Science.gov

Sample records for 100-ns rise time

  1. Dynamics of high-speed micro-drop impact: numerical simulations and experiments at frame-to-frame times below 100 ns.

    PubMed

    Visser, Claas Willem; Frommhold, Philipp Erhard; Wildeman, Sander; Mettin, Robert; Lohse, Detlef; Sun, Chao

    2015-03-01

    Technologies including (3D-) (bio-)printing, diesel engines, laser-induced forward transfer, and spray cleaning require optimization and therefore understanding of micrometer-sized droplets impacting at velocities beyond 10 m s(-1). However, as yet, this regime has hardly been addressed. Here we present the first time-resolved experimental investigation of microdroplet impact at velocities up to V0 = 50 m s(-1), on hydrophilic and -phobic surfaces at frame rates exceeding 10(7) frames per second. A novel method to determine the 3D-droplet profile at sub-micron resolution at the same frame rates is presented, using the fringe pattern observed from a bottom view. A numerical model, which is validated by the side- and bottom-view measurements, is employed to study the viscous boundary layer inside the droplet and the development of the rim. The spreading dynamics, the maximal spreading diameter, the boundary layer thickness, the rim formation, and the air bubble entrainment are compared to theory and previous experiments. In general, the impact dynamics are equal to millimeter-sized droplet impact for equal Reynolds-, Weber- and Stokes numbers (Re, We, and St, respectively). Using our numerical model, effective scaling laws for the progression of the boundary layer thickness and the rim diameter are provided. The dimensionless boundary layer thickness develops in time (t) according to δBL ~ D0/√Re(t/τ)0.45, and the diameter of the rim develops as DRim ~ D0/√We(t/τ)0.68, with drop diameter D0 and inertial time scale τ = D0/V0. These scalings differ from previously assumed, but never validated, values. Finally, no splash is observed, at variance with many predictions but in agreement with models including the influence of the surrounding gas. This confirms that the ambient gas properties are key ingredients for splash threshold predictions. PMID:25607820

  2. Autonomous Magnetoexplosive Generator of Megavolt, 100 NS Pulses

    NASA Astrophysics Data System (ADS)

    Gurin, V. Ye.; Kataev, V. N.; Korolev, P. V.; Kargin, V. I.; Makartsev, G. F.; Nudikov, V. N.; Pikar, A. S.; Popkov, N. F.; Saratov, A. F.

    2004-11-01

    Here we present the results of the work carried out at different stages aimed at the development of autonomous magnetocumulative generators having 100 ns megavolt pulses. This generator is meant to replace the PIRIT-01 stationary facility by a magnetocumulative energy source. Using a generator with permanent magnets as a source of initial energy and multiplying this energy by a cascade of magnetoexplosive generators allows 100 kJ of energy accumulation in a contour. The generator that has a permanent magnet does not need an additional energy source for its operation. It is convenient to operate and is always available for service. Shortening the MC generator current pulse up to 1 μs is implemented using a high-voltage explosive driven opening switch. In the first sharpening cascade, the voltage increases up to 500 kV. Further shortening of the current pulse duration up to 100 ns and the voltage rise up to 1 MV are performed using plasma opening switches according to the two-stage formation scheme. Such a scheme allows the decrease of electric field strength on the insulator surface and the use of magnetic insulation in the high-voltage section of the facility.

  3. PS II model-based simulations of single turnover flash-induced transients of fluorescence yield monitored within the time domain of 100 ns-10 s on dark-adapted Chlorella pyrenoidosa cells.

    PubMed

    Belyaeva, N E; Schmitt, F-J; Steffen, R; Paschenko, V Z; Riznichenko, G Yu; Chemeris, Yu K; Renger, G; Rubin, A B

    2008-01-01

    The set up described in Steffen et al. (Biochemistry 40:173-180, 2001) was used to monitor in the time domain from 100 ns to 10 s single turnover flash-induced transients of the normalized fluorescence yield (SFITFY) on dark-adapted cells of the thermophilic algae Chlorella pyrenoidosa Chick. Perfect data fit was achieved within the framework of a previously proposed model for the PS II reaction pattern (Lebedeva et al., Biophysics 47:968-980, 2002; Belyaeva et al., Biophysics 51:860-872, 2006) after its modification by taking into account nonradiative decay processes including nonphotochemical quenching due to time-dependent populations of P680(+*) and (3)Car. On the basis of data reported in the literature, a consistent set of rate constants was obtained for electron transfer at the donor and acceptor sides of PS II, pH in lumen and stroma, the initial redox state of plastoquinone pool and the rate of plastoquinone oxidation. The evaluation of the rate constant values of dissipative processes due to quenching by carotenoid triplets in antennae and P680(+*)Q(A)(-*) recombination as well as the initial state populations after excitation with a single laser flash are close to that outlined in (Steffen et al., Biochemistry 44:3123-3133, 2005a). The simulations based on the model of the PS II reaction pattern provide information on the time courses of population probabilities of different PS II states. We analyzed the maximum (F(m)(STF)) and minimum (F(0)) of the normalized FL yield dependence on the rate of the recombination processes (radiative and dissipative nonradiative) and of P680(+*) reduction. The developed PS II model provides a basis for theoretical comparative analyses of time-dependent fluorescence signals, observed at different photosynthetic samples under various conditions (e.g. presence of herbicides, other stress conditions, excitation with actinic pulses of different intensity, and duration). PMID:18937044

  4. Amplitude- and rise-time-compensated filters

    DOEpatents

    Nowlin, Charles H.

    1984-01-01

    An amplitude-compensated rise-time-compensated filter for a pulse time-of-occurrence (TOOC) measurement system is disclosed. The filter converts an input pulse, having the characteristics of random amplitudes and random, non-zero rise times, to a bipolar output pulse wherein the output pulse has a zero-crossing time that is independent of the rise time and amplitude of the input pulse. The filter differentiates the input pulse, along the linear leading edge of the input pulse, and subtracts therefrom a pulse fractionally proportional to the input pulse. The filter of the present invention can use discrete circuit components and avoids the use of delay lines.

  5. Dual-energy bone densitometry using a single 100 ns x-ray pulse.

    PubMed

    Seely, J F; Boyer, C N; Holland, G E

    1998-10-01

    A pulsed, portable hard x-ray source has been developed for medical imaging and flash x-ray absorptiometry. The source is powered by a Marx generator that drives a field emission x-ray tube which produces a 30-300 keV x-ray pulse of 100 ns duration. The x-ray fluence has dual-energy properties. The x-ray energy is relatively high early in the pulse and lower later in the pulse. The feasibility of using a single x-ray pulse for precision bone densitometry was analyzed. A computer simulation model was developed for the x-ray source, the filtration that enhances the dual-energy distribution, the absorption of the energy distribution by bone mineral and soft tissue, and the dual-energy detection system. It is feasible to determine the bone mineral density (BMD) of axial sites such as the lumbar spine and proximal femur with 2% precision over an area that is 15-20 mm in size, depending on the bone mineral and soft tissue thicknesses. An algorithm for determining the absolute BMD, to an accuracy of 2%, using a Plexiglas/TiO2 calibration phantom is discussed. At a distance of 50 cm from the source, the patient exposure is 3.7 mR. The average absorbed bone and tissue doses are 0.6 and 4.3 mrem, respectively. Factors that facilitate diagnostic measurements in clinical settings are the short patient observation time and the portability of the x-ray source. PMID:9800712

  6. Compton suppression through rise-time analysis.

    PubMed

    Selvi, S; Celiktas, C

    2007-11-01

    We studied Compton suppression for 60Co and 137Cs radioisotopes using a signal selection criterion based on contrasting the fall time of the signals composing the photo peak with those composing the Compton continuum. The fall time criterion is employed by using the pulse shape analysis observing the change in the fall times of the gamma-ray pulses. This change is determined by measuring the changes in the rise times related to the fall time of the scintillator and the timing signals related to the fall time of the input signals. We showed that Compton continuum suppression is achieved best via the precise timing adjustment of an analog rise-time analyzer connected to a NaI(Tl) scintillation spectrometer. PMID:17703943

  7. Short rise time intense electron beam generator

    DOEpatents

    Olson, C.L.

    1984-03-16

    A generator for producing an intense relativisitc electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  8. Short rise time intense electron beam generator

    DOEpatents

    Olson, Craig L.

    1987-01-01

    A generator for producing an intense relativistic electron beam having a subnanosecond current rise time includes a conventional generator of intense relativistic electrons feeding into a short electrically conductive drift tube including a cavity containing a working gas at a low enough pressure to prevent the input beam from significantly ionizing the working gas. Ionizing means such as a laser simultaneously ionize the entire volume of working gas in the cavity to generate an output beam having a rise time less than one nanosecond.

  9. Aluminum and tungsten X-pinch experiments on 100 kA, 100 ns linear transformer driver stage

    SciTech Connect

    Wu Jian; Sun Tieping; Wu Gang; Wang Liangping; Han Juanjuan; Li Mo; Cong Peitian; Qiu Aici; Lv Min

    2011-05-15

    X-pinch experiments have been carried out on a 100 kA, 100 ns linear transformer driver stage recently built up. The X-pinches exhibited a source size of about 10 {mu}m, a pulse duration of 3 ns, 3-5 keV radiation energy of 3.9 mJ, and a burst time jitter of tens of nanosecond with the 2-wire 8 {mu}m W X-pinch load. The generator output current and the X-pinch characteristics depended on the X-pinch wire materials in the tests. X-ray backlighting images from the insects showed the significant phase-contrast effect.

  10. Aluminum and tungsten X-pinch experiments on 100 kA, 100 ns linear transformer driver stage

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Sun, Tie-Ping; Wu, Gang; Wang, Liang-Ping; Han, Juan-Juan; Li, Mo; Cong, Pei-Tian; Qiu, Ai-Ci; Lv, Min

    2011-05-01

    X-pinch experiments have been carried out on a 100 kA, 100 ns linear transformer driver stage recently built up. The X-pinches exhibited a source size of about 10 μm, a pulse duration of 3 ns, 3-5 keV radiation energy of 3.9 mJ, and a burst time jitter of tens of nanosecond with the 2-wire 8 μm W X-pinch load. The generator output current and the X-pinch characteristics depended on the X-pinch wire materials in the tests. X-ray backlighting images from the insects showed the significant phase-contrast effect.

  11. Rugged calorimeter with a fast rise time

    SciTech Connect

    McMurtry, W.M.; Dolce, S.R.

    1980-01-01

    An intrinsic 1-mil-thick gold foil calorimeter has been developed which rises to 95% of the energy deposited in less than 2 microseconds. This calorimeter is very rugged, and can withstand rough handling without damage. The time constant is long, in the millisecond range, because of its unique construction. Use of this calorimeter has produced 100% data recovery, and agreement with true deposition to less than 10%.

  12. RISE/FALL TIME ENHANCEMENT OF THE SPALLATION NEUTRON SOURCE LINAC LEBT CHOPPER SYSTEM

    SciTech Connect

    Peplov, Vladimir V; Saethre, Robert B

    2013-01-01

    The Spallation Neutron Source (SNS) Linac Low Energy Beam Transport (LEBT) chopper system provides fast chopping of the H- ion beam in the LEBT structure. Four identical pulsed power supplies (pulsers) create a series of 2.5 kV pulses to the four deflection electrodes floating on the focusing voltage of -50 kV. Each pulser is connected to the electrode through the network which consists of high voltage (HV) cables, a blocking capacitor, HV feed-through connectors, current-limiting resistors and transient voltage suppressors. Effective beam chopping requires minimal rise/fall time of the rectangular HV pulses on the load. In the present configuration these values are approximately 100 ns. Methods of reducing rise/fall time on the LEBT electrodes are discussed. Results of simulation and comparative measurements of the original and upgraded system on the test stand are presented. Furthermore, the effect of these changes on reliability degradation caused by arcing in the LEBT structure is discussed.

  13. Mapping Rise Time Information with Down-Shift Analysis

    SciTech Connect

    Tunnell, T. W., Machorro, E. A., Diaz, A. B.

    2011-11-01

    These viewgraphs summarize the application of recent developments in digital down-shift (DDS) analysis of up converted PDV data to map out how well the PDV diagnostic would capture rise time information (mid point and rise time) in short rise time (<1 ns) shock events. The mapping supports a PDV vs VISAR challenge. The analysis concepts are new (~September FY 2011), simple, and run quickly, which makes them good tools to map out (with ~1 million Monte Carlo simulations) how well PDV captures rise time information as function of baseline velocity, rise time, velocity jump, and signal-to-noise ratios.

  14. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia National Laboratories.

    SciTech Connect

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A. , Tomsk, Russia); Kim, Alexandre A. , Tomsk, RUSSIA); Wakeland, Peter Eric; McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry, Jr.; Struve, Kenneth William; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-04-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory.

  15. Destruction of hazardous air pollutants using a fast rise time pulsed corona reactor

    SciTech Connect

    Korzekwa, R.A.; Grothaus, M.G.; Hutcherson, R.K.; Roush, R.A.; Brown, R.

