Districts of Malawi to assess the nutritional status of children under 2 years of age and its determinants in order to prepare a nutrition education intervention programme. The intention of this study was to assess the nutritional status of infants aged 0–<6 months with regard to food intake. Methods: Interviews were conducted on randomly selected families with children under 2 years; anthropometric measurements were obtained from mothers and their children. Only infants between 0 and <6 months were selected for analysis (n  =  196). An ANCOVA test was performed on age of the infant with mothers’ height and weight as covariates. Results: Prevalence of stunting (infants’ length-for-age Z-score (LAZ) <−2SD) was 39%, wasting (WLZ <−2SD) 2%, and underweight (WAZ <−2SD) 13%. Of the infants under 6 months, 43% were exclusively breastfed. Predominant breastfeeding and mixed breastfeeding were less common (21% and 36%, respectively). The ANCOVA confirmed the association between exclusive breastfeeding and LAZ and WAZ: exclusively breastfed infants had a higher mean (SE) LAZ (−1·13, 0·12) and WAZ (−0·41, 0·13) than infants not being exclusively breastfed (−1·59, 0·11, and −0·97, 0·11, respectively). There was no overall significant association between breastfeeding practice and WLZ. Conclusion: Exclusive breastfeeding of infants under 6 months is associated with higher mean LAZ and WAZ. Promotion of exclusive breastfeeding in low-income countries is important in preventing growth retardation. PMID:25005815

  15. Energetics and the resistive tearing mode - Effects of Joule heating and radiation

    NASA Technical Reports Server (NTRS)

    Steinolfson, R. S.

    1983-01-01

    The contribution of energy flux to the dynamics of magnetic field reconnection is analytically studied in order to determine the influence of Joule heating and radiation on the linear development of the tearing instability in slab geometry. A temperature-dependent Coulomb-like resistivity is used to provide the coupling between the dynamics and the energy equation. Analytical expressions are derived for the growth rates utilizing constant-psi and long-wavelength approximations. The solutions indicate the occurrence of several modes in addition to the usual tearing mode, several of which have relatively slow, complex growth rates. At large values of the magnetic Reynolds number, there are at least two modes with purely exponential growth when the radiative loss decreases with increasing temperature. If the radiation is neglected, the Joule heating alone also results in two modes with real, positive growth at large S. Below a particular value of S, all the modes are generally stabilized.

  16. Planck intermediate results. XXXVIII. E- and B-modes of dust polarization from the magnetized filamentary structure of the interstellar medium

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartolo, N.; Battaner, E.; Benabed, K.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bracco, A.; Burigana, C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Chamballu, A.; Chary, R.-R.; Chiang, H. C.; Christensen, P. R.; Colombo, L. P. L.; Combet, C.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.-M.; Dickinson, C.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Falgarone, E.; Ferrière, K.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frolov, A.; Galeotta, S.; Galli, S.; Ganga, K.; Ghosh, T.; Giard, M.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gruppuso, A.; Guillet, V.; Hansen, F. K.; Harrison, D. L.; Helou, G.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hornstrup, A.; Hovest, W.; Huang, Z.; Huffenberger, K. M.; Hurier, G.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; León-Tavares, J.; Levrier, F.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Melchiorri, A.; Mennella, A.; Migliaccio, M.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Novikov, D.; Novikov, I.; Oppermann, N.; Oxborrow, C. A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Perdereau, O.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Pratt, G. W.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Serra, P.; Soler, J. D.; Stolyarov, V.; Sudiwala, R.; Sunyaev, R.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-02-01

    The quest for a B-mode imprint from primordial gravity waves on the polarization of the cosmic microwave background (CMB) requires the characterization of foreground polarization from Galactic dust. We present a statistical study of the filamentary structure of the 353 GHz Planck Stokes maps at high Galactic latitude, relevant to the study of dust emission as a polarized foreground to the CMB. We filter the intensity and polarization maps to isolate filaments in the range of angular scales where the power asymmetry between E-modes and B-modes is observed. Using the Smoothed Hessian Major Axis Filament Finder (SMAFF), we identify 259 filaments at high Galactic latitude, with lengths larger or equal to 2° (corresponding to 3.5 pc in length for a typical distance of 100 pc). Thesefilaments show a preferred orientation parallel to the magnetic field projected onto the plane of the sky, derived from their polarization angles. We present mean maps of the filaments in Stokes I, Q, U, E, and B, computed by stacking individual images rotated to align the orientations of the filaments. Combining the stacked images and the histogram of relative orientations, we estimate the mean polarization fraction of the filaments to be 11%. Furthermore, we show that the correlation between the filaments and the magnetic field orientations may account for the E and B asymmetry and the CℓTE/CℓEE ratio, reported in the power spectra analysis of the Planck353 GHz polarization maps. Future models of the dust foreground for CMB polarization studies will need to take into account the observed correlation between the dust polarization and the structure of interstellar matter.

  17. Water equivalent hydrogen estimates from the first 200 sols of Curiosity's traverse (Bradbury Landing to Yellowknife Bay): Results from the Dynamic Albedo of Neutrons (DAN) passive mode experiment

    NASA Astrophysics Data System (ADS)

    Tate, C. G.; Moersch, J.; Jun, I.; Ming, D. W.; Mitrofanov, I.; Litvak, M.; Behar, A.; Boynton, W. V.; Deflores, L.; Drake, D.; Ehresmann, B.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Hassler, D. M.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Malakhov, A.; Milliken, R.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Varenikov, A.; Vostrukhin, A.; Zeitlin, C.

    2015-12-01

    The Dynamic Albedo of Neutrons (DAN) experiment on the Mars Science Laboratory (MSL) rover Curiosity is designed to detect neutrons to determine hydrogen abundance within the subsurface of Mars (Mitrofanov, I.G. et al. [2012]. Space Sci. Rev. 170, 559-582. http://dx.doi.org/10.1007/s11214-012-9924-y; Litvak, M.L. et al. [2008]. Astrobiology 8, 605-613. http://dx.doi.org/10.1089/ast.2007.0157). While DAN has a pulsed neutron generator for active measurements, in passive mode it only measures the leakage spectrum of neutrons produced by the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Galactic Cosmic Rays (GCR). DAN passive measurements provide better spatial coverage than the active measurements because they can be acquired while the rover is moving. Here we compare DAN passive-mode data to models of the instrument's response to compositional differences in a homogeneous regolith in order to estimate the water equivalent hydrogen (WEH) content along the first 200 sols of Curiosity's traverse in Gale Crater, Mars. WEH content is shown to vary greatly along the traverse. These estimates range from 0.5 ± 0.1 wt.% to 3.9 ± 0.2 wt.% for fixed locations (usually overnight stops) investigated by the rover and 0.6 ± 0.2 wt.% to 7.6 ± 1.3 wt.% for areas that the rover has traversed while continuously acquiring DAN passive data between fixed locations. Estimates of WEH abundances at fixed locations based on passive mode data are in broad agreement with those estimated at the same locations using active mode data. Localized (meter-scale) anomalies in estimated WEH values from traverse measurements have no particular surface expression observable in co-located images. However at a much larger scale, the hummocky plains and bedded fractured units are shown to be distinct compositional units based on the hydrogen content derived from DAN passive measurements. DAN passive WEH estimates are also shown to be consistent with geologic models inferred from other

  18. Heat-activated thermosensitive liposomal cisplatin (HTLC) results in effective growth delay of cervical carcinoma in mice.

    PubMed

    Dou, Yannan N; Zheng, Jinzi; Foltz, Warren D; Weersink, Robert; Chaudary, Naz; Jaffray, David A; Allen, Christine

    2014-03-28

    Cisplatin (CDDP) has been identified as the primary chemotherapeutic agent for the treatment of cervical cancer, but dose limiting toxicity is a key issue associated with its clinical application. A suite of liposome formulations of CDDP has been developed in efforts to reduce systemic toxicity, but their therapeutic advantage over the free drug has been modest due to insufficient drug release at the tumor site. This report describes the development of a novel heat-activated thermosensitive liposome formulation containing CDDP (HTLC) designed to release approximately 90% of the loaded drug in less than 5min under mild heating conditions (42°C). Physico-chemical characteristics of HTLC were assessed in terms of gel to liquid crystalline phase transition temperature (Tm), drug loading efficiency, particle size, and stability. The pharmacokinetic profile and biodistribution of HTLC in non-tumor-bearing mice were evaluated over a 24h period. A sophisticated spatio-temporal elucidation of HTLC release in tumor-bearing mice was achieved by way of real-time monitoring using a magnetic resonance (MR) imaging protocol, wherein a custom-built laser-based conformal heat source was applied at the tumor volume to trigger the release of HTLC co-encapsulated with the MR contrast agent gadoteridol (Gd-HP-DO3A). MR thermometry (MRT) demonstrated that a relatively uniform temperature distribution was achieved in the tumor volume using the external laser-based heating setup. In mice bearing subcutaneously-implanted ME-180 cervical tumors, the combination of HTLC and heat resulted in a 2-fold increase in tumor drug levels at 1h post-administration compared to HTLC without heating. Furthermore, the overall tumor accumulation levels for the HTLC groups (with and without heat) at 1h post-injection were significantly higher than the corresponding free CDDP group. This translated into a significant improvement in therapeutic efficacy evaluated as tumor growth delay (p<0.05) for the heated

  19. High-harmonic Fast Wave Heating and Current Drive Results for Deuterium H-mode Plasmas in the National Spherical Torus Experiment

    SciTech Connect

    G. Taylor, P.T. Bonoli, R.W. Harvey, J.C. hosea, E.F. Jaeger, B.P. LeBlanc, C.K. Phillisp, P.M. Ryan, E.J. Valeo, J.R. Wilson, J.C. Wright, and the NSTX Team

    2012-07-25

    A critical research goal for the spherical torus (ST) program is to initiate, ramp-up, and sustain a discharge without using the central solenoid. Simulations of non-solenoidal plasma scenarios in the National Spherical Torus Experiment (NSTX) [1] predict that high-harmonic fast wave (HHFW) heating and current drive (CD) [2] can play an important roll in enabling fully non-inductive (fNI {approx} 1) ST operation. The NSTX fNI {approx} 1 strategy requires 5-6 MW of HHFW power (PRF) to be coupled into a non-inductively generated discharge [3] with a plasma current, Ip {approx} 250-350 kA, driving the plasma into an HHFW H-mode with Ip {approx} 500 kA, a level where 90 keV deuterium neutral beam injection (NBI) can heat the plasma and provide additional CD. The initial approach on NSTX has been to heat Ip {approx} 300 kA, inductively heated, deuterium plasmas with CD phased HHFW power [2], in order to drive the plasma into an H-mode with fNI {approx} 1.

  20. In vitro colonic metabolism of coffee and chlorogenic acid results in selective changes in human faecal microbiota growth.

    PubMed

    Mills, Charlotte E; Tzounis, Xenofon; Oruna-Concha, Maria-Jose; Mottram, Don S; Gibson, Glenn R; Spencer, Jeremy P E

    2015-04-28

    Coffee is a relatively rich source of chlorogenic acids (CGA), which, as other polyphenols, have been postulated to exert preventive effects against CVD and type 2 diabetes. As a considerable proportion of ingested CGA reaches the large intestine, CGA may be capable of exerting beneficial effects in the large gut. Here, we utilise a stirred, anaerobic, pH-controlled, batch culture fermentation model of the distal region of the colon in order to investigate the impact of coffee and CGA on the growth of the human faecal microbiota. Incubation of coffee samples with the human faecal microbiota led to the rapid metabolism of CGA (4 h) and the production of dihydrocaffeic acid and dihydroferulic acid, while caffeine remained unmetabolised. The coffee with the highest levels of CGA (P<0·05, relative to the other coffees) induced a significant increase in the growth of Bifidobacterium spp. relative to the control vessel at 10 h after exposure (P<0·05). Similarly, an equivalent quantity of CGA (80·8 mg, matched with that in high-CGA coffee) induced a significant increase in the growth of Bifidobacterium spp. (P<0·05). CGA alone also induced a significant increase in the growth of the Clostridium coccoides-Eubacterium rectale group (P<0·05). This selective metabolism and subsequent amplification of specific bacterial populations could be beneficial to host health.

  1. NEONATAL EXPOSURE TO DECABROMINATED DIPHENYL ETHER (PBDE 209) RESULTS IN CHANGES IN BIOCHEMICAL SUBSTRATES OF NEURONAL SURVIVAL, GROWTH, AND SYNAPTOGENESIS

    EPA Science Inventory

    Mammals have a marked period of rapid brain growth and development (BGS), which is postnatal in mice and rats, spanning the first 3-4 weeks of life and reaching its peak around postnatal day 10. CaMKII, GAP-43 and BDNF play important roles during the BGS in mammals. One class of ...

  2. Trajectories of Heroin Addiction: Growth Mixture Modeling Results Based on a 33-Year Follow-Up Study

    ERIC Educational Resources Information Center

    Hser, Yih-Ing; Huang, David; Chou, Chih-Ping; Anglin, M. Douglas

    2007-01-01

    This study investigates trajectories of heroin use and subsequent consequences in a sample of 471 male heroin addicts who were admitted to the California Civil Addict Program in 1964-1965 and followed over 33 years. Applying a two-part growth mixture modeling strategy to heroin use level during the first 16 years of the addiction careers since…

  3. Experimental Results Investigating Impact Velocity Effects on Crater Growth and the Transient Depth-to-Diameter Ratio

    NASA Technical Reports Server (NTRS)

    Barnouin, O. S.; Ernst, C. M.; Heinick, J. T.; Cintala, M. J.; Crawford, D. A.; Matsui, T.

    2011-01-01

    We performed vertical hypervelocity impacts (0.5-6 km/s) at the NASA Ames Vertical Gun Range to evaluate if increasing impact velocity, which alters the coupling time between the projectile and target, might change the rates of crater growth and transient crater shape.

  4. Modeling of metal thin film growth: Linking angstrom-scale molecular dynamics results to micron-scale film topographies

    NASA Astrophysics Data System (ADS)

    Hansen, U.; Rodgers, S.; Jensen, K. F.

    2000-07-01

    A general method for modeling ionized physical vapor deposition is presented. As an example, the method is applied to growth of an aluminum film in the presence of an ionized argon flux. Molecular dynamics techniques are used to examine the surface adsorption, reflection, and sputter reactions taking place during ionized physical vapor deposition. We predict their relative probabilities and discuss their dependence on energy and incident angle. Subsequently, we combine the information obtained from molecular dynamics with a line of sight transport model in a two-dimensional feature, incorporating all effects of reemission and resputtering. This provides a complete growth rate model that allows inclusion of energy- and angular-dependent reaction rates. Finally, a level-set approach is used to describe the morphology of the growing film. We thus arrive at a computationally highly efficient and accurate scheme to model the growth of thin films. We demonstrate the capabilities of the model predicting the major differences on Al film topographies between conventional and ionized sputter deposition techniques studying thin film growth under ionized physical vapor deposition conditions with different Ar fluxes.

  5. Results of Pulse-Scaling Experiments on Rapid-Growth DKDP Triplers Using the Optical Sciences Laser at 351 nm

    SciTech Connect

    Runkel, M; Burnham, A K; Milam, D; Sell, W; Feit, M; Rubenchik, A

    2000-12-11

    Results are reported from recently performed bulk-damage, pulse-scaling experiments on DKDP tripler samples taken from NIF-size, rapid-growth boule BD7. The tests were performed on LLNL's Optical Sciences Laser. A matrix of samples was exposed to single shots at 351 mn (3 {omega}) with average fluences from 4 to 8 J/cm{sup 2} for pulse durations of 1, 3 and 10 ns. The damage sites were scatter-mapped after testing to determine the damage evolution as a function of local beam fluence. The average bulk damage microcavity (pinpoint) density varied nearly linearly with fluence with peak values of approximately 16,000 pp/mm{sup 3} at 1 ns, 10,000 pp/mm{sup 3} at 3 ns and 400 pp/mm{sup 3} at 10 ns for fluences in the 8-10 J/cm{sup 2} range. The average size of a pinpoint was 10(+14,-9) {micro}m at 1 ns, 37 {+-} 20 {micro}m at 3 ns and {approx} 110 {micro}m at 10 ns, although all pulse durations produced pinpoints with a wide distribution of sizes. Analysis of the pinpoint density data yielded pulse-scaling behavior of t{sup 0.35}. Significant planar cracking around the pinpoint as was observed for the 10 ns case but not for the 1 and 3 ns pulses. Crack formation around pinpoints has also been observed frequently for Zeus ADT tests at {approx}8 ns. The high pinpoint densities also lead to significant eruption of near-surface bulk damage. Measurements of the damage site area for surface and bulk gave ratios (A{sub surf}/A{sub bulk}) of 2:1 at 1 ns, 7:1 at 3 ns and 110:1 at 10 ns. Maximum aperture averaged transmission losses on the order 15 percent have been measured by photometry for the worst damage at 1 and 3 ns for beam fluences in the 8-10 J/cm{sup 2} range. Analysis of this data yielded a pulse-scaling behavior of t{sup 0.25} for the obscured area. It was also determined that the crystals used in this test would survive unconditioned exposure to 4 J/cm{sup 2} shots on the NIF laser and still meet the obscuration requirement of 0.1%.

  6. Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode

    SciTech Connect

    Baumgaertel, J. A.; Redi, M. H.; Budny, R. V.; Rewoldt, G.; Dorland, W.

    2005-10-19

    Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearing modes may cause high heat transport through high electron thermal conductivity. It is hoped that microtearing will be stable along with good electron transport in the proposed low collisionality International Thermonuclear Experimental Reactor (ITER). Stability of the microtearing mode is investigated for conditions at mid-radius in a high density NSTX high performance (H-mode) plasma, which is compared to the proposed ITER plasmas. The microtearing mode is driven by the electron temperature gradient, and believed to be mediated by ion collisions and magnetic shear. Calculations are based on input files produced by TRXPL following TRANSP (a time-dependent transport analysis code) analysis. The variability of unstable mode growth rates is examined as a function of ion and electron collisionalities using the parallel gyrokinetic computational code GS2. Results show the microtearing mode stability dependence for a range of plasma collisionalities. Computation verifies analytic predictions that higher collisionalities than in the NSTX experiment increase microtearing instability growth rates, but that the modes are stabilized at the highest values. There is a transition of the dominant mode in the collisionality scan to ion temperature gradient character at both high and low collisionalities. The calculations suggest that plasma electron thermal confinement may be greatly improved in the low-collisionality ITER.

  7. Shear fatigue crack growth - A literature survey

    NASA Technical Reports Server (NTRS)

    Liu, H. W.

    1985-01-01

    Recent studies of shear crack growth are reviewed, emphasizing test methods and data analyses. The combined mode I and mode II elastic crack tip stress fields are considered. The development and design of the compact shear specimen are described, and the results of fatigue crack growth tests using compact shear specimens are reviewed. The fatigue crack growth tests are discussed and the results of inclined cracks in tensile panels, center cracks in plates under biaxial loading, cracked beam specimens with combined bending and shear loading, center-cracked panels and double edge-cracked plates under cyclic shear loading are examined and analyzed in detail.

  8. Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity

    SciTech Connect

    Chen, Amy; Cuevas, Ileana; Kenny, Paraic A; Miyake, Hiroshi; Mace, Kimberley; Ghajar, Cyrus; Boudreau, Aaron; Bissell, Mina; Boudreau, Nancy

    2009-05-26

    Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1{alpha}-independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression.

  9. Recombinant growth factor mixtures induce cell cycle progression and the upregulation of type I collagen in human skin fibroblasts, resulting in the acceleration of wound healing processes.

    PubMed

    Lee, Do Hyun; Choi, Kyung-Ha; Cho, Jae-We; Kim, So Young; Kwon, Tae Rin; Choi, Sun Young; Choi, Yoo Mi; Lee, Jay; Yoon, Ho Sang; Kim, Beom Joon

    2014-05-01

    Application of growth factor mixtures has been used for wound healing and anti-wrinkles agents. The aim of this study was to evaluate the effect of recombinant growth factor mixtures (RGFM) on the expression of cell cycle regulatory proteins, type I collagen, and wound healing processes of acute animal wound models. The results showed that RGFM induced increased rates of cell proliferation and cell migration of human skin fibroblasts (HSF). In addition, expression of cyclin D1, cyclin E, cyclin-dependent kinase (Cdk)4, and Cdk2 proteins was markedly increased with a growth factor mixtures treatment in fibroblasts. Expression of type I collagen was also increased in growth factor mixtures-treated HSF. Moreover, growth factor mixtures-induced the upregulation of type I collagen was associated with the activation of Smad2/3. In the animal model, RGFM-treated mice showed accelerated wound closure, with the closure rate increasing as early as on day 7, as well as re-epithelization and reduced inflammatory cell infiltration than phosphate-buffered saline (PBS)-treated mice. In conclusion, the results indicated that RGFM has the potential to accelerate wound healing through the upregulation of type I collagen, which is partly mediated by activation of Smad2/3-dependent signaling pathway as well as cell cycle progression in HSF. The topical application of growth factor mixtures to acute and chronic skin wound may accelerate the epithelization process through these molecular mechanisms.

  10. Observation of nonlinear neoclassical {nabla}{sub p}-driven tearing modes in TFTR

    SciTech Connect

    Chang, Z.; Callen, J.D.; Hegna, C.C.; Fredrickson, E.D.; Budny, R.V.; McGuire, K.M.; Zarnstorff, M.C.

    1994-08-22

    A quantitative comparison is made between the tearing-type modes observed supershot plasmas and the nonlinear, neoclassical pressure gradient ({nabla}{sub p}) driven tearing mode theory. Good agreement is found on the nonlinear magnetic island evolution of a single helicity mode (m/n = 3/2, 4/3 or 5/4, where m and n are the poloidal and toroidal mode numbers, respectively). Statistical data on the island width and growth rate are also found to be consistent with this theory. The results imply that the supershot plasmas are the classical current-driven tearing modes.

  11. Conductive indium-tin oxidenanowire and nanotube arrays made by electrochemically assisted deposition in template membranes: switching between wire and tube growth modes by surface chemical modification of the template

    NASA Astrophysics Data System (ADS)

    Kovtyukhova, Nina I.; Mallouk, Thomas E.

    2011-04-01

    Tin-doped indium hydroxide (InSnOH) nanowires (NWs) and nanotubes (NTs) were grown from acidic aqueous solutions of inorganic precursors in a simple one-step electrochemically assisted deposition (EAD) process inside Au-plugged anodic aluminium oxide and polycarbonatemembranes. When the membranes were used without any pre-treatment, InSnOH crystals nucleated on the both the Au-cathode and pore wall surfaces. By adjusting the surface chemistry of Au or the pore walls, it was possible to switch between NW and NT growth modes. InSnOH was converted into indiumtin oxide (ITO) by annealing the InSnOH-filled membranes at 300 °C. The resulting wires and tubes were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray and electron diffraction, Auger electron spectroscopy and electrical conductivity measurements. InSnOH and ITO NWs and NTs consisted of ~25-50 nm in size crystalline grains with the cubic crystal structures of In(OH)3 and In2O3, respectively, and showed essentially the same morphological features as planar ITO films made by the same method. Separate tin oxide/hydroxide phases were not observed by any of the characterization methods. After heating in air at 600 °C, the ITO NWs had resistivity on the order of 10°Ω cm. EAD is an inexpensive and scalable solution-based technique, and allows one to grow dense arrays of vertically aligned, crystalline and conductive ITO NWs and NTs.

  12. Correlation between erythropoietic activity and body growth rate in hypertransfused polycythemic growing rats as the result of an erythropoietin-dependent operating mechanism

    SciTech Connect

    Bozzini, C.E.; Alippi, R.M.; Barcelo, A.C.; Caro, J.

    1989-02-01

    The established relationship between erythropoietic activity and body growth rate in the polycythemic growing rat could be the result of either an erythropoietin (EPO)-dependent or an EPO-independent operating mechanism. The present study was thus undertaken to elucidate the nature of the aforementioned mechanism by assessing the ratio between plasma immunoreactive EPO (iEPO) concentration and erythropoietic activity in young hypertransfused rats for different body growth rates. Red blood cell (RBC)-59Fe uptake was about 75% in 21-day-old rats; it rapidly decreased with time when the animals were placed on a protein-free diet, approaching a level of about 1% by the 10th day of protein starvation. Over the same period plasma iEPO decreased from 55 mU/ml to 7 mU/ml. Body growth rate was 0. Following this ''protein depletion period'' the rats received diets containing different amounts of casein (''protein repletion period'') added isocalorically to the protein-free diet to elicit a rise in body growth rate. Statistically significant relationships (p less than 0.001) were found between dietary casein concentration and body growth rate (r = 0.991), dietary casein concentration and RBC-59Fe uptake (r = 0.991), dietary casein concentration and plasma iEPO level (r = 0.992), body growth rate and RBC-59Fe (r = 0.986), and body growth rate and plasma iEPO level (r = 0.994) in hypertransfused polycythemic rats during the protein repletion period. These findings suggest that the correlation between erythropoietic activity and growth rate in the growing rat is the result of an erythropoietin-dependent operating mechanism, which appears to be independent of the ratio tissue oxygen supply/tissue oxygen demand.

  13. Growth hormone deficiency in 'little' mice results in aberrant body composition, reduced insulin-like growth factor-I and insulin-like growth factor-binding protein-3 (IGFBP-3), but does not affect IGFBP-2, -1 or -4.

    PubMed

    Donahue, L R; Beamer, W G

    1993-01-01

    Although GH is known to regulate somatic growth during development, its role in regulating adult body composition is less well defined. The effects of GH on individual body compartments--water, fat, protein and mineral--are achieved both by the action of GH and by a GH-induced hormone, insulin-like growth factor-I (IGF-I). We used a genetic model of GH deficiency, the 'little' (gene symbol lit) mouse, to determine the GH regulation of IGF-I and its insulin-like growth factor-binding proteins (IGFBPs) and to define the interaction between these hormones and each body compartment in adults. Our results showed that GH-deficient lit/lit mice had reduced levels of serum IGF-I (range 38-130 micrograms/l) compared with normal lit/+ littermates (range 432-567 micrograms/l) between 2 and 52 weeks of age. The lit/lit mice did not experience the fivefold increase in IGF-I between 2 and 4 weeks of age that was seen in lit/+ mice. In lit/lit serum, overall binding of 125I-labelled IGF-I to the four IGFBPs was reduced, solely in response to a reduced amount of IGFBP-3. No overall differences were found between lit/lit and lit/+ mice in the binding of 125I-labelled IGF-I to IGFBP-2, -1 or -4. Age-related declines in IGF-I and IGFBPs were seen in lit/lit mice. However, adult levels of IGF-I were maintained in lit/+ mice to at least 52 weeks of age, as were levels of IGFBP-1 and -4, while IGFBP-3 and -2 declined with age. With respect to body composition, comparison of lit/lit with lit/+ mice showed that the lit/lit mice were characterized by abnormally large adipose tissue stores and reduced body water, protein and mineral from 2 weeks onward. These changes occurred despite normal energy intake in lit/lit mice up to 52 weeks of age, indicating that neither undernutrition nor hyperphagia is characteristic of this GH-induced model of obesity. Furthermore, lit/lit males accrued more body fat beginning at an earlier age than lit/lit females. With advancing age, the per cent body fat

  14. Plasma Modes

    NASA Astrophysics Data System (ADS)

    Dubin, D. H. E.