    1998-04-01

    Increasingly stringent environmental regulation imposed on both the military and civilian sectors has created a growing demand for alternative abatement methods for a variety of hazardous compounds. One alternative, the nonthermal plasma, shows promise of providing an efficient means for the destruction of dilute concentrations of hazardous air pollutants. The Dahlgren Laboratory of the Naval Surface Warfare Center has extensively investigated one type of nonthermal plasma discharge, the pulsed corona reactor, for the destruction of volatile organic compounds and chemical warfare agents. In this reactor, a fast rise time ({approximately}10ns), short duration ({lt}100ns), high-voltage pulse is repetitively delivered to a wire-cylinder electrode geometry, thereby producing a multitude of streamer discharges along its length. The resulting nonthermal plasma contains highly reactive chemical radicals which can interact with and destroy the hazardous molecules entrained in the ambient atmosphere flowing through the reactor volume. Increased electrical efficiency was obtained using a combination of high efficiency constant-current capacitor-charging, high repetition-rate spark gap switching, and resonant energy transfer to the reactor. Promising results have been obtained for toluene, methylene chloride, and dichlorodifluoromethane in air at concentrations of a few hundred parts per million. The device has been operated at voltages up to 30 kV, pulse repetition rates up to 1.4 kHz, and flow rates up to 60 scr(l)/min. Detailed electrical measurements have been made to properly characterize the electrical properties of the pulsed corona reactor and to validate subsequent improvements in the reactor energy efficiency. {copyright} {ital 1998 American Institute of Physics.}

  16. Fast rise times and the physical mechanism of deep earthquakes

    NASA Technical Reports Server (NTRS)

    Houston, H.; Williams, Q.

    1991-01-01

    A systematic global survey of the rise times and stress drops of deep and intermediate earthquakes is reported. When the rise times are scaled to the seismic moment release of the events, their average is nearly twice as fast for events deeper than about 450 km as for shallower events.

  17. Detection of Sound Rise Time by Adults with Dyslexia

    ERIC Educational Resources Information Center

    Hamalainen, J.; Leppanen, P.H.T.; Torppa, M.; Muller, K.; Lyytinen, H.

    2005-01-01

    Low sensitivity to amplitude modulated (AM) sounds is reported to be associated with dyslexia. An important aspect of amplitude modulation cycles are the rise and fall times within the sound. In this study, simplified stimuli equivalent to just one cycle were used and sensitivity to varying rise times was explored. Adult participants with dyslexia…

  18. An evaluation of rise time characterization and prediction methods

    NASA Technical Reports Server (NTRS)

    Robinson, Leick D.

    1994-01-01

    One common method of extrapolating sonic boom waveforms from aircraft to ground is to calculate the nonlinear distortion, and then add a rise time to each shock by a simple empirical rule. One common rule is the '3 over P' rule which calculates the rise time in milliseconds as three divided by the shock amplitude in psf. This rule was compared with the results of ZEPHYRUS, a comprehensive algorithm which calculates sonic boom propagation and extrapolation with the combined effects of nonlinearity, attenuation, dispersion, geometric spreading, and refraction in a stratified atmosphere. It is shown there that the simple empirical rule considerably overestimates the rise time estimate. In addition, the empirical rule does not account for variations in the rise time due to humidity variation or propagation history. It is also demonstrated that the rise time is only an approximate indicator of perceived loudness. Three waveforms with identical characteristics (shock placement, amplitude, and rise time), but with different shock shapes, are shown to give different calculated loudness. This paper is based in part on work performed at the Applied Research Laboratories, the University of Texas at Austin, and supported by NASA Langley.

  19. Rise Time Measurement for Ultrafast X-Ray Pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  20. Rise time measurement for ultrafast X-ray pulses

    DOEpatents

    Celliers, Peter M.; Weber, Franz A.; Moon, Stephen J.

    2005-04-05

    A pump-probe scheme measures the rise time of ultrafast x-ray pulses. Conventional high speed x-ray diagnostics (x-ray streak cameras, PIN diodes, diamond PCD devices) do not provide sufficient time resolution to resolve rise times of x-ray pulses on the order of 50 fs or less as they are being produced by modern fast x-ray sources. Here, we are describing a pump-probe technique that can be employed to measure events where detector resolution is insufficient to resolve the event. The scheme utilizes a diamond plate as an x-ray transducer and a p-polarized probe beam.

  1. Subnanosecond-rise-time, low-impedance pulse generator

    SciTech Connect

    Druce, R.; Vogtlin, G.

    1983-06-03

    This paper describes a fast rise, low-impedance pulse generator that has been developed at the Lawrence Livermore National Laboratory. The design specifications of this generator are: 50-kV operating voltage, 1-ohm output impedance, subnanosecond rise time, and a 2 to 10 nanosecond pulse length. High repetition rate is not required. The design chosen is a parallel-plate, folded Blumlein generator. A tack switch is utilized for its simple construction and high performance. The primary diagnostic is a capacitive voltage divider with a B probe used to measure the current waveform.

  2. SNLS: Supernova Rise Times from the SNLS Sample

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Hook, I.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Perett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Sullivan, M.; Taillet, R.; Baumont, S.; Bronder, J.; Lusset, V.; Ripoche, P.; Mourao, A.; Perlmutter, S.; Tao, C.

    2005-12-01

    Type Ia supernovae (SNe Ia) provide the most direct evidence for the acceleration of the Universe. This evidence relies on a comparison between the luminosities of distant and nearby SNe Ia, and hence is potentially sensitive to any evolution in the mean lightcurve properties between these two samples. One method for testing for the presence of such effects is to measure and compare the rise time, which is the time between explosion and maximum luminosity, of the two samples. The Supernova Legacy Survey provides an excellent data sample for the analysis of this issue, since it's 'rolling search' nature yields lightcurves which are well sampled prior to maximum light. Here we discuss measurements of the rise time from SNLS data and what they can tell us about evolutionary effects.

  3. A note on some statistical properties of rise time parameters used in muon arrival time measurements

    NASA Technical Reports Server (NTRS)

    Vanderwalt, D. J.; Devilliers, E. J.

    1985-01-01

    Most investigations of the muon arrival time distribution in EAS during the past decade made use of parameters which can collectively be called rise time parameters. The rise time parameter T sub A/B is defined as the time taken for the integrated pulse from a detector to rise from A% to B% of its full amplitude. The use of these parameters are usually restricted to the determination of the radial dependence thereof. This radial dependence of the rise time parameters are usually taken as a signature of the particle interaction characteristics in the shower. As these parameters have a stochastic nature, it seems reasonable that one should also take notice of this aspect of the rise time parameters. A statistical approach to rise time parameters is presented.

  4. Functional Domain Motions in Proteins on the 1 100 ns Timescale: Comparison of Neutron Spin-Echo Spectroscopy of Phosphoglycerate Kinase with Molecular-Dynamics Simulation

    SciTech Connect

    Smolin, Nikolai; Biehl, R; Kneller, Gerald; Richter, Dieter O; Smith, Jeremy C

    2011-01-01

    Protein function often requires large-scale domain motion. An exciting new development in the experimental characterization of domain motions in proteins is the application of neutron spin-echo spectroscopy (NSE). NSE directly probes coherent (i.e., pair correlated) scattering on the 1 100 ns timescale. Here, we report on all-atom molecular-dynamics (MD) simulation of a protein, phosphoglycerate kinase, from which we calculate small-angle neutron scattering (SANS) and NSE scattering properties. The simulation-derived and experimental-solution SANS results are in excellent agreement. The contributions of translational and rotational whole-molecule diffusion to the simulation-derived NSE and potential problems in their estimation are examined. Principal component analysis identifies types of domain motion that dominate the internal motion's contribution to the NSE signal, with the largest being classic hinge bending. The associated free-energy profiles are quasiharmonic and the frictional properties correspond to highly overdamped motion. The amplitudes of the motions derived by MD are smaller than those derived from the experimental analysis, and possible reasons for this difference are discussed. The MD results confirm that a significant component of the NSE arises from internal dynamics. They also demonstrate that the combination of NSE with MD is potentially useful for determining the forms, potentials of mean force, and time dependence of functional domain motions in proteins.

  5. Neural processing of amplitude and formant rise time in dyslexia.

    PubMed

    Peter, Varghese; Kalashnikova, Marina; Burnham, Denis

    2016-06-01

    This study aimed to investigate how children with dyslexia weight amplitude rise time (ART) and formant rise time (FRT) cues in phonetic discrimination. Passive mismatch responses (MMR) were recorded for a/ba/-/wa/contrast in a multiple deviant odd-ball paradigm to identify the neural response to cue weighting in 17 children with dyslexia and 17 age-matched control children. The deviant stimuli had either partial or full ART or FRT cues. The results showed that ART did not generate an MMR in either group, whereas both partial and full FRT cues generated MMR in control children while only full FRT cues generated MMR in children with dyslexia. These findings suggest that children, both controls and those with dyslexia, discriminate speech based on FRT cues and not ART cues. However, control children have greater sensitivity to FRT cues in speech compared to children with dyslexia. PMID:27017263

  6. Supernova Rates, Rise-Times, and their Relations to Progenitors

    NASA Astrophysics Data System (ADS)

    Gonzalez Gaitan, Santiago

    Supernovae are fundamental in astronomy: they inject high mass elements into the interstellar medium enriching the chemistry of galaxies, they feed processes of star formation and active galactic nuclei, and they have been a key for the developments in cosmology of the past decades. This dissertation presents a set of subluminous type Ia supernovae (SNe Ia) at z > 0.1 from the Supernova Legacy Survey (SNLS). These faint and short-lived transients are found in massive and passive host galaxies. We measure a volumetric rate as a function of redshift that is different from the normal SN Ia population. The observations point towards a long delay time since the birth of the progenitors systems and argue for progenitor stars of initial low mass. We calculate a stretch-corrected rise-time since explosion to maximum brightness for different sets of SNe Ia. We find that a fiducial 17 day quadratic rise is sufficient to explain all SNe Ia, including subluminous ones, arguing for their homogeneity throughout the entire light-curve. Subluminous SNe Ia are powered by as little as 0.05 solar masses of radioactive nickel synthesized in the explosion. Theoretical models need to explain these challenging weak explosions within the framework of SNe Ia. Finally, we develop one of the first robust automated techniques to identify plateau supernovae (SNe IIP) in large photometric transient surveys. This simple method was tested with a variety of real and simulated SN samples and proved to be effective across different redshifts. Such a photometric typing will be of great power for coming surveys and will allow numerous scientific studies of SNe IIP.

  7. Study of the effect of current rise time on the formation of the precursor column in cylindrical wire array Z pinches at 1 MA

    SciTech Connect

    Bott, S. C.; Haas, D. M.; Eshaq, Y.; Ueda, U.; Beg, F. N.; Hammer, D. A.; Kusse, B.; Greenly, J.; Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Douglass, J. D.; Bell, K.; Knapp, P.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki Vidal, F. A.

    2009-07-15

    The limited understanding of the mechanisms driving the mass ablation rate of cylindrical wires arrays is presently one of the major limitations in predicting array performance at the higher current levels required for inertial confinement fusion (ICF) ignition. Continued investigation of this phenomenon is crucial to realize the considerable potential for wire arrays to drive both ICF and inertial fusion energy, by enabling a predictive capability in computational modeling. We present the first study to directly compare the mass ablation rates of wire arrays as a function of the current rise rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250ns [Mitchell et al., Rev. Sci. Instrum. 67, 1533 (1996)]) and COBRA (1 MA, 100ns [Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]) generators, and results are used to infer the change in the effective ablation velocity induced by the rise rate of the drive current. Laser shadowography, gated extreme ultraviolet (XUV) imaging, and x-ray diodes are used to compare the dynamical behavior on the two generators, and X-pinch radiography and XUV spectroscopy provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model developed previously from MAGPIE data, based on a fixed ablation velocity. For COBRA the column formation time occurs at 116{+-}5 ns and for Al arrays and 146{+-}5 ns for W arrays, with Al column temperature in the range of 70-165 eV. These values lie close to model predictions, inferring only a small change in the ablation velocity is induced by the factor of 2.5 change in current rise time. Estimations suggest the effective ablation velocities for MAGPIE and COBRA experiments vary by a maximum of 30%.

  8. A sub-nanosecond rise time intense electron beam source

    NASA Astrophysics Data System (ADS)

    Kumar, R.; Chandra, R.; Mitra, S.; Beg, M. D.; Sharma, D. K.; Sharma, A.; Mittal, K. C.

    2014-04-01

    This paper presents the design and development of a 75 kV, 55 A, 2 nanosecond duration, <= 850 ps rise time, single shot, intense ( >= 100 A/cm2) electron beam source and also the measurement technique adopted in sub-nanosecond regime. A 200 kV (nanosecond pulse) coaxial pulse forming line (PFL) based pulser is designed to drive a cold cathode explosive emission electron gun. The electron gun diode consists with a planer graphite cathode, which has the emission area of 8 mm diameter and a SS 304L anode mesh. Vacuum is achieved of the order of 3.5e-5 mbar by using a diffusion pump, backed by rotary pump. At the diagnostic side for diode voltage measurement a fast response copper sulphate aqueous solution resistive voltage divider is designed and implemented. For the beam current diagnostic a graphite Faraday cup is designed with taking care of response time in GHz (1.0-3.0 GHz) regime. The circuit diagram, voltage and current waveforms and the experimental setup is presented.

  9. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia Laboratories and HCEI.

    SciTech Connect

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A. , Tomsk, Russia); Kim, Alexandre A. , Tomsk, Russia); Wakeland, Peter Eric; McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry, Jr.; Struve, Kenneth William; Savage, Mark Edward; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-09-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory. An extensive evaluation of the LTD technology is being performed at SNL and the High Current Electronic Institute (HCEI) in Tomsk Russia. Two types of High Current LTD cavities (LTD I-II, and 1-MA LTD) were constructed and tested individually and in a voltage adder configuration (1-MA cavity only). All cavities performed remarkably well and the experimental results are in full agreement with analytical and numerical calculation predictions. A two-cavity voltage adder is been assembled and currently undergoes evaluation. This is the first step towards the completion of the 10-cavity, 1-TW module. This MYKONOS voltage adder will be the first ever IVA built with a transmission line insulated with deionized water. The LTD II cavity renamed LTD III will serve as a test bed for evaluating a number of different types of switches, resistors, alternative capacitor configurations, cores

  10. High-power megavolt pulse generator with nanosecond rise time

    SciTech Connect

    Basov, G.F.; Bastrikov, A.N.; Koval`chuk, B.M.

    1995-10-01

    A pulse generator with a power of 0.1 TW, an amplitude of up to 2 MV and {approximately}1.5-nsec rise time is described. A Marx voltage pulse generator charges a low-inductance capacitor (1.8 nF) and a radial line (0.9 nF) to a voltage of {approximately}2 MV in 200 nsec. At the peak voltage, a water switch is actuated at the center of the radial line resulting in {approximately} 2.5-MV voltage pulse at the end of the line. This pulse propagates along the oil-insulated line. The line is connected to an oil-filled peaking switch with a metal diaphragm, which reduces the transfer capacitance of the discharge gap to 5 pF to match the radial-line wave impedance to the load connected to the switch output. A crossover switch may be used when operating in the short-pulse mode. A pulse with a width of up to 20 nsec has been generated across a load equivalent matched to the line.

  11. Fast rise time IR detectors for lepton colliders

    NASA Astrophysics Data System (ADS)

    Drago, A.; Bini, S.; Cestelli Guidi, M.; Marcelli, A.; Pace, E.

    2016-07-01

    Diagnostics is a fundamental issue for accelerators whose demands are continuously increasing. In particular bunch-by-bunch diagnostics is a key challenge for the latest generation of lepton colliders and storage rings. The Frascati Φ-factory, DAΦNE, colliding at 1.02 GeV in the centre of mass, hosts in the main rings few synchrotron radiation beamlines and two of them collect the synchrotron radiation infrared emission: SINBAD from the electron ring and 3+L from the positron ring. At DAΦNE each bucket is 2.7 ns long and particles are gathered in bunches emitting pulsed IR radiation, whose intensity in the long wavelength regime is directly proportional to the accumulated particles. Compact uncooled photoconductive HgCdTe detectors have been tested in both beamlines using dedicated optical layouts. Actually, the fast rise time of HgCdTe semiconductors give us the chance to test bunch-by-bunch devices for both longitudinal and transverse diagnostics. For the longitudinal case, single pixel detectors have been used, while for the transverse diagnostics, multi-pixel array detectors, with special custom design, are under test. This contribution will briefly describe the status of the research on fast IR detectors at DAΦNE, the results obtained and possible foreseen developments.

  12. Measurements of Magneto-Rayleigh-Taylor Instability Growth during the Implosion of Initially Solid Al Tubes Driven by the 20-MA, 100-ns Z Facility

    SciTech Connect

    Sinars, D. B.; Slutz, S. A.; Herrmann, M. C.; McBride, R. D.; Cuneo, M. E.; Peterson, K. J.; Vesey, R. A.; Nakhleh, C.; Tomlinson, K.; Edens, A. D.; Lopez, M. R.; Smith, I. C.; Shores, J.; Bigman, V.; Bennett, G. R.; Atherton, B. W.; Savage, M.; Stygar, W. A.; Leifeste, G. T.; Porter, J. L.

    2010-10-29

    The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast ({approx}100 ns) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of 25-400 {mu}m were used to seed the instability. Radiographs with 15 {mu}m resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to 50 {mu}m wavelengths.

  13. Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

    NASA Astrophysics Data System (ADS)

    Zhou, Lin; Li, Zhenghong; Wang, Zhen; Liang, Chuan; Li, Mingjia; Qi, Jianmin; Chu, Yanyun

    2016-03-01

    The linear-transformer-driver (LTD) is a recently developed pulsed-power technology that shows great promise for a number of applications. These include a Z -pinch-driven fission-fusion-hybrid reactor that is being developed by the Chinese Academy of Engineering Physics. In support of the reactor development effort, we are planning to build an LTD-based accelerator that is optimized for driving wire-array Z -pinch loads. The accelerator comprises six modules in parallel, each of which has eight series 0.8-MA LTD cavities in a voltage-adder configuration. Vacuum transmission lines are used from the interior of the adder to the central vacuum chamber where the load is placed. Thus the traditional stack-flashover problem is eliminated. The machine is 3.2 m tall and 12 m in outer diameter including supports. A prototype cavity was built and tested for more than 6000 shots intermittently at a repetition rate of 0.1 Hz. A novel trigger, in which only one input trigger pulse is needed by utilizing an internal trigger brick, was developed and successfully verified in these shots. A full circuit modeling was conducted for the accelerator. The simulation result shows that a current pulse rising to 5.2 MA in 91 ns (10%-90%) can be delivered to the wire-array load, which is 1.5 cm in height, 1.2 cm in initial radius, and 1 mg in mass. The maximum implosion velocity of the load is 32 cm /μ s when compressed to 0.1 of the initial radius. The maximum kinetic energy is 78 kJ, which is 11.7% of the electric energy stored in the capacitors. This accelerator is supposed to enable a radiation energy efficiency of 20%-30%, providing a high efficient facility for research on the fast Z pinch and technologies for repetition-rate-operated accelerators.

  14. Effect of Current Rise-time on the Formation of Precursor Structures and Mass Ablation Rate in Cylindrical Wire Array Z-Pinches

    SciTech Connect

    Bott, S. C.; Eshaq, Y.; Ueda, U.; Haas, D. M.; Beg, F. N.; Hammer, D. A.; Kusse, B.; Greenly, J.; Shelkovenko, T. A.; Pikuz, S. A.; Blesener, I. C.; McBride, R. D.; Douglass, J. D.; Bell, K.; Knapp, P.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Hall, G. N.; Suzuki, F. A.

    2009-01-21

    We present the first study to directly compare the mass ablation rates of cylindrical wire arrays as a function of the current rise-rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250 ns) and COBRA (1 MA, 100 ns) generators, and results are used to infer the change in the mass ablation rate induced by the rise-rate of the drive current. Laser shadowography, gated XUV imaging and x-ray diodes are used to compare the dynamical behavior both generators, and x-pinch radiography and XUV spectroscopy and provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model based on a fixed ablation rate, and the close correlation achieved suggests that the effective ablation velocity is not a strong function of the current rise rate.

  15. Abrupt rise of new machine ecology beyond human response time

    PubMed Central

    Johnson, Neil; Zhao, Guannan; Hunsader, Eric; Qi, Hong; Johnson, Nicholas; Meng, Jing; Tivnan, Brian

    2013-01-01

    Society's techno-social systems are becoming ever faster and more computer-orientated. However, far from simply generating faster versions of existing behaviour, we show that this speed-up can generate a new behavioural regime as humans lose the ability to intervene in real time. Analyzing millisecond-scale data for the world's largest and most powerful techno-social system, the global financial market, we uncover an abrupt transition to a new all-machine phase characterized by large numbers of subsecond extreme events. The proliferation of these subsecond events shows an intriguing correlation with the onset of the system-wide financial collapse in 2008. Our findings are consistent with an emerging ecology of competitive machines featuring ‘crowds' of predatory algorithms, and highlight the need for a new scientific theory of subsecond financial phenomena. PMID:24022120

  16. Coefficient of restitution dependence of intruder rise time in two-dimensional Brazil-nut effect

    NASA Astrophysics Data System (ADS)

    Kesuma, T.; Aji, D. P. Purwa; Viridi, S.; Suprijadi

    2016-04-01

    Brazil-Nut Effect (BNE) is a granular material phenomenon, where larger grains (usually known as intruder) rise to the top when the granular system vibrated. We observe a single intruder rise time of BNE phenomenon in a two-dimensional molecular dynamics simulation of hard spheres collision scheme. Some experiments have shown that some granular properties, such as size and density ratio, play an important role to determine the rise time. However, other property, such as coefficients of restitution, is considered not to have a measurable impact. We explore the intruder inelasticity dependence of the rise time by varying its coefficient of restitution. We found that the intruder rise time tends to be flat for relatively high coefficient of restitution and increases exponentially below a certain deflecting point for low coefficient of restitution. This holds for specific mass ratio.

  17. High voltage electrical amplifier having a short rise time

    DOEpatents

    Christie, David J.; Dallum, Gregory E.

    1991-01-01

    A circuit, comprising an amplifier and a transformer is disclosed that produces a high power pulse having a fast response time, and that responds to a digital control signal applied through a digital-to-analog converter. The present invention is suitable for driving a component such as an electro-optic modulator with a voltage in the kilovolt range. The circuit is stable at high frequencies and during pulse transients, and its impedance matching circuit matches the load impedance with the output impedance. The preferred embodiment comprises an input stage compatible with high-speed semiconductor components for amplifying the voltage of the input control signal, a buffer for isolating the input stage from the output stage; and a plurality of current amplifiers connected to the buffer. Each current amplifier is connected to a field effect transistor (FET), which switches a high voltage power supply to a transformer which then provides an output terminal for driving a load. The transformer comprises a plurality of transmission lines connected to the FETs and the load. The transformer changes the impedance and voltage of the output. The preferred embodiment also comprises a low voltage power supply for biasing the FETs at or near an operational voltage.

  18. Dependence of current rise time on laser-triggered discharge plasma

    NASA Astrophysics Data System (ADS)

    Lim, Soowon; Kamohara, Takashi; Hosseini, S. Hamid R.; Katsuki, Sunao

    2016-07-01

    A powerful, stable extreme ultraviolet (EUV) source is the most important component for EUV lithography and EUV mask inspection. Here, we investigate the characteristics of laser-triggered discharge plasma at three different current rise times, fast, middle and slow. A height-adjustable coaxial birdcage was used to change circuit inductance. The rise time was varied between 30 ns–55 ns with peak current of 10 kA. The time-integrated EUV (at 13.5 nm in 2% bandwidth) intensity for the fast rise time was found to be 55% stronger than that of the slow rise time despite its lower energy. A high-speed Mach–Zehnder interferogram and visible imaging of the pinch plasma were employed to discuss plasma compression processes qualitatively and quantitatively. Also discharge produced debris was investigated using a silicon-crystal witness plate. The fast rise current was found to have advantages such as lower debris, higher EUV intensity, and possibility of suppressing instability in comparison with the slow rise time. As expected, total debris amounts lessened proportionally to the primary charged energy, as found from a comparison of fast and slow rise currents.

  19. Influence of voltage rise time on microwave generation in relativistic backward wave oscillator

    NASA Astrophysics Data System (ADS)

    Wu, Ping; Sun, Jun; Teng, Yan; Deng, Yuqun; Shi, Yanchao; Chen, Changhua

    2015-10-01

    In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-long SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.

  20. Influence of voltage rise time on microwave generation in relativistic backward wave oscillator

    SciTech Connect

    Wu, Ping; Deng, Yuqun; Sun, Jun; Teng, Yan; Shi, Yanchao; Chen, Changhua

    2015-10-15

    In relativistic backward wave oscillators (RBWOs), although the slow wave structure (SWS) and electron beam determine the main characteristics of beam-wave interaction, many other factors can also significantly affect the microwave generation process. This paper investigates the influence of voltage rise time on beam-wave interaction in RBWOs. Preliminary analysis and PIC simulations demonstrate if the voltage rise time is moderately long, the microwave frequency will gradually increase during the startup process until the voltage reaches its amplitude, which can be explained by the dispersion relation. However, if the voltage rise time is long enough, the longitudinal resonance of the finitely-long SWS will force the RBWO to work with unwanted longitudinal modes for a while and then gradually hop to the wanted longitudinal mode, and this will lead to an impure microwave frequency spectrum. Besides, a longer voltage rise time will delay the startup process and thus lead to a longer microwave saturation time. And if unwanted longitudinal modes are excited due to long voltage rise time, the microwave saturation time will be further lengthened. Therefore, the voltage rise time of accelerators adopted in high power microwave technology should not be too long in case unwanted longitudinal modes are excited.