    This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

  15. Neoclassical tearing modes in a tokamak

    SciTech Connect

    Hahm, T.S.

    1988-12-01

    Linear tearing instability is studied in the banana collisionality regime in tokamak geometry. Neoclassical effects produce significant modifications of Ohm's law and the vorticity equation, so that the growth rate of tearing modes driven by ..delta..' is dramatically reduced compared to the usual resistive magnetohydrodynamic values. Consequences of this result, regarding the presence of pressure-gradient-driven neoclassical resistive interchange instabilities and the evolution of magnetic islands in the Rutherford regime, are discussed.

  16. Neoclassical tearing modes in a tokamak

    SciTech Connect

    Hahm, T.S.

    1988-08-01

    Linear tearing instability is studied in the banana collisionality regime in tokamak geometry. Neoclassical effects produce significant modifications of Ohm's law and the vorticity equation so that the growth rate of tearing modes driven by ..delta..' is dramatically reduced compared to the usual resistive MHD value. Consequences of this result, regarding the presence of pressure-gradient-driven neoclassical resistive interchange instabilities and the evolution of magnetic islands in the Rutherford regime, are discussed. 10 refs.

  17. High-resolution transmission electron microscopy study on the growth modes of GaSb islands grown on a semi-insulating GaAs (001) substrate

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Lee, J. Y.; Noh, Y. G.; Kim, M. D.; Oh, J. E.

    2007-06-01

    The initial growth behaviors of GaSb on a GaAs substrate were studied using a high-resolution electron microscope (HRTEM). Four types of GaSb islands were observed by HRTEM. HRTEM micrographs showed that strain relaxation mechanisms were different in the four types of islands. Although 90° misfit dislocations relieve misfit strain in the islands, additional mechanisms are required to relax the remaining strain. The existence of elastic deformation near the surface related to dislocations and intermediate layers between GaSb and GaAs were demonstrated in island growths. Finally, the generation of planar defects to relieve strain was observed in a specific GaSb growth.

  18. Matrix metalloproteinase-2 ablation in dystrophin-deficient mdx muscles reduces angiogenesis resulting in impaired growth of regenerated muscle fibers.

    PubMed

    Miyazaki, Daigo; Nakamura, Akinori; Fukushima, Kazuhiro; Yoshida, Kunihiro; Takeda, Shin'ichi; Ikeda, Shu-ichi

    2011-05-01

    Matrix metalloproteases (MMPs) are a family of endopeptidases classified into subgroups based on substrate preference in normal physiological processes such as embryonic development and tissue remodeling, as well as in various disease processes via degradation of extracellular matrix components. Among the MMPs, MMP-9 and MMP-2 have been reported to be up-regulated in skeletal muscles in the lethal X-linked muscle disorder Duchenne muscular dystrophy (DMD), which is caused by loss of dystrophin. A recent study showed that deletion of the MMP9 gene in mdx, a mouse model for DMD, improved skeletal muscle pathology and function; however, the role of MMP-2 in the dystrophin-deficient muscle is not well known. In this study, we aimed at verifying the role of MMP-2 in the dystrophin-deficient muscle by using mdx mice with genetic ablation of MMP-2 (mdx/MMP-2(-/-)). We found impairment of regenerated muscle fiber growth with reduction of angiogenesis in mdx/MMP-2(-/-) mice at 3 months of age. Expression of vascular endothelial growth factor-A (VEGF-A), an important angiogenesis-related factor, decreased in mdx/MMP-2(-/-) mice at 3 months of age. MMP-2 had not a critical role in the degradation of dystrophin-glycoprotein complex (DGC) components such as β-dystroglycan and β-sarcoglycan in the regeneration process of the dystrophic muscle. Accordingly, MMP-2 may be essential for growth of regenerated muscle fibers through VEGF-associated angiogenesis in the dystrophin-deficient skeletal muscle.

  19. Deletion of chloroplast NADPH-dependent thioredoxin reductase results in inability to regulate starch synthesis and causes stunted growth under short-day photoperiods.

    PubMed

    Lepistö, Anna; Pakula, Eveliina; Toivola, Jouni; Krieger-Liszkay, Anja; Vignols, Florence; Rintamäki, Eevi

    2013-09-01

    Plastid-localized NADPH-dependent thioredoxin reductase C (NTRC) is a unique NTR enzyme containing both reductase and thioredoxin domains in a single polypeptide. Arabidopsis thaliana NTRC knockout lines (ntrc) show retarded growth, especially under short-day (SD) photoperiods. This study identified chloroplast processes that accounted for growth reduction in SD-acclimated ntrc. The strongest reduction in ntrc growth occurred under photoperiods with nights longer than 14 h, whereas knockout of the NTRC gene did not alter the circadian-clock-controlled growth of Arabidopsis. Lack of NTRC modulated chloroplast reactive oxygen species (ROS) metabolism, but oxidative stress was not the primary cause of retarded growth of SD-acclimated ntrc. Scarcity of starch accumulation made ntrc leaves particularly vulnerable to photoperiods with long nights. Direct interaction of NTRC and ADP-glucose pyrophosphorylase, a key enzyme in starch synthesis, was confirmed by yeast two-hybrid analysis. The ntrc line was not able to maximize starch synthesis during the light period, which was particularly detrimental under SD conditions. Acclimation of Arabidopsis to SD conditions also involved an inductive rise of ROS production in illuminated chloroplasts that was not counterbalanced by the activation of plastidial anti-oxidative systems. It is proposed that knockout of NTRC challenges redox regulation of starch synthesis, resulting in stunted growth of the mutant lines acclimated to the SD photoperiod.

  20. A Highly Tilted Binding Mode by a Self-Reactive T Cell Receptor Results in Altered Engagement of Peptide and MHC

    SciTech Connect

    D Sethi; D Schubert; A Anders; A Heroux; D Bonsor; C Thomas; E Sundberg; J Pyrdol; K Wucherpfennig

    2011-12-31

    Self-reactive T cells that escape elimination in the thymus can cause autoimmune pathology, and it is therefore important to understand the structural mechanisms of self-antigen recognition. We report the crystal structure of a T cell receptor (TCR) from a patient with relapsing-remitting multiple sclerosis that engages its self-peptide-major histocompatibility complex (pMHC) ligand in an unusual manner. The TCR is bound in a highly tilted orientation that prevents interaction of the TCR-{alpha} chain with the MHC class II {beta} chain helix. In this structure, only a single germline-encoded TCR loop engages the MHC protein, whereas in most other TCR-pMHC structures all four germline-encoded TCR loops bind to the MHC helices. The tilted binding mode also prevents peptide contacts by the short complementarity-determining region (CDR) 3{beta} loop, and interactions that contribute to peptide side chain specificity are focused on the CDR3{alpha} loop. This structure is the first example in which only a single germline-encoded TCR loop contacts the MHC helices. Furthermore, the reduced interaction surface with the peptide may facilitate TCR cross-reactivity. The structural alterations in the trimolecular complex are distinct from previously characterized self-reactive TCRs, indicating that there are multiple unusual ways for self-reactive TCRs to bind their pMHC ligand.

  1. A highly tilted binding mode by a self-reactive T cell receptor results in altered engagement of peptide and MHC

    SciTech Connect

    Sethi, D.K.; Heroux, A.; Schubert, D. A.; Anders, A.-K.; Bonsor, D. A.; Thomas, C. P.; Sundberg, E. J.; Pyrdol, J.; Wucherpfennig, K. W.

    2011-01-17

    Self-reactive T cells that escape elimination in the thymus can cause autoimmune pathology, and it is therefore important to understand the structural mechanisms of self-antigen recognition. We report the crystal structure of a T cell receptor (TCR) from a patient with relapsing-remitting multiple sclerosis that engages its self-peptide-major histocompatibility complex (pMHC) ligand in an unusual manner. The TCR is bound in a highly tilted orientation that prevents interaction of the TCR-{alpha} chain with the MHC class II {beta} chain helix. In this structure, only a single germline-encoded TCR loop engages the MHC protein, whereas in most other TCR-pMHC structures all four germline-encoded TCR loops bind to the MHC helices. The tilted binding mode also prevents peptide contacts by the short complementarity-determining region (CDR) 3{beta} loop, and interactions that contribute to peptide side chain specificity are focused on the CDR3{alpha} loop. This structure is the first example in which only a single germline-encoded TCR loop contacts the MHC helices. Furthermore, the reduced interaction surface with the peptide may facilitate TCR cross-reactivity. The structural alterations in the trimolecular complex are distinct from previously characterized self-reactive TCRs, indicating that there are multiple unusual ways for self-reactive TCRs to bind their pMHC ligand.

  2. ARS Research Review on "Novel immunotherapeutics as alternatives to antimicrobial growth promoters for enteric pathogens: An update on the mode of action"

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With anticipated human population growth in the next decades, agricultural animal scientists need to focus on improving animal production to meet the demands. Furthermore, poultry industry is faced with new array of challenges. Among these are global food security, climate change, emerging infecti...

  3. Results from the PharmaSat Nanosatellite Mission: Dose Dependence of Growth and Metabolic Parameters for S. cerevisiae Grown in Microgravity and Challenged by Voriconazole

    NASA Astrophysics Data System (ADS)

    Ricco, Antonio; Parra, Macarena; Niesel, David; Ly, Diana; Kudlicki, Andrzej; McGinnis, Michael; Hines, John

    We report cellular growth and metabolic activity results for Saccharomyces cerevisiae grown aboard PharmaSat, a 5.0-kg autonomous, self-contained biological nanosatellite launched as a secondary payload in May of 2009 and presently in Earth orbit at 450 km. The response of S. cerevisiae to three dose levels bracketing the minimum inhibitory concentration (MIC) of the antifungal voriconazole was monitored in microgravity using 3-color absorbance to measure metabolic activity and turbidity (cell number), which were characterized chiefly by two param-eters: (1) the doubling time and (2) the time delay before the onset of rapid growth. Growth was conducted in forty-eight 100-L microwells containing the yeast—one fluidically separate bank of 12 wells for each voriconazole concentration, plus a control bank. Yeast were main-tained in stasis until the satellite had been deployed, the orbit stabilized, the communications links established, and the growth temperature of 27 ° C stabilized. To re-initiate yeast growth, RPMI growth medium was added. The S. cerevisiae were grown for approximately 12 hr, at which time they were challenged with varying concentrations (0, 0.25xMIC, MIC, 4xMIC) of voriconazole; the optical density and the color change of the redox-based viability indicator alamar blue were recorded as growth proceeded for an additional 84 hr. Results telemetered to the ground reveal a 33 percent longer lag time in microgravity and 60 percent longer dou-bling time than identical ground control experiments. Lag and doubling times are essentially unaffected by voriconazole at 0.125 g/mL in either environment; they lengthen similarly at 0.5 g/mL, voriconazole's MIC. At four times MIC, ground controls show no significant growth nor metabolic activity as tracked by alamar blue; in space, while there was also no measurable cellu-lar growth, remarkably, metabolic activity was clearly present (n = 12 wells). Explanations for the differences in metabolic activity and

  4. Mode 2 fracture mechanics

    NASA Technical Reports Server (NTRS)

    Buzzard, Robert J.; Ghosn, Louis

    1988-01-01

    Current development of high-performance rolling element bearings for aircraft engines (up to 3 million DN, where DN is the product of shaft diameter in millimeters and speed in revolutions per minute) has aroused concern about fatigue crack growth in the inner bearing race that leads to catastrophic failure of the bearing and the engine. A failure sequence was postulated by Srawley, and an analytical program was undertaken to simulate fatigue crack propagation in the inner raceway of such a bearing. A fatigue specimen was developed at NASA by which fatigue data may be obtained relative to the cracking problems. The specimen may be used to obtain either mode 2 data alone or a combination of mixed-mode (1 and 2) data as well and was calibrated in this regard. Mixed-mode fracture data for M-50 bearing steel are presented, and a method for performing reversed-loading tests is described.

  5. Dopaminergic agonists that result in ocular growth inhibition also elicit transient increases in choroidal thickness in chicks.

    PubMed

    Nickla, Debora L; Totonelly, Kristen; Dhillon, Balprit

    2010-11-01

    The dopaminergic system has been implicated in ocular growth regulation in chicks and monkeys. In both, dopamine D2 agonists inhibit the development of myopia in response to form deprivation, and in chicks, to negative lenses as well. Because there is mounting evidence that the choroidal response to defocus plays a role in ocular growth regulation, we asked whether the effective agonists also elicit transient thickening of the choroid concomitant with the growth inhibition. Negative lenses mounted on velcro rings were worn on one eye starting at age 8-12 days. Intravitreal injections (20 μl; dose = 10 nmole) of the agonist (dissolved in saline) or saline, were given through the superior temporal sclera using a 30G needle. Eyes were injected daily at noon, for 4 days, and the lenses immediately replaced. Agonists used were apomorphine (non-specific; n = 17), quinpirole (D2; n = 10), SKF-38393 (D1; n = 9), and saline controls (n = 22). For the antagonists, the same protocol was used, but on each day, the lenses were removed for 2 h. Immediately prior to lens-removal, the antagonist was injected (20 μl; dose = 5 nmole). Antagonists used were methylergonovine (non-specific; n = 12), spiperone (D2; n = 20), SCH-23390 (D1; n = 6) and saline controls (n = 27). Comparisons to saline (continuous lens wear) controls were from the agonist experiment. Axial dimensions were measured using high frequency A-scan ultrasonography at the start of lens wear, and on day 4 prior to the injections, and then again 3 h later. Refractive errors were measured using a Hartinger's refractometer at the end of the experiment. Apomorphine and quinpirole inhibited the refractive response to the hyperopic defocus induced by the negative lenses (drug vs saline controls: -1.3 and 1.2 D vs -5.6 D; p < 0.005 for both). This effect was axial: both drugs prevented the excessive ocular elongation (change in axial length: 233 and 205 μm vs 417 μm; p < 0.01 for both

  6. Simultaneous catabolism of plant-derived aromatic compounds results in enhanced growth for members of the Roseobacter lineage.

    PubMed

    Gulvik, Christopher A; Buchan, Alison

    2013-06-01

    Plant-derived aromatic compounds are important components of the dissolved organic carbon pool in coastal salt marshes, and their mineralization by resident bacteria contributes to carbon cycling in these systems. Members of the roseobacter lineage of marine bacteria are abundant in coastal salt marshes, and several characterized strains, including Sagittula stellata E-37, utilize aromatic compounds as primary growth substrates. The genome sequence of S. stellata contains multiple, potentially competing, aerobic ring-cleaving pathways. Preferential hierarchies in substrate utilization and complex transcriptional regulation have been demonstrated to be the norm in many soil bacteria that also contain multiple ring-cleaving pathways. The purpose of this study was to ascertain whether substrate preference exists in S. stellata when the organism is provided a mixture of aromatic compounds that proceed through different ring-cleaving pathways. We focused on the protocatechuate (pca) and the aerobic benzoyl coenzyme A (box) pathways and the substrates known to proceed through them, p-hydroxybenzoate (POB) and benzoate, respectively. When these two substrates were provided at nonlimiting carbon concentrations, temporal patterns of cell density, gene transcript abundance, enzyme activity, and substrate concentrations indicated that S. stellata simultaneously catabolized both substrates. Furthermore, enhanced growth rates were observed when S. stellata was provided both compounds simultaneously compared to the rates of cells grown singly with an equimolar concentration of either substrate alone. This simultaneous-catabolism phenotype was also demonstrated in another lineage member, Ruegeria pomeroyi DSS-3. These findings challenge the paradigm of sequential aromatic catabolism reported for soil bacteria and contribute to the growing body of physiological evidence demonstrating the metabolic versatility of roseobacters.

  7. Dual-mode characteristics of the Buneman instability in a bounded slab plasma

    SciTech Connect

    Hong, Woo-Pyo; Jung, Young-Dae

    2015-06-15

    The dual-mode characteristics of the Buneman instability are investigated in a slab plasma, including the geometric effects. The dual symmetric and anti-symmetric dispersion modes of the Buneman instability are obtained by the plasma dielectric function with the spectral reflection conditions for the slab geometry. The result shows that the magnitudes of the growth rate for the symmetric mode are always greater than those for the anti-symmetric mode. It is also found that the geometric effect suppresses the position of the maximum growth rate for the Buneman instability in bounded slab plasmas since the maximum conditions for the symmetric and anti-symmetric modes of the Buneman instability are given by 0.60modes of the Buneman instability are also discussed.

  8. Some results of the growth of semiconductor crystals in microgravity conditions (to the 50th anniversary of Yuri Gagarin's flight into space)

    NASA Astrophysics Data System (ADS)

    Shul'pina, I. L.; Zakharov, B. G.; Parfen'ev, R. V.; Farbshtein, I. I.; Serebryakov, Yu. A.; Prokhorov, I. A.

    2012-07-01

    The history of the growth of semiconductor crystals aboard space vehicles and their subsequent investigation has been described shortly. It has been shown using Ge(Ga), GaSb(Si), and GaSb(Te) crystals as an example that the formation of segregation growth striations can be avoided during their recrystallization by the vertical Bridgman method in conditions of physical simulation of microgravity on the Earth, mainly due to the essential weakening of the thermal gravitation convection. By their structure and impurity distribution, they approach the crystals grown in space. The investigation of recrystallization of Te has made it possible to determine the role of the detachment effect characteristic of the microgravity conditions and the features of the microstructure of the samples that crystallize with a free surface. The analysis of the results obtained from experiments in space allows us to better understand the processes occurring during the crystallization of the melts and to improve the crystal growth in terrestrial conditions.

  9. A Candida albicans Strain Expressing Mammalian Interleukin-17A Results in Early Control of Fungal Growth during Disseminated Infection

    PubMed Central

    Huppler, Anna R.; Whibley, Natasha; Woolford, Carol A.; Childs, Erin E.; He, Jie; Biswas, Partha S.; McGeachy, Mandy J.; Mitchell, Aaron P.

    2015-01-01

    Candida albicans is normally a commensal fungus of the human mucosae and skin, but it causes life-threatening systemic infections in hospital settings in the face of predisposing conditions, such as indwelling catheters, abdominal surgery, or antibiotic use. Immunity to C. albicans involves various immune parameters, but the cytokine interleukin-17A (IL-17A) (also known as IL-17) has emerged as a centrally important mediator of immune defense against both mucosal and systemic candidiasis. Conversely, IL-17A has been suggested to enhance the virulence of C. albicans, indicating that it may exert detrimental effects on pathogenesis. In this study, we hypothesized that a C. albicans strain expressing IL-17A would exhibit reduced virulence in vivo. To that end, we created a Candida-optimized expression cassette encoding murine IL-17A, which was transformed into the DAY286 strain of C. albicans. Candida-derived IL-17A was indistinguishable from murine IL-17A in terms of biological activity and detection in standard enzyme-linked immunosorbent assays (ELISAs). Expression of IL-17A did not negatively impact the growth of these strains in vitro. Moreover, the IL-17A-expressing C. albicans strains showed significantly reduced pathogenicity in a systemic model of Candida infection, mainly evident during the early stages of disease. Collectively, these findings suggest that IL-17A mitigates the virulence of C. albicans. PMID:26150537

  10. Tumour growth results in changes in placental amino acid transport in the rat: a tumour necrosis factor alpha-mediated effect.

    PubMed

    Carbó, N; López-Soriano, F J; Fiers, W; Argilés, J M

    1996-01-01

    The implantation of a fast growing tumour (Yoshida AH-130 ascites hepatoma) to late pregnant rats resulted in no changes in fetal growth, this possibly being associated with an important increase in the fetal uptake of maternal-derived amino acids [Carbó, López-Soriano and Argilés (1995) Endocrinology 136, 3579-3584]. The present investigation was undertaken to see whether the presence of the tumour induced changes in placental transport systems. For alanine transport, although no changes in affinity (Km) were observed, tumour growth resulted in a 192% increase in Vmax in the Na(+)-independent component. Kinetic analysis of the Na(+)-dependent component resulted in two clearly different components: while the low-affinity and high-capacity component was unaffected by tumour growth, the high-affinity, low-capacity component of the tumour-bearing rats showed an important increase in Vmax. (78%). With regard to leucine transport, tumour burden induced important increases in the Na(+)-independent component, not only in Km (262%) but also in Vmax. (189%). Since elevated tumour necrosis factor-alpha (TNF) concentrations have been reported in this kind of tumour model, we performed the same type of transport experiments in rats chronically treated with TNF, the results obtained showing great similarities with those observed with tumour growth. The Vmax. of Na(+)-independent alanine transport was also increased by the cytokine (104%) while no changes were observed in affinity. TNF treatment also induced an increase in the Vmax. (67%) of the Na(+)-dependent (high-affinity, low-capacity) component while no changes in affinity were observed. Concerning leucine kinetics, TNF treatment, as in the case of tumour growth, also increased Km (155%) and Vmax. (72%) associated with Na(+)-independent transport. Interestingly, treatment with the cytokine increased both the Km (43%) and Vmax. (64%) of the Na(+)-dependent component. The inhibition patterns suggest the existence of more

  11. Criterion for mixed mode fracture in composite bonded joints

    NASA Technical Reports Server (NTRS)

    Mall, S.; Kochhar, N. K.

    1986-01-01

    A study was undertaken to characterize the debond growth mechanism of adhesively bonded composite joints under mode I, mixed mode I-II, and mode II static loadings. The bonded system consisted of graphite-epoxy composite adherends bonded with a toughened epoxy adhesive. The mode I, mode II and mixed mode I-II fracture energies of the tested adhesives were found to be equal to each other. The criterion for mixed mode fracture in composite bonded joints was found.

  12. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae

    DOE PAGESBeta

    Narayanan, Venkatachalam; Sànchez i Nogué, Violeta; van Niel, Ed W. J.; Gorwa-Grauslund, Marie F.

    2016-08-26

    Here, lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotypemore » involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 +/- 5 h to yield 0.45 +/- 0.01 g ethanol g glucose-1) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.« less

  13. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae.

    PubMed

    Narayanan, Venkatachalam; Sànchez I Nogué, Violeta; van Niel, Ed W J; Gorwa-Grauslund, Marie F

    2016-12-01

    Lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotype involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 ± 5 h to yield 0.45 ± 0.01 g ethanol g glucose(-1)) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination.

  14. Adaptation to low pH and lignocellulosic inhibitors resulting in ethanolic fermentation and growth of Saccharomyces cerevisiae.

    PubMed

    Narayanan, Venkatachalam; Sànchez I Nogué, Violeta; van Niel, Ed W J; Gorwa-Grauslund, Marie F

    2016-12-01

    Lignocellulosic bioethanol from renewable feedstocks using Saccharomyces cerevisiae is a promising alternative to fossil fuels owing to environmental challenges. S. cerevisiae is frequently challenged by bacterial contamination and a combination of lignocellulosic inhibitors formed during the pre-treatment, in terms of growth, ethanol yield and productivity. We investigated the phenotypic robustness of a brewing yeast strain TMB3500 and its ability to adapt to low pH thereby preventing bacterial contamination along with lignocellulosic inhibitors by short-term adaptation and adaptive lab evolution (ALE). The short-term adaptation strategy was used to investigate the inherent ability of strain TMB3500 to activate a robust phenotype involving pre-culturing yeast cells in defined medium with lignocellulosic inhibitors at pH 5.0 until late exponential phase prior to inoculating them in defined media with the same inhibitor cocktail at pH 3.7. Adapted cells were able to grow aerobically, ferment anaerobically (glucose exhaustion by 19 ± 5 h to yield 0.45 ± 0.01 g ethanol g glucose(-1)) and portray significant detoxification of inhibitors at pH 3.7, when compared to non-adapted cells. ALE was performed to investigate whether a stable strain could be developed to grow and ferment at low pH with lignocellulosic inhibitors in a continuous suspension culture. Though a robust population was obtained after 3600 h with an ability to grow and ferment at pH 3.7 with inhibitors, inhibitor robustness was not stable as indicated by the characterisation of the evolved culture possibly due to phenotypic plasticity. With further research, this short-term adaptation and low pH strategy could be successfully applied in lignocellulosic ethanol plants to prevent bacterial contamination. PMID:27566648

  15. Genetic Exchange in an Arbuscular Mycorrhizal Fungus Results in Increased Rice Growth and Altered Mycorrhiza-Specific Gene Transcription▿†

    PubMed Central

    Colard, Alexandre; Angelard, Caroline; Sanders, Ian R.

    2011-01-01

    Arbuscular mycorrhizal fungi (AMF) are obligate symbionts with most terrestrial plants. They improve plant nutrition, particularly phosphate acquisition, and thus are able to improve plant growth. In exchange, the fungi obtain photosynthetically fixed carbon. AMF are coenocytic, meaning that many nuclei coexist in a common cytoplasm. Genetic exchange recently has been demonstrated in the AMF Glomus intraradices, allowing nuclei of different Glomus intraradices strains to mix. Such genetic exchange was shown previously to have negative effects on plant growth and to alter fungal colonization. However, no attempt was made to detect whether genetic exchange in AMF can alter plant gene expression and if this effect was time dependent. Here, we show that genetic exchange in AMF also can be beneficial for rice growth, and that symbiosis-specific gene transcription is altered by genetic exchange. Moreover, our results show that genetic exchange can change the dynamics of the colonization of the fungus in the plant. Our results demonstrate that the simple manipulation of the genetics of AMF can have important consequences for their symbiotic effects on plants such as rice, which is considered the most important crop in the world. Exploiting natural AMF genetic variation by generating novel AMF genotypes through genetic exchange is a potentially useful tool in the development of AMF inocula that are more beneficial for crop growth. PMID:21784911

  16. Arsenite-Induced Pseudo-Hypoxia Results in Loss of Anchorage-Dependent Growth in BEAS-2B Pulmonary Epithelial Cells

    PubMed Central

    Zhao, Fei; Malm, Scott W.; Hinchman, Alyssa N.; Li, Hui; Beeks, Connor G.; Klimecki, Walter T.

    2014-01-01

    Epidemiology studies have established a strong link between lung cancer and arsenic exposure. Currently, the role of disturbed cellular energy metabolism in carcinogenesis is a focus of scientific interest. Hypoxia inducible factor-1 alpha (HIF-1A) is a key regulator of energy metabolism, and it has been found to accumulate during arsenite exposure under oxygen-replete conditions. We modeled arsenic-exposed human pulmonary epithelial cells in vitro with BEAS-2B, a non-malignant lung epithelial cell line. Constant exposure to 1 µM arsenite (As) resulted in the early loss of anchorage-dependent growth, measured by soft agar colony formation, beginning at 6 weeks of exposure. This arsenite exposure resulted in HIF-1A accumulation and increased glycolysis, similar to the physiologic response to hypoxia, but in this case under oxygen-replete conditions. This “pseudo-hypoxia” response was necessary for the maximal acquisition of anchorage-independent growth in arsenite-exposed BEAS-2B. The HIF-1A accumulation and induction in glycolysis was sustained throughout a 52 week course of arsenite exposure in BEAS-2B. There was a time-dependent increase in anchorage-independent growth during the exposure to arsenite. When HIF-1A expression was stably suppressed, arsenite-induced glycolysis was abrogated, and the anchorage-independent growth was reduced. These findings establish that arsenite exerts a hypoxia-mimetic effect, which plays an important role in the subsequent gain of malignancy-associated phenotypes. PMID:25513814

  17. Identification of factors associated with good response to growth hormone therapy in children with short stature: results from the ANSWER Program®

    PubMed Central

    2011-01-01

    Objective To identify factors associated with growth in children on growth hormone (GH) therapy using data from the American Norditropin Studies: Web-enabled Research (ANSWER) Program® registry. Methods GH-naïve children with GH deficiency, multiple pituitary hormone deficiency, idiopathic short stature, Turner syndrome, or a history of small for gestational age were eligible (N = 1,002). Using a longitudinal statistical approach, predictive factors were identified in patients with GHD for change from baseline in height standard deviation score (ΔHSDS) following 2 years of treatment. Results Gradual increases in ΔHSDS over time were observed for all diagnostic categories. Significant predictive factors of ΔHSDS, ranked by significance were: height velocity (HV) at 4 months > baseline age > baseline HSDS > baseline body mass index (BMI) SDS > baseline insulin-like growth factor I (IGF-I) SDS; gender was not significant. HV at 4 months and baseline BMI SDS were positively correlated, whereas baseline age, HSDS, and IGF-I SDS were negatively correlated with ΔHSDS. Conclusions These results may help guide GH therapy based on pretreatment characteristics and early growth response. PMID:21899782

  18. Effectiveness of an educational intervention to improve child feeding practices and growth in rural China: updated results at 18 months of age.

    PubMed

    Zhang, Jingxu; Shi, Ling; Chen, Da-Fang; Wang, Jing; Wang, Yan

    2013-01-01

    Inappropriate complementary feeding practices have led to, in part, significant disparities in growth and nutritional status between rural and urban children in China. A cluster-randomised, controlled trial was implemented in Laishui, China to assess the effectiveness of an educational intervention on caregivers' feeding practices and children's growth. Eight townships were randomly assigned to the intervention or control. Five hundred ninety-nine healthy infants were enrolled at 2-4 months old, and were followed up at ages 6, 9, 12, 15 and 18 months. The intervention group received information on enhanced home-prepared recipes and food preparation and hygiene through group training, counselling and home visit. Key outcomes were children's physical growth, caregivers' knowledge and behaviours on complementary feeding, and the infant and child feeding index (ICFI). Analysis was by intention to treat. The intervention group achieved better knowledge and practices related to complementary feeding, and significantly higher ICFI scores at each follow-up point. Children in the intervention group achieved higher z-scores for weight-for-age (WAZ) and weight-for-height (WHZ) than the control (0.18 vs. 0.01 and 0.49 vs. 0.19, respectively) at 18 months old, and were less likely to have stunted growth (odds ratio = 0.71, 95% confidence interval: 0.53-0.94). Mixed model showed that the intervention group achieved significantly better linear growth over time, including WAZ (P = 0.016), WHZ (P = 0.030) and HAZ (P = 0.078). These results indicated that an educational intervention delivered through local health services can enhance caregivers' knowledge and practices of complementary feeding and ultimately improve children's growth.

  19. Nonaxisymmetric instabilities in rotating shear flows - Internal gravity modes in stratified media and analogies with plane flows

    NASA Technical Reports Server (NTRS)

    Ghosh, P.; Abramowicz, M. A.

    1991-01-01

    The role of the internal gravity modes in mediating the growth of nonaxisymmetric instabilities is investigated by studying the instability of stratified incompressible differentially rotating fluid cylinders to global nonaxisymmetric modes. The results indicate that, in addition to a modified version of the well-known principal branch mediated by surface modes of the system (analogous to f-modes of stars), there exist unstable branches of the dispersion relation mediated by internal gravity modes of the system (similar to the g-modes of stars). These branches arise due to the interaction between the g-modes. It is shown that the maximum growth rate on one of the new branches can sometimes equal or exceed that on the principal branch, thus modifying the principal branch.

  20. Growth of intra-caldera lava domes controlled by various modes of caldera collapse, the Štiavnica volcano-plutonic complex, Western Carpathians

    NASA Astrophysics Data System (ADS)

    Tomek, Filip; Žák, Jiří; Holub, František V.; Chlupáčová, Marta; Verner, Kryštof

    2016-02-01

    The Štiavnica volcano-plutonic complex is an erosional relic of Miocene caldera-stratovolcano in the Western Carpathians. The complex exposes a vertical section from the volcano basement through subvolcanic intrusions and a ring fault to volcanic edifice, comprising mostly andesitic lava flows and domes. This paper examines internal structure, magnetic fabric as derived from the anisotropy of magnetic susceptibility (AMS), and emplacement dynamics of three intra-caldera andesite domes (referred to as Domes 1-3) located near the presumed ring fault. Magnetic fabrics, carried by multi-domain titanomagnetite and titanomaghemite, are interpreted as recording various mechanisms of dome growth controlled by active caldera collapse. Dome 1 is explained as a lava coulée, fed by conduits located along the ring fault, with a long lava outflow down the sloping caldera floor. Dome 2 represents an elongated, ring fault-parallel dome wherein the lava flowed a short distance over a flat floor. Dome 3 is interpreted as a composite dome fed from multiple linear fissures opened at a high angle to the ring fault. Subsequently, the dome was intruded by ring fault-parallel dikes that may have potentially fed overlying, now largely eroded lava domes and flows. Finally, we suggest that all domes formed during collapse of the Štiavnica caldera and the various mechanisms of their growth reflect different stages of the caldera evolution from piston (Dome 2) through trap-door (Dome 1) to piecemeal (Dome 3).

  1. Growth regimes during homoepitaxial growth of GaN by ammonia molecular beam epitaxy

    SciTech Connect

    Corrion, A. L.; Wu, F.; Speck, J. S.

    2012-09-01

    c-plane GaN films were grown by ammonia molecular beam epitaxy on metal-organic chemical vapor deposition templates for a wide range of NH{sub 3}:Ga flux ratios and growth temperatures, and the resulting films were characterized using atomic force microscopy, reflection high-energy electron diffraction, and transmission electron microscopy. Three distinct nitrogen-rich growth regimes - unstable layer-by-layer, quasi-stable step flow, and dislocation-mediated pitting - were identified based on the growth mode and film properties. In addition, step flow growth was observed under conditions of gallium droplet accumulation. The results indicate the existence of two regimes for step-flow growth of GaN by ammonia MBE - both gallium-rich and nitrogen-rich. Growth mode instabilities and mound formation were observed and are discussed in the context of a step-edge energy barrier to adatom diffusion over a terrace.

  2. Leukocyte- and platelet-rich fibrin (L-PRF) for long-term delivery of growth factor in rotator cuff repair: review, preliminary results and future directions.

    PubMed

    Zumstein, Matthias A; Berger, Simon; Schober, Martin; Boileau, Pascal; Nyffeler, Richard W; Horn, Michael; Dahinden, Clemens A

    2012-06-01

    Surgical repair of the rotator cuff repair is one of the most common procedures in orthopedic surgery. Despite it being the focus of much research, the physiological tendon-bone insertion is not recreated following repair and there is an anatomic non-healing rate of up to 94%. During the healing phase, several growth factors are upregulated that induce cellular proliferation and matrix deposition. Subsequently, this provisional matrix is replaced by the definitive matrix. Leukocyte- and platelet-rich fibrin (L-PRF) contain growth factors and has a stable dense fibrin matrix. Therefore, use of LPRF in rotator cuff repair is theoretically attractive. The aim of the present study was to determine 1) the optimal protocol to achieve the highest leukocyte content; 2) whether L-PRF releases growth factors in a sustained manner over 28 days; 3) whether standard/gelatinous or dry/compressed matrix preparation methods result in higher growth factor concentrations. 1) The standard L-PRF centrifugation protocol with 400 x g showed the highest concentration of platelets and leukocytes. 2) The L-PRF clots cultured in medium showed a continuous slow release with an increase in the absolute release of growth factors TGF-β1, VEGF and MPO in the first 7 days, and for IGF1, PDGF-AB and platelet activity (PF4=CXCL4) in the first 8 hours, followed by a decrease to close to zero at 28 days. Significantly higher levels of growth factor were expressed relative to the control values of normal blood at each culture time point. 3) Except for MPO and the TGFβ-1, there was always a tendency towards higher release of growth factors (i.e., CXCL4, IGF-1, PDGF-AB, and VEGF) in the standard/gelatinous- compared to the dry/compressed group. L-PRF in its optimal standard/gelatinous-type matrix can store and deliver locally specific healing growth factors for up to 28 days and may be a useful adjunct in rotator cuff repair.

  3. Cardiac looping may be driven by compressive loads resulting from unequal growth of the heart and pericardial cavity. Observations on a physical simulation model

    PubMed Central

    Bayraktar, Meriç; Männer, Jörg

    2014-01-01

    The transformation of the straight embryonic heart tube into a helically wound loop is named cardiac looping. Such looping is regarded as an essential process in cardiac morphogenesis since it brings the building blocks of the developing heart into an approximation of their definitive topographical relationships. During the past two decades, a large number of genes have been identified which play important roles in cardiac looping. However, how genetic information is physically translated into the dynamic form changes of the looping heart is still poorly understood. The oldest hypothesis of cardiac looping mechanics attributes the form changes of the heart loop (ventral bending → simple helical coiling → complex helical coiling) to compressive loads resulting from growth differences between the heart and the pericardial cavity. In the present study, we have tested the physical plausibility of this hypothesis, which we call the growth-induced buckling hypothesis, for the first time. Using a physical simulation model, we show that growth-induced buckling of a straight elastic rod within the confined space of a hemispherical cavity can generate the same sequence of form changes as observed in the looping embryonic heart. Our simulation experiments have furthermore shown that, under bilaterally symmetric conditions, growth-induced buckling generates left- and right-handed helices (D-/L-loops) in a 1:1 ratio, while even subtle left- or rightward displacements of the caudal end of the elastic rod at the pre-buckling state are sufficient to direct the buckling process toward the generation of only D- or L-loops, respectively. Our data are discussed with respect to observations made in biological “models.” We conclude that compressive loads resulting from unequal growth of the heart and pericardial cavity play important roles in cardiac looping. Asymmetric positioning of the venous heart pole may direct these forces toward a biased generation of D- or L-loops. PMID

  4. Monolayer growth modes of Re and Nb on 4H -SiC(0001) and 4H-SiC(0001¯)

    NASA Astrophysics Data System (ADS)

    Bryant, K. W.; Bozack, M. J.

    2005-01-01

    Auger electron spectroscopy (AES) and secondary electron emission have been used to specify the room temperature monolayer adsorption characteristics of Re and Nb on the basal, polar surfaces of 4H -SiC. Measurement of the secondary electron emission current relates the absorbed crystal current to the change in AES peak-to-peak signal intensities for both substrate and adsorbate. For the 4H-SiC(0001) Si-face surface, both metals grow by formation of a single monolayer followed by growth of simultaneous monolayers. For the 4H -SiC(0001¯) C-face surface, both metals grow layer by layer (Frank-van der Merwe). Measurements of the coefficient of attenuation, inelastic mean free path, and coverage versus Auger intensities are also reported.

  5. Effect of the barrier growth mode on the luminescence and conductivity micron scale uniformity of InGaN light emitting diodes

    NASA Astrophysics Data System (ADS)

    Wallace, M. J.; Edwards, P. R.; Kappers, M. J.; Hopkins, M. A.; Oehler, F.; Sivaraya, S.; Oliver, R. A.; Humphreys, C. J.; Allsopp, D. W. E.; Martin, R. W.

    2015-03-01

    In this paper, we present a combined cathodoluminescence (CL) and electron beam induced current (EBIC) study of the optical and electrical properties of InGaN light emitting diodes grown using different active region growth methods. In one device, both the quantum wells and quantum barriers were deposited at their optimum temperatures (2 T), whereas in the other device, each barrier was grown in a two step process with the first few nanometers at a lower temperature (Q2T). It was found that in the Q2T sample, small micron scale domains of lower emission intensity correlate strongly to a lower EBIC signal, whereas in the 2 T sample which has a more uniform emission pattern and an anti-correlation exists between CL emission intensity and EBIC signal.

  6. Effect of the barrier growth mode on the luminescence and conductivity micron scale uniformity of InGaN light emitting diodes

    SciTech Connect

    Wallace, M. J.; Edwards, P. R.; Martin, R. W.; Kappers, M. J.; Oehler, F.; Oliver, R. A.; Humphreys, C. J.; Hopkins, M. A.; Sivaraya, S.; Allsopp, D. W. E.

    2015-03-21

    In this paper, we present a combined cathodoluminescence (CL) and electron beam induced current (EBIC) study of the optical and electrical properties of InGaN light emitting diodes grown using different active region growth methods. In one device, both the quantum wells and quantum barriers were deposited at their optimum temperatures (2 T), whereas in the other device, each barrier was grown in a two step process with the first few nanometers at a lower temperature (Q2T). It was found that in the Q2T sample, small micron scale domains of lower emission intensity correlate strongly to a lower EBIC signal, whereas in the 2 T sample which has a more uniform emission pattern and an anti-correlation exists between CL emission intensity and EBIC signal.

  7. The growth mode and microstructure of Ag-doped YBa 2Cu 3O 7-δ thin films prepared by dual beam pulsed-laser deposition

    NASA Astrophysics Data System (ADS)

    Xu, S. Y.; Ong, C. K.; You, L. P.; Li, J.; Wang, S. J.

    Ag-doped c-axis YBa 2Cu 3O 7-δ thin films were fabricated by using dual-beam pulsed-laser deposition. When a small amount of silver was doped in the film grown at 700 °C, the Jc value was obviously enhanced. The temperature dependence of Jc was found proportional to ( 1- T/T c0 ) {3}/{2} at T close to Tc). In the films grown at 730 °C, we observed long bar-like structures with lengths in tens of μm, oriented along or at 45° to the a/ b axes of the film. The bars consisted mainly a-axis YBCO grains and a mixture of polycrystalline and amorphous oxides. Defects on substrate surface and growth temperature were found dominating in formation of the bars, which could be attributed to a Ag-assisted diffusion mechanism during the deposition process.

  8. Fatigue Crack Growth Rate Test Results for Al-Li 2195 Parent Metal, Variable Polarity Plasma Arc Welds and Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Wagner, John A.; Domack, Marcia S.

    2000-01-01

    The fatigue crack growth rate of aluminum-lithium (Al-Li) alloy 2195 plate and weldments was determined at 200-F, ambient temperature and -320-F. The effects of stress ratio (R), welding process, orientation and thickness were studied. Results are compared with plate data from the Space Shuttle Super Lightweight Tank (SLWT) allowables program. Data from the current series of tests, both plate and weldment, falls within the range of data generated during the SLWT allowables program.

  9. [How to express results of 24-hour gastric pH measurement? Choice of a mode of expression in 27 healthy subjects].

    PubMed

    Vallot, T; Elouaer-Blanc, L; Garcia del Risco, F; Mignon, M; Vatier, J; Bonfils, S

    1988-01-01

    Twenty-four hour intragastric acidity was studied in 27 healthy subjects (mean age = 29 yrs) by continuous recording in standardized conditions. Data obtained were expressed according to several analytical methods as used extensively elsewhere. In our study, there was a wide discrepancy in results from one subject to another. The use of median values of pH was more appropriate than mean values to express half-hour acidity levels for 24 hours. The median value of H+ concentration is recommended as well. The median value of pH varied from 1 to 4.8 with a slight rise during the second half of the night. During the postprandial period, increase of pH values was prolonged over 2 h 30 in 50 p. 100 of subjects. Profile of pH allowed to demonstrate the distribution of pH value without excluding the extreme values. Both periodicity of pH measurement (30 or 60 min) and parameters used to quantify acidity (percentage of time or pH value at or below threshold values) did not modify results. As measured over a 24 hours period, the percentage of time (mean +/- SEM) at or below pH 1.5 and 3.5 was 54 +/- 3 p. 100 and 85 +/- 2 p. 100, respectively. Daytime and night-time profiles were similar. Mean 24 h H+ concentration (mean +/- SEM) was 47 +/- 35 mmol/l, with, once again, similarity between day and night-time values. The mean 24 h pH values underestimated true acidity with respect to median values.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. What is Local Mode (LM)? Global Mode (GM)? Calibration Mode?

    Atmospheric Science Data Center

    2014-12-08

    ... measurement in Global Mode (GM), Local Mode (LM), and Calibration. Global Mode is the normal acquisition with pole to pole coverage ... targets approximately 300 km in length Calibration Implemented bi-monthly Spectralon solar ...

  11. Two stage activated sludge plants--influence of different operational modes on sludge bulking and nitrification.

    PubMed

    Wandl, G; Müller-Rechberger, H; Matsché, N; Svardal, K; Winkler, S

    2002-01-01

    Conventional two stage activated sludge plants often lack sufficient nutrient removal performance due to substrate limitation for denitrification in the second stage. For the extension of the Vienna Main WWTP a two stage concept has been developed and tested by means of a pilot plant (scale 1:10.000). The new concept enables the operation of two different modes: In BYPASS-mode a portion of the primary clarifier effluent is fed directly to the second stage; the HYBRID-mode includes the exchange of mixed liquor between the two stages; over the course of the pilot plant investigations it turned out that nutrient removal is strongly increased in comparison to conventional two stage mode, but the two modes of operation lead to different results with regard to the sludge quality and the nitrification performance. BYPASS mode yields a higher SVI in both stages and a lower nitrification performance in comparison to HYBRID mode. This is caused by the negative influence of the primary effluent on the biocoenosis of the second stage. Additionally, the reduced sludge loading of the first stage in this mode results in a higher sludge age which favours the growth of filaments (Microthrix and Nocardia). In HYBRID-mode the higher load of the first stage results in a lower sludge age, fatty components are metabolized and incorporated in the sludge, thus, the growth of filaments is significantly reduced. Additionally, nitrification inhibiting substances are degraded in the first stage, which results in a higher nitrification performance in the second stage.

  12. Effects of 60 Hz electromagnetic fields on early growth in three plant species and a replication of previous results

    SciTech Connect

    Davis, M.S.

    1996-05-01

    In an attempt to replicate the findings of Smith et al., seeds of Raphanus sativus L. (radish), Sinapsis alba L. (mustard), and Hordeum vulgare L. (barley) were grown for between 9 and 21 days in continuous electromagnetic fields (EMFs) at ion-cyclotron resonance conditions for stimulation of Ca{sup 2+} (B{sub H} = 78.3 {micro}T, B{sub HAC} = 40 {micro}T peak-peak at 60 Hz, B{sub v} = 0). On harvesting, radish showed results similar to those of Smith et al. Dry stem weight and plant height were both significantly greater (Mann-Whitney tests, Ps < 0.05) in EMF-exposed plants than in control plants in each EMF experiment. Wet root weight was significantly greater in EMF-exposed plants in two out of three experiments, as were dry leaf weight, dry whole weight, and stem diameter. Dry root weight, wet leaf weight, and wet whole weight were significantly greater in EMF-exposed plants in one of three experiments. All significant differences indicated an increase in weight or size in the EMF-exposed plants. In each of the sham experiments, no differences between exposed and control plants were evident. Mustard plants failed to respond to the EMFs in any of the plant parameters measured. In one experiment, barley similarly failed to respond; but in another showed significantly greater wet root weight and significantly smaller stem diameter and dry seed weight at the end of the experiment in exposed plants compared to control plants. Although these results give no clue about the underlying bioelectromagnetic mechanism, they demonstrate that, at least for one EMF-sensitive biosystem, results can be independently replicated in another laboratory. Such replication is crucial in establishing the validity of bioelectromagnetic science.

  13. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode.

    PubMed

    Chiappim, W; Testoni, G E; Doria, A C O C; Pessoa, R S; Fraga, M A; Galvão, N K A M; Grigorov, K G; Vieira, L; Maciel, H S

    2016-07-29

    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  14. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode

    NASA Astrophysics Data System (ADS)

    Chiappim, W.; Testoni, G. E.; Doria, A. C. O. C.; Pessoa, R. S.; Fraga, M. A.; Galvão, N. K. A. M.; Grigorov, K. G.; Vieira, L.; Maciel, H. S.

    2016-07-01

    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  15. Relationships among growth mechanism, structure and morphology of PEALD TiO2 films: the influence of O2 plasma power, precursor chemistry and plasma exposure mode.

    PubMed

    Chiappim, W; Testoni, G E; Doria, A C O C; Pessoa, R S; Fraga, M A; Galvão, N K A M; Grigorov, K G; Vieira, L; Maciel, H S

    2016-07-29

    Titanium dioxide (TiO2) thin films have generated considerable interest over recent years, because they are functional materials suitable for a wide range of applications. The efficient use of the outstanding functional properties of these films relies strongly on their basic characteristics, such as structure and morphology, which are affected by deposition parameters. Here, we report on the influence of plasma power and precursor chemistry on the growth kinetics, structure and morphology of TiO2 thin films grown on Si(100) by plasma-enhanced atomic layer deposition (PEALD). For this, remote capacitively coupled 13.56 MHz oxygen plasma was used to act as a co-reactant during the ALD process using two different metal precursors: titanium tetrachloride (TiCl4) and titanium tetraisopropoxide (TTIP). Furthermore, we investigate the effect of direct plasma exposure during the co-reactant pulse on the aforementioned material properties. The extensive characterization of TiO2 films using Rutherford backscattering spectroscopy, ellipsometry, x-ray diffraction (XRD), field-emission scanning electron microscopy, and atomic force microscopy (AFM) have revealed how the investigated process parameters affect their growth per cycle (GPC), crystallization and morphology. The GPC tends to increase with plasma power for both precursors, however, for the TTIP precursor, it starts decreasing when the plasma power is greater than 100 W. From XRD analysis, we found a good correlation between film crystallinity and GPC behavior, mainly for the TTIP process. The AFM images indicated the formation of films with grain size higher than film thickness (grain size/film thickness ratio ≈20) for both precursors, and plasma power analysis allows us to infer that this phenomenon can be directly related to the increase of the flux of energetic oxygen species on the substrate/growing film surface. Finally, the effect of direct plasma exposure on film structure and morphology was evidenced

  16. Control of phytoplankton growth by iron and silicic acid availability in the subantarctic Southern Ocean: Experimental results from the SAZ Project

    NASA Astrophysics Data System (ADS)

    Hutchins, D. A.; Sedwick, P. N.; Ditullio, G. R.; Boyd, P. W.; QuéGuiner, B.; Griffiths, F. B.; Crossley, C.

    2001-12-01

    Subantarctic Southern Ocean surface waters in the austral summer and autumn are characterized by high concentrations of nitrate and phosphate but low concentrations of dissolved iron (Fe, ˜0.05 nM) and silicic acid (Si, <1 μM). During the Subantarctic Zone AU9706 cruise in March 1998 we investigated the relative importance of Fe and Si in controlling phytoplankton growth and species composition at a station within the subantarctic water mass (46.8°S, 142°E) using shipboard bottle incubation experiments. Treatments included unamended controls; 1.9 nM added iron (+Fe); 9 μM added silicic acid (+Si); and 1.9 nM added iron plus 9 μM added silicic acid (+Fe+Si). We followed a detailed set of biological and biogeochemical parameters over 8 days. Fe added alone clearly increased community growth rates and nitrate drawdown and altered algal community composition relative to control treatments. Surprisingly, small, lightly silicified pennate diatoms grew when Fe was added either with or without Si, despite the extremely low ambient silicic acid concentrations. Pigment analyses suggest that lightly silicified chrysophytes (type 4 haptophytes) may have preferentially responded to Si added either with or without Fe. However, for many of the parameters measured the +Fe+Si treatments showed large increases relative to both the +Fe and +Si treatments. Our results suggest that iron is the proximate limiting nutrient for chlorophyll production, photosynthetic efficiency, nitrate drawdown, and diatom growth, but that Si also exerts considerable control over algal growth and species composition. Both nutrients together are needed to elicit a maximum growth response, suggesting that both Fe and Si play important roles in structuring the subantarctic phytoplankton community.

  17. A coupled model approach to reduce nonpoint-source pollution resulting from predicted urban growth: A case study in the Ambos Nogales watershed

    USGS Publications Warehouse

    Norman, L.M.; Guertin, D.P.; Feller, M.

    2008-01-01

    The development of new approaches for understanding processes of urban development and their environmental effects, as well as strategies for sustainable management, is essential in expanding metropolitan areas. This study illustrates the potential of linking urban growth and watershed models to identify problem areas and support long-term watershed planning. Sediment is a primary source of nonpoint-source pollution in surface waters. In urban areas, sediment is intermingled with other surface debris in transport. In an effort to forecast the effects of development on surface-water quality, changes predicted in urban areas by the SLEUTH urban growth model were applied in the context of erosion-sedimentation models (Universal Soil Loss Equation and Spatially Explicit Delivery Models). The models are used to simulate the effect of excluding hot-spot areas of erosion and sedimentation from future urban growth and to predict the impacts of alternative erosion-control scenarios. Ambos Nogales, meaning 'both Nogaleses,' is a name commonly used for the twin border cities of Nogales, Arizona and Nogales, Sonora, Mexico. The Ambos Nogales watershed has experienced a decrease in water quality as a result of urban development in the twin-city area. Population growth rates in Ambos Nogales are high and the resources set in place to accommodate the rapid population influx will soon become overburdened. Because of its remote location and binational governance, monitoring and planning across the border is compromised. One scenario described in this research portrays an improvement in water quality through the identification of high-risk areas using models that simulate their protection from development and replanting with native grasses, while permitting the predicted and inevitable growth elsewhere. This is meant to add to the body of knowledge about forecasting the impact potential of urbanization on sediment delivery to streams for sustainable development, which can be

  18. Preliminary results of field mapping of methane plumes offshore of Coal Oil Point, California with a RESON 7125 multibeam sonar in water-column mode

    NASA Astrophysics Data System (ADS)

    Finlayson, D. P.; Hatcher, G.; Lorenson, T. D.; Greinert, J.; Maillard, E.; Weirathmueller, M.; Leifer, I.