  1. CONSTRAINING PHYSICAL PROPERTIES OF TYPE IIn SUPERNOVAE THROUGH RISE TIMES AND PEAK LUMINOSITIES

    SciTech Connect

    Moriya, Takashi J.; Maeda, Keiichi

    2014-08-01

    We investigate the diversity in the wind density, supernova ejecta energy, and ejecta mass in Type IIn supernovae based on their rise times and peak luminosities. We show that the wind density and supernova ejecta properties can be estimated independently if both the rise time and peak luminosity are observed. The peak luminosity is mostly determined by the supernova properties and the rise time can be used to estimate the wind density. We find that the ejecta energies of Type IIn supernovae need to vary by factors of 0.2-5 from the average if their ejecta masses are similar. The diversity in the observed rise times indicates that their wind densities vary by factors of 0.2-2 from the average. We show that Type IIn superluminous supernovae should have not only large wind density but also large ejecta energy and/or small ejecta mass to explain their large luminosities and the rise times at the same time. We also note that shock breakout does not necessarily occur in the wind even if it is optically thick, except for the case of superluminous supernovae, and we analyze the observational data both with and without assuming that the shock breakout occurs in the dense wind of Type IIn supernovae.

  2. Rise Time of the Simulated VERITAS 12 m Davies-Cotton Reflector

    SciTech Connect

    White, Richard J.

    2005-02-21

    The Very Energetic Radiation Imaging Telescope Array System (VERITAS) will utilise Imaging Atmospheric Cherenkov Telescopes (IACTs) based on a Davies-Cotton design with f-number f/1.0 to detect cosmic gamma-rays. Unlike a parabolic reflector, light from the Davies-Cotton does not arrive isochronously at the camera. Here the effect of the telescope geometry on signal rise-time is examined. An almost square-pulse arrival time profile with a rise time of 1.7 ns is found analytically and confirmed through simulation.

  3. Transistorized Marx bank pulse circuit provides voltage multiplication with nanosecond rise-time

    NASA Technical Reports Server (NTRS)

    Jung, E. A.; Lewis, R. N.

    1968-01-01

    Base-triggered avalanche transistor circuit used in a Marx bank pulser configuration provides voltage multiplication with nanosecond rise-time. The avalanche-mode transistors replace conventional spark gaps in the Marx bank. The delay time from an input signal to the output signal to the output is typically 6 nanoseconds.

  4. Rise Time. Operational Control Tests for Wastewater Treatment Facilities. Instructor's Manual [and] Student Workbook.

    ERIC Educational Resources Information Center

    Carnegie, John W.

    The rise time test (along with the settleometer procedure) is used to monitor sludge behavior in the secondary clarifier of an activated sludge system. The test monitors the effect of the nitrification/denitrification process and aids the operator in determining optimum clarifier sludge detention time and, to some extent, optimum degree of…

  5. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  6. Measurement of the Rise-Time in a Single Sided Ladder Detector

    SciTech Connect

    Gerber, C.E.; /Fermilab

    1997-11-10

    In this note we report on the measurement of the preamplifier output rise time for a SVXII chip mounted on a D0 single sided ladder. The measurements were performed on the ladder 001-883-L, using the laser test stand of Lab D. The rise time was measured for different values of the response (or bandwidth) of the preamplifier. As a bigger bandwidth results in longer rise times and therefore in less noise, the largest possible bandwidth consistent with the time between bunch crossings should be chosen to operate the detectors. The rise time is defined as the time elapsed between 10% and 90% of the charge is collected. It is also interesting to measure the time for full charge collection and the percentage of charge collected in 132 ns and 396 ns. The results are shown in table 1, for bandwidths between 2 and 63 (binary numbers). The uncertainty on the time measurement is considered to be {approx} 10 ns. Figure 1 schematically defines the four quantities measured: rise time, time of full charge collection, and percentage of charge collected in 132 ns and 396 ns. Figures 2 to 8 are the actual measurements for bandwidths of 2, 4, 8, 12, 24, 32 and 63. Figure 9 is a second measurement for BW=24, used as a consistency check of the system and the time measurement performed on the plots. The data indicate that the single sided ladders can be operated at BW=63 for 396 ns and BW=12 for 132 ns, achieving full charge collection. This will result in smaller noise than originally anticipated.

  7. Extremum seeking-based optimization of high voltage converter modulator rise-time

    SciTech Connect

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2013-02-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetition rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.

  8. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  9. Brainstem auditory evoked responses in man. 1: Effect of stimulus rise-fall time and duration

    NASA Technical Reports Server (NTRS)

    Hecox, K.; Squires, N.; Galambos, R.

    1975-01-01

    Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.

  10. Rise Time Perception in Children with Reading and Combined Reading and Language Difficulties

    ERIC Educational Resources Information Center

    Beattie, Rachel L.; Manis, Franklin R.

    2013-01-01

    Using a non-speech-specific measure of prosody, rise time perception, Goswami and her colleagues have found that individuals with dyslexia perform significantly worse than nonimpaired readers. Studies have also found that children and adults with specific language impairment were impaired on these tasks. Despite the high comorbidity of these…

  11. Rise Time Perception and Detection of Syllable Stress in Adults with Developmental Dyslexia

    ERIC Educational Resources Information Center

    Leong, Victoria; Hamalainen, Jarmo; Soltesz, Fruzsina; Goswami, Usha

    2011-01-01

    Introduction: The perception of syllable stress has not been widely studied in developmental dyslexia, despite strong evidence for auditory rhythmic perceptual difficulties. Here we investigate the hypothesis that perception of sound rise time is related to the perception of syllable stress in adults with developmental dyslexia. Methods: A…

  12. DOI Determination by Rise Time Discrimination in Single-Ended Readout for TOF PET Imaging

    PubMed Central

    Wiener, R.I.; Surti, S.; Karp, J.S.

    2013-01-01

    Clinical TOF PET systems achieve detection efficiency using thick crystals, typically of thickness 2–3cm. The resulting dispersion in interaction depths degrades spatial resolution for increasing radial positions due to parallax error. Furthermore, interaction depth dispersion results in time pickoff dispersion and thus in degraded timing resolution, and is therefore of added concern in TOF scanners. Using fast signal digitization, we characterize the timing performance, pulse shape and light output of LaBr3:Ce, CeBr3 and LYSO. Coincidence timing resolution is shown to degrade by ~50ps/cm for scintillator pixels of constant cross section and increasing length. By controlling irradiation depth in a scintillator pixel, we show that DOI-dependence of time pickoff is a significant factor in the loss of timing performance in thick detectors. Using the correlated DOI-dependence of time pickoff and charge collection, we apply a charge-based correction to the time pickoff, obtaining improved coincidence timing resolution of <200ps for a uniform 4×4×30mm3 LaBr3 pixel. In order to obtain both DOI identification and improved timing resolution, we design a two layer LaBr3[5%Ce]/LaBr3[30%Ce] detector of total size 4×4×30mm3, exploiting the dependence of scintillator rise time on [Ce] in LaBr3:Ce. Using signal rise time to determine interaction layer, excellent interaction layer discrimination is achieved, while maintaining coincidence timing resolution of <250ps and energy resolution <7% using a R4998 PMT. Excellent layer separation and timing performance is measured with several other commercially-available TOF photodetectors, demonstrating the practicality of this design. These results indicate the feasibility of rise time discrimination as a technique for measuring event DOI while maintaining sensitivity, timing and energy performance, in a well-known detector architecture. PMID:24403611

  13. Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems

    PubMed Central

    2014-01-01

    Background Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Methods Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. Results The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. Conclusions In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery. PMID:25074069

  14. Accurate measurement of the rise and decay times of fast scintillators with solid state photon counters

    NASA Astrophysics Data System (ADS)

    Seifert, S.; Steenbergen, J. H. L.; van Dam, H. T.; Schaart, D. R.

    2012-09-01

    In this work we present a measurement setup for the determination of scintillation pulse shapes of fast scintillators. It is based on a time-correlated single photon counting approach that utilizes the correlation between 511 keV annihilation photons to produce start and stop signals in two separate crystals. The measurement is potentially cost-effective and simple to set up while maintaining an excellent system timing resolution of 125 ps. As a proof-of-concept the scintillation photon arrival time histograms were recorded for two well-known, fast scintillators: LYSO:Ce and LaBr3:5%Ce. The scintillation pulse shapes were modeled as a linear combination of exponentially distributed charge transfer and photon emission processes. Correcting for the system timing resolution, the exponential time constants were extracted from the recorded histograms. A decay time of 43 ns and a rise time of 72 ps were determined for LYSO:Ce thus demonstrating the capability of the system to accurately measure very fast rise times. In the case of LaBr3:5%Ce two processes were observed to contribute to the rising edge of the scintillation pulse. The faster component (270 ps) contributes with 72% to the rising edge of the scintillation pulse while the second, slower component (2.0 ns) contributes with 27%. The decay of the LaBr3:5%Ce scintillation pulse was measured to be 15.4 ns with a small contribution (2%) of a component with a larger time constant (130 ns).

  15. Rise and fall time behavior of the gyrotron backward-wave oscillator.

    PubMed

    Pao, K F; Chang, T H; Chen, S H; Chu, K R

    2006-10-01

    The rise and fall time behavior of a pulsed microwave oscillator is a problem of academic interest. It is also of importance to radar and other applications because it can lead to phase and frequency jitters or even lock the entire pulse into an undesired mode. Here we present a study of the rise and fall time behavior in the gyrotron backward-wave oscillator (gyro-BWO). Single-mode simulations reveal that, during the rise and fall portions of the electron beam pulse, oscillation frequencies of the axial modes vary in such a way that their transit angles remain at the respective optimum values. Thus, axial mode competition and mode switching can readily take place in these transient stages. Time-dependent simulations demonstrate that, under both the gradual and instant turn-on conditions, the axial modes compete in a pattern governed by the characteristic asymmetry of the mode profiles. Other aspects of physics interest include the analysis and explanation of a resultant hysteresis effect between the rise and fall portions of the beam pulse. These understandings are expected to provide the basis for achieving a stable gyro-BWO operating at a single mode throughout the entire beam pulse. PMID:17155180

  16. Pulse Rise Time Characterization of a High Pressure Xenon Gamma Detector for use in Resolution Enhancement

    SciTech Connect

    TROYER, G.L.

    2000-08-25

    High pressure xenon ionization chamber detectors are possible alternatives to traditional thallium doped sodium iodide (NaI(Tl)) and hyperpure germanium as gamma spectrometers in certain applications. Xenon detectors incorporating a Frisch grid exhibit energy resolutions comparable to cadmium/zinc/telluride (CZT) (e.g. 2% {at} 662keV) but with far greater sensitive volumes. The Frisch grid reduces the position dependence of the anode pulse risetimes, but it also increases the detector vibration sensitivity, anode capacitance, voltage requirements and mechanical complexity. We have been investigating the possibility of eliminating the grid electrode in high-pressure xenon detectors and preserving the high energy resolution using electronic risetime compensation methods. A two-electrode cylindrical high pressure xenon gamma detector coupled to time-to-amplitude conversion electronics was used to characterize the pulse rise time of deposited gamma photons. Time discrimination was used to characterize the pulse rise time versus photo peak position and resolution. These data were collected to investigate the effect of pulse rise time compensation on resolution and efficiency.

  17. Effect of air on energy and rise-time spectra measured by proportional gas counter

    SciTech Connect

    Kawano, T.; Tanaka, M.; Isozumi, S.; Isozumi, Y.; Tosaki, M.; Sugiyama, T.

    2015-03-15

    Air exerts a negative effect on radiation detection using a gas counter because oxygen contained in air has a high electron attachment coefficient and can trap electrons from electron-ion pairs created by ionization from incident radiation in counting gas. This reduces radiation counts. The present study examined the influence of air on energy and rise-time spectra measurements using a proportional gas counter. In addition, a decompression procedure method was proposed to reduce the influence of air and its effectiveness was investigated. For the decompression procedure, the counting gas inside the gas counter was decompressed below atmospheric pressure before radiation detection. For the spectrum measurement, methane as well as various methane and air mixtures were used as the counting gas to determine the effect of air on energy and rise-time spectra. Results showed that the decompression procedure was effective for reducing or eliminating the influence of air on spectra measurement using a proportional gas counter. (authors)

  18. Fast Rise Time and High Voltage Nanosecond Pulses at High Pulse Repetition Frequency

    NASA Astrophysics Data System (ADS)

    Miller, Kenneth E.; Ziemba, Timothy; Prager, James; Picard, Julian; Hashim, Akel

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is conducting research to decrease the rise time and increase the output voltage of the EHT Nanosecond Pulser product line, which allows for independently, user-adjustable output voltage (0 - 20 kV), pulse width (20 - 500 ns), and pulse repetition frequency (0 - 100 kHz). The goals are to develop higher voltage pulses (50 - 60 kV), decrease the rise time from 20 to below 10 ns, and maintain the high pulse repetition capabilities. These new capabilities have applications to pseudospark generation, corona production, liquid discharges, and nonlinear transmission line driving for microwave production. This work is supported in part by the US Navy SBIR program.

  19. Rise time of voltage pulses in NbN superconducting single photon detectors

    NASA Astrophysics Data System (ADS)

    Smirnov, K. V.; Divochiy, A. V.; Vakhtomin, Yu. B.; Sidorova, M. V.; Karpova, U. V.; Morozov, P. V.; Seleznev, V. A.; Zotova, A. N.; Vodolazov, D. Yu.

    2016-08-01

    We have found experimentally that the rise time of voltage pulse in NbN superconducting single photon detectors increases nonlinearly with increasing the length of the detector L. The effect is connected with dependence of resistance of the detector Rn, which appears after photon absorption, on its kinetic inductance Lk and, hence, on the length of the detector. This conclusion is confirmed by our calculations in the framework of two temperature model.

  20. Extremum seeking-based optimization of high voltage converter modulator rise-time

    DOE PAGESBeta

    Scheinker, Alexander; Bland, Michael; Krstic, Miroslav; Audia, Jeff

    2014-01-01

    We digitally implement an extremum seeking (ES) algorithm, which optimizes the rise time of the output voltage of a high voltage converter modulator (HVCM) at the Los Alamos Neutron Science Center (LANSCE) HVCM test stand by iteratively, simultaneously tuning the first 8 switching edges of each of the three phase drive waveforms (24 variables total). We achieve a 50 μs rise time, which is reduction in half compared to the 100 μs achieved at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. Considering that HVCMs typically operate with an output voltage of 100 kV, with a 60Hz repetitionmore » rate, the 50 μs rise time reduction will result in very significant energy savings. The ES algorithm will prove successful, despite the noisy measurements and cost calculations, confirming the theoretical results that the algorithm is not affected by noise whose frequency components are independent of the perturbing frequencies.« less

  1. Effects of lung time constant, gas analyser delay and rise time on measurements of respiratory dead-space.

    PubMed

    Tang, Yongquan; Turner, Martin J; Baker, A Barry

    2005-12-01

    This study evaluated effects of mechanical time constants (tau(m)) of the respiratory system, delays between flow and CO(2) partial pressure (P(CO)(2)) signals and rise time of the CO(2) analyser on dead-space measurements. A computer model simulated low alveolar dead-space, high alveolar dead-space, 0.2 time delays and anatomic and physiological dead-spaces were calculated. The CO(2) analyser was simulated as a critically damped second-order system with 10-90% rise times of 25-400 ms. The error in measured dead-space increases approximately 2.5% per 10 ms signal delay for normal lungs (tau(m) = 1 s), but has low sensitivity (0.58% per 10 ms) to the rise time of the CO(2) analyser. Sensitivity of physiological dead-space, but not anatomic dead-space to delay is decreased in high alveolar dead-space and abnormal V/Q distribution. Shorter tau(m) increase the error sensitivity of both physiological and anatomic dead-spaces to both delay and rise time. P(CO)(2) and flow should be well synchronized, particularly when tau(m) are short, to avoid dead-space errors. PMID:16311457

  2. Effect of stratification and geometrical spreading on sonic boom rise time

    NASA Technical Reports Server (NTRS)

    Cleveland, Robin O.; Hamilton, Mark F.; Blackstock, David T.

    1994-01-01

    The purpose of our investigation is to determine the effect of unsteadiness (not associated with turbulence) on rise time. The unsteadiness considered here is due to (1) geometrical spreading, (2) stratification, which includes variation in density, temperature, and relative humidity, and (3) N shaped waveform. A very general Burgers equation, which includes all these effects, is the propagation model for our study. The equation is solved by a new computational algorithm in which all the calculations are done in the time domain. The present paper is a progress report in which some of the factors contributing to unsteadiness are studied, namely geometrical spreading and variation in relative humidity. The work of Pierce and Kang, which motivated our study, is first reviewed. We proceed with a discussion of the Burgers equation model and the algorithm for solving the equation. Some comparison tests to establish the validity of the algorithm are presented. The algorithm is then used to determine the distance required for a steady-state shock, on encountering an abrupt change in relative humidity, to reach a new steady state based on the new humidity. It is found that the transition distance for plane shocks of amplitude 70 Pa is about 4 km when the change in relative humidity is 10 percent. Shocks of amplitude 140 Pa require less distance. The effect of spherical and cylindrical spreading is also considered. We demonstrate that a spreading shock wave never reaches steady state and that its rise time will be less than the equivalent steady state shock. Finally we show that an N wave has a slightly shorter rise time than a step shock of the same amplitude.

  3. Rise Times of Solar Energetic Particle Events and Speeds of CMEs

    NASA Astrophysics Data System (ADS)

    Kahler, S.; Reames, D.

    2002-12-01

    Gradual solar energetic particle (SEP) events are assumed to be produced in coronal and interplanetary shocks driven by fast coronal mass ejections (CMEs). These fast CMEs are decelerated as they move through the slower ambient solar wind. However, the Alfven speed is decreasing with increasing distance. Faster CMEs may therefore continue to drive strong shocks for longer characteristic times than do the slower CMEs, such that shock production and injection of SEPs of a given energy will also continue longer with the faster CMEs. We test this proposition observationally by comparing the times to maxima of 20 MeV SEP events with the observed speeds of associated CMEs. The SEP/CME events are sorted by solar longitude to factor out the longitudinal dependence of the SEP rise times. A preliminary analysis comparing 20 MeV protons from the GSFC EPACT detector on the Wind satellite with CMEs observed by the LASCO coronagraph on the SOHO spacecraft showed a correlation between SEP rise times and CME speeds. We expand the database to include the 1996-2001 period for a more definitive test of the correlation. The implications of the results will be discussed.

  4. CHARACTERISTICS OF A FAST RISE TIME POWER SUPPLY FOR A PULSED PLASMA REACTOR FOR CHEMICAL VAPOR DESTRUCTION

    EPA Science Inventory

    Rotating spark gap devices for switching high-voltage direct current (dc) into a corona plasma reactor can achieve pulse rise times in the range of tens of nanoseconds. The fast rise times lead to vigorous plasma generation without sparking at instantaneous applied voltages highe...

  5. Subjective response to sonic booms having different shapes, rise times, and durations

    NASA Technical Reports Server (NTRS)

    Mccurdy, David A.

    1994-01-01

    Two laboratory experiments were conducted to quantify the subjective response of people to simulated outdoor sonic booms having different pressure signatures. The specific objectives of the experiments were to compare subjective response to sonic booms when described in terms of 'loudness' and 'annoyance'; to determine the ability of various noise metrics to predict subjective response to sonic booms; to determine the effects on subjective response of rise time, duration, and level; and to compare the subjective response to 'N-wave' sonic boom signatures with the subjective response to 'minimized' sonic boom signatures. The experiments were conducted in a computer-controlled, man-rated sonic boom simulator capable of reproducing user-specified pressure signatures for a wide range of sonic boom parameters. One hundred and fifty sonic booms representing different combinations of two wave shapes, four rise times, seven durations, and three peak overpressures were presented to 36 test subjects in each experiment. The test subjects in the first experiment made judgments of 'loudness' while the test subjects in the second experiment judged 'annoyance.' Subjective response to sonic booms was the same whether expressed in terms of loudness or in terms of annoyance. Analyses of several different noise metrics indicated that A-weighted sound exposure level and Perceived Level were the best predictors of subjective response. Further analyses indicated that, of these two noise metrics, only Perceived Level completely accounted for the effects of wave shape, rise time, and peak overpressure. Neither metric fully accounted for the effect of duration. However, the magnitude of the duration effect was small over the very wide range of durations considered.

  6. Rise time in 20-32 keV impulsive X-radiation

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.; Takakura, T.

    1974-01-01

    A new property of the X-ray impulsive component observed in solar flares is discussed, giving attention to the relation between the slope of the electron power spectrum and the rise time in the 20-32 keV X-ray spike. This particular energy range was chosen because it offered the greatest number of impulsive events while being sufficiently high to avoid contamination by soft X radiation. It is found for the thin-target model that the electron spectrum tends to be softer when the acceleration rate is smaller.

  7. Rise time of inverted triangular prism intruder in vibrating granular bed: Experiments and model

    NASA Astrophysics Data System (ADS)

    Nuraini, N.; Adriani, I. K.; Baladram, M. S.; Viridi, S.

    2012-05-01

    Experiment results and a qualitative model of the phenomenon called Brazil nut effect (BNE) with inverted triangular prism are reported in this work. The model is constructed by considering some forces (earth gravitational force, buoyant force, and fluid viscous force) and using Newton's second law of motion. The rise time of BNE T is defined as time needed for the intruder to be on granular surface with all of his parts (no part is still immersed in the granular bed). One side of the triangular base of the intruder l is varied from 1.5 to 5 cm with other two sides are kept in constant values (1 and 3 cm). It has been observed in experiment that l with value 3-4 cm gives the smaller rise time. Plot of T versus l has the form of concave up parabolic curve with minimum lies at l between 3-4 cm. This observation has been confirmed by the proposed model with the same order of magnitude and similar curve trend.

  8. Rise time and response measurements on a LiSOCl2 cell

    NASA Technical Reports Server (NTRS)

    Bastien, Caroline; Lecomte, Eric J.

    1992-01-01

    Dynamic impedance tests were performed on a 180 Ah LiSOCl2 cell in the frame of a short term work contract awarded by Aerospatiale as part of the Hermes Space Plane development work. These tests consisted of rise time and response measurements. The rise time test was performed to show the ability to deliver 4 KW, in the nominal voltage range (75-115 V), within less than 100 microseconds, and after a period at rest of 13 days. The response measurements test consisted of step response and frequency response tests. The frequency response test was performed to characterize the response of the LiSOCl2 cell to a positive or negative load step of 10 A starting from various currents. The test was performed for various depths of discharge and various temperatures. The test results were used to build a mathematical, electrical model of the LiSOCl2 cell which are also presented. The test description, test results, electrical modelization description, and conclusions are presented.

  9. Evolution of the solar radius during the solar cycle 24 rise time

    NASA Astrophysics Data System (ADS)

    Meftah, Mustapha

    2015-08-01

    One of the real motivations to observe the solar radius is the suspicion that it might be variable. Possible temporal variations of the solar radius are important as an indicator of internal energy storage and as a mechanism for changes in the total solar irradiance. Measurements of the solar radius are of great interest within the scope of the debate on the role of the Sun in climate change. Solar energy input dominates the surface processes (climate, ocean circulation, wind, etc.) of the Earth. Thus, it appears important to know on what time scales the solar radius and other fundamental solar parameters, like the total solar irradiance, vary in order to better understand and assess the origin and mechanisms of the terrestrial climate changes. The current solar cycle is probably going to be the weakest in 100 years, which is an unprecedented opportunity for studying the variability of the solar radius during this period. This paper presents more than four years of solar radius measurements obtained with a satellite and a ground-based observatory during the solar cycle 24 rise time. Our measurements show the benefit of simultaneous measurements obtained from ground and space observatories. Space observations are a priori most favourable, however, space entails also technical challenges, a harsh environment, and a finite mission lifetime. The evolution of the solar radius during the rising phase of the solar cycle 24 show small variations that are out of phase with solar activity.

  10. Fluorescence Rise Time Measurements for High Temperature Fluorescence-Based Thermometry

    SciTech Connect

    Allison, S.W.

    2005-03-24

    Certain ceramic-like phosphor materials exhibit bright fluorescence with a pronounced temperature dependence over a range which spans the cryogenic to 1700 C, depending on the specific phosphor. To measure temperature, a surface, for instance a turbine blade, is coated with the material. An optical system, sometimes including optical fibers, conveys stimulating light and collects the emission for analysis. Either emission intensity or decay time may indicate temperature. Previously fielded tests have involved surfaces such as blades, vanes, pistons, in-take valves, sheets of galvanneal steel, etc. The fluorescent coatings may be applied to small parts via sputtering methods or to large areas by mixture with inorganic binders. Presented here are results characterizing fluorescence rise times as a means of determining temperature from ambient to 700 C for Y{sub 2}O{sub 3}:Eu.

  11. Generation of high-voltage pulses with subnanosecond front rise times in open discharge

    SciTech Connect

    Bokhan, P. A.; Gugin, P. P.; Lavrukhin, M. A.; Zakrevsky, Dm. E.

    2013-03-15

    The investigation results for plasma switching devices of high-voltage pulses with pulse rise times less than 1 ns are presented. The approach is based on using conditions suitable for bringing a gas discharge chamber in a state with high conductivity due to generation of an electron beam owing to photoelectron emission from the device cathode. It is shown that in co-axial geometry pulses, switching time 0.45 ns on an active load R{sub L} = 50 {Omega} at voltage U = 20 kV can be achieved. It is shown with the method of doubled impulses that such a device can regenerate the acceptable electric strength during 10 {mu}s. It is indicated of the principle possibility of working in the pulse-periodical regime to the repetition rate of 100 kHz.