    2010-12-01

    From June 17 - 23 2010, the U. S. Geological Survey (USGS) in collaboration with the Bureau of Ocean Energy Management Regulation and Enforcement(BOEMRE), the Royal Netherlands Institute for Sea Research (NIOZ) , RESON Inc. and the University of California, Santa Barbara(UCSB) conducted a comprehensive marine-seep gas-plume mapping study offshore of Coal Oil Point, California. The ultimate goal of the experiment is to quantify the amount of methane emitted from natural seeps using multibeam sonar, with results calibrated using field measurements of aqueous and atmospheric methane in the seep fields. Success will lead to better estimates of natural marine methane contributions to the global methane budget. We mapped selected seeps, some twice, with a pole-mounted RESON 7125 multibeam with a 10-degree forward rake. Other equipment included a Benthos Stingray ROV equipped with high-definition video cameras and in situ gas sampling apparatus, Niskin bottles for water column sampling of dissolved methane, and a Picarro G1301 cavity ringdown spectrometer for mapping atmospheric methane concentrations. This paper focuses primarily on the data reduction and data visualization strategies employed while processing the more than 1.2 TB of raw water column data collected by the multibeam system over several high-output oil and gas seep areas. Water depths ranged from about 30 to 80m. Turnkey software solutions for processing these data are currently unavailable so most of the processing code was developed in-house by the USGS. The main challenge in processing the sonar water-column data is ray-tracing the large volume of data, with each ping containing more than 4500 times as many samples as a conventional multibeam ping. We employed two strategies to make processing tractable on conventional workstations: (1) decimate the raw data based on desired output resolution before ray-tracing; and (2) design the ray-tracing program to run in parallel on multi-core workstations

  19. Nonaxisymmetric modes of MRI in dissipative Keplerian disks

    NASA Astrophysics Data System (ADS)

    Kitchatinov, L. L.; Rüdiger, G.

    2010-04-01

    Aims: Deviations from the axial symmetry are necessary to maintain self-sustained MRI-turbulence by a dynamo mechanism. We define the parameter region where the nonaxisymmetric MRI modes are excited and study their geometries and growth rates. Methods: The linear eigenvalue problem for global nonaxisymmetric modes of standard-MRI in Keplerian disks is solved numerically with allowance for finite diffusion. Results: For small magnetic Prandtl numbers the microscopic viscosity completely drops out of the analysis so that the stability maps and the growth rates expressed in terms of the magnetic Reynolds number Rm and the Lundquist number S do not depend on the magnetic Prandtl number Pm. The minimum magnetic field for the onset of nonaxisymmetric MRI grows with the rotation rate. For a given S all nonaxisymmetric modes disappear for a sufficiently large Rm. This is a consequence of the radial fine-structure of the nonaxisymmetric modes resulting from the winding effect of differential rotation. It is this fine-structure which also provides serious resolution problems for the numerical simulation of MRI at large Rm. Conclusions: For weak magnetic fields slightly above the critical value for the onset of MRI only axisymmetric modes are unstable. Nonaxisymmetric modes need stronger fields and not too large Rm. If Pm is small its real value does not play any role in MRI.

  20. Motions caused by the growth of Bacillus subtilis macrofibres in fluid medium result in new forms of movement of the multicellular structures over solid surfaces.

    PubMed

    Mendelson, N H; Sarlls, J E; Thwaites, J J

    2001-04-01

    Bacillus subtilis macrofibres, highly ordered multicellular structures, undergo twisting and writhing motions when they grow in fluid medium as a result of forces generated by the elongation of individual cells. Macrofibres are denser than the fluid medium in which they are cultured, consequently they settle to the bottom of the growth chamber and grow in contact with it. The ramifications of growth on plastic and glass surfaces were examined. Macrofibres were observed to rotate about a vertical axis near the centre of their length in a chiral-specific direction. Right-handed fibres rotated clockwise on plastic surfaces at approximately 4 degrees min(-1), left-handed structures of lower twist rotate anti-clockwise at about half that rate. Very large ball structures produced late in macrofibre formation perched on many small protruding fibres but rotated only when driven by large fibres attached to their periphery. Closer examination showed that fibres made contact with surfaces at only a few points along their length (between 1 and 6 on glass). The regions in contact with the surface changed periodically as a result of rotation of the fibre shaft caused by growth. Every time the weight of a fibre transferred from one contact point to another, each section of the fibre took a small step approximately proportional to its distance from the fibre mid-point. The net result was a rolling of each section over the surface so that the fibre rotation about a vertical axis was produced. Macrofibres also took large steps when part of the structure rose off the floor, swept through an arc in the fluid and then returned to the floor at a new location. The rate of movement during a large step, measured as the change of angle between the moving and stationary portions of the fibre, was 5 degrees s(-1). These observations reveal that the forces derived from helical growth that lead to macrofibre formation also cause characteristic macrofibre motion that differs from classical

  1. The combination of 4-anilinoquinazoline and cinnamic acid: a novel mode of binding to the epidermal growth factor receptor tyrosine kinase.

    PubMed

    Li, Dong-Dong; Lv, Peng-Cheng; Zhang, Hui; Zhang, Hong-Jia; Hou, Ya-Ping; Liu, Kai; Ye, Yong-Hao; Zhu, Hai-Liang

    2011-08-15

    A novel type of cinnamic acid quinazoline amide derivatives (20-42), which designed the combination between quinazoline as the backbone and various substituted cinnamic acid as the side chain, have been synthesized and their biological activities were evaluated within cytotoxicity assay firstly and then potent EGFR inhibitory activity. Compound 42 demonstrated the most potent inhibitory activity (IC(50)=0.94 μM for EGFR), which could be optimized as a potential EGFR inhibitor in the further study. Docking simulation was performed to position compound 42 into the EGFR active site to determine the probable binding model. Analysis of the binding conformation of 42 in active site displayed compound 42 was stabilized by hydrogen bonding interactions with Lys822, which was different from other derivatives. In the further study, Compounds 43 and 44 had been synthesized and their biological activities were also evaluated, which were the same as that we expected. Compound 43 has demonstrated significant EGFR (IC(50)=0.12 μM) and tumor growth inhibitory activity as a potential anticancer agent.

  2. Nonlinear excitation of subcritical fast ion-driven modes

    NASA Astrophysics Data System (ADS)

    Lesur, M.; Itoh, K.; Ido, T.; Itoh, S.-I.; Kosuga, Y.; Sasaki, M.; Inagaki, S.; Osakabe, M.; Ogawa, K.; Shimizu, A.; Ida, K.; the LHD experiment group

    2016-05-01

    In collisionless plasma, it is known that linearly stable modes can be destabilized (subcritically) by the presence of structures in phase-space. The growth of such structures is a nonlinear, kinetic mechanism, which provides a channel for free-energy extraction, different from conventional inverse Landau damping. However, such nonlinear growth requires the presence of a seed structure with a relatively large threshold in amplitude. We demonstrate that, in the presence of another, linearly unstable (supercritical) mode, wave–wave coupling can provide a seed, which can lead to subcritical instability by either one of two mechanisms. Both mechanisms hinge on a collaboration between fluid nonlinearity and kinetic nonlinearity. If collisional velocity diffusion is low enough, the seed provided by the supercritical mode overcomes the threshold for nonlinear growth of phase-space structure. Then, the supercritical mode triggers the conventional subcritical instability. If collisional velocity diffusion is too large, the seed is significantly below the threshold, but can still grow by a sustained collaboration between fluid and kinetic nonlinearities. Both of these subcritical instabilities can be triggered, even when the frequency of the supercritical mode is rapidly sweeping. These results were obtained by modeling the subcritical mode kinetically, and the impact of the supercritical mode by simple wave–wave coupling equations. This model is applied to bursty onset of geodesic acoustic modes in an LHD experiment. The model recovers several key features such as relative amplitude, timescales, and phase relations. It suggests that the strongest bursts are subcritical instabilities, with sustained collaboration between fluid and kinetic nonlinearities.

  3. Combination of vatalanib and a 20-HETE synthesis inhibitor results in decreased tumor growth in an animal model of human glioma

    PubMed Central

    Shankar, Adarsh; Borin, Thaiz F; Iskander, Asm; Varma, Nadimpalli RS; Achyut, Bhagelu R; Jain, Meenu; Mikkelsen, Tom; Guo, Austin M; Chwang, Wilson B; Ewing, James R; Bagher-Ebadian, Hassan; Arbab, Ali S

    2016-01-01

    Background Due to the hypervascular nature of glioblastoma (GBM), antiangiogenic treatments, such as vatalanib, have been added as an adjuvant to control angiogenesis and tumor growth. However, evidence of progressive tumor growth and resistance to antiangiogenic treatment has been observed. To counter the unwanted effect of vatalanib on GBM growth, we have added a new agent known as N-hydroxy-N′-(4-butyl-2 methylphenyl)formamidine (HET0016), which is a selective inhibitor of 20-hydroxyeicosatetraenoic acid (20-HETE) synthesis. The aims of the studies were to determine 1) whether the addition of HET0016 can attenuate the unwanted effect of vatalanib on tumor growth and 2) whether the treatment schedule would have a crucial impact on controlling GBM. Methods U251 human glioma cells (4×105) were implanted orthotopically. Two different treatment schedules were investigated. Treatment starting on day 8 (8–21 days treatment) of the tumor implantation was to mimic treatment following detection of tumor, where tumor would have hypoxic microenvironment and well-developed neovascularization. Drug treatment starting on the same day of tumor implantation (0–21 days treatment) was to mimic cases following radiation therapy or surgery. There were four different treatment groups: vehicle, vatalanib (oral treatment 50 mg/kg/d), HET0016 (intraperitoneal treatment 10 mg/kg/d), and combined (vatalanib and HET0016). Following scheduled treatments, all animals underwent magnetic resonance imaging on day 22, followed by euthanasia. Brain specimens were equally divided for immunohistochemistry and protein array analysis. Results Our results demonstrated a trend that HET0016, alone or in combination with vatalanib, is capable of controlling the tumor growth compared with that of vatalanib alone, indicating attenuation of the unwanted effect of vatalanib. When both vatalanib and HET0016 were administered together on the day of the tumor implantation (0–21 days treatment), tumor

  4. Suppression of OsKu80 results in defects in developmental growth and increased telomere length in rice (Oryza sativa L.).

    PubMed

    Byun, Mi Young; Cui, Li Hua; Kim, Woo Taek

    2015-12-25

    The Ku70-Ku80 heterodimer plays a critical role in the maintenance of genomic stability in humans and yeasts. In this report, we identified and characterized OsKu80 in rice, a model monocot crop. OsKu80 forms a heterodimer with OsKu70 in yeast and plant cells, as demonstrated by yeast two-hybrid, in vivo co-immunoprecipitation, and bimolecular fluorescence complementation assays. RNAi-mediated knock-down T3 transgenic rice plants (Ubi:RNAi-OsKu80) displayed a retarded growth phenotype at the post-germination stage. In addition, the Ubi:RNAi-OsKu80 knock-down progeny exhibited noticeably increased telomere length as compared to wild-type rice. These results are discussed with the idea that OsKu80 plays a role in developmental growth and telomere length regulation in rice plants.

  5. Linear calculations of edge current driven kink modes with BOUT++ code

    SciTech Connect

    Li, G. Q. Xia, T. Y.; Xu, X. Q.; Snyder, P. B.; Turnbull, A. D.; Ma, C. H.; Xi, P. W.

    2014-10-15

    This work extends previous BOUT++ work to systematically study the impact of edge current density on edge localized modes, and to benchmark with the GATO and ELITE codes. Using the CORSICA code, a set of equilibria was generated with different edge current densities by keeping total current and pressure profile fixed. Based on these equilibria, the effects of the edge current density on the MHD instabilities were studied with the 3-field BOUT++ code. For the linear calculations, with increasing edge current density, the dominant modes are changed from intermediate-n and high-n ballooning modes to low-n kink modes, and the linear growth rate becomes smaller. The edge current provides stabilizing effects on ballooning modes due to the increase of local shear at the outer mid-plane with the edge current. For edge kink modes, however, the edge current does not always provide a destabilizing effect; with increasing edge current, the linear growth rate first increases, and then decreases. In benchmark calculations for BOUT++ against the linear results with the GATO and ELITE codes, the vacuum model has important effects on the edge kink mode calculations. By setting a realistic density profile and Spitzer resistivity profile in the vacuum region, the resistivity was found to have a destabilizing effect on both the kink mode and on the ballooning mode. With diamagnetic effects included, the intermediate-n and high-n ballooning modes can be totally stabilized for finite edge current density.

  6. Linear calculations of edge current driven kink modes with BOUT++ code

    NASA Astrophysics Data System (ADS)

    Li, G. Q.; Xu, X. Q.; Snyder, P. B.; Turnbull, A. D.; Xia, T. Y.; Ma, C. H.; Xi, P. W.

    2014-10-01

    This work extends previous BOUT++ work to systematically study the impact of edge current density on edge localized modes, and to benchmark with the GATO and ELITE codes. Using the CORSICA code, a set of equilibria was generated with different edge current densities by keeping total current and pressure profile fixed. Based on these equilibria, the effects of the edge current density on the MHD instabilities were studied with the 3-field BOUT++ code. For the linear calculations, with increasing edge current density, the dominant modes are changed from intermediate-n and high-n ballooning modes to low-n kink modes, and the linear growth rate becomes smaller. The edge current provides stabilizing effects on ballooning modes due to the increase of local shear at the outer mid-plane with the edge current. For edge kink modes, however, the edge current does not always provide a destabilizing effect; with increasing edge current, the linear growth rate first increases, and then decreases. In benchmark calculations for BOUT++ against the linear results with the GATO and ELITE codes, the vacuum model has important effects on the edge kink mode calculations. By setting a realistic density profile and Spitzer resistivity profile in the vacuum region, the resistivity was found to have a destabilizing effect on both the kink mode and on the ballooning mode. With diamagnetic effects included, the intermediate-n and high-n ballooning modes can be totally stabilized for finite edge current density.

  7. Heterogeneous engineered cartilage growth results from gradients of media-supplemented active TGF-β and is ameliorated by the alternative supplementation of latent TGF-β.

    PubMed

    Albro, Michael B; Nims, Robert J; Durney, Krista M; Cigan, Alexander D; Shim, Jay J; Vunjak-Novakovic, Gordana; Hung, Clark T; Ateshian, Gerard A

    2016-01-01

    Transforming growth factor beta (TGF-β) has become one of the most widely utilized mediators of engineered cartilage growth. It is typically exogenously supplemented in the culture medium in its active form, with the expectation that it will readily transport into tissue constructs through passive diffusion and influence cellular biosynthesis uniformly. The results of this investigation advance three novel concepts regarding the role of TGF-β in cartilage tissue engineering that have important implications for tissue development. First, through the experimental and computational analysis of TGF-β concentration distributions, we demonstrate that, contrary to conventional expectations, media-supplemented exogenous active TGF-β exhibits a pronounced concentration gradient in tissue constructs, resulting from a combination of high-affinity binding interactions and a high cellular internalization rate. These gradients are sustained throughout the entire culture duration, leading to highly heterogeneous tissue growth; biochemical and histological measurements support that while biochemical content is enhanced up to 4-fold at the construct periphery, enhancements are entirely absent beyond 1 mm from the construct surface. Second, construct-encapsulated chondrocytes continuously secrete large amounts of endogenous TGF-β in its latent form, a portion of which undergoes cell-mediated activation and enhances biosynthesis uniformly throughout the tissue. Finally, motivated by these prior insights, we demonstrate that the alternative supplementation of additional exogenous latent TGF-β enhances biosynthesis uniformly throughout tissue constructs, leading to enhanced but homogeneous tissue growth. This novel demonstration suggests that latent TGF-β supplementation may be utilized as an important tool for the translational engineering of large cartilage constructs that will be required to repair the large osteoarthritic defects observed clinically.

  8. Coupled perturbed modes and internal solitary waves.

    PubMed

    Higham, C J; Tindle, C T

    2003-05-01

    Coupled perturbed mode theory combines conventional coupled modes and perturbation theory. The theory is used to directly calculate mode coupling in a range-dependent shallow water problem involving propagation through continental shelf internal solitary waves. The solitary waves considered are thermocline depressions, separating well-mixed upper and lower layers. The method is fast and accurate. Results highlight mode coupling associated with internal solitary waves, and mode capture or loss to and from the discrete mode spectrum.

  9. Concurrent Evaluation of Magma Production, Volcano Growth, and Geochemical Structure in Mantle Plumes: Hawaii Drilling Project (HSDP) Results

    NASA Astrophysics Data System (ADS)

    Depaolo, D. J.

    2007-12-01

    The Hawaii Scientific Drilling Project (HSDP) completed its drilling and coring of the northeast flank of the Mauna Kea volcano in early 2007. The project obtained a nearly continuous core consisting of lava flows, hyaloclastite, minor intrusives and sediment from a 3260 m section of the Mauna Kea volcano, covering an age range from 200 to over 600 ka. It also recovered a 280m section of the Mauna Loa volcano. When combined with surface and dredge samples, there now is a 600-700 ky record of the lava output from Mauna Kea as well as a 200 ky record from Mauna Loa. These records can be interpreted in terms of the geochemical structure of the Hawaiian plume, given a model for the sampling of the plume by melting and melt transport. The continuous nature of the HSDP core, with the implied continuous monitoring of the lava output from the volcano, has dictated that we develop models for the plume behavior just below the lithosphere, and for how magma is collected from the plume melting region and supplied to an individual volcano. Although there are as yet no detailed physical models for the melt collection and transport, we have experimented with simple geometric models. These models can be constrained by the volume and volume-age structure of the Hawaiian volcanoes, and by available geodynamic models for the Hawaiian plume. Using these models we can interpret geochemical data from the lavas in terms of plume structure. Any systematic variability in Hawaiian lavas with depth (age) in the drillcore can be attributed to structure in the plume, and one of the interesting results is that there is such structure even though melting within the plume samples only the innermost third or so the plume radius. The data show that there is radial geochemical zoning of the melting region of the plume in terms of He, Pb, Nd, Sr and Hf isotopes. This geochemical structure represents the hot core of the plume and does not reflect entrainment of ambient lower or upper mantle. To first

  10. Tyrosine kinase inhibitors. 11. Soluble analogues of pyrrolo- and pyrazoloquinazolines as epidermal growth factor receptor inhibitors: synthesis, biological evaluation, and modeling of the mode of binding.

    PubMed

    Palmer, B D; Trumpp-Kallmeyer, S; Fry, D W; Nelson, J M; Showalter, H D; Denny, W A

    1997-05-01

    A new route to N-1-substituted pyrazolo- and pyrroloquinazolines has been developed from the known quinazolones 19 and 23, via conversion to the corresponding thiones, S-methylation to the thioethers, N-1-alkylation, and coupling with 3-bromoaniline. C-3-Substituted pyrroloquinazolines were prepared by Mannich base chemistry. A series of compounds bearing solubilizing side chains at these positions has been prepared and evaluated for inhibition of the tyrosine kinase activity of the isolated epidermal growth factor receptor (EGFR) and of its autophosphorylation in EGF-stimulated A431 cells. Several analogues, particularly C-3-substituted pyrroloquinazolines, retained high potency in both assays. A model for the binding of the general class of 4-anilinoquinazolines to the EGFR was constructed from structural information (particularly for the catalytic subunit of the cAMP-dependent protein kinase) and structure-activity relationships (SAR) in the series. In this model, the pyrrole ring in pyrroloquinazolines (and the 6- and 7-positions of quinazoline and related pyridopyrimidine inhibitors) occupies the entrance of the ATP binding pocket of the enzyme, with the pyrrole nitrogen located at the bottom of the cleft and the pyrrole C-3 position pointing toward a pocket corresponding to the ribose binding site of ATP. This allows considerable bulk tolerance for C-3 substituents and lesser but still significant bulk tolerance for N-1 substituents. The observed high selectivity of these compounds for binding to EGFR over other similar tyrosine kinases is attributed to the 4-anilino ring binding in an adjacent hydrophobic pocket which has an amino acid composition unique to the EGFR. The SAR seen for inhibition of the isolated enzyme by the pyrazolo- and pyrroloquinazolines discussed here is fully consistent with this binding model. For the N-1-substituted compounds, inhibition of autophosphorylation in A431 cells correlates well with inhibition of the isolated enzyme, as

  11. Unusual hydrocarbon chain packing mode and modification of crystallite growth habit in the self-assembled nanocomposites zinc-aluminum-hydroxide oleate and elaidate (cis-and trans-[Zn2Al(OH)6(CH3(CH2)7CH=CH(CH2)7COO-)] and magnesium analogues.

    SciTech Connect

    Wang, Yifeng; Braterman, Paul S.; Xu, Zhi-Ping; Brinker, C. Jeffrey; Xu, Huifang; Yu, Kui

    2004-05-01

    We report a novel packing mode specific to the cis unsaturated hydrocarbon chain in the title compound, a self-assembled layered double hydroxide-surfactant hybrid nanomaterial, and its influence on crystallite morphology and structure. The kink imposed by the cis double bond in oleate leads to partial overlap between chains on adjacent layers, with incomplete space filling, in contrast to the more usual (and more efficient) mono- and bilayer packings exhibited by the trans analogues. Incorporation of surfactant into the growing crystallite leads to a reversal of the usual LDH growth habit and results in crystallite shapes featuring ribbonlike sheets. The thermal decomposition behavior of the as-prepared organic/inorganic nanocomposites in air and N{sub 2} is described.

  12. Whistler-mode wave propagation in the pre-noon magnetosphere

    NASA Astrophysics Data System (ADS)

    Watt, C. E.; Rankin, R.; Degeling, A. W.

    2012-12-01

    Statistical surveys of the occurrence of whistler-mode waves by CRRES and THEMIS [Meredith et al., 2003 and Li et al., 2009] indicate whistler-mode waves are most common on the dawnside magnetosphere. We perform extensive raytracing to analyse the growth and propagation of millions of whistler-mode raypaths, in an attempt to include all possible source regions of whistler-mode waves over a wide region in latitude. We describe the observational constraints on the myriad of choices for those plasma properties which control wave growth, focusing specifically on the pre-noon sector. We demonstrate that waves observed at any particular location are often a superposition of different waves with different paths and histories. We compare solutions from an uncompressed and compressed magnetosphere to investigate the effects of magnetic field topology on the possible source region of whistler-mode waves in the pre-noon magnetosphere and compare the results with statistical surveys of wave amplitudes.

  13. Assessment of Crack Path Prediction in Non-Proportional Mixed-Mode Fatigue

    NASA Technical Reports Server (NTRS)

    Highsmith, Shelby, Jr.; Johnson, Steve; Swanson, Gregory; Sayyah, Tarek; Pettit, Richard

    2008-01-01

    Non-proportional mixed-mode loading is present in many systems and a growing crack can experience any manner of mixed-mode loading. Prediction of the resulting crack path is important when assessing potential failure modes or when performing a failure investigation. Current crack path selection criteria are presented along with data for Inconel 718 under non-proportional mixed-mode loading. Mixed-mode crack growth can transition between path deflection mechanisms with very different orientations. Non-proportional fatigue loadings lack a single parameter for input to current crack path criteria. Crack growth transitions were observed in proportional and non-proportional FCG tests. Different paths displayed distinct fracture surface morphologies. New crack path drivers & transition criteria must be developed.

  14. Diminished respirative growth and enhanced assimilative sugar uptake result in higher specific fermentation rates by the mutant Pichia stipitis FPL-061

    SciTech Connect

    Sreenath, H.K.; Jeffries, T.W. |

    1997-12-31

    A mutant strain of Pichia stipitis, FPL-061, was obtained by selecting for growth on L-xylose in the presence of respiratory inhibitors. The specific fermentation rate of FPL-061, was higher than that of the parent, Pichia stipitis CBS 6054, because of its lower cell yield and growth rate and higher specific substrate uptake rate. With a mixture of glucose and xylose, the mutant strain FPL-061 produced 29.4 g ethanol/L with a yield of 0.42 g ethanol/g sugar consumed. By comparison, CBS 6054 produced 25.7 g ethanol/L with a yield of 0.35 g/g. The fermentation was most efficient at an aeration rate of 9.2 mmoles O{sub 2} L{sup -1} h{sup -1}. At high aeration rates (22 mmoles O{sub 2} L{sup -1} h{sup -1}), the mutant cell yield was less than that of the parent. At low aeration rates, (1.1 to 2.5 O{sub 2} L{sup -1} h{sup -1}), cell yields were similar, the ethanol formation rates were low, and xylitol accumulation was observed in both the strains. Both strains respired the ethanol once sugar was exhausted. We infer from the results that the mutant, P. stipitis FPL-061, diverts a larger fraction of its metabolic energy from cell growth into ethanol production. 21 refs., 5 figs.

  15. Whispering Bloch modes

    PubMed Central

    Craster, R. V.

    2016-01-01

    We investigate eigenvalue problems for the planar Helmholtz equation in open systems with a high order of rotational symmetry. The resulting solutions have similarities with the whispering gallery modes exploited in photonic micro-resonators and elsewhere, but unlike these do not necessarily require a surrounding material boundary, with confinement instead resulting from the geometry of a series of inclusions arranged in a ring. The corresponding fields exhibit angular quasi-periodicity reminiscent of Bloch waves, and hence we refer to them as whispering Bloch modes (WBMs). We show that if the geometry of the system is slightly perturbed such that the rotational symmetry is broken, modes with asymmetric field patterns can be observed, resulting in field enhancement and other potentially desirable effects. We investigate the WBMs of two specific geometries first using expansion methods and then by applying a two-scale asymptotic scheme. PMID:27493564

  16. Impact of the Great East Japan Earthquake on feeding methods and newborn growth at 1 month postpartum: results from the Fukushima Health Management Survey.

    PubMed

    Kyozuka, Hyo; Yasuda, Shun; Kawamura, Makoto; Nomura, Yasuhisa; Fujimori, Keiya; Goto, Aya; Yasumura, Seiji; Abe, Masafumi

    2016-05-01

    This study examined the effects of three disasters (the Great East Japan Earthquake of March 11, 2011, followed by a tsunami and the Fukushima Daiichi Nuclear Power Plant accident) on feeding methods and growth in infants born after the disasters. Using results from the Fukushima Health Management Survey, Soso District (the affected area where the damaged nuclear power plant is located) and Aizu District (a less-affected area located farthest from the plant) were compared. In this study, newborn and maternal background characteristics were examined, as well as feeding methods, and other factors for newborn growth at the first postpartum examination for 1706 newborns born after the disaster in the affected (n = 836) and less-affected (n = 870) areas. Postpartum examinations took place 1 month after birth. Feeding method trends were examined, and multivariate regression analyses were used to investigate effects on newborn mass gain. There were no significant differences in background characteristics among newborns in these areas. When birth dates were divided into four periods to assess trends, no significant change in the exclusive breastfeeding rate was found, while the exclusive formula-feeding rate was significantly different across time periods in the affected area (p = 0.02). Multivariate analyses revealed no significant independent associations of maternal depression and change in medical facilities (possible disaster effects) with other newborn growth factors in either area. No area differences in newborn growth at the first postpartum examination or in exclusive breastfeeding rates were found during any period. Exclusive formula-feeding rates varied across time periods in the affected, but not in the less-affected area. It is concluded that effective guidance to promote breast-feeding and prevent exclusive use of formula is important for women in post-disaster circumstances.