  12. Moon Rise

    NASA Video Gallery

    Aboard the International Space Station in May 2012, Expedition 31 astronaut Don Pettit opened the shutters covering the cupola observation windows in time to watch the moon rise. The time-lapse sce...

  13. High-Voltage Power Supply With Fast Rise and Fall Times

    NASA Technical Reports Server (NTRS)

    Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

    2007-01-01

    A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

  14. The Rise Time of Type Ia Supernovae from the Supernova Legacy Survey

    NASA Astrophysics Data System (ADS)

    Conley, A.; Howell, D. A.; Howes, A.; Sullivan, M.; Astier, P.; Balam, D.; Basa, S.; Carlberg, R. G.; Fouchez, D.; Guy, J.; Hook, I.; Neill, J. D.; Pain, R.; Perrett, K.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Aubourg, E.; Bronder, J.; Ellis, R. S.; Fabbro, S.; Filiol, M.; Le Borgne, D.; Palanque-Delabrouille, N.; Perlmutter, S.; Ripoche, P.

    2006-10-01

    We compare the rise times of nearby and distant Type Ia supernovae (SNe Ia) as a test for evolution using 73 high-redshift spectroscopically confirmed SNe Ia from the first 2 years of the 5 year Supernova Legacy Survey (SNLS) and published observations of nearby SNe. Because of the ``rolling'' search nature of the SNLS, our measurement is approximately 6 times more precise than previous studies, allowing for a more sensitive test of evolution between nearby and distant SNe. Adopting a simple t2 early-time model (as in previous studies), we find that the rest-frame B rise times for a fiducial SN Ia at high and low redshift are consistent, with values 19.10+0.18-0.17(stat)+/-0.2(syst) and 19.58+0.22-0.19 days, respectively; the statistical significance of this difference is only 1.4 σ. The errors represent the uncertainty in the mean rather than any variation between individual SNe. We also compare subsets of our high-redshift data set based on decline rate, host galaxy star formation rate, and redshift, finding no substantive evidence for any subsample dependence. Based on observations obtained with MegaPrime/MegaCam, a joint project of the Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at CFHT, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of NRC and CNRS.

  15. Temporal features of spectral integration in the inferior colliculus: effects of stimulus duration and rise time.

    PubMed

    Gans, Donald; Sheykholeslami, Kianoush; Peterson, Diana Coomes; Wenstrup, Jeffrey

    2009-07-01

    This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16-31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11-32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals<23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range-frequencies in the first sonar harmonic-generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway. PMID:19403742

  16. Diffusion of fast rising strong magnetic fields into conductors

    NASA Astrophysics Data System (ADS)

    Labetskaya, N. A.; Oreshkin, V. I.; Chaikovsky, S. A.; Datsko, I. M.; Kuskova, N. I.; Rud, A. D.

    2014-11-01

    The basic processes occurring in a conductor exploding in a current skinning mode are the propagation of a nonlinear magnetic diffusion wave in the conductor and the formation of low-temperature plasma at its surface. An experimental study of the phenomenon of nonlinear magnetic diffusion into conductors in magnetic fields of induction rising at a rate up to 3·109 T/s was carried out on the MIG generator capable of producing a peak current up to 2.5 MA within a rise time of 100 ns. It has been found experimentally that the average velocity of a nonlinear magnetic diffusion wave in an aluminum conductor placed in a strong magnetic field (up to 300 T) rising at a high rate (on average, 3·109 T/s) is (2.7÷3.3)·105 cm/s. This is comparable to the velocity of sound in aluminum under normal conditions and reasonably agrees with predictions of numerical simulations.

  17. Distinguishing Between Electrons and γ-Rays in Experiment TGV Using a Pulse Rise Time

    NASA Astrophysics Data System (ADS)

    Čermák, P.; Štekl, I.; Beneš, P.; Brudanin, V. B.; Rukhadze, N. I.; Egorov, V. G.; Kovalenko, V. E.; Kovalík, A.; Pismenniy, R.; Salamatin, A. V.; Timkin, V.; Vylov, Ts.; Vénos, D.

    2002-04-01

    The TGV (Telescope Germanium Vertical) collaboration is interested in the measurement of double-beta decay of 48Ca (TGV I) and 106Cd (TGV II). The background in the experiment TGV I has been suppressed by several methods. One of them was based on distinguishing between electrons and -rays due to the different rise time of the signals obtained from semiconductor detector. Two experimental setups have been tested, the first one used a charge-sensitive analog-to-digital converter, while the second one utilized digital oscilloscope. The reduction of the background counting rate (due to -rays) in single HPGe detector by a factor of (1.4-3.8) was reached.

  18. Breakdown in Atmospheric Pressure Plasma Jets: Nearby Grounds and Voltage Rise Time

    NASA Astrophysics Data System (ADS)

    Lietz, Amanda; Kushner, Mark J.

    2015-09-01

    Atmospheric pressure plasma jets (APPJs) are being investigated to stimulate therapeutic responses in biological systems. These responses are not always consistent. One source of variability may be the design of the APPJs - the number and placement of electrodes, pulse power format - which affects the production of reactive species. In this study, the consequences of design parameters of an APPJ were computationally investigated using nonPDPSIM, a 2 d model. The configuration is a cylindrical tube with one or two ring exterior electrodes, with or without a center pin electrode. The APPJ operates in He/O2 flowing into humid air. We found that the placement of the electrical ground on and around the system is important to the breakdown characteristics of the APPJ, and the electron density and temperature of the resulting plasma. With a single powered ring electrode, the placement of the nearest ground may vary depending on the setup, and this significantly affects the discharge. With two-ring electrodes, the nearest ground plane is well defined, however more distant ground planes can also influence the discharge. With an ionization wave (IW) that propagates out of the tube and into the plume in tens of ns, the rise time of the voltage waveform can be on the same timescale, and so variations in the voltage rise time could produce different IW properties. The effect of ground placement and voltage waveform on IW formation (ns timescales) and production of reactive neutrals (ms timescales) will be discussed. Work supported by DOE (DE-SC0001319) and NSF (CHE-1124724). Done...processed 598 records...15:12:56

  19. A hybrid model for simulation of secondary electron emission in plasma immersion ion implantation under different pulse rise time

    SciTech Connect

    Navab Safa, N. Ghomi, H.

    2015-02-15

    A hybrid fluid Particle in Cell–Monte Carlo Collision (PiC–MCC) model is presented to study the effect of secondary electron emission on the plasma immersion ion implantation process under different pulse rise time. The model describes the temporal evolution of various parameters of plasma such as ion density, ion velocity, secondary electron density, and secondary electron current for different rise times. A 3D–3 V PiC–MCC model is developed to simulate the secondary electrons which are emitted from the sample surface while the plasma ions and electrons are treated using a 1D fluid model. The simulation results indicate that the secondary electron density and secondary electron current increase as the rise time decreases. The main differences between the results for different rise times are found during the initial phase of the pulse. The results are explained through studying the fundamental parameters of plasma.

  20. Rapid rise time pulsed magnetic field circuit for pump-probe field effect studies.

    PubMed

    Salaoru, T A; Woodward, Jonathan R

    2007-03-01

    Here we describe an electronic circuit capable of producing rapidly switched dc magnetic fields of up to 20 mT with a rise time of 10 ns and a pulse length variable from 50 ns to more than 10 micros, suitable for use in the study of magnetic field effects on radical pair (RP) reactions. This corresponds to switching the field on a time scale short relative to the lifetime of typical RPs and maintaining it well beyond their lifetimes. Previous experiments have involved discharging a capacitor through a low inductance coil for a limited time using a switching circuit. These suffer from decaying field strength over the duration of the pulse given primarily by the ratio of the pulse width to the RC constant of the circuit. We describe here a simple yet elegant solution that completely eliminates this difficulty by employing a feedback loop. This allows a constant field to be maintained over the entire length of the pulse. PMID:17411229

  1. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    SciTech Connect

    Hanson, D.L.; Spielman, R.B.; Seamen, J.F.; Struve, K.W.

    1993-07-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel application of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B{sup 2}/2{mu}{sub 0} = {mu}{sub 0}I{sup 2}/8{pi}{sup 2}r{sup 2} generated at radius r by a current I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode on a Y-cut lithium niobate stress gauge, current densities up to 1/2{pi}cr = 78MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20--25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a cooper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  2. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    NASA Astrophysics Data System (ADS)

    Hanson, D. L.; Spielman, R. B.; Seamen, J. F.; Struve, K. W.

    1993-02-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel application of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B(sup 2)/2(mu)(sub 0) = (mu)(sub 0)I(sup 2)/8(pi)(sup 2)r(sup 2) generated at radius r by a current I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode on a Y-cut lithium niobate stress gauge, current densities up to 1/2(pi)cr = 78MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20-25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a copper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  3. Application of piezoelectric stress gauges to the measurement of fast-rise-time multimegampere electric currents

    NASA Astrophysics Data System (ADS)

    Hanson, D. L.; Struve, K. W.; Spielman, R. B.; Seamen, J. F.

    1994-07-01

    Modeling of load behavior in Z-pinch plasma radiation sources driven by high current generators requires accurate measurement of fast-rise-time multimegampere electrical currents close to the load. Using a novel applications of high pressure technology, we have demonstrated that fast-response piezoelectric stress transducers can measure such currents under conditions of extremely high current density, induced electric fields, and bremsstrahlung radiation where conventional current diagnostics fail. Large signal, nanosecond-time-resolution lithium niobate piezoelectric stress gauges are employed to directly measure the magnetic pressure B2/dμ0=μ0I2/ 8π2r2 generated at radius r by a curret I flowing in a radial transmission line near the load of a pulsed power current source. With a current diagnostic consisting of a pure tungsten electrode of a Y-cut lithium niobate stress gauge, current densities up to I/2πr=78 MA/m can be measured before the electrode yield strength and piezoelectric operating stress limit are exceeded. Based on this work, we have developed a compact modular current probe for use on the high current (20-25 MA) DECADE simulator being constructed for the Defense Nuclear Agency. We also describe recent work extending this measurement technique to higher current densities (125 MA/m) using a copper-sapphire electrode impedance stack on an X-cut quartz piezoelectric element.

  4. Timed Rise from Floor as a Predictor of Disease Progression in Duchenne Muscular Dystrophy: An Observational Study

    PubMed Central

    Mazzone, Elena S.; Coratti, Giorgia; Sormani, Maria Pia; Messina, Sonia; Pane, Marika; D'Amico, Adele; Colia, Giulia; Fanelli, Lavinia; Berardinelli, Angela; Gardani, Alice; Lanzillotta, Valentina; D’Ambrosio, Paola; Petillo, Roberta; Cavallaro, Filippo; Frosini, Silvia; Bello, Luca; Bonfiglio, Serena; De Sanctis, Roberto; Rolle, Enrica; Forcina, Nicola; Magri, Francesca; Vita, Gianluca; Palermo, Concetta; Donati, Maria Alice; Procopio, Elena; Arnoldi, Maria Teresa; Baranello, Giovanni; Mongini, Tiziana; Pini, Antonella; Battini, Roberta; Pegoraro, Elena; Torrente, Yvan; Previtali, Stefano C.; Bruno, Claudio; Politano, Luisa; Comi, Giacomo P.; D’Angelo, Maria Grazia; Bertini, Enrico; Mercuri, Eugenio

    2016-01-01

    Background The role of timed items, and more specifically, of the time to rise from the floor, has been reported as an early prognostic factor for disease progression and loss of ambulation. The aim of our study was to investigate the possible effect of the time to rise from the floor test on the changes observed on the 6MWT over 12 months in a cohort of ambulant Duchenne boys. Subjects and methods A total of 487 12-month data points were collected from 215 ambulant Duchenne boys. The age ranged between 5.0 and 20.0 years (mean 8.48 ±2.48 DS). Results The results of the time to rise from the floor at baseline ranged from 1.2 to 29.4 seconds in the boys who could perform the test. 49 patients were unable to perform the test at baseline and 87 at 12 month The 6MWT values ranged from 82 to 567 meters at baseline. 3 patients lost the ability to perform the 6mwt at 12 months. The correlation between time to rise from the floor and 6MWT at baseline was high (r = 0.6, p<0.01). Conclusions Both time to rise from the floor and baseline 6MWT were relevant for predicting 6MWT changes in the group above the age of 7 years, with no interaction between the two measures, as the impact of time to rise from the floor on 6MWT change was similar in the patients below and above 350 m. Our results suggest that, time to rise from the floor can be considered an additional important prognostic factor of 12 month changes on the 6MWT and, more generally, of disease progression. PMID:26982196

  5. A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener

    SciTech Connect

    Jaitly, N.C.; Coleman, M.D.; Ramrus, A.; Earley, L.M.; Downing, J.N.; Reisch, H.H.; Caudill, L.D.; Eversol, S.A.