  17. Infertility in a line of mice with the high growth mutation is due to luteal insufficiency resulting from disruption at the hypothalamic-pituitary axis.

    PubMed

    Cargill, S L; Medrano, J F; Anderson, G B

    1999-07-01

    Animals with extreme body growth frequently experience poor reproductive performance, but the cause for this association has not been clearly established. A line of mice homozygous for the high growth (hg) mutation, a mutation that has a major effect on post-weaning growth, exhibits several reproductive deficits including an abnormally high incidence of luteal failure. The objective of the present study was to investigate luteal failure in high-growth (HG) mice during pregnancy and to determine whether the cause of the apparent luteal failure resides in the ovary or the hypothalamic-pituitary unit. In HG females with a demonstrated history of infertility, progesterone injections (1 mg s.c. daily) beginning on Day 1 postcoitum (p.c.) increased the proportion of animals pregnant at Day 17 of gestation. Twice-daily injections of 100 microgram of ovine prolactin (PRL) in alkaline saline given to another group of females beginning on Day 1 p.c. increased the proportion of HG females that were pregnant on Day 6 of gestation compared with saline-injected HG females, although PRL did not increase the pregnancy rate in HG females when compared with a group of noninjected control females. When ovaries from HG females were transplanted into ovariectomized congenic C57 hosts, the C57 graft hosts displayed normal estrous cycles, and upon mating the majority of graft hosts became pregnant. In contrast, when ovaries from C57 females were transplanted into ovariectomized HG hosts, the HG graft hosts displayed normal estrous cycles, but upon mating most were unable to maintain pregnancy. These results suggest that the hypothalamic-pituitary unit of the HG female provides an inadequate signal to the ovaries to maintain pregnancy. Luteal failure in HG females may be due to insufficient PRL as required for establishment and early maintenance of the CL during pregnancy in mice.

  18. Impact of the Great East Japan Earthquake on feeding methods and newborn growth at 1 month postpartum: results from the Fukushima Health Management Survey.

    PubMed

    Kyozuka, Hyo; Yasuda, Shun; Kawamura, Makoto; Nomura, Yasuhisa; Fujimori, Keiya; Goto, Aya; Yasumura, Seiji; Abe, Masafumi

    2016-05-01

    This study examined the effects of three disasters (the Great East Japan Earthquake of March 11, 2011, followed by a tsunami and the Fukushima Daiichi Nuclear Power Plant accident) on feeding methods and growth in infants born after the disasters. Using results from the Fukushima Health Management Survey, Soso District (the affected area where the damaged nuclear power plant is located) and Aizu District (a less-affected area located farthest from the plant) were compared. In this study, newborn and maternal background characteristics were examined, as well as feeding methods, and other factors for newborn growth at the first postpartum examination for 1706 newborns born after the disaster in the affected (n = 836) and less-affected (n = 870) areas. Postpartum examinations took place 1 month after birth. Feeding method trends were examined, and multivariate regression analyses were used to investigate effects on newborn mass gain. There were no significant differences in background characteristics among newborns in these areas. When birth dates were divided into four periods to assess trends, no significant change in the exclusive breastfeeding rate was found, while the exclusive formula-feeding rate was significantly different across time periods in the affected area (p = 0.02). Multivariate analyses revealed no significant independent associations of maternal depression and change in medical facilities (possible disaster effects) with other newborn growth factors in either area. No area differences in newborn growth at the first postpartum examination or in exclusive breastfeeding rates were found during any period. Exclusive formula-feeding rates varied across time periods in the affected, but not in the less-affected area. It is concluded that effective guidance to promote breast-feeding and prevent exclusive use of formula is important for women in post-disaster circumstances. PMID:26875100

  19. Validation and ease of use of a new pen device for self-administration of recombinant human growth hormone: results from a two-center usability study

    PubMed Central

    Rapaport, Robert; Saenger, Paul; Schmidt, Heinrich; Hasegawa, Yukihiro; Colle, Michel; Loche, Sandro; Marcantonio, Sandra; Bonfig, Walter; Zabransky, Markus; Lifshitz, Fima

    2013-01-01

    Close adherence to the recommended treatment regimen is important for the success of recombinant human growth hormone therapy, although nonadherence can be common. Ease of use and safety during use/storage are among several important factors in the design of a growth hormone injection device intended for long-term use. This study was performed to validate the usability and assess the ease of use of a new pen device (SurePal™) that has been developed to support daily administration of the recombinant human growth hormone product, Omnitrope® (somatropin). The primary objectives of the study were to assess if study participants, representing intended users of the pen in clinical practice, were able to perform an injection procedure into an injection pad effectively and safely and disassemble the pen without receiving a needlestick injury. A total of 106 participants (61 adults and 45 children/adolescents) were enrolled at two study centers (one in the US, one in Germany). Results for both primary usability tasks met the predefined acceptance criteria, with >85% of participants successfully performing each task. All of the other tasks/handling steps assessed were also successfully performed by most participants, with high success rates reflected in the high proportion of participants who classified each task as “very easy” or “easy”. After a second use of the device, 87%–97% of participants rated it as “very easy” or “easy” to use. In summary, the new pen device is safe and easy to use for both adults and children, and will help to support effective, long-term daily administration of the recombinant human growth hormone product, Omnitrope®. PMID:24039458

  20. Validation and ease of use of a new pen device for self-administration of recombinant human growth hormone: results from a two-center usability study.

    PubMed

    Rapaport, Robert; Saenger, Paul; Schmidt, Heinrich; Hasegawa, Yukihiro; Colle, Michel; Loche, Sandro; Marcantonio, Sandra; Bonfig, Walter; Zabransky, Markus; Lifshitz, Fima

    2013-01-01

    Close adherence to the recommended treatment regimen is important for the success of recombinant human growth hormone therapy, although nonadherence can be common. Ease of use and safety during use/storage are among several important factors in the design of a growth hormone injection device intended for long-term use. This study was performed to validate the usability and assess the ease of use of a new pen device (SurePal™) that has been developed to support daily administration of the recombinant human growth hormone product, Omnitrope® (somatropin). The primary objectives of the study were to assess if study participants, representing intended users of the pen in clinical practice, were able to perform an injection procedure into an injection pad effectively and safely and disassemble the pen without receiving a needlestick injury. A total of 106 participants (61 adults and 45 children/adolescents) were enrolled at two study centers (one in the US, one in Germany). Results for both primary usability tasks met the predefined acceptance criteria, with >85% of participants successfully performing each task. All of the other tasks/handling steps assessed were also successfully performed by most participants, with high success rates reflected in the high proportion of participants who classified each task as "very easy" or "easy". After a second use of the device, 87%-97% of participants rated it as "very easy" or "easy" to use. In summary, the new pen device is safe and easy to use for both adults and children, and will help to support effective, long-term daily administration of the recombinant human growth hormone product, Omnitrope®.

  1. On Ideal Stability of Cylindrical Localized Interchange Modes

    SciTech Connect

    Umansky, M V

    2007-05-15

    Stability of cylindrical localized ideal pressure-driven interchange plasma modes is revisited. Converting the underlying eigenvalue problem into the form of the Schroedinger equation gives a new simple way of deriving the Suydam stability criterion and calculating the growth rates of unstable modes. Near the marginal stability limit the growth rate is exponentially small and the mode has a double-peak structure.

  2. Saturation of single toroidal number Alfvén modes

    NASA Astrophysics Data System (ADS)

    Wang, X.; Briguglio, S.

    2016-08-01

    The results of numerical simulations are presented to illustrate the saturation mechanism of a single toroidal number Alfvén mode, driven unstable, in a tokamak plasma, by the resonant interaction with energetic ions. The effects of equilibrium geometry non-uniformities and finite mode radial width on the wave-particle nonlinear dynamics are discussed. Saturation occurs as the fast-ion density flattening produced by the radial flux associated to the resonant particles captured in the potential well of the Alfvén wave extends over the whole region where mode-particle power exchange can take place. The occurrence of two different saturation regimes is shown. In the first regime, dubbed resonance detuning, that region is limited by the resonance radial width (that is, the width of the region where the fast-ion resonance frequency matches the mode frequency). In the second regime, called radial decoupling, the power exchange region is limited by the mode radial width. In the former regime, the mode saturation amplitude scales quadratically with the growth rate; in the latter, it scales linearly. The occurrence of one or the other regime can be predicted on the basis of linear dynamics: in particular, the radial profile of the fast-ion resonance frequency and the mode structure. Here, we discuss how such properties can depend on the considered toroidal number and compare simulation results with the predictions obtained from a simplified nonlinear pendulum model.

  3. Dancing bunches as Van Kampen modes

    SciTech Connect

    Burov, A.; /Fermilab

    2011-03-01

    Van Kampen modes are eigen-modes of Jeans-Vlasov equation [1-3]. Their spectrum consists of continuous and, possibly, discrete parts. Onset of a discrete van Kampen mode means emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch wake is sufficient to drive instability. Longitudinal instabilities observed at Tevatron [4], RHIC [5] and SPS [6] can be explained as loss of Landau damping (LLD), which is shown here to happen at fairly low impedances. For repulsive wakes and single-harmonic RF, LLD is found to be extremely sensitive to steepness of the bunch distribution function at small amplitudes. Based on that, a method of beam stabilization is suggested. Emergence of a discrete van Kampen mode means either loss of Landau damping or instability. Longitudinal bunch stability is analysed in weak head-tail approximation for inductive impedance and single-harmonic RF. The LLD threshold intensities are found to be rather low: for cases under study all of them do not exceed a few percent of the zero-amplitude incoherent synchrotron frequency shift, strongly decreasing for shorter bunches. Because of that, LLD can explain longitudinal instabilities happened at fairly low impedances at Tevatron [4], and possibly for RHIC [5] and SPS [6], being in that sense an alternative to the soliton explanation [5, 20]. Although LLD itself results in many cases in emergence of a mode with zero growth rate, any couple-bunch (and sometimes multi-turn) wake would drive instability for that mode, however small this wake is. LLD is similar to a loss of immune system of a living cell, when any microbe becomes fatal for it. The emerging discrete mode is normally very different from the rigid-bunch motion; thus the rigid-mode model significantly overestimates the LLD threshold. The power low of LLD predicted in Ref. [17] agrees with results of this paper. However, the numerical factor in that scaling low strongly depends on the bunch distribution function

  4. Branch Mode Selection during Early Lung Development

    PubMed Central

    Menshykau, Denis; Kraemer, Conradin; Iber, Dagmar

    2012-01-01

    Many organs of higher organisms, such as the vascular system, lung, kidney, pancreas, liver and glands, are heavily branched structures. The branching process during lung development has been studied in great detail and is remarkably stereotyped. The branched tree is generated by the sequential, non-random use of three geometrically simple modes of branching (domain branching, planar and orthogonal bifurcation). While many regulatory components and local interactions have been defined an integrated understanding of the regulatory network that controls the branching process is lacking. We have developed a deterministic, spatio-temporal differential-equation based model of the core signaling network that governs lung branching morphogenesis. The model focuses on the two key signaling factors that have been identified in experiments, fibroblast growth factor (FGF10) and sonic hedgehog (SHH) as well as the SHH receptor patched (Ptc). We show that the reported biochemical interactions give rise to a Schnakenberg-type Turing patterning mechanisms that allows us to reproduce experimental observations in wildtype and mutant mice. The kinetic parameters as well as the domain shape are based on experimental data where available. The developed model is robust to small absolute and large relative changes in the parameter values. At the same time there is a strong regulatory potential in that the switching between branching modes can be achieved by targeted changes in the parameter values. We note that the sequence of different branching events may also be the result of different growth speeds: fast growth triggers lateral branching while slow growth favours bifurcations in our model. We conclude that the FGF10-SHH-Ptc1 module is sufficient to generate pattern that correspond to the observed branching modes. PMID:22359491

  5. Branch mode selection during early lung development.

    PubMed

    Menshykau, Denis; Kraemer, Conradin; Iber, Dagmar

    2012-01-01

    Many organs of higher organisms, such as the vascular system, lung, kidney, pancreas, liver and glands, are heavily branched structures. The branching process during lung development has been studied in great detail and is remarkably stereotyped. The branched tree is generated by the sequential, non-random use of three geometrically simple modes of branching (domain branching, planar and orthogonal bifurcation). While many regulatory components and local interactions have been defined an integrated understanding of the regulatory network that controls the branching process is lacking. We have developed a deterministic, spatio-temporal differential-equation based model of the core signaling network that governs lung branching morphogenesis. The model focuses on the two key signaling factors that have been identified in experiments, fibroblast growth factor (FGF10) and sonic hedgehog (SHH) as well as the SHH receptor patched (Ptc). We show that the reported biochemical interactions give rise to a Schnakenberg-type Turing patterning mechanisms that allows us to reproduce experimental observations in wildtype and mutant mice. The kinetic parameters as well as the domain shape are based on experimental data where available. The developed model is robust to small absolute and large relative changes in the parameter values. At the same time there is a strong regulatory potential in that the switching between branching modes can be achieved by targeted changes in the parameter values. We note that the sequence of different branching events may also be the result of different growth speeds: fast growth triggers lateral branching while slow growth favours bifurcations in our model. We conclude that the FGF10-SHH-Ptc1 module is sufficient to generate pattern that correspond to the observed branching modes. PMID:22359491

  6. Global modes of flute instability of a rotating cylindrical plasma

    SciTech Connect

    Sorokina, E. A.

    2009-05-15

    The influence of rotation on the flute instability of a cylindrical gravitating plasma in a straight inhomogeneous magnetic field is studied in the framework of one-fluid magnetohydrodynamics. The dispersion relation and integral expression for the instability growth rate of eigenmodes are derived. It is shown that, in the framework of the given problem, rotation is a destabilizing factor, and the corresponding theorem is proved for the general case. For a linear radial profile of the rotation frequency, the structure of eigenmodes is calculated. The growth rate of these modes is shown to increase with increasing rotation velocity and azimuthal mode number. It is found that plasma rotation in the eigenmode localization region leads to the displacement of perturbation from the rotation region, which results in a decrease in the instability growth rate. The absence of eigenmodes (i.e., exponential instability of the system) for certain profiles of the density and rotation frequency is demonstrated.

  7. Head-Tail Modes for Strong Space Charge

    SciTech Connect

    Burov, Alexey

    2008-12-01

    Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.

  8. Response of potato to discontinuous exposures of atmospheric ethylene: results of a long-term experiment in open-top chambers and crop growth modelling

    NASA Astrophysics Data System (ADS)

    Dueck, Th. A.; Van Dijk, C. J.; Grashoff, C.; Groenwold, J.; Schapendonk, A. H. C. M.; Tonneijck, A. E. G.

    A field experiment in open-top chambers (OTCs) was performed to quantitatively assess the growth and yield response of potato to discontinuous exposures to atmospheric ethylene (200, 400 and 800 ppb, applied twice weekly and 200 and 400 ppb applied 4 times weekly, each for 3 h/event). To evaluate the effect of ethylene on potato tuber yield, a module was developed for an existing crop growth simulation model by incorporating the effects of ethylene on epinasty and photosynthesis. Explorations with the model showed that in a worst case scenario, ethylene-induced epinasty had only a marginal effect on tuber yield. Short-term exposures to ethylene under laboratory conditions inhibited photosynthesis, but it recovered within 48 h. When exposed to ethylene for longer than 12 h, irreversible damage of the photosynthesis apparatus occurred. Exposure to ethylene in the OTCs resulted in epinasty and reduced flowering. The number of flowers on potato decreased with increasing concentrations of ethylene, irrespective of the exposure frequency. Calculations showed that the number of flowers was significantly reduced at ca. 170 ppb ethylene, averaged over the hours of exposure. Ethylene concentrations up to 800 ppb, administered 4 times weekly for 3 h during the growing season, did not affect vegetative growth and yield in fumigated potatoes. Under these experimental conditions, the modified simulation model incorporating the effects of ethylene on epinasty and photosynthesis forecasts a 5% effect on tuber yield at concentrations of 1600 ppb. All results indicate that ethylene concentrations higher than 800 ppb are required to adversely affect tuber yield of potato.

  9. Effects of dietary vanadium on growth and lipid storage in a larval anuran: results from studies employing ad libitum and rationed feeding.

    PubMed

    Rowe, Christopher L; Heyes, Andrew; Hopkins, William

    2009-01-31

    Vanadium (V) exerts a variety of effects related to metabolic function in vertebrates, including modifying glycolytic pathways and lipid metabolism. However, little is known about toxicity of V to wildlife in natural systems. We conducted parallel, independent studies to evaluate the effect of dietary exposure to vanadium on survival, metabolism, growth, and lipid storage of larval leopard frogs (Rana sphenocephala). In one study ("Ad lib") larvae were fed unlimited food and in the other ("Ration") larvae were fed a restricted diet. Experimental diets contained 10 ppm dw V(total) (Control, "C"), 109 ppm (Low, "L"), and 363 ppm (High, "H"). In neither study did V affect metabolic rate or survival to forelimb emergence. However, in the Ration study, 31% of individuals in H that had initiated metamorphosis died prior to completion of metamorphosis, compared with 22% in M and 9% in C, however the difference was not significant at alpha=0.05. Mortality during metamorphosis in the Ad lib study was more variable, yet followed a similar trend (26, 14, and 12% mortality in H, L, and C). In both studies, individuals that died during the metamorphic period were smaller at the time of forelimb emergence than those that survived. In the Ration study, individuals in H also had significantly lower growth rates, delayed metamorphosis, and reduced lipid content at metamorphosis compared to C and L. Growth was not affected by V in the Ad lib study. Our results suggest that habitat contamination by V may present risks to amphibians during the metamorphic period attributable to energetic responses influencing size at the initiation of metamorphosis and body lipid stores. Furthermore, while we cannot make formal comparisons between the studies, our results imply that protocols that employ ad libitum feeding regimes could fail to capture the effects of contaminants as they may be expressed in natural situations in which resources are typically more limited.

  10. Hydrogen local vibrational modes in semiconductors

    SciTech Connect

    McCluskey, M D

    1997-06-01

    Following, a review of experimental techniques, theory, and previous work, the results of local vibrational mode (LVM) spectroscopy on hydrogen-related complexes in several different semiconductors are discussed. Hydrogen is introduced either by annealing in a hydrogen ambient. exposure to a hydrogen plasma, or during growth. The hydrogen passivates donors and acceptors in semiconductors, forming neutral complexes. When deuterium is substituted for hydrogen. the frequency of the LVM decreases by approximately the square root of two. By varying the temperature and pressure of the samples, the microscopic structures of hydrogen-related complexes are determined. For group II acceptor-hydrogen complexes in GaAs, InP, and GaP, hydrogen binds to the host anion in a bond-centered orientation, along the [111] direction, adjacent to the acceptor. The temperature dependent shift of the LVMs are proportional to the lattice thermal energy U(T), a consequence of anharmonic coupling between the LVM and acoustical phonons. In the wide band gap semiconductor ZnSe, epilayers grown by metalorganic chemical vapor phase epitaxy (MOCVD) and doped with As form As-H complexes. The hydrogen assumes a bond-centered orientation, adjacent to a host Zn. In AlSb, the DX centers Se and Te are passivated by hydrogen. The second, third, and fourth harmonics of the wag modes are observed. Although the Se-D complex has only one stretch mode, the Se-H stretch mode splits into three peaks. The anomalous splitting is explained by a new interaction between the stretch LVM and multi-phonon modes of the lattice. As the temperature or pressure is varied, and anti-crossing is observed between LVM and phonon modes.

  11. The effective degeneracy of protein normal modes.

    PubMed

    Na, Hyuntae; Song, Guang

    2016-01-01

    Normal modes are frequently computed and used to portray protein dynamics and interpret protein conformational changes. In this work, we investigate the nature of normal modes and find that the normal modes of proteins, especially those at the low frequency range (0-600 cm(-1)), are highly susceptible to degeneracy. Two or more modes are degenerate if they have the same frequency and consequently any orthogonal transformation of them also is a valid representation of the mode subspace. Thus, degenerate modes can no longer characterize unique directions of motions as regular modes do. Though the normal modes of proteins are usually of different frequencies, the difference in frequency between neighboring modes is so small that, under even slight structural uncertainty that unavoidably exists in structure determination, it can easily vanish and as a result, a mode becomes effectively degenerate with its neighboring modes. This can be easily observed in that some modes seem to disappear and their matching modes cannot be found when the structure used to compute the modes is modified only slightly. We term this degeneracy the effective degeneracy of normal modes. This work is built upon our recent discovery that the vibrational spectrum of globular proteins is universal. The high density of modes observed in the vibrational frequency spectra of proteins renders their normal modes highly susceptible to degeneracy, under even the smallest structural uncertainty. Indeed, we find the degree of degeneracy of modes is proportional to the density of modes in the vibrational spectrum. This means that for modes at the same frequency, degeneracy is more severe for larger proteins. Degeneracy exists also in the modes of coarse-grained models, but to a much lesser extent than those of all-atom models. In closing, we discuss the implications of the effective degeneracy of normal modes: how it may significantly affect the ways in which normal modes are used in various normal modes

  12. Genome‐scale analysis of the cotton KCS gene family revealed a binary mode of action for gibberellin A regulated fiber growth

    PubMed Central

    Xiao, Guang‐Hui; Wang, Kun; Huang, Gai

    2015-01-01

    Abstract Production of β‐ketoacyl‐CoA, which is catalyzed by 3‐ketoacyl‐CoA synthase (KCS), is the first step in very long chain fatty acid (VLCFA) biosynthesis. Here we identified 58 KCS genes from Gossypium hirsutum, 31 from G. arboreum and 33 from G. raimondii by searching the assembled cotton genomes. The gene family was divided into the plant‐specific FAE1‐type and the more general ELO‐type. KCS transcripts were widely expressed and 32 of them showed distinct subgenome‐specific expressions in one or more cotton tissues/organs studied. Six GhKCS genes rescued the lethality of elo2Δelo3Δ yeast double mutant, indicating that this gene family possesses diversified functions. Most KCS genes with GA‐responsive elements (GAREs) in the promoters were significantly upregulated by gibberellin A3 (GA). Exogenous GA3 not only promoted fiber length, but also increased the thickness of cell walls significantly. GAREs present also in the promoters of several cellulose synthase (CesA) genes required for cell wall biosynthesis and they were all induced significantly by GA3. Because GA treatment resulted in longer cotton fibers with thicker cell walls and higher dry weight per unit cell length, we suggest that it may regulate fiber elongation upstream of the VLCFA‐ethylene pathway and also in the downstream steps towards cell wall synthesis. PMID:26399709

  13. Fast particle destabilization of TAE modes

    SciTech Connect

    Cheng, C.Z.; Gorelenkov, N.N.; Hsu, C.T.

    1995-09-01

    High-n TAE modes are studied based on a kinetic model that includes full thermal ion finite Larmor radius effects, trapped electron collisions and fast particle instability drive. Lower KTAE modes are shown to be non-existent. Like TAE modes, upper KTAE modes are shown to exist due to thermal ion FLR effects in the dissipationless limit. Dissipation effects on the stability of both TAE and upper KTAE modes can be treated perturbatively. However, due to their extended mode structure in the ballooning space, upper KTAE modes usually remain stable or weakly unstable even with large fast particle free energy. On the other hand, TAE modes can be strongly destabilized. A new resonant TAE mode (RTAE) can be excited when the fast particle drive is significantly large. The RTAE mode is a beam-like mode with its frequency determined mainly by the wave-particle resonance condition. The frequency of the RTAE mode can be much less than the TAE gap frequency and may be interpreted as the BAE observed in DIII-D experiments. As plasma {beta} increases, the TAE, RTAE and kinetic ballooning modes strongly couple; the TAE mode changes into the RTAE mode and eventually connects to the kinetic ballooning mode. Numerical results and analytical analysis on the stability of the RTAE and KTAE modes will be presented and compared with the TAE mode stability.

  14. An investigation of fatigue crack propagation under mode 1 and mixed mode 1/2 loadings

    NASA Astrophysics Data System (ADS)

    Paul, Tapan Kumar

    An investigation on fatigue crack propagation under mode 1 and mixed mode (1 and 2) loadings has been performed. Fatigue crack growth data in the case of plane strain mode 1 have been obtained by performing experiments on compact tension specimens of 4340 steel for increasing Delta-K(sub 1), decreasing Delta-K(sub 1), and constant Delta-K(sub 1) loading conditions. Under mixed mode plane stress condition, the fatigue crack growth trajectory has been determined by performing experiments on the center cracked thin disk specimen of aluminum 2024. With two mixed mode loading ratios, the subsequent propagation of the main crack has been performed by producing a series of kinks and forks. For practical applications such as the case of a flaw or a crack in aircraft or ship structure in which the loading axis (with respect to the crack) frequently changes, a zig-zag or complicated crack trajectory is very important in both experimental and theoretical studies. In order to apply any specific crack growth criterion for the analysis of the experimental results, a detailed analysis for the stresses near the crack front and the extent of yielding is necessary. A full field solution, based on small deformation, three dimensional elastic-plastic finite element analysis of the centrally cracked thin disk under mode 1 loading has been performed. The solution for the stresses under small-scale yielding and locally fully plastic state has been compared with the HRR plane stress solution. At the outside of the three dimensional zone, within a distance of r sigma(sub 0)/J = 18, HRR dominance is maintained in the presence of a significant amount of compressive stress along the crack flanks. Ahead of this region, the HRR field overestimate the stresses. These results demonstrate a completely reversed state of stress in the near crack front compared to that in the plane strain case. The combined effect of geometry and finite thickness of the specimen on elastic-plastic crack tip stress

  15. Iron snow, crystal floats, and inner-core growth: modes of core solidification and implications for dynamos in terrestrial planets and moons

    NASA Astrophysics Data System (ADS)

    Breuer, Doris; Rueckriemen, Tina; Spohn, Tilman

    2015-12-01

    data further suggest core formation under reducing conditions that may have resulted in an Fe-S-Si composition, further complicating the core crystallization process. Mars, with its early and strong paleo-field, likely has not yet started to freeze out an inner iron core.

  16. Mode multi/demultiplexing with parallel waveguide for mode division multiplexed transmission.

    PubMed

    Hanzawa, Nobutomo; Saitoh, Kuimasa; Sakamoto, Taiji; Matsui, Takashi; Tsujikawa, Kyozo; Koshiba, Masanori; Yamamoto, Fumihiko

    2014-12-01

    We propose a planar lightwave circuit (PLC)-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The PLCb-ased mode MUX/DEMUX has advantage of selectively exciting higher-order mode. We realize three-mode (LP(01), LP(11)a, and LP(21)a) multiplexing by using an asymmetric parallel waveguide. We then design and fabricate a PLC-based mode MUX/DEMUX on one chip by using our proposed LP(11) mode rotator to allow us to utilize the LP(11)b mode. We successfully multiplex the LP(01), LP(11)a, and LP(11)b modes and achieve a relatively low insertion loss over the C-band using our fabricated mode MUX/DEMUX. Our results indicate that the PLC-based mode MUX/DEMUX with a uniform height has the potential to increase the mode number by using an LP(11)b mode.

  17. Simulation and design of feedback control on resistive wall modes in Keda Torus eXperiment

    SciTech Connect

    Li, Chenguang; Liu, Wandong; Li, Hong

    2014-12-15

    The feedback control of resistive wall modes (RWMs) in Keda Torus eXperiment (KTX) (Liu et al., Plasma Phys. Controlled Fusion 56, 094009 (2014)) is investigated by simulation. A linear model is built to describe the growth of the unstable modes in the absence of feedback and the resulting mode suppression due to feedback, given the typical reversed field pinch plasma equilibrium. The layout of KTX with two shell structures (the vacuum vessel and the stabilizing shell) is taken into account. The feedback performance is explored both in the scheme of “clean mode control” (Zanca et al., Nucl. Fusion 47, 1425 (2007)) and “raw mode control.” The discrete time control model with specific characteristic times will mimic the real feedback control action and lead to the favored control cycle. Moreover, the conceptual design of feedback control system is also presented, targeting on both RWMs and tearing modes.

  18. A current-driven electromagnetic mode in sheared and toroidal configurations

    NASA Astrophysics Data System (ADS)

    Pusztai, István; Catto, Peter J.; Parra, Felix I.; Barnes, Michael

    2014-03-01

    The induced electric field in a tokamak drives a parallel electron current flow. In an inhomogeneous, finite beta plasma, when this electron flow is comparable to the ion thermal speed, the Alfvén mode wave solutions of the electromagnetic gyrokinetic equation can become nearly purely growing kink modes. Using the new ‘low-flow’ version of the gyrokinetic code GS2 developed for momentum transport studies (Barnes et al 2013 Phys. Rev. Lett. 111 055005), we are able to model the effect of the induced parallel electric field on the electron distribution to study the destabilizing influence of current on stability. We identify high mode number kink modes in GS2 simulations and make comparisons to analytical theory in sheared magnetic geometry. We demonstrate reassuring agreement with analytical results both in terms of parametric dependences of mode frequencies and growth rates, and regarding the radial mode structure.

  19. Intercode comparison of gyrokinetic global electromagnetic modes

    NASA Astrophysics Data System (ADS)

    Görler, T.; Tronko, N.; Hornsby, W. A.; Bottino, A.; Kleiber, R.; Norscini, C.; Grandgirard, V.; Jenko, F.; Sonnendrücker, E.

    2016-07-01

    Aiming to fill a corresponding lack of sophisticated test cases for global electromagnetic gyrokinetic codes, a new hierarchical benchmark is proposed. Starting from established test sets with adiabatic electrons, fully gyrokinetic electrons, and electrostatic fluctuations are taken into account before finally studying the global electromagnetic micro-instabilities. Results from up to five codes involving representatives from different numerical approaches as particle-in-cell methods, Eulerian and Semi-Lagrangian are shown. By means of spectrally resolved growth rates and frequencies and mode structure comparisons, agreement can be confirmed on ion-gyro-radius scales, thus providing confidence in the correct implementation of the underlying equations.

  20. Circulating concentrations of insulin-like growth factor-I, insulin-like growth factor binding protein-3, genetic polymorphisms and mammographic density in premenopausal Mexican women: results from the ESMaestras cohort

    PubMed Central

    Rinaldi, S.; Biessy, C.; Hernandez, M; Lesueur, F.; dos-Santos-Silva, I.; Rice, M. S.; Lajous, M.; Lopez-Ridaura, R.; Torres-Mejía, G.; Romieu, I.

    2015-01-01

    The insulin-like growth factor (IGF) axis plays an essential role in the development of the mammary gland. High circulating levels of IGF-I and of its major binding protein IGFBP3 have been related with increased mammographic density in Caucasian premenopausal women. Some common single nucleotide polymorphisms (SNPs) in genes of the IGF pathway have also been suggested to play a role in mammographic density. We conducted a cross-sectional study nested within the large Mexican ESMaestras cohort, to investigate the relation between circulating levels of IGF-I, IGFBP-3, the IGF-I/IGFBP-3 ratio, five common SNPs in the IGF-1, IGFBP-3 and IGF-1R genes, and mammographic density in 593 premenopausal Mexican women. Mean age at mammogram was 43.1 (standard deviation–SD=3.7) years, and average body mass index (BMI) at recruitment was 28.5 kg/m2. Mean percent mammographic density was 36.5% (SD: 17.1), with mean dense tissue area of 48.3 (SD: 33.3) cm2. Mean IGF-I and IGFBP-3 concentrations were 15.33 (SD: 5.52) nmol/l and 114.96 (SD: 21.34) nmol/l, respectively. No significant associations were seen between percent density and biomarker concentrations but women with higher IGF-I and IGF-I/IGFBP-3 concentrations had lower absolute dense (ptrend =0.03 and 0.09, respectively) and non-dense tissue areas (ptrend <0.001 for both parameters). However, these associations were null after adjustment by BMI. SNPs in specific genes were associated with circulating levels of growth factors, but not with mammographic density features. These results do not support the hypothesis of a strong association between circulating levels of growth hormones and mammographic density in Mexican premenopausal women. PMID:24037648

  1. Circulating concentrations of insulin-like growth factor-I, insulin-like growth factor-binding protein-3, genetic polymorphisms and mammographic density in premenopausal Mexican women: results from the ESMaestras cohort.

    PubMed

    Rinaldi, S; Biessy, C; Hernandez, M; Lesueur, F; dos-Santos-Silva, I; Rice, M S; Lajous, M; Lopez-Ridaura, R; Torres-Mejía, G; Romieu, I

    2014-03-15

    The insulin-like growth factor (IGF) axis plays an essential role in the development of the mammary gland. High circulating levels of IGF-I and of its major binding protein IGFBP3 have been related with increased mammographic density in Caucasian premenopausal women. Some common single nucleotide polymorphisms (SNPs) in genes of the IGF pathway have also been suggested to play a role in mammographic density. We conducted a cross-sectional study nested within the large Mexican ESMaestras cohort to investigate the relation between circulating levels of IGF-I, IGFBP-3, the IGF-I/IGFBP-3 ratio, five common SNPs in the IGF-1, IGFBP-3 and IGF-1R genes and mammographic density in 593 premenopausal Mexican women. Mean age at mammogram was 43.1 (standard deviation, SD = 3.7) years, and average body mass index (BMI) at recruitment was 28.5 kg/m(2). Mean percent mammographic density was 36.5% (SD: 17.1), with mean dense tissue area of 48.3 (SD: 33.3) cm(2) . Mean IGF-I and IGFBP-3 concentrations were 15.33 (SD: 5.52) nmol/l and 114.96 (SD: 21.34) nmol/l, respectively. No significant associations were seen between percent density and biomarker concentrations, but women with higher IGF-I and IGF-I/IGFBP-3 concentrations had lower absolute dense (p(trend) = 0.03 and 0.09, respectively) and nondense tissue areas (p(trend) < 0.001 for both parameters). However, these associations were null after adjustment by BMI. SNPs in specific genes were associated with circulating levels of growth factors, but not with mammographic density features. These results do not support the hypothesis of a strong association between circulating levels of growth hormones and mammographic density in Mexican premenopausal women.

  2. Peginterferon for Chronic Hepatitis C in Children affects Growth and Body Composition: Results from the Pediatric Study of Hepatitis C (PEDS-C) Trial

    PubMed Central

    Jonas, Maureen M.; Balistreri, William; Gonzalez-Peralta, Regino P.; Haber, Barbara; Lobritto, Steven; Mohan, Parvathi; Molleston, Jean P.; Murray, Karen F.; Narkewicz, Michael R.; Rosenthal, Philip; Schwarz, Kathleen B.; Barton, Bruce A.; Shepherd, John A.; Mitchell, Paul D.; Duggan, Christopher

    2012-01-01

    Background Weight loss and changes in growth are noted in children treated with interferonα Objectives To prospectively determine changes in weight, height, body mass index and body composition during and after treatment of children with hepatitis C. Methods Children treated with PEG-IFNα2a +/− ribavirin in the PEDS-C trial underwent anthropometric measurements, DXA scan, dietary and activity assessments during and after treatment. Results 114 (55% male) children mean age 11±3 years were randomized, and 107 received treatment for at least 24 weeks. Subjects were divided into 3 groups according to duration of treatment: 24 (N=14), 48 (N=82), or 72 (N=11) weeks. Decrements of up to 0.50 z score were observed for weight, height and BMI while on therapy among all groups (P≤0.01 compared to baseline). In the group treated for 48 weeks, 29 (33%) subjects had greater than 0.5 unit decrement in height-for-age Z score. While weight-for-age and BMI z scores returned to baseline after cessation of therapy, mean HAZ score was slower to rebound, still lower than baseline at 96 weeks post-therapy for the long treatment duration group (P=0.03) and lower than baseline in most children treated for 48 weeks. Percent body fat, fat-free mass z scores and triceps skinfold z scores decreased with therapy. Dietary energy intake and levels of physical activity did not change during treatment. Conclusions PEG-IFNα2a was associated with significant changes in body weight, linear growth, body mass index and body composition in children. These effects were generally reversible with cessation of therapy, although height-for-age z scores had not returned to baseline after 2 years of observation in many. Longer term growth data are needed among children treated for chronic HCV. PMID:22383118

  3. Early Pleistocene onset of Trough-Mouth Fan (TMF) growth on the NW Barents Sea margin: new results based on seismic reflection data

    NASA Astrophysics Data System (ADS)

    Rebesco, Michele; Sverre Laberg, Jan; Pedrosa Gonzalez, Maria Teresa; Camerlenghi, Angelo; Giulia Lucchi, Renata

    2013-04-01

    Among the seismic reflection data acquired within the IPY NICE-STREAM activity (the Spanish SVAIS cruise on board BIO Hespérides in summer 2007 and the Italian EGLACOM cruise on board R/V OGS-Explora in summer 2008), a series of multi-channel profiles provides a nearly 400 km long continuous tie between Ocean Drilling Program Site 986 (offshore Svalbard) and the Kveithola Trough deposits (on the continental shelf just NW of the Bear Island). This tie crosses in strike direction (subparallel to the shelf edge) three TMFs: Bellsund, Hornsund and Storfjorden. Beyond their tie function, these profiles allow us to analyze the characteristics of these TMFs. The seismic units below reflector R4A are relatively uniform in thickness all along the profile, notwithstanding a general northward thinning trend. Conversely, thickening within TMFs is evident essentially only above this reflector. This suggests that for these TMFs the growth appears to have started after the formation of reflection R4A. Thus, the reflection (with an estimated age of about 1.3 Ma) lies in a stratigraphic interval that is recognized as pivotal for the glaciation of the area and the development of the margin. We suggest that it is the reflector that best correspond to the onset of the TMF growth and hence to the onset of the most significant phase of glacial development of the western Barents Sea continental margin. This inference is consistent with a recent finding that contourites produced by deposition of sediments suspended within alongslope bottom currents on the same margin start to develop in correspondence with the same reflector. The availability of suspended sediments for these contourites since Early Pleistocene is ascribed to originate from frequent episodes of small-scale mass-wasting events produced during TMS growth and resulting in more favourable depositional conditions for the Isfjorden and Bellsund contourite drifts.

  4. Crossflow effects on the growth rate of inviscid Goertler vortices in a hypersonic boundary layer

    NASA Technical Reports Server (NTRS)

    Fu, Yibin; Hall, Philip

    1992-01-01

    The effects of crossflow on the growth rate of inviscid Goertler vortices in a hypersonic boundary layer with pressure gradient are studied. Attention is focused on the inviscid mode trapped in the temperature adjustment layer; this mode has greater growth rate than any other mode. The eigenvalue problem which governs the relationship between the growth rate, the crossflow amplitude, and the wavenumber is solved numerically, and the results are then used to clarify the effects of crossflow on the growth rate of inviscid Goertler vortices. It is shown that crossflow effects on Goertler vortices are fundamentally different for incompressible and hypersonic flows. The neutral mode eigenvalue problem is found to have an exact solution, and as a by-product, we have also found the exact solution to a neutral mode eigenvalue problem which was formulated, but unsolved before, by Bassom and Hall (1991).

  5. Prediction of delamination growth under cyclic loading

    SciTech Connect

    Krueger, R.; Koenig, M.

    1997-12-31

    The growth of delaminations in carbon fiber-reinforced epoxy (CFRE) specimens during R = 0.1 and R = {minus}1 fatigue loading has been studied. Artificial circular and square delaminations as well as ply cuts have been introduced at various interfaces during manufacturing to simulate a pre-damaged structure and to cause delamination growth. Criteria based on fracture mechanics will be used to describe the delamination failure. Predicting delamination growth with this approach requires the distribution of the local energy release rate along the delamination front. For obtaining this energy release rate distribution, the virtual crack closure method was found to be most favorable for three-dimensional finite element analysis as the separation of the total energy release rate into the contributing modes is inherent to the method and only one complete finite element analysis is necessary. Plots of measured delamination progression per load cycle (da/dN-values) versus computed energy release rates have been included in a Paris law diagram as obtained experimentally using double cantilever beam (DCB) specimens to characterize Mode 1 and end-notched flexure (ENF) and transverse crack tension (TCT) specimens to characterize Mode 2 failure, respectively. Computed mixed-mode results lie well within the scatter band of the experimentally determined Paris law for Mode 1 and Mode 2 failure.

  6. Abrogation of upstream open reading frame-mediated translational control of a plant S-adenosylmethionine decarboxylase results in polyamine disruption and growth perturbations.

    PubMed

    Hanfrey, Colin; Franceschetti, Marina; Mayer, Melinda J; Illingworth, Crista; Michael, Anthony J

    2002-11-15

    S-Adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in polyamine biosynthesis. We show that the plant AdoMetDC activity is subject to post-transcriptional control by polyamines. A highly conserved small upstream open reading frame (uORF) in the AdoMetDC mRNA 5' leader is responsible for translational repression of a downstream beta-glucuronidase reporter cistron in transgenic tobacco plants. Elimination of the small uORF from an AdoMetDC cDNA led to increased relative translational efficiency of the AdoMetDC proenzyme in transgenic plants. The resulting increased activity of AdoMetDC caused disruption to polyamine levels with depletion of putrescine, reduction of spermine levels, and a more than 400-fold increase in the level of decarboxylated S-adenosylmethionine. These changes were associated with severe growth and developmental defects. The high level of decarboxylated S-adenosylmethionine was not associated with any change in 5'-methylcytosine content in genomic DNA and S-adenosylmethionine levels were more or less normal, indicating a highly efficient system for maintenance of S-adenosylmethionine levels in plants. This work demonstrates that uORF-mediated translational control of AdoMetDC is essential for polyamine homeostasis and for normal growth and development.

  7. Dependence of mode I and mixed mode I/III fracture toughness on temperature for a ferritic/martensitic stainless steel

    SciTech Connect

    Li, H.; Jones, R.H.; Gelles, D.S.

    1995-04-01

    The objective is to investigate the dependence of mode I and mixed mode I/III fracture toughness on temperature in the range of {minus}95{degrees}C to 25{degrees}C for a low activation ferritic/martensitic stainless steel (F82-H). Mode I and mixed Mode I/III fracture toughnesses were investigated in the range of {minus}95 to 25{degree}C for a F82-H steel heat-treated in the following way; 1000{degree}C/20 h/air-cooled (AC), 1100{degree}C/7 min/AC, and 700{degree}C/2 h/AC. The results indicate that crack tip plasticity was increased by mixed mode loading, and suggest that at low temperature, mode I fracture toughness is the critical design parameter, but at temperatures above room temperature, expecially concerning fatigure and creep-fatigue crack growth rate, a mixed mode loading may be more harmful than a mode I loading for this steel because a mixed mode loading results in lower fracture toughness and higher crack tip plasticity (or dislocation activity).

  8. Collisionless drift-tearing modes in the magnetopause

    NASA Technical Reports Server (NTRS)

    Gladd, N. T.

    1990-01-01

    The linear stability properties of collisionless drift-tearing modes are analyzed in a modified Harris equilibrium model of the magnetopause. Particular attention is paid to the relevance of the parametric behavior of growth rates to the 'magnetic percolation' theory of flux transfer event formation (Galeev et al., 1986). Numerical methods are used to solve the drift-tearing eigenmode equations and the results are compared with those previously obtained by analytical methods. The analytical results are found to correctly model important parametric dependencies but to typically overestimate the rate of growth. The eigenmode equations are numerically difficult, and an integration scheme utilizing Ricatti transforms is developed to affect their solution.

  9. The effect of mixed mode precracking on the mode 1 fracture toughness of composite laminates

    NASA Technical Reports Server (NTRS)

    Shankar, Prashanth; Bascom, Williard D.; Nairn, John A.

    1993-01-01

    We subjected double cantilever beam specimens from four different composite materials to mixed-mode precracking. Three different precracking mode 1 to mode 2 ratios were used--1 to 4, 1 to 1, and 4 to 1. Following precracking the specimens were tested for mode I fracture toughness. The mixed-mode precracking often influenced the mode 1 toughness and its influence persisted for as much as 60 mm of mode 1 crack growth. We tested composites with untoughened matrices, composites with rubber-toughened matrices, and composites with interlayer toughening. Depending on material type and precracking mode ratio, the precracking could cause either a significant increase or a significant decrease in the mode 1 fracture toughness.

  10. Characterization of mode 1 and mixed-mode failure of adhesive bonds between composite adherends

    NASA Technical Reports Server (NTRS)

    Mall, S.; Johnson, W. S.

    1985-01-01

    A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

  11. Characterization of mode I and mixed-mode failure of adhesive bonds between composite adherends

    NASA Technical Reports Server (NTRS)

    Mall, S.; Johnson, W. S.

    1986-01-01

    A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue beyond growth mechanism under mode 1 and mixed-mode 1 and 2 loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: a double-cantilever-beam specimen for mode 1 loading and a cracked-lapshear specimen for mixed-mode 1 and 2 loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under mixed-mode 1 and 2 loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under mode 1 loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.

  12. Insulin-like growth factor I and risk of epithelial invasive ovarian cancer by tumour characteristics: results from the EPIC cohort

    PubMed Central

    Ose, J; Fortner, R T; Schock, H; Peeters, P H; Onland-Moret, N C; Bueno-de-Mesquita, H B; Weiderpass, E; Gram, I T; Overvad, K; Tjonneland, A; Dossus, L; Fournier, A; Baglietto, L; Trichopoulou, A; Benetou, V; Trichopoulos, D; Boeing, H; Masala, G; Krogh, V; Matiello, A; Tumino, R; Popovic, M; Obón-Santacana, M; Larrañaga, N; Ardanaz, E; Sánchez, M-J; Menéndez, V; Chirlaque, M-D; Travis, R C; Khaw, K-T; Brändstedt, J; Idahl, A; Lundin, E; Rinaldi, S; Kuhn, E; Romieu, I; Gunter, M J; Merritt, M A; Riboli, E; Kaaks, R

    2015-01-01

    Background: Prospective studies on insulin-like growth factor I (IGF-I) and epithelial ovarian cancer (EOC) risk are inconclusive. Data suggest risk associations vary by tumour characteristics. Methods: We conducted a nested case–control study in the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate IGF-I concentrations and EOC risk by tumour characteristics (n=565 cases). Multivariable conditional logistic regression models were used to estimate associations. Results: We observed no association between IGF-I and EOC overall or by tumour characteristics. Conclusions: In the largest prospective study to date was no association between IGF-I and EOC risk. Pre-diagnostic serum IGF-I concentrations may not influence EOC risk. PMID:25349976

  13. Facing rim cavities fluctuation modes

    NASA Astrophysics Data System (ADS)

    Casalino, Damiano; Ribeiro, André F. P.; Fares, Ehab

    2014-06-01

    Cavity modes taking place in the rims of two opposite wheels are investigated through Lattice-Boltzmann CFD simulations. Based on previous observations carried out by the authors during the BANC-II/LAGOON landing gear aeroacoustic study, a resonance mode can take place in the volume between the wheels of a two-wheel landing gear, involving a coupling between shear-layer vortical fluctuations and acoustic modes resulting from the combination of round cavity modes and wheel-to-wheel transversal acoustic modes. As a result, side force fluctuations and tonal noise side radiation take place. A parametric study of the cavity mode properties is carried out in the present work by varying the distance between the wheels. Moreover, the effects due to the presence of the axle are investigated by removing the axle from the two-wheel assembly. The azimuthal properties of the modes are scrutinized by filtering the unsteady flow in narrow bands around the tonal frequencies and investigating the azimuthal structure of the filtered fluctuation modes. Estimation of the tone frequencies with an ad hoc proposed analytical formula confirms the observed modal properties of the filtered unsteady flow solutions. The present study constitutes a primary step in the description of facing rim cavity modes as a possible source of landing gear tonal noise.

  14. A deficiency in the flavoprotein of Arabidopsis mitochondrial complex II results in elevated photosynthesis and better growth in nitrogen-limiting conditions.

    PubMed

    Fuentes, Daniela; Meneses, Marco; Nunes-Nesi, Adriano; Araújo, Wagner L; Tapia, Rodrigo; Gómez, Isabel; Holuigue, Loreto; Gutiérrez, Rodrigo A; Fernie, Alisdair R; Jordana, Xavier

    2011-11-01

    Mitochondrial complex II (succinate dehydrogenase [SDH]) plays roles both in the tricarboxylic acid cycle and the respiratory electron transport chain. In Arabidopsis (Arabidopsis thaliana), its flavoprotein subunit is encoded by two nuclear genes, SDH1-1 and SDH1-2. Here, we characterize heterozygous SDH1-1/sdh1-1 mutant plants displaying a 30% reduction in SDH activity as well as partially silenced plants obtained by RNA interference. We found that these plants displayed significantly higher CO(2) assimilation rates and enhanced growth than wild-type plants. There was a strong correlation between CO(2) assimilation and stomatal conductance, and both mutant and silenced plants displayed increased stomatal aperture and density. By contrast, no significant differences were found for dark respiration, chloroplastic electron transport rate, CO(2) uptake at saturating concentrations of CO(2), or biochemical parameters such as the maximum rates of carboxylation by Rubisco and of photosynthetic electron transport. Thus, photosynthesis is enhanced in SDH-deficient plants by a mechanism involving a specific effect on stomatal function that results in improved CO(2) uptake. Metabolic and transcript profiling revealed that mild deficiency in SDH results in limited effects on metabolism and gene expression, and data suggest that decreases observed in the levels of some amino acids were due to a higher flux to proteins and other nitrogen-containing compounds to support increased growth. Strikingly, SDH1-1/sdh1-1 seedlings grew considerably better in nitrogen-limiting conditions. Thus, a subtle metabolic alteration may lead to changes in important functions such as stomatal function and nitrogen assimilation.

  15. Effect of plasma motion on tearing modes in cylindrical plasmas

    NASA Astrophysics Data System (ADS)

    Xu, J. Q.; Peng, X. D.

    2015-10-01

    The effect of equilibrium plasma motion on the resistive m/n = 2/1 tearing mode (TM) in low β plasmas is investigated in cylindrical geometry (with m and n being poloidal and toroidal mode numbers). Without equilibrium plasma motion but with viscosity, the TM stability is mainly determined by the Reynolds number S and reaches maximum near S = 104, which is consistent with previous findings. The poloidal plasma rotation has stabilizing effect on TM; however, the rotation shear has destabilization effect in the low viscosity regime. The axial plasma motion has strong stabilizing effect on TM in the low viscosity regime for Prandtl number Pr < 1, while its shear has slight stabilizing effect with the decrease of growth rate less than 15%. When the axial velocity becomes large enough, the mode frequency tends to be independent of the Prandtl number. In the presence of parallel plasma motion, the growth rate is determined by the axial component at low parallel velocity, while determined by poloidal component at large parallel velocity. The parallel plasma motion drives the TM rotating in the opposite direction. It is shown that the equilibrium motion reduces the growth rate of TM by changing the phase difference and coupling coefficient between potential perturbation and magnetic flux perturbation (deviating from π/2 ), which results in a lower mode frequency. Compared to the role of velocity shear, the magnitude of plasma velocity itself at the m/n = 2/1 rational surface is dominant in determining the TM characteristics.

  16. The coupled dipole modes of the NLC accelerator structure

    SciTech Connect

    Bane, K.L.F.; Gluckstern, R.; Holtkamp, N.

    1992-03-01

    The proposed accelerator cavity of the Next Linear Collider (NLC) is a disk-loaded structure composed of 200 cells, operating at 11.42 GHz. The proposed mode of operation is to accelerate bunches in trains of 10, with a bunch spacing of 42 cm. One problem is that one bunch in a train can excite transverse wakefields in the accelerator cavity which, in turn, can deflect following bunches and result in emittance growth. A method of curing this problem is to detune the transverse modes of the cavity. Beam dynamics simulations for the NLC have shown that by keeping the transverse wakefield at the positions of the nine trailing bunches at or below 1 MW/nC/m{sup 2} we can void emittance growth. Earlier, approximate calculations of the wakefields, which did not include the cell-to-cell coupling of the modes, have shown that by the proper Gaussian detuning the above level of cancellation can be achieved. A specific goal of this report is to see if this conclusion still holds when coupling is included in the calculation. Note that in this paper we focus on the modes belonging to the first dipole passband, which are the most important. A special feature of these modes in the detuned NLC cavity is that the cell-to-cell coupling changes sign somewhere in the middle of the structure.

  17. Simulations of overstable inertial-acoustic modes in black hole accretion discs

    NASA Astrophysics Data System (ADS)

    Fu, Wen; Lai, Dong

    2013-06-01

    We present two-dimensional inviscid hydrodynamic simulations of overstable inertial-acoustic oscillation modes (p modes) in black hole accretion discs. These global spiral waves are trapped in the innermost region of the disc, and are driven overstable by wave absorption at the corotation resonance (rc) when the gradient of the background disc vortensity (vorticity divided by surface density) at rc is positive and the disc inner boundary is sufficiently reflective. Previous linear calculations have shown that the growth rates of these modes can be as high as 10 per cent of the rotation frequency at the disc inner edge. We confirm these linear growth rates and the primary disc oscillation frequencies in our simulations when the mode amplitude undergoes exponential growth. We show that the mode growth saturates when the radial velocity perturbation becomes comparable to the disc sound speed. During the saturation stage, the primary disc oscillation frequency differs only slightly (by less than a few per cent) from the linear mode frequency. Sharp features in the fluid velocity profiles at this stage suggest that the saturation results from non-linear wave steepening and shock dissipation.

  18. Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

    NASA Astrophysics Data System (ADS)

    Tang, T. F.; Xu, X. Q.; Ma, C. H.; Bass, E. M.; Holland, C.; Candy, J.

    2016-03-01

    A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan based on "Cyclone base case parameter set." We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.