    1992-09-01

    The DARHT Facility is being designed at Los Alamos national Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power supply (ICPPS) which provides 250 kV, 70 ns pulses via four Blumieins. Each Blumiein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumiein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described.

  6. Considerations for human exposure standards for fast-rise-time high-peak-power electromagnetic pulses.

    PubMed

    Merritt, J H; Kiel, J L; Hurt, W D

    1995-06-01

    Development of new emitter systems capable of producing high-peak-power electromagnetic pulses with very fast rise times and narrow pulse widths is continuing. Such directed energy weapons systems will be used in the future to defeat electronically vulnerable targets. Human exposures to these pulses can be expected during testing and operations. Development of these technologies for radar and communications purposes has the potential for wider environmental exposure, as well. Current IEEE C95.1-1991 human exposure guidelines do not specifically address these types of pulses, though limits are stated for pulsed emissions. The process for developing standards includes an evaluation of the relevant bioeffects data base. A recommendation has been made that human exposure to ultrashort electromagnetic pulses that engender electromagnetic transients, called precursor waves, should be avoided. Studies that purport to show the potential for tissue damage induced by such pulses were described. The studies cited in support of the recommendation were not relevant to the issues of tissue damage by propagated pulses. A number of investigations are cited in this review that directly address the biological effects of electromagnetic pulses. These studies have not shown evidence of tissue damage as a result of exposure to high-peak-power pulsed microwaves. It is our opinion that the current guidelines are sufficiently protective for human exposure to these pulses. PMID:7646411

  7. A 200 kV fast rise time, low jitter, trigger system with magnetic pulse sharpener

    SciTech Connect

    Jaitly, N.C.; Ramrus, A.; Coleman, M.D.; Earley, L.M.; Downing, J.N.; Reisch, H.H.; Caudill, L.D.; Eversol, S.A.

    1993-12-31

    The DARHT Facility is being designed at Los Alamos National Laboratory to produce high resolution flash radiographs of hydrodynamic experiments. Two linear induction accelerators (LIA), each in the range of 16 to 20 MeV, will be used to produce intense bremsstrahlung X-ray pulses of short duration (60 ns flat top). Each LIA will produce a 3 kA, high brightness, electron beam using a 4 MeV injector and a series of 250 kV induction cells. Technology demonstration of key accelerator subsystems is under progress at the DARHT Integrated Test Stand (ITS). The eight inductions cells present in the ITS are driven by a Maxwell prototype Induction Cell Pulsed Power Supply (ICPPS) which provides 250 kV, 70ns pulses via four Blumleins. Each Blumlein drives two cells and is triggered using independently controlled trigger units. This turnkey DARHT Trigger System, consisting of four separate trigger units, provides 200 kV trigger pulses with low jitter and fast rise time to each of the four Blumlein coaxial spark gaps. Details of the trigger system design and results obtained during extensive testing at Maxwell are described.

  8. Diversity of Decline-Rate-Corrected Type 1a Supernova Rise times:One Mode or Two?

    SciTech Connect

    Strovink, Mark

    2007-05-01

    B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernova (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 {+-} 0.36 days, while five SNe rise in 16.64 {+-} 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96{sub -0.25}{sup +0.52} days--a first measurement of this dispersion. The corresponding global mean rise time is 17.44 {+-} 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is {approx}2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by {approx}0.03 magnitudes.

  9. EARLY-PHASE PHOTOMETRY AND SPECTROSCOPY OF TRANSITIONAL TYPE Ia SN 2012ht: DIRECT CONSTRAINT ON THE RISE TIME

    SciTech Connect

    Yamanaka, Masayuki; Nogami, Daisaku; Maeda, Keiichi; Kawabata, Miho; Masumoto, Kazunari; Matsumoto, Katsura; Tanaka, Masaomi; Takaki, Katsutoshi; Ueno, Issei; Itoh, Ryosuke; Kawabata, Koji S.; Moritani, Yuki; Akitaya, Hiroshi; Yoshida, Michitoshi; Arai, Akira; Honda, Satoshi; Nishiyama, Koichi; Kabashima, Fujio

    2014-02-20

    We report photometric and spectroscopic observations of the nearby Type Ia Supernova (SN Ia) 2012ht from –15.8 days to +49.1 days after B-band maximum. The decline rate of the light curve is Δm {sub 15}(B) = 1.39 ± 0.05 mag, which is intermediate between normal and subluminous SNe Ia, and similar to that of the ''transitional'' Type Ia SN 2004eo. The spectral line profiles also closely resemble those of SN 2004eo. We were able to observe SN 2012ht at a very early phase, when it was still rising and was about three magnitudes fainter than at the peak. The rise time to the B-band maximum is estimated to be 17.6 ± 0.5 days and the time of the explosion is MJD 56277.98 ± 0.13. SN 2012ht is the first transitional SN Ia whose rise time is directly measured without using light curve templates, and the fifth SN Ia overall. This rise time is consistent with those of the other four SNe within the measurement error, even including the extremely early detection of SN 2013dy. The rising part of the light curve can be fitted by a quadratic function, and shows no sign of a shock-heating component due to the interaction of the ejecta with a companion star. The rise time is significantly longer than that inferred for subluminous SNe such as SN 1991bg, which suggests that a progenitor and/or explosion mechanism of transitional SNe Ia are more similar to normal SNe Ia rather than to subluminous SNe Ia.

  10. MOSFET solid state switching circuit improves the 0 to 99% rise time for framing camera deflection electronics

    SciTech Connect

    Rivera, A.T.; Thomas, S.

    1996-09-01

    We have improved the 0 to 99% rise time voltage on our 2 frame deflection plates from 160 to 65 nS with the addition of a peaking circuit that works in conjunction with our primary 2 frame deflection circuitry. Our peaking technique has applications to other HV pulsers including those which must drive 51 ohm loads. Generally, rise time voltages are measured between 10 and 90%. To minimize the camera image blur resulting from the dynamic influence of deflection plate potentials acting on photocathode electrons, it was necessary to design a circuit that would rise from 0 to the 99% voltage level in under 100nS. Once this voltage was reached, it was necessary to stay within 1% of the attained voltage level for a duration of 1 uS. This was accomplished with the use of MOSFET solid state switching.

  11. Turbulence Scales, Rise Times, Caustics, and the Simulation of Sonic Boom Propagation

    NASA Technical Reports Server (NTRS)

    Pierce, Allan D.

    1996-01-01

    The general topic of atmospheric turbulence effects on sonic boom propagation is addressed with especial emphasis on taking proper and efficient account of the contributions of the portion oi the turbulence that is associated with extremely high wavenumber components. The recent work reported by Bart Lipkens in his doctoral thesis is reexamined to determine whether the good agreement between his measured rise times with the 1971 theory of the author is fortuitous. It is argued that Lipken's estimate of the distance to the first caustic was a gross overestimate because of the use of a sound speed correlation function shaped like a gaussian curve. In particular, it is argued that the expected distance to the first caustic varies with the kinematic viscosity nu and the energy epsilon dissipated per unit mass per unit time, and the sound speed c as : d(sub first caustic) = nu(exp 7/12) c(exp 2/3)/ epsilon(exp 5/12)(nu x epsilon/c(exp 4))(exp a), where the exponent a is greater than -7/12 and can be argued to be either O or 1/24. In any event, the surprising aspect of the relationship is that it actually goes to zero as the viscosity goes to zero with s held constant. It is argued that the apparent overabundance of caustics can be grossly reduced by a general computational and analytical perspective that partitions the turbulence into two parts, divided by a wavenumber k(sub c). Wavenumbers higher than kc correspond to small-scale turbulence, and the associated turbulence can be taken into account by a renormalization of the ambient sound speed so that the result has a small frequency dependence that results from a spatial averaging over of the smaller-scale turbulent fluctuations. Selection of k(sub c). can be made so large that only a very small number of caustics are encountered if one adopts the premise that the frequency dispersion of pulses is caused by that part of the turbulence spectrum which lies in the inertial range originally predicted by Kolmogoroff. The

  12. Learning Novel Phonological Representations in Developmental Dyslexia: Associations with Basic Auditory Processing of Rise Time and Phonological Awareness

    ERIC Educational Resources Information Center

    Thomson, Jennifer M.; Goswami, Usha

    2010-01-01

    Across languages, children with developmental dyslexia are known to have impaired lexical phonological representations. Here, we explore associations between learning new phonological representations, phonological awareness, and sensitivity to amplitude envelope onsets (rise time). We show that individual differences in learning novel phonological…

  13. Interaction-powered Supernovae: Rise-time versus Peak-luminosity Correlation and the Shock-breakout Velocity

    NASA Astrophysics Data System (ADS)

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Sullivan, Mark; Gal-Yam, Avishay; Kulkarni, Shrinivas R.; Nugent, Peter E.; Ben-Ami, Sagi; Bersier, David; Cao, Yi; Cenko, S. Bradley; De Cia, Annalisa; Filippenko, Alexei V.; Fransson, Claes; Kasliwal, Mansi M.; Laher, Russ; Surace, Jason; Quimby, Robert; Yaron, Ofer

    2014-06-01

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ~104 km s-1). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  14. Interaction-powered supernovae: rise-time versus peak-luminosity correlation and the shock-breakout velocity

    SciTech Connect

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Gal-Yam, Avishay; Ben-Ami, Sagi; De Cia, Annalisa; Yaron, Ofer; Sullivan, Mark; Kulkarni, Shrinivas R.; Cao, Yi; Nugent, Peter E.; Bersier, David; Cenko, S. Bradley; Filippenko, Alexei V.; Fransson, Claes; Kasliwal, Mansi M.; Laher, Russ; Surace, Jason; Quimby, Robert

    2014-06-20

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ∼10{sup 4} km s{sup –1}). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  15. Universal relations for solitary waves in granular crystals under shocks with finite rise and decay times

    NASA Astrophysics Data System (ADS)

    Arif Hasan, M.; Nemat-Nasser, Sia

    2016-04-01

    We focus on solitary waves generated in arrays of lightly contacting spherical elastic granules by shock forces of steep rise and slow decay durations and establish a priori: (i) whether the peak value of the resulting solitary wave would be greater than, equal to, or less than the peak value of the input shock force; (ii) the magnitude of the peak value of the solitary waves; (iii) the magnitude of the linear momentum in each solitary wave; (iv) the magnitude of the linear momentum added to the remaining granules if the first granule is ejected; and (v) a quantitative estimate of the effect of the granules' radius, density, and stiffness on force amplification or mitigation. We have supported the analytical results by direct numerical simulations.

  16. Early to Rise? The Effect of Daily Start Times on Academic Performance

    ERIC Educational Resources Information Center

    Edwards, Finley

    2012-01-01

    Local school districts often stagger daily start times for their schools in order to reduce busing costs. This paper uses data on all middle school students in Wake County, NC from 1999 to 2006 to identify the causal effect of daily start times on academic performance. Using variation in start times within schools over time, the effect is a two…

  17. Spark-Timing Control Based on Correlation of Maximum-Economy Spark Timing, Flame-front Travel, and Cylinder-Pressure Rise

    NASA Technical Reports Server (NTRS)

    Cook, Harvey A; Heinicke, Orville H; Haynie, William H

    1947-01-01

    An investigation was conducted on a full-scale air-cooled cylinder in order to establish an effective means of maintaining maximum-economy spark timing with varying engine operating conditions. Variable fuel-air-ratio runs were conducted in which relations were determined between the spark travel, and cylinder-pressure rise. An instrument for controlling spark timing was developed that automatically maintained maximum-economy spark timing with varying engine operating conditions. The instrument also indicated the occurrence of preignition.

  18. Investigation of spatial gusts with extreme rise time on the extreme loads of pitch-regulated wind turbines

    NASA Astrophysics Data System (ADS)

    Bierbooms, Wim

    2005-01-01

    It is assumed that the extreme loading of pitch-regulated turbines is caused by gusts with an extreme rise time rather than an extreme gust amplitude. A special kind of wind field simulation, so-called constrained stochastic simulation, is dealt with in order to generate the desired gusts. Just as in wind field simulation for fatigue purposes, it is assumed that turbulence is Gaussian; a possibility is mentioned of how to deal with non-Gaussian behaviour. On the basis of the presented theory it can be stated that the stochastic gusts produced in this way are, in a statistical sense, not distinguishable from gusts selected from a (very long) time series. An example of a spatial gust as well as the mean spatial gust shape is shown. For a reference turbine the maximum blade root flapping moment has been determined as a function of the gust centre in the rotor plane; the maximum response is obtained in the case where the gust hits one of the rotor blades at 75% of the radius. When the gust duration is large compared with the integral time constant of the controller, the controller can handle the gust as expected. However, even for small rise times it turns out that the maximum flap moment due to the gust is not significantly higher than that due to the background turbulence and 1P excitations. This may indicate that perhaps extreme rise time gusts do not lead to extreme loading of pitch-regulated wind turbines. For a final judgement a proper probabilistic approach is necessary; an outline of such an approach has been sketched. Furthermore, it is recommended to do research on other gust types in order to find out the type which leads to the extreme wind turbine loading. Copyright

  19. Extracting Short Rise-Time Velocity Profiles with Digital Down-Shift Analysis of Optically Up-Converted PDV Data

    SciTech Connect

    Abel Diaz, Nathan Riley, Cenobio Gallegos, Matthew Teel, Michael Berninger, Thomas W. Tunnell

    2010-09-08

    This work describes the digital down-shift (DDS) technique, a new method of extracting short rise-time velocity profiles in the analysis of optically up-converted PDV data. The DDS technique manipulates the PDV data by subtracting a constant velocity (i.e., the DDS velocity νDDS) from the velocity profile. DDS exploits the simple fact that the optically up-converted data ride on top of a base velocity (ν0, the apparent velocity at no motion) with a rapid rise to a high velocity (νf) of a few km/s or more. Consequently, the frequency content of the signal must describe a velocity profile that increases from ν0 to ν0 + νf. The DDS technique produces velocity reversals in the processed data before shock breakout when ν0 < νDDS < ν0 + νf. The DDS analysis process strategically selects specific DDS velocities (velocity at which the user down shifts the data) that produce anomalous reversals (maxima and/or minima), which are predictable and easy to identify in the mid-range of the data. Additional analysis determines when these maxima and minima occur. By successive application of the DDS technique and iterative analysis, velocity profiles are extracted as time as a function of velocity rather than as a function of time as it would be in a conventional velocity profile. Presented results include a description of DDS, velocity profiles extracted from laser-driven shock data with rise times of 200 ps or less, and a comparison with other techniques.