  19. Dynamic Instability of Barlike Modes

    NASA Astrophysics Data System (ADS)

    Durisen, Richard H.; Pickett, Brian K.; Bate, Matthew R.; Imamura, James N.; Brandl, Andreas; Sterzik, Michael F.

    Numerical simulations during the 1980's established that prompt binary formation (or ``fission'') through dynamic growth of barlike modes is aborted by gravitational torques. Because these instabilities may occur during star formation and because their outcome over long times is still uncertain, we have combined various linear analyses with simulations by hydrodynamics codes to refine our understanding. We show that it is in fact the torques which cause nonlinear saturation of the mode amplitude. Excellent agreement for the early nonlinear phase is obtained using radically different hydrodynamics codes. However, the ultimate outcome is sensitive to assumptions about dissipative heating and is also somewhat code-dependent.

  20. Mode conversion in ITER

    NASA Astrophysics Data System (ADS)

    Jaeger, E. F.; Berry, L. A.; Myra, J. R.

    2006-10-01

    Fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) can convert to much shorter wavelength modes such as ion Bernstein waves (IBW) and ion cyclotron waves (ICW) [1]. These modes are potentially useful for plasma control through the generation of localized currents and sheared flows. As part of the SciDAC Center for Simulation of Wave-Plasma Interactions project, the AORSA global-wave solver [2] has been ported to the new, dual-core Cray XT-3 (Jaguar) at ORNL where it demonstrates excellent scaling with the number of processors. Preliminary calculations using 4096 processors have allowed the first full-wave simulations of mode conversion in ITER. Mode conversion from the fast wave to the ICW is observed in mixtures of deuterium, tritium and helium3 at 53 MHz. The resulting flow velocity and electric field shear will be calculated. [1] F.W. Perkins, Nucl. Fusion 17, 1197 (1977). [2] E.F. Jaeger, L.A. Berry, J.R. Myra, et al., Phys. Rev. Lett. 90, 195001-1 (2003).

  1. Effect of density gradients in confined supersonic shear layers. Part 2: 3-D modes

    NASA Technical Reports Server (NTRS)

    Peroomian, Oshin; Kelly, R. E.

    1994-01-01

    The effect of basic flow density gradients on the supersonic wall modes were investigated in Part 1 of this analysis. In that investigation only the 2-D modes were studied. Tam and Hu investigated the 3-D modes in a confined vortex sheet and reported that the first 2-D Class A mode (A01) had the highest growth rate compared to all other 2-D and 3-D modes present in the vortex sheet for that particular set of flow patterns. They also showed that this result also held true for finite thickness shear layers with delta(sub w) less than 0.125. For free shear layers, Sandham and Reynolds showed that the 3-D K-H mode became the dominant mode for M(sub c) greater than 0.6. Jackson and Grosch investigated the effect of crossflow and obliqueness on the slow and fast odes present in a M(sub c) greater than 1 environment and showed that for certain combination of crossflow and wave angles the growth rates could be increased by up to a factor of 2 with respect to the 2-D case. The case studied here is a confined shear layer shown in Part 1. All solution procedures and basic low profiles are the same as in Part 1. The effect of density gradients on the 3-D modes present in the density ratios considered in Part 1 are investigated.

  2. Spanwise bifurcations beneath the bluff-body instability modes

    NASA Astrophysics Data System (ADS)

    Sau, Amalendu; Peng, Y. F.; Hwang, R. R.

    2016-06-01

    A new family of bifurcations is detected in a cylinder wake. The simulations reveal the presence of physically significant spanwise wavy flow undulation in the near-wake of a square cylinder which plays an important role in the modal transition. The alternate process of vortex shedding initiates a systematic cross-stream momentum transfer that activates self-sustained spanwise oscillation of the physical wake, leading to the growth of sequence of Hopf bifurcations along the topological cores of von Kármán vortices. The study exhibits how exactly such self-excited spanwise oscillatory fluctuations of pressure, velocity, and KE keep growing along a vortex-core for increased Re and distinctly influence the growth of "Mode A" and "Mode B" instability. It reports existence of two distinct stages of wake undulation over 125 ≤ Re ≤ 240. While the weakly subcritical spanwise-periodic oscillations of pressure, velocity, vorticity, and associated uniform and wider length-scale bifurcations along the von Kármán vortex corelines dominate during "Mode A" instability, the transition to the "Mode B" is prompted following faster and random eruption (and swapping) of significantly smaller but variable length-scaled bifurcations and accompanied low frequency non-uniform fluctuation of flow variables. Such unstable flow perturbations and resulting bifurcations along the von Kármán vortex cores apparently influence generation of longitudinal vortical ribs (Mode A and Mode B) in the wake. The appearance of a slow varying secondary frequency at the bifurcation points seemed crucial for initiating the spanwise flow irregularity and transition to "Mode B."

  3. Deficiency of maize starch-branching enzyme i results in altered starch fine structure, decreased digestibility and reduced coleoptile growth during germination

    PubMed Central

    2011-01-01

    Background Two distinct starch branching enzyme (SBE) isoforms predate the divergence of monocots and dicots and have been conserved in plants since then. This strongly suggests that both SBEI and SBEII provide unique selective advantages to plants. However, no phenotype for the SBEI mutation, sbe1a, had been previously observed. To explore this incongruity the objective of the present work was to characterize functional and molecular phenotypes of both sbe1a and wild-type (Wt) in the W64A maize inbred line. Results Endosperm starch granules from the sbe1a mutant were more resistant to digestion by pancreatic α-amylase, and the sbe1a mutant starch had an altered branching pattern for amylopectin and amylose. When kernels were germinated, the sbe1a mutant was associated with shorter coleoptile length and higher residual starch content, suggesting that less efficient starch utilization may have impaired growth during germination. Conclusions The present report documents for the first time a molecular phenotype due to the absence of SBEI, and suggests strongly that it is associated with altered physiological function of the starch in vivo. We believe that these results provide a plausible rationale for the conservation of SBEI in plants in both monocots and dicots, as greater seedling vigor would provide an important survival advantage when resources are limited. PMID:21599988

  4. Early versus delayed minimal enteral feeding and risk for necrotizing enterocolitis in preterm growth-restricted infants with abnormal antenatal Doppler results.

    PubMed

    Karagianni, Paraskevi; Briana, Despina D; Mitsiakos, George; Elias, Anestis; Theodoridis, Theodoros; Chatziioannidis, Elias; Kyriakidou, Maria; Nikolaidis, Nikolaos

    2010-05-01

    We studied the effect of early (< or = 5 days) versus delayed (> or = 6 days) initiation of minimal enteral feeding (MEF) on the incidence of necrotizing enterocolitis (NEC) and feeding intolerance in preterm infants with intrauterine growth restriction (IUGR) and abnormal antenatal Doppler results. We performed a randomized, nonblinded pilot trial of infants receiving early or delayed MEF in addition to parenteral feeding within 48 hours of life. Demographic data, maternal preeclampsia, antenatal steroid exposure, Doppler studies, as well as cases of NEC and feeding intolerance were all recorded. Of the 84 infants enrolled, 81 completed the study: 40 received early (median age: 2 days, range: 1 to 5 days) and 41 delayed (median age: 7 days, range: 6 to 14 days) MEF. The incidence of NEC and feeding intolerance was not significantly different between groups (p = 0.353 and p = 0.533, respectively). Birth weight was an independent risk factor for NEC in both groups. Early MEF of preterm infants with IUGR and abnormal antenatal Doppler results may not have a significant effect on the incidence of NEC or feeding intolerance. Furthermore, birth weight seems to be an independent risk factor for the development of NEC, irrespectively of the timing of MEF introduction.

  5. Electrically controlled optical-mode switch for fundamental mode and first order mode

    NASA Astrophysics Data System (ADS)

    Imansyah, Ryan; Tanaka, Tatsushi; Himbele, Luke; Jiang, Haisong; Hamamoto, Kiichi

    2016-08-01

    We have proposed an optical mode switch, the principle of which is based on the partial phase shift of injected light; therefore, one important issue is to clarify the proper design criteria for the mode combiner section. We focused on the bending radius of the S-bend waveguide issue that is connected to the multi mode waveguide in the Y-junction section that acts as mode combiner. Long radius leads to undesired mode coupling before the Y-junction section, whereas a short radius causes radiation loss. Thus, we simulated this mode combiner by the beam-propagation method to obtain the proper radius. In addition, we used a trench pin structure to simplify the fabrication process into a single-step dry-etching process. As a result, we successfully fabricated an optical-mode switch with the bending radius R = 610 µm. It showed the successful electrical mode switching and the achieved mode crosstalk was approximately -10 dB for 1550 nm wavelength with the injection current of 60 mA (5.7 V).

  6. Electrically controlled optical-mode switch for fundamental mode and first order mode

    NASA Astrophysics Data System (ADS)

    Imansyah, Ryan; Tanaka, Tatsushi; Himbele, Luke; Jiang, Haisong; Hamamoto, Kiichi

    2016-08-01

    We have proposed an optical mode switch, the principle of which is based on the partial phase shift of injected light; therefore, one important issue is to clarify the proper design criteria for the mode combiner section. We focused on the bending radius of the S-bend waveguide issue that is connected to the multi mode waveguide in the Y-junction section that acts as mode combiner. Long radius leads to undesired mode coupling before the Y-junction section, whereas a short radius causes radiation loss. Thus, we simulated this mode combiner by the beam-propagation method to obtain the proper radius. In addition, we used a trench pin structure to simplify the fabrication process into a single-step dry-etching process. As a result, we successfully fabricated an optical-mode switch with the bending radius R = 610 µm. It showed the successful electrical mode switching and the achieved mode crosstalk was approximately ‑10 dB for 1550 nm wavelength with the injection current of 60 mA (5.7 V).

  7. Normal Modes of Black Hole Accretion Disks

    SciTech Connect

    Ortega-Rodriguez, Manuel; Silbergleit, Alexander S.; Wagoner, Robert V.; /Stanford U., Phys. Dept. /KIPAC, Menlo Park

    2006-11-07

    This paper studies the hydrodynamical problem of normal modes of small adiabatic oscillations of relativistic barotropic thin accretion disks around black holes (and compact weakly magnetic neutron stars). Employing WKB techniques, we obtain the eigen frequencies and eigenfunctions of the modes for different values of the mass and angular momentum of the central black hole. We discuss the properties of the various types of modes and examine the role of viscosity, as it appears to render some of the modes unstable to rapid growth.

  8. On recent results in the modelling of neoclassical-tearing-mode stabilization via electron cyclotron current drive and their impact on the design of the upper EC launcher for ITER

    NASA Astrophysics Data System (ADS)

    Poli, E.; Angioni, C.; Casson, F. J.; Farina, D.; Figini, L.; Goodman, T. P.; Maj, O.; Sauter, O.; Weber, H.; Zohm, H.; Saibene, G.; Henderson, M. A.

    2015-01-01

    Electron cyclotron wave beams injected from a launcher placed in the upper part of the vessel will be used in ITER to control MHD instabilities, in particular neoclassical tearing modes (NTMs). Simplified NTM stabilization criteria have been used in the past to guide the optimization of the launcher. Their derivation is reviewed in this paper and their range of applicability clarified. Moreover, possible effects leading to a deterioration of the predicted performance are discussed. Particularly critical in this context is the broadening of the electron-cyclotron (EC) deposition profiles. It is argued that the most detrimental effect for ITER is likely to be the scattering of the EC beams from density fluctuations due to plasma turbulence, resulting in a beam broadening by about a factor of two. The combined impact of these effects with that of beam misalignment (with respect to the targeted surface) is investigated by solving the Rutherford equation in a form that retains the most relevant terms. The perspectives for NTM stabilization in the Q = 10 ITER scenario are discussed.

  9. Criterion for mixed mode fracture in composite bonded joints

    NASA Technical Reports Server (NTRS)

    Mall, S.; Kochhar, N. K.

    1986-01-01

    A study was undertaken to characterize the debond growth mechanism of adhesively bonded composite joints under mode I, mixed mode I-II, and mode II static loadings. The bonded system consisted of graphite/epoxy (T300/5208) composite adherends bonded with a toughened epoxy (EC 3445) adhesive. The mode I, mode II and mixed-mode I-II fracture energies of the tested adhesive were found to be equal to each other. Furthermore, the criterion for mixed mode fracture in composite bonded joints was determined.

  10. The quest for the solar g modes

    NASA Astrophysics Data System (ADS)

    Appourchaux, T.; Belkacem, K.; Broomhall, A.-M.; Chaplin, W. J.; Gough, D. O.; Houdek, G.; Provost, J.; Baudin, F.; Boumier, P.; Elsworth, Y.; García, R. A.; Andersen, B. N.; Finsterle, W.; Fröhlich, C.; Gabriel, A.; Grec, G.; Jiménez, A.; Kosovichev, A.; Sekii, T.; Toutain, T.; Turck-Chièze, S.

    2010-02-01

    Solar gravity modes (or g modes)—oscillations of the solar interior on which buoyancy acts as the restoring force—have the potential to provide unprecedented inference on the structure and dynamics of the solar core, inference that is not possible with the well-observed acoustic modes (or p modes). The relative high amplitude of the g-mode eigenfunctions in the core and the evanesence of the modes in the convection zone make the modes particularly sensitive to the physical and dynamical conditions in the core. Owing to the existence of the convection zone, the g modes have very low amplitudes at photospheric levels, which makes the modes extremely hard to detect. In this article, we review the current state of play regarding attempts to detect g modes. We review the theory of g modes, including theoretical estimation of the g-mode frequencies, amplitudes and damping rates. Then we go on to discuss the techniques that have been used to try to detect g modes. We review results in the literature, and finish by looking to the future, and the potential advances that can be made—from both data and data-analysis perspectives—to give unambiguous detections of individual g modes. The review ends by concluding that, at the time of writing, there is indeed a consensus amongst the authors that there is currently no undisputed detection of solar g modes.

  11. Delamination growth in composite materials

    NASA Technical Reports Server (NTRS)

    Gillespie, J. W., Jr.; Carlsson, L. A.; Pipes, R. B.; Rothschilds, R.; Trethewey, B.; Smiley, A.

    1986-01-01

    The Double Cantilever Beam (DCB) and the End Notched Flexure (ENF) specimens are employed to characterize MODE I and MODE II interlaminar fracture resistance of graphite/epoxy (CYCOM 982) and graphite/PEEK (APC2) composites. Sizing of test specimen geometries to achieve crack growth in the linear elastic regime is presented. Data reduction schemes based upon beam theory are derived for the ENF specimen and include the effects of shear deformation and friction between crack surfaces on compliance, C, and strain energy release rate, G sub II. Finite element (FE) analyses of the ENF geometry including the contact problem with friction are presented to assess the accuracy of beam theory expressions for C and G sub II. Virtual crack closure techniques verify that the ENF specimen is a pure Mode II test. Beam theory expressions are shown to be conservative by 20 to 40 percent for typical unidirectional test specimen geometries. A FE parametric study investigating the influence of delamination length and depth, span, thickness and material properties on G sub II is presented. Mode I and II interlaminar fracture test results are presented. Important experimental parameters are isolated, such as precracking techniques, rate effects, and nonlinear load-deflection response. It is found that subcritical crack growth and inelastic materials behavior, responsible for the observed nonlinearities, are highly rate-dependent phenomena with high rates generally leading to linear elastic response.

  12. Results of a combined model of root system growth and soil water uptake: evaluating the significance of root system architecture to plant water uptake

    NASA Astrophysics Data System (ADS)

    Bouda, M.; Saiers, J. E.

    2012-12-01

    Root system hydraulic architecture is a key determinant of plants' ability to withdraw water from the soil, satisfying transpirational demand. Presently, the representation of this component of the hydrological cycle in large-scale models is generally very simplistic, even though transpiration accounts for much of the terrestrial heat and water surface fluxes, and exercises control over photosynthetic uptake of CO2. In order to address this gap, we have developed a modelling approach that relies on several components. The first is RootGrow, original MATLAB code that simulates the stochastic growth of a root system as a function of an intrinsic set of parameters as well as its environment. We ran RootGrow coupled to the second component, a finite-element 3D simulation of the physics of water transport in the soil and root system using COMSOL, resulting in a combined model of root system development and water uptake. Model results show that root system architecture can affect water uptake by two separate mechanisms: (a) root system geometry determines the distribution of absorbing surface area throughout the soil domain, and (b) root system topology affects the water potential at the absorbing surfaces. In this study we sample the model's parameter space to demonstrate over what ranges of physically meaningful parameters (including hydraulic conductivity of plant tissues, soil type, and soil moisture level) these mechanisms significantly affect root systems' water withdrawal rate. The two mechanisms identified and our quantitative results will form the basis of a third component in this approach: developing simple analytical relationships characterising water uptake as a function of root system architecture that can be used in Ecosystem Demography Model v2.1 (ED2), a large-scale Dynamic Vegetation Model, based on a method of upscaling individual-based models of plant ecology.

  13. The mode of inheritance of Scheuermann's disease.

    PubMed

    Zaidman, A M; Zaidman, M N; Strokova, E L; Korel, A V; Kalashnikova, E V; Rusova, T V; Mikhailovsky, M V

    2013-01-01

    The mode of Scheuermann's disease inheritance and its phenotypic traits in probands and their relatives were studied in 90 pedigrees (90 probands and 385 relatives). The disorder was identified as a genetically related pathology inherited by autosomal dominant type, controlled by a mutant major gene, as a kyphotic deformity without signs of vertebral bodies' anomaly and torsion. Morphological and biochemical studies showed disturbance in the structure of vertebral growth plate anterior aspects at the level of deformity, defects in proliferation and differentiation of chondrocytes, and change in proteoglycan spectrum in cells and matrix. Twelve candidate genes were studied in chondrocytes isolated from vertebral growth plates of patients with Scheuermann's disease. The study results included disorder in the IHH gene expression and preservation of the expression of PAX1, two aggrecan isoforms, link protein, types I and II collagen, lumican, versican, growth hormone and growth factor receptor genes, and proliferation gene. Preservation of the SOX9 gene (transcription gene) probably indicates posttranscriptional genetic disorders. The study is under way.

  14. Overexpression of Peptide-Encoding OsCEP6.1 Results in Pleiotropic Effects on Growth in Rice (O. sativa).

    PubMed

    Sui, Zhipeng; Wang, Tianya; Li, Hongjian; Zhang, Ming; Li, Yangyang; Xu, Ruibin; Xing, Guofang; Ni, Zhongfu; Xin, Mingming

    2016-01-01

    Plant peptide hormones play an important role in regulating plant developmental programs via cell-to-cell communication in a non-cell autonomous manner. To characterize the biological relevance of C-TERMINALLY ENCODED PEPTIDE (CEP) genes in rice, we performed a genome-wide search against public databases using a bioinformatics approach and identified six additional CEP members. Expression analysis revealed a spatial-temporal pattern of OsCEP6.1 gene in different tissues and at different developmental stages of panicle. Interestingly, the expression level of the OsCEP6.1 was also significantly up-regulated by exogenous cytokinin. Application of a chemically synthesized 15-amino acid OsCEP6.1 peptide showed that OsCEP6.1 had a negative role in regulating root and seedling growth, which was further confirmed by transgenic lines. Furthermore, the constitutive expression of OsCEP6.1 was sufficient to lead to panicle architecture and grain size variations. Scanning electron microscopy analysis revealed that the phenotypic variation of OsCEP6.1 overexpression lines resulted from decreased cell size but not reduced cell number. Moreover, starch accumulation was not significantly affected. Taken together, these data suggest that the OsCEP6.1 peptide might be involved in regulating the development of panicles and grains in rice. PMID:26973672

  15. Constitutive over-expression of rice chymotrypsin protease inhibitor gene OCPI2 results in enhanced growth, salinity and osmotic stress tolerance of the transgenic Arabidopsis plants.

    PubMed

    Tiwari, Lalit Dev; Mittal, Dheeraj; Chandra Mishra, Ratnesh; Grover, Anil

    2015-07-01

    Protease inhibitors are involved primarily in defense against pathogens. In recent years, these proteins have also been widely implicated in response of plants to diverse abiotic stresses. Rice chymotrypsin protease inhibitor gene OCPI2 is highly induced under salt and osmotic stresses. The construct containing the complete coding sequence of OCPI2 cloned downstream to CaMV35S promoter was transformed in Arabidopsis and single copy, homozygous transgenic lines were produced. The transgenic plants exhibited significantly enhanced tolerance to NaCl, PEG and mannitol stress as compared to wild type plants. Importantly, the vegetative and reproductive growth of transgenic plants under unstressed, control conditions was also enhanced: transgenic plants were more vigorous than wild type, resulting into higher yield in terms of silique number. The RWC values and membrane stability index of transgenic in comparison to wild type plants was higher. Higher proline content was observed in the AtOCPI2 lines, which was associated with higher transcript expression of pyrroline-5-carboxylate synthase and lowered levels of proline dehydrogenase genes. The chymotrypsin protease activities were lower in the transgenic as against wild type plants, under both unstressed, control as well as stressed conditions. It thus appears that rice chymotrypsin protease inhibitor gene OCPI2 is a useful candidate gene for genetic improvement of plants against salt and osmotic stress. PMID:25910649

  16. Constitutive over-expression of rice chymotrypsin protease inhibitor gene OCPI2 results in enhanced growth, salinity and osmotic stress tolerance of the transgenic Arabidopsis plants.

    PubMed

    Tiwari, Lalit Dev; Mittal, Dheeraj; Chandra Mishra, Ratnesh; Grover, Anil

    2015-07-01

    Protease inhibitors are involved primarily in defense against pathogens. In recent years, these proteins have also been widely implicated in response of plants to diverse abiotic stresses. Rice chymotrypsin protease inhibitor gene OCPI2 is highly induced under salt and osmotic stresses. The construct containing the complete coding sequence of OCPI2 cloned downstream to CaMV35S promoter was transformed in Arabidopsis and single copy, homozygous transgenic lines were produced. The transgenic plants exhibited significantly enhanced tolerance to NaCl, PEG and mannitol stress as compared to wild type plants. Importantly, the vegetative and reproductive growth of transgenic plants under unstressed, control conditions was also enhanced: transgenic plants were more vigorous than wild type, resulting into higher yield in terms of silique number. The RWC values and membrane stability index of transgenic in comparison to wild type plants was higher. Higher proline content was observed in the AtOCPI2 lines, which was associated with higher transcript expression of pyrroline-5-carboxylate synthase and lowered levels of proline dehydrogenase genes. The chymotrypsin protease activities were lower in the transgenic as against wild type plants, under both unstressed, control as well as stressed conditions. It thus appears that rice chymotrypsin protease inhibitor gene OCPI2 is a useful candidate gene for genetic improvement of plants against salt and osmotic stress.

  17. The effect of beam and plasma parameters on the four modes of plasma-loaded traveling-wave tube with tape helix

    NASA Astrophysics Data System (ADS)

    Saviz, S.

    2014-07-01

    Field theory is applied to analyze the behavior of the electromagnetic wave in the presence of a solid electron beam and magnetized plasma-loaded tape helix traveling-wave tube. The obtained dispersion relation implicitly includes azimuthal variations and all spatial harmonics of the tape helix. Results indicate that the frequency and the phase velocity of ( X bp - X p ) and ( O bp - X p ) modes increase with cyclotron frequency and for ( O bp - O p ) and ( X bp - O p ) modes decrease. In the strong magnetic field limit, the maximum growth rate and frequency of all modes are constant at different values of cyclotron frequency and beam energy. If the plasma density increases, the frequency and phase velocity of four modes will increase. The maximum growth rates of the four modes in the lower plasma density are equal and for higher values of plasma density the ( O bp - X p ) mode has greatest value. The phase velocity and the frequency of ( X bp - X p ) with ( X bp - O p ) modes and ( O bp - O p ) with ( O bp - X p ) modes are coinciding with each other and for first case increase with beam density, but for latter decrease. The maximum growth rate of ( O bp - O p ) mode and the maximum frequency of ( X bp - X p ) mode have highest values as a function of the electron beam density.

  18. Increasing the metabolizable protein supply enhanced growth performance and led to variable results on innate and humoral immune response of preconditioning beef steers.

    PubMed

    Moriel, P; Artioli, L F A; Poore, M H; Confer, A W; Marques, R S; Cooke, R F

    2015-09-01

    . 100% and 115% MP steers (3.1, 2.4, and 2.5 ± 0.21 log, respectively). Preconditioning MP supply did not affect ( ≥ 0.26) ubsequent finishing growth performance and carcass characteristics. Thus, increasing MP supply from 85% to 115% of daily requirement of preconditioning beef steers had variable results on innate and humoral immune response and enhanced growth performance during a 42-d preconditioning period without affecting carcass characteristics at slaughter. PMID:26440347

  19. Development of a method that eliminates false-positive results due to nerve growth factor interference in the assessment of fulranumab immunogenicity.

    PubMed

    Dai, Sheng; Schantz, Allen; Clements-Egan, Adrienne; Cannon, Michael; Shankar, Gopi

    2014-05-01

    Fulranumab, a human IgG2 monoclonal antibody that neutralizes nerve growth factor (NGF), is currently in development for the treatment of pain. Our initial immunogenicity test method was found to be prone to NGF interference, leading to a high apparent incidence of anti-drug antibody (ADA) in phase 1 studies. The ADA immunoassay comprised a homogeneous bridging electrochemiluminescence (ECL) format with biotin and ruthenium-labeled fulranumab bound together ("bridged") by ADA in test samples for detection. In this assay, NGF produced a false-positive signal due to its ability to bridge fulranumab molecules. Thus, we developed a specificity assay to eliminate the NGF false-positive results. We encountered the challenge of eliminating drug interference as well as drug target interference, and discovered that the acid-dissociation-based pretreatment of samples used for mitigating drug interference dramatically increased drug target interference. Several strategies were investigated to eliminate the NGF interference; yet only one strategy specifically removed NGF and produced true fulranumab-specific ADA results by using competitive inhibition with fulranumab and utilizing an alternative NGF binding antibody to eliminate NGF interference. Using this new method, we confirmed that the high apparent anti-fulranumab antibody incidence (>60%) in clinical study samples was in fact due to fulranumab-bound NGF released during the acid-dissociation step of the ADA testing method. We conclude that our revised method accurately identifies anti-fulranumab antibodies by incorporating steps to eliminate fulranumab and NGF interference. We advise that acid-dissociation pretreatment must not be universally applied to improve ADA assays without investigating its bioanalytical risks versus benefits.

  20. A Prospective, Ultrasound-Based Study to Evaluate Risk Factors for Uterine Fibroid Incidence and Growth: Methods and Results of Recruitment

    PubMed Central

    Harmon, Quaker E.; Upson, Kristen; Moore, Kristen R.; Barker-Cummings, Christie; Baker, Susan; Cooper, Tracy; Wegienka, Ganesa

    2015-01-01

    Abstract Background: Uterine fibroids are common, benign, smooth-muscle tumors that can cause major morbidity for reproductive-age women, often requiring invasive treatment. Despite this personal and public health burden, no prior study has attempted to periodically screen fibroid-free women with ultrasound to detect incident disease and identify risk factors. Methods: We designed a study to prospectively investigate development of fibroids by enrolling women without a clinical diagnosis of fibroids and screening for fibroids with ultrasound at baseline. Enrollment procedures included extensive questionnaires and specimen collection (blood, urine, vaginal swabs). The cohort is followed at approximately 20-month intervals. At each follow-up there are updates to the questionnaire data, further specimen collection, and an ultrasound examination. We identify incident disease and measure tumor growth. The two exposures of primary interest are vitamin D insufficiency and reproductive tract infections. This manuscript provides a detailed description of the study methods, recruitment results, and participant characteristics. Results: The Study of Environment, Lifestyle and Fibroids enrolled 1,696 African American women aged 23–34 years. “Family and friends” was a leading recruitment source. More than 95% of participants contributed all the requested biological specimens at baseline. Study ultrasound examinations revealed undiagnosed fibroids in 378 women (22% of participants). The retention rate for the first follow-up was 87%. Conclusions: Study design aspects likely to be important for long-term studies in young African Americans include personalized recruitment, multiple steps to the enrollment process that rely on the initiative of the participant, and methods for tracing highly mobile study subjects. PMID:26334691

  1. When can the magnetosphere support cavity modes?

    NASA Astrophysics Data System (ADS)

    Hartinger, Michael; Welling, Daniel; Moldwin, Mark; Ridley, Aaron

    2014-05-01

    The Earth's magnetosphere supports several types of Ultra Low Frequency (ULF) waves; these include trapped fast mode waves often referred to as cavity modes, waveguide modes, and tunneling modes/virtual resonance. All trapped fast mode waves require a stable outer boundary to sustain wave activity. The magnetopause, often treated as the outer boundary for cavity/waveguide modes in the dayside magnetosphere, is often not stable, particularly during geomagnetic storms. We examine how magnetopause motion affects the magnetosphere's ability to sustain trapped fast mode waves on the dayside using idealized simulations obtained from the BATSRUS global magnetohydrodynamic (MHD) code. We present the first observations of cavity modes in BATSRUS, replicating results from other global MHD codes. We further show how varying solar wind conditions - in particular, increasing density and dynamic pressure fluctuations - affect magnetopause motion and, in turn, trapped fast mode waves.

  2. Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber

    PubMed Central

    Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W.

    2011-01-01

    The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg–Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers. PMID:21731106

  3. Endotaxial growth of CoSi2 within (111) oriented Si in a molecular beam epitaxy system

    NASA Technical Reports Server (NTRS)

    George, T.; Fathauer, R. W.

    1991-01-01

    A new mode of growth is reported in which buried metallic layers can be fabricated within a single-crystal semiconductor through preferential subsurface growth on previously-grown 'seed' regions. The deposition of Co at 800 C at a rate of 0.01 nm/s on (111) Si substrates containing buried CoSi2 columns 40-100 nm below the Si surface results in the growth and coalescence of these subsurface columns. The formation of a CoSi2 layer on the Si surface is suppressed by this growth mode. It is proposed that the high diffusion rate of Co at 800 C, coupled with the high growth rate of CoSi2 at the subsurface columns, is responsible for this preferred 'endotaxial' growth mode. This growth technique was used to produce a continuous buried single-crystal layer of CoSi2 under a single-crystal Si capping layer.

  4. Mode identification from spectroscopy of gravity-mode pulsators

    NASA Astrophysics Data System (ADS)

    Pollard, K. R.; Brunsden, E.; Cottrell, P. L.; Davie, M.; Greenwood, A.; Wright, D. J.; De Cat, P.

    2014-02-01

    The gravity modes present in γ Doradus stars probe the deep stellar interiors and are thus of particular interest in asteroseismology. For the MUSICIAN programme at the University of Canterbury, we obtain extensive high-resolution echelle spectra of γ Dor stars from the Mt John University Observatory in New Zealand. We analyze these to obtain the pulsational frequencies and identify these with the multiple pulsational modes excited in the star. A summary of recent results from our spectroscopic mode-identification programme is given.

  5. Influence of circulating fast ions on nonlinear kink-tearing modes in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Xian-Qu

    2016-08-01

    Nonlinear radial displacement modified by the kinetic effect of circulating fast ions is derived. It is found that circulating fast ions play a crucial role in the nonlinear dynamics of m = 1 kink-tearing modes. For a large fraction of fast ions, resonant fast ions can destabilize the mode by wave-particle interaction and enhance the mode saturation level significantly, meanwhile, fast-ion current has a modification on the mode amplitude depending on the plasma pressure gradient. A relation of mode amplitude to linear growth rate is explored by this model, which is valid to study the effects of circulating or trapped fast particles on the mode. The calculation results for the ITER-like parameters suggest that the kink-tearing mode with a global structure is dominated by the wave-particle interaction rather than the fast-ion current, particularly for the small island in which the fraction of fast ions is ignorable in comparison with the ideal region. The dependence of radial displacement on the mode frequency is discussed for different stabilities of the MHD modes.

  6. A heme oxygenase isoform is essential for aerobic growth in the cyanobacterium Synechocystis sp. PCC 6803: modes of differential operation of two isoforms/enzymes to adapt to low oxygen environments in cyanobacteria.

    PubMed

    Aoki, Rina; Goto, Takeaki; Fujita, Yuichi

    2011-10-01

    Heme oxygenase (HO) catalyzes the oxygen-dependent cleavage of heme to produce biliverdin IXα in phycobilin biosynthesis. In the genome of the cyanobacterium Synechocystis sp. PCC 6803 there are two genes, ho1 (sll1184) and ho2 (sll1875), encoding HO isoforms. Reverse transcription-PCR indicated that ho1 is constitutively expressed, and ho2 is induced under micro-oxic conditions. A mutant lacking ho1 (Δho1) failed to grow under aerobic conditions while it did grow at a significantly slower rate than the wild type under anaerobic (micro-oxic) conditions. When micro-oxically grown Δho1 was incubated under aerobic conditions, the cells underwent chlorosis with a significant decrease in phycocyanin accompanied by anomalous accumulation of protoporphyrin IX. These results suggested that HO1 is essential for aerobic growth as the sole HO and is dispensable under micro-oxic conditions. A mutant lacking ho2 (Δho2) grew under both aerobic and micro-oxic conditions like the wild type at low light intensity (50 μmol(photon) m⁻² s⁻¹). At higher light intensity (120 μmol(photon) m⁻² s⁻¹) the Δho2 mutant showed significant growth retardation under micro-oxic conditions. It is suggested that HO2 operates as a dominant HO under high light and micro-oxic environments and acts as an accessory HO at low light intensity. Constitutive expression of HO2 in a neutral site of the chromosome restored aerobic growth of Δho1, suggesting that HO2 has an activity high enough to substitute for HO1 under aerobic conditions. The differential operation of two isoforms/enzymes in cyanobacterial tetrapyrrole biosynthesis to adapt to low oxygen environments is discussed, including three other reactions.

  7. List mode multichannel analyzer

    SciTech Connect

    Archer, Daniel E.; Luke, S. John; Mauger, G. Joseph; Riot, Vincent J.; Knapp, David A.

    2007-08-07

    A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

  8. Overview of MAST results

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.; Akers, R. J.; Appel, L. C.; Applegate, D.; Axon, K. B.; Baranov, Y.; Brickley, C.; Bunting, C.; Buttery, R. J.; Carolan, P. G.; Challis, C.; Ciric, D.; Conway, N. J.; Cox, M.; Cunningham, G.; Darke, A.; Dnestrovskij, A.; Dowling, J.; Dudson, B.; Dunstan, M. R.; Delchambre, E.; Field, A. R.; Foster, A.; Gee, S.; Gryaznevich, M. P.; Helander, P.; Hender, T. C.; Hole, M.; Howell, D. H.; Joiner, N.; Keeling, D.; Kirk, A.; Lehane, I. P.; Lisgo, S.; Lloyd, B.; Lott, F.; Maddison, G. P.; Manhood, S. J.; Martin, R.; McArdle, G. J.; McClements, K. G.; Meyer, H.; Morris, A. W.; Nelson, M.; O'Brien, M. R.; Patel, A.; Pinfold, T.; Preinhaelter, J.; Price, M. N.; Roach, C. M.; Rozhansky, V.; Saarelma, S.; Saveliev, A.; Scannell, R.; Sharapov, S.; Shevchenko, V.; Shibaev, S.; Stammers, K.; Storrs, J.; Sykes, A.; Tabasso, A.; Tallents, S.; Taylor, D.; Tournianski, M. R.; Turner, A.; Turri, G.; Valovic, M.; Volpe, F.; Voss, G.; Walsh, M. J.; Watkins, J. R.; Wilson, H. R.; Wisse, M.; MAST, the; NBI; ECRH Teams

    2005-10-01

    Significant progress has been made on the Mega Ampere Spherical Tokamak (MAST) towards a fundamental understanding of transport, stability and edge physics and addressing technological issues for future large devices. Collaborative studies of the L-H transition with NSTX and ASDEX Upgrade confirm that operation in a connected double-null configuration significantly reduces the threshold power, Pthr. The MAST data provide support for a theory for the transition based on finite β drift wave turbulence suppression by self-generated zonal flows. Analysis of low and high field side density gradients in the H-mode pedestal provides support for an analytical model of the density pedestal width dependent on the neutral penetration depth. Adding MAST data to international confinement databases has enhanced confidence in scalings for ITER by significantly expanding the range of β and ɛ explored and indicates a slightly stronger ɛ dependence than in current scalings. Studies of core transport have been conducted for well-diagnosed L-mode, H-mode and internal transport barrier (ITB) discharges using TRANSP, and microstability and turbulence studies have been carried out using GS2. Linear micro-stability analysis indicates that ITG modes are typically unstable on all flux surfaces with growth rates that are comparable to the equilibrium E × B flow shearing rate. Mixing length estimates of transport coefficients from ITG (neglecting flow shear) give diffusion coefficients that are broadly comparable with observed thermal diffusivities. Non-linear, collisionless ETG calculations have been performed and suggest radially extended electrostatic streamers up to 100ρe across in radius. Transport from ITG could easily be suppressed in regions where the E × B shear flow rate, ωSE, exceeds the ITG growth rate, possibly contributing to ITBs. Toroidal rotation, driven by neutral beam torque, is the dominant contribution to ωSE via the vphiBθ term in the radial electric field

  9. Deletion of open reading frame UL26 from the human cytomegalovirus genome results in reduced viral growth, which involves impaired stability of viral particles.

    PubMed

    Lorz, Kerstin; Hofmann, Heike; Berndt, Anja; Tavalai, Nina; Mueller, Regina; Schlötzer-Schrehardt, Ursula; Stamminger, Thomas

    2006-06-01

    We previously showed that open reading frame (ORF) UL26 of human cytomegalovirus, a member of the US22 multigene family of betaherpesviruses, encodes a novel tegument protein, which is imported into cells in the course of viral infection. Moreover, we demonstrated that pUL26 contains a strong transcriptional activation domain and is capable of stimulating the major immediate-early (IE) enhancer-promoter. Since this suggested an important function of pUL26 during the initiation of the viral replicative cycle, we sought to ascertain the relevance of pUL26 by construction of a viral deletion mutant lacking the UL26 ORF using the bacterial artificial chromosome mutagenesis procedure. The resulting deletion virus was verified by PCR, enzyme restriction, and Southern blot analyses. After infection of human foreskin fibroblasts, the UL26 deletion mutant showed a small-plaque phenotype and replicated to significantly lower titers than wild-type or revertant virus. In particular, we noticed a striking decrease of infectious titers 7 days postinfection in a multistep growth experiment, whereas the release of viral DNA from infected cells was not impaired. A further investigation of this aspect revealed a significantly diminished stability of viral particles derived from the UL26 deletion mutant. Consistent with this, we observed that the tegument composition of the deletion mutant deviates from that of the wild-type virus. We therefore hypothesize that pUL26 plays a role not only in the onset of IE gene transcription but also in the assembly of the viral tegument layer in a stable and correct manner. PMID:16699023

  10. The cardiovascular health of urban African Americans: diet-related results from the Genes, Nutrition, Exercise, Wellness, and Spiritual Growth (GoodNEWS) trial.

    PubMed

    Carson, Jo Ann S; Michalsky, Linda; Latson, Bernadette; Banks, Kamakki; Tong, Liyue; Gimpel, Nora; Lee, Jenny J; Dehaven, Mark J

    2012-11-01

    African Americans have a higher incidence of cardiovascular disease (CVD) than Americans in general and are thus prime targets for efforts to reduce CVD risk. Dietary intake data were obtained from African Americans participating in the Genes, Nutrition, Exercise, Wellness, and Spiritual Growth (GoodNEWS) Trial. The 286 women and 75 men who participated had a mean age of 49 years; 53% had hypertension, 65% had dyslipidemia, and 51% met criteria for metabolic syndrome. Their dietary intakes were compared with American Heart Association and National Heart, Lung, and Blood Institute nutrition parameters to identify areas for improvement to reduce CVD risk in this group of urban church members in Dallas, TX. Results from administration of the Dietary History Questionnaire indicated median daily intakes of 33.6% of energy from total fat, 10.3% of energy from saturated fat, 171 mg cholesterol, 16.3 g dietary fiber, and 2,453 mg sodium. A beneficial median intake of 2.9 cups fruits and vegetables per day was coupled with only 2.7 oz fish/week and an excessive intake of 13 tsp added sugar/day. These data indicate several changes needed to bring the diets of these individuals--and likely many other urban African Americans--in line with national recommendations, including reduction of saturated fat, sodium, and sugar intake, in addition to increased intake of fatty fish and whole grains. The frequent inclusion of vegetables should be encouraged in ways that promote achievement of recommended intakes of energy, fat, fiber, and sodium.

  11. Effects of health information in youth on adult physical activity: 20-year study results from the Amsterdam growth and health longitudinal study.

    PubMed

    Kemper, Han C G; Verhagen, E A L M; Milo, D; Post, G B; Van Lenthe, F; Van Mechelen, W; Twisk, J W R; De Vente, W

    2002-01-01

    In the Amsterdam Growth and Health Longitudinal Study (AGAHLS), a group of apparently healthy males and females (n = 200) were interviewed about their physical activities on eight separate occasions over a period of 20 years between 13 and 33 years of age (multi-measured group: MM). Information about their health was given based on their personally measured lifestyle (activity, diet, smoking) and biological risk characteristics for chronic diseases (medical check-ups). A comparable group of boys and girls (n = 200) was only measured on two occasions (bi-measured group: BM): at 13 and 33 years. Physical activity was estimated with a structured interview. Total physical activity and sports activity were estimated in three intensity levels (light, moderate, and heavy). It was hypothesized that the eight repeated medical check-ups with health information in the MM group would result in a healthier lifestyle with respect to the determinants and levels of habitual physical activity compared to the BM group. Contrary to the hypothesis, males and females in the BM group showed a significantly higher increase or a lower decrease in physical activities compared to the MM group. This negative effect on the physical activity pattern at 33 years in the MM group may have been caused by more underreporting of physical activities than in the BM group. In conclusion, there does not appear to be a significant effect of long-term (multi-measured) health information with medical check-ups during adolescence and young adulthood on level of physical activity in males and females at 33 years of age. PMID:12112566

  12. Shifts in the Vascular endothelial growth factor (Vegf) isoforms result in transcriptome changes correlated with early neural stem cell proliferation and differentiation in mouse forebrain

    PubMed Central

    Cain, Jacob T.; Berosik, Matthew A.; Snyder, Stephanie D.; Crawford, Natalie F.; Nour, Shirin I.; Schaubhut, Geoffrey J.; Darland, Diane C.

    2014-01-01

    Regulation of neural stem cell (NSC) fate decisions is critical during the transition from a multicellular mammalian forebrain neuroepithelium to the multi-layered neocortex. Forebrain development requires coordinated vascular investment alongside NSC differentiation. Vascular endothelial growth factor A (Vegf) has proven to be a pleiotrophic gene whose multiple protein isoforms regulate a broad range of effects in neurovascular systems. To test the hypothesis that the Vegf isoforms (120, 164, and 188) are required for normal forebrain development, we analyzed the forebrain transcriptome of mice expressing specific Vegf isoforms, Vegf120, VegfF188, or a combination of Vegf120/188. Transcriptome analysis identified differentially expressed genes in embryonic day (E) 9.5 forebrain, a time point preceding dramatic neuroepithelial expansion and vascular investment in the telencephalon. Meta-analysis identified gene pathways linked to chromosome-level modifications, cell fate regulation, and neurogenesis that were altered in Vegf isoform mice. Based on these gene network shifts, we predicted that NSC populations would be affected in later stages of forebrain development. In the E11.5 telencephalon, we quantified mitotic cells [Phospho-Histone H3 (pHH3)-positive] and intermediate progenitor cells (Tbr2/Eomes-positive), observing quantitative and qualitative shifts in these populations. We observed qualitative shifts in cortical layering at P0, particularly with Ctip2-positive cells in layer V. The results identify a suite of genes and functional gene networks that can be used to further dissect the role of Vegf in regulating NSC differentiation and downstream consequences for NSC fate decisions. PMID:24124161

  13. Space-time evolution of whistler mode wavegrowth in the magnetosphere

    NASA Technical Reports Server (NTRS)

    Carlson, C. R.; Helliwell, R. A.; Inan, U. S.

    1990-01-01

    The modeling and simulation of the growth of ducted single-frequency whistler-mode waves through cyclotron resonance with radiation belt electrons are considered. The Siple transmitter and a geomagnetically conjugate receiving station are used for the present study. The results can be applied to slowly varying frequency signals and to broadband 'noiselike' signals.

  14. DISCHARGE IMPROVEMENT THROUGH CONTROL OF NEOCLASSICAL TEARING MODES BY LOCALIZED ECCD IN DIII-D

    SciTech Connect

    PRATER,R; LAHAYE,RJ; LOHR,J; LUCE,TC; PETTY,CC; FERRON,JR; HUMPHREYS,DA; STRAIT,EJ; PERKINS,FW; HARVEY,RW

    2002-10-01

    A271 DISCHARGE IMPROVEMENT THROUGH CONTROL OF NEOCLASSICAL TEARING MODES BY LOCALIZED ECCD IN DIII-D. Neoclassical tearing modes (NTMs) are MHD modes which can limit the performance of high beta discharges in tokamaks, in some cases leading to a major disruption. The destabilizing effect which results in NTM growth is a helical decrease in the bootstrap current caused by a local reduction of the plasma pressure gradient by seed magnetic islands. The NTM is particularly well suited to control since the mode is linearly stable although nonlinearly unstable, so if the island amplitude can be decreased below a threshold size the mode will decay and vanish. One means of shrinking the island is the replacement of the missing bootstrap current by a localized current generated by electron cyclotron current drive (ECCD). This method has been applied to the m=3/n=2 neoclassical tearing mode in DIII-D, in H-mode plasmas with ongoing ELMs and sawteeth, both of which generate seed islands periodically. In the case of the 3/2 mode, full suppression was obtained robustly by applying about 1.5 MW of ECCD very near the rational surface of the mode. When the mode first appears in the plasma the stored energy decreases by 20%, but after the mode is stabilized by the ECCD the beta may be raised above the initial threshold pressure by 20% by additional neutral beam heating, thereby generating an improvement in the limiting beta of nearly a factor 2. An innovative automated search algorithm was implemented to find and retain the optimum location for the ECCD in the presence of the mode.

  15. Effects of friction and high torque on fatigue crack propagation in Mode III

    NASA Astrophysics Data System (ADS)

    Nayeb-Hashemi, H.; McClintock, F. A.; Ritchie, R. O.

    1982-12-01

    Turbo-generator and automotive shafts are often subjected to complex histories of high torques. To provide a basis for fatigue life estimation in such components, a study of fatigue crack propagation in Mode III (anti-plane shear) for a mill-annealed AISI 4140 steel (RB88, 590 MN/m2 tensile strength) has been undertaken, using torsionally-loaded, circumferentially-notched cylindrical specimens. As demonstrated previously for higher strength AISI 4340 steel, Mode III cyclic crack growth rates (dc/dN) IIIcan be related to the alternating stress intensity factor ΔKIII for conditions of small-scale yielding. However, to describe crack propagation behavior over an extended range of crack growth rates (˜10-6 to 10-2 mm per cycle), where crack growth proceeds under elastic-plastic and full plastic conditions, no correlation between (dc/dN) III and ΔKIII is possible. Accordingly, a new parameter for torsional crack growth, termed the plastic strain intensity Γ III, is introduced and is shown to provide a unique description of Mode III crack growth behavior for a wide range of testing conditions, provided a mean load reduces friction, abrasion, and interlocking between mating fracture surfaces. The latter effect is found to be dependent upon the mode of applied loading (i.e., the presence of superimposed axial loads) and the crack length and torque level. Mechanistically, high-torque surfaces were transverse, macroscopically flat, and smeared. Lower torques showed additional axial cracks (longitudinal shear cracking) perpendicular to the main transverse surface. A micro-mechanical model for the main radi l Mode III growth, based on the premise that crack advance results from Mode II coalescence of microcracks initiated at inclusions ahead of the main crack front, is extended to high nominal stress levels, and predicts that Mode III fatigue crack propagation rates should be proportional to the range of plastic strain intensity (ΔΓIII if local Mode II growth rates are

  16. Fasinumab (REGN475), an antinerve growth factor monoclonal antibody, for the treatment of acute sciatic pain: results of a proof-of-concept study

    PubMed Central

    Tiseo, Paul J; Ren, Haobo; Mellis, Scott

    2014-01-01

    Objective To evaluate the efficacy and safety of subcutaneously administered fasinumab (REGN475), a nerve growth factor-neutralizing antibody, in patients with acute sciatic pain receiving standard of care therapy. Methods This was a double-blind, parallel-group, proof-of-concept study. Patients with unilateral, moderate-to-severe sciatic pain of 2–16 weeks’ duration were randomized to a subcutaneous dose of placebo (n=51), fasinumab 0.1 mg/kg (n=53), or 0.3 mg/kg (n=53); follow-up was 12 weeks. Pain was assessed in a daily diary using a numerical rating scale (NRS) (0= no pain, 10= worst pain) for average and worst leg and back pain. The primary efficacy end point was the area under the curve of NRS scores for average leg pain from baseline to week 4. Key secondary end points included changes in average and worst leg and back pain from baseline to the end of week 4 and to each weekly study visit. Patient functioning (Oswestry Disability Index) and concomitant analgesic use were also assessed. Safety and tolerability were evaluated by treatment-emergent adverse events (TEAEs). Results Demographic and clinical characteristics were similar among the treatment groups; 141 (88.7%) patients completed the study. For the primary end point, mean ± standard deviation area under the curve values from baseline to week 4 were not significantly different between placebo (96.8±6.0) and fasinumab 0.1 mg/kg (112.7±58.3; P=0.0610) or fasinumab 0.3 mg/kg (112.4±55.8; P=0.0923). All secondary efficacy end points of changes in pain and function demonstrated responses that were similar between placebo and fasinumab groups. Incidence of TEAEs was 45.1%, 50.9%, and 64.8% in the placebo, fasinumab 0.1mg/kg, and fasinumab 0.3 mg/kg groups, respectively. The most commonly reported TEAEs included paresthesia, arthralgia, pain in extremity, and headache. Conclusion Administration of fasinumab provided no significant clinical benefit compared with placebo for the pain or functional

  17. Dietary predictors of the insulin-like growth factor system in adolescent females: results from the Dietary Intervention Study in Children (DISC)123

    PubMed Central

    Gardiner, Joseph C; Dorgan, Joanne F; Rosen, Cliff J; Velie, Ellen M

    2010-01-01

    Background: The insulin-like growth factor (IGF) system is associated with the adult diet and chronic disease. Childhood diet may influence chronic disease through its effect on the IGF system; however, there is limited information describing the dietary predictors of the IGF system in adolescents. Objective: We examined associations between dietary food intake [fat, protein (animal and vegetable), carbohydrate, lactose, dietary fiber, calcium, zinc, and sodium] and serum IGF-I, IGF binding protein 1 (IGFBP-1), IGF binding protein 3 (IGFBP-3), and the IGF-I:IGFBP-3 molar ratio in adolescent females. Design: One hundred fifty-nine adolescent females in the Dietary Intervention Study in Children (age range: 14–18 y; 0.2–6.3 y postmenarche) were included. The dietary intake was assessed via three 24-h dietary recalls. IGF-related biomarkers were determined by using radioimmunoassays. Associations between dietary intakes and biomarkers were assessed with Pearson's correlations and multivariable linear regression. Dietary intakes and biomarkers were logarithmically transformed; thus, β coefficients represented percentages. Results: In analyses adjusted for energy, age, and time since menarche, significant correlations (P < 0.05) were as follows: IGF-I with total protein, lactose, calcium, and sodium; IGFBP-3 with total fat (inverse), lactose, fiber, and calcium; IGF-I/IGFBP-3 with lactose and calcium; and IGFBP-1 with vegetable protein. In multivariable analyses, significant predictors of IGF-I were energy (β = 0.14, P < 0.05) and calcium (β = 0.14, P < 0.01), the significant predictor of IGFBP-3 was calcium (β = 0.07, P < 0.05), and significant predictors of IGFBP-1 were vegetable protein (β = 0.49, P < 0.05) and body mass index–for-age percentile (β = −0.01, P < 0.001). Conclusion: This study provides evidence that dietary intake affects IGF-related biomarkers—particularly elevated calcium with IGF-I and IGFBP-3 and elevated vegetable protein with

  18. Dynamically encircling an exceptional point for asymmetric mode switching

    NASA Astrophysics Data System (ADS)

    Doppler, Jörg; Mailybaev, Alexei A.; Böhm, Julian; Kuhl, Ulrich; Girschik, Adrian; Libisch, Florian; Milburn, Thomas J.; Rabl, Peter; Moiseyev, Nimrod; Rotter, Stefan

    2016-09-01

    Physical systems with loss or gain have resonant modes that decay or grow exponentially with time. Whenever two such modes coalesce both in their resonant frequency and their rate of decay or growth, an ‘exceptional point’ occurs, giving rise to fascinating phenomena that defy our physical intuition. Particularly intriguing behaviour is predicted to appear when an exceptional point is encircled sufficiently slowly, such as a state-flip or the accumulation of a geometric phase. The topological structure of exceptional points has been experimentally explored, but a full dynamical encircling of such a point and the associated breakdown of adiabaticity have remained out of reach of measurement. Here we demonstrate that a dynamical encircling of an exceptional point is analogous to the scattering through a two-mode waveguide with suitably designed boundaries and losses. We present experimental results from a corresponding waveguide structure that steers incoming waves around an exceptional point during the transmission process. In this way, mode transitions are induced that transform this device into a robust and asymmetric switch between different waveguide modes. This work will enable the exploration of exceptional point physics in system control and state transfer schemes at the crossroads between fundamental research and practical applications.

  19. Experimental investigation on flow modes of electrospinning