  20. Simple scaling laws for influenza A rise time, duration, and severity.

    PubMed

    Chang, David B; Young, Carl S

    2007-06-21

    Simple scaling laws are developed for the severity and characteristic time scales of influenza A infection in man. The scaling laws are based on a model of the infection described by six coupled ordinary differential equations that describe the time courses of the numbers of infectious viral particles, activated cytotoxic T-lymphocytes, interferon molecules, infected cells, uninfected cells, and the subset of uninfected cells that are protected by interferon from viral infection. Computer simulations show that the disease can be regarded approximately as a two-stage process. In the first stage, the growth in the number of infected cells is determined primarily by the interferon-enhanced limitation in the available number of target cells. In the second stage, the bulk of the duration of the infection is determined mainly by the destruction of the infected cells by the cytotoxic T-lymphocytes. The severity and characteristic times of the infection are found to depend simply on the logarithm of the initial number of viruses. PMID:17379249

  1. Rise-time response of nickel-foil-on-Kapton-substrate, hot-film, shear-stress sensors

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.

    1991-01-01

    An existing nickel-foil-on-Kapton-substrate sensor design was modified by including two heated elements in an attempt to minimize or reduce substrate conduction effects. The rise-time responses of the original and modified sensors were then investigated in unsteady flows of 0.5-1-s duration, consistent with flows encountered in wind-energy applications. The results obtained indicate a measurable degradation in transient performance due to the activation of the dynamic guard heater. Transient heat conduction within the substrate remains the limiting factor in such applications.

  2. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    PubMed Central

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-01-01

    Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. Results: The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS. PMID:27559352

  3. A metacalibrated time-tree documents the early rise of flowering plant phylogenetic diversity.

    PubMed

    Magallón, Susana; Gómez-Acevedo, Sandra; Sánchez-Reyes, Luna L; Hernández-Hernández, Tania

    2015-07-01

    The establishment of modern terrestrial life is indissociable from angiosperm evolution. While available molecular clock estimates of angiosperm age range from the Paleozoic to the Late Cretaceous, the fossil record is consistent with angiosperm diversification in the Early Cretaceous. The time-frame of angiosperm evolution is here estimated using a sample representing 87% of families and sequences of five plastid and nuclear markers, implementing penalized likelihood and Bayesian relaxed clocks. A literature-based review of the palaeontological record yielded calibrations for 137 phylogenetic nodes. The angiosperm crown age was bound within a confidence interval calculated with a method that considers the fossil record of the group. An Early Cretaceous crown angiosperm age was estimated with high confidence. Magnoliidae, Monocotyledoneae and Eudicotyledoneae diversified synchronously 135-130 million yr ago (Ma); Pentapetalae is 126-121 Ma; and Rosidae (123-115 Ma) preceded Asteridae (119-110 Ma). Family stem ages are continuously distributed between c. 140 and 20 Ma. This time-frame documents an early phylogenetic proliferation that led to the establishment of major angiosperm lineages, and the origin of over half of extant families, in the Cretaceous. While substantial amounts of angiosperm morphological and functional diversity have deep evolutionary roots, extant species richness was probably acquired later. PMID:25615647

  4. Local time distributions of repetition periods for rising tone lower band chorus waves in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Shue, Jih-Hong; Hsieh, Yi-Kai; Tam, Sunny W. Y.; Wang, Kaiti; Fu, Hui Shan; Bortnik, Jacob; Tao, Xin; Hsieh, Wen-Chieh; Pi, Gilbert

    2015-10-01

    Whistler mode chorus waves generally occur outside the plasmapause in the magnetosphere. The most striking feature of the waves is their occurrence in discrete elements. One of the parameters that describe the discrete elements is the repetition period (Trp), the time between consecutive elements. The Trp has not been studied statistically before. We use high-resolution waveform data to derive distributions of Trp for different local times. We find that the average Trp for the nightside (0.56 s) and dawnside (0.53 s) are smaller than those for the dayside (0.81 s) and duskside (0.97 s). Through a comparison with the background plasma and magnetic fields, we also find that the total magnetic field and temperature are the main controlling factors that affect the variability of Trp. These results are important for understanding the generation mechanism of chorus and choosing parameters in simulations that model the acceleration and loss of electrons by wave-particle interactions.

  5. Composition and timing of carbonate vein precipitation within the igneous basement of the Early Cretaceous Shatsky Rise, NW Pacific

    NASA Astrophysics Data System (ADS)

    Geldmacher, J.; Li, S.; Hauff, F. F.; Garbe-Schoenberg, C.; Yu, S.; Zhao, S.; Rausch, S.

    2013-12-01

    Shatsky Rise is an Early Cretaceous large igneous province located in the NW Pacific ca. 1500 km east of Japan and is the third-largest oceanic plateau on Earth (after Ontong Java and Kerguelen). Numerous calcium carbonate veins were recovered from the igneous basement of Shatsky Rise during Integrated Ocean Drilling Program Expedition 324 (Sager et al., 2010). The chemical (Sr/Ca, Mg/Ca) and isotopic (87Sr/86Sr, 143Nd/144Nd, δ18O, δ13C) compositions of these veins were determined to constrain the timing of vein formation and to provide valuable data for the reconstruction of past seawater composition. A dominant control of seawater chemistry on calcite composition is evident for most investigated vein samples with varying compositional contribution from the basaltic basement. The Sr/Ca ratio of the vein calcite is positively correlated with Mg/Ca and with δ18O, indicating warmer/colder precipitation temperatures with decreasing/increasing Sr/Ca (and Mg/Ca) ratios, respectively. Distinctly higher formation temperatures (as inferred from oxygen isotope ratios) indicative of hydrothermal vein formation are only observed at one site (Site U1350, drilled into the central part of Shatsky Rise). The highest 87Sr/86Sr ratios (least basement influence) of vein samples at each drill site range form 0.707264 to 0.707550 and are believed to best reflect contemporaneous Early Cretaceous seawater composition. In principle, age information can be deduced by correlating these ratios with the global seawater Sr isotope evolution. Since the Sr isotopic composition of seawater has fluctuated three times between the early and mid Cretaceous (McArthur et al., 2001) no unambiguous precipitation ages can be constrained by this method and vein precipitation could have occurred at any time between ˜80 and 140 Ma. However, based on combined chemical and isotopic data and correlations of vein composition with formation depth and inferred temperature, we argue for a rather early

  6. TIME EVOLUTION OF PLASMA PARAMETERS DURING THE RISE OF A SOLAR PROMINENCE INSTABILITY

    SciTech Connect

    Orozco Suárez, D.; Asensio Ramos, A.; Trujillo Bueno, J.; Díaz, A. J.

    2014-04-10

    We present high-spatial resolution spectropolarimetric observations of a quiescent hedgerow prominence taken in the He I 1083.0 nm triplet. The observation consisted of a time series in sit-and-stare mode of ∼36 minutes duration. The spectrograph's slit crossed the prominence body and we recorded the time evolution of individual vertical threads. Eventually, we observed the development of a dark Rayleigh-Taylor plume that propagated upward with a velocity, projected onto the plane of the sky, of 17 km s{sup –1}. Interestingly, the plume apex collided with the prominence threads pushing them aside. We inferred Doppler shifts, Doppler widths, and magnetic field strength variations by interpreting the He I Stokes profiles with the HAZEL code. The Doppler shifts show that clusters of threads move coherently while individual threads have oscillatory patterns. Regarding the plume we found strong redshifts (∼9-12 km s{sup –1}) and large Doppler widths (∼10 km s{sup –1}) at the plume apex when it passed through the prominence body and before it disintegrated. We associate the redshifts with perspective effects while the Doppler widths are more likely due to an increase in the local temperature. No local variations of the magnetic field strength associated with the passage of the plume were found; this leads us to conclude that the plumes are no more magnetized than the surroundings. Finally, we found that some of the threads' oscillations are locally damped, what allowed us to apply prominence seismology techniques to infer additional prominence physical parameters.

  7. An advanced vision-based system for real-time displacement measurement of high-rise buildings

    NASA Astrophysics Data System (ADS)

    Lee, Jong-Han; Ho, Hoai-Nam; Shinozuka, Masanobu; Lee, Jong-Jae

    2012-12-01

    This paper introduces an advanced vision-based system for dynamic real-time displacement measurement of high-rise buildings using a partitioning approach. The partitioning method is based on the successive estimation of relative displacements and rotational angles at several floors using a multiple vision-based displacement measurement system. In this study, two significant improvements were made to realize the partitioning method: (1) time synchronization, (2) real-time dynamic measurement. Displacement data and time synchronization information are wirelessly transferred via a network using the TCP/IP protocol. The time synchronization process is periodically conducted by the master system to guarantee the system time at the master and slave systems are synchronized. The slave system is capable of dynamic real-time measurement and it is possible to economically expand measurement points at slave levels using commercial devices. To verify the accuracy and feasibility of the synchronized multi-point vision-based system and partitioning approach, many laboratory tests were carried out on a three-story steel frame model. Furthermore, several tests were conducted on a five-story steel frame tower equipped with a hybrid mass damper to experimentally confirm the effectiveness of the proposed system.

  8. Peri-parturient rise of Cryptosporidium oocysts in cows: new insights provided by duplex quantitative real-time PCR.

    PubMed

    De Waele, Valérie; Berzano, Marco; Speybroeck, Niko; Berkvens, Dirk; Mulcahy, Grace M; Murphy, Thomas M

    2012-10-26

    In order to clarify if a peri-parturient rise of Cryptosporidium parvum oocysts occurs in cows, faecal samples from 42 cows on two farms were collected. These samples were taken during the pre-parturient, the peri-parturient and the post-parturient periods. Two methods were used to detect the oocysts, a nested-PCR coupled with sequencing and a duplex real-time PCR (qPCR) that quantified Cryptosporidium spp. DNA concentration. The qPCR results were adjusted using a hierarchical Bayesian model taking into account within and between run variation. Generalised Estimating Equation models (GEE) were used to determine if peri-parturient cows were at greater risk of being infected than pre- or post-parturient cows. Fourteen dairy cows exhibited a peri-parturient and post-parturient rise in the excretion of Cryptosporidium spp. oocysts, other than the zoonotic C. parvum. The cows in the suckler beef farm were the only ones infected with the zoonotic species C. parvum at calving. Due to the low concentration of oocysts excreted mainly from species other than C. parvum, it would appear unlikely that cows act as a source of infection for their calves or contribute significantly to environmental contamination. PMID:22681972

  9. RISE TIME DELAY DISCRIMINATOR

    DOEpatents

    Johnstone, C.W.

    1959-09-29

    A pulse-height discriminator for generating an output pulse when the accepted input pulse is approximately at its maximum value is described. A gating tube and a negative bias generator responsive to the derivative of the input pulse and means for impressing the output of the bias generator to at least one control electrode of the gating tube are included.

  10. Investigation on F layer height rise and equatorial spread F onset time: Signature of standing large-scale wave

    NASA Astrophysics Data System (ADS)

    Joshi, Lalit Mohan; Balwada, S.; Pant, T. K.; Sumod, S. G.

    2015-04-01

    Equatorial spread F observations have been categorized into three categories based on ionograms recorded over Sriharikota. First category comprised cases where the onset of equatorial spread F (ESF) was concurrent with the peak h'F time. Second and third categories comprised cases where the onset of ESF happened with a delay of 30 min and more than 30 min, respectively, with reference to the peak h'F time. Average peak h'F in the first category was more than 35 km higher than that in the second and third categories. Also, the peak vertical (upward) plasma drift was higher in the first category. Assuming the genesis of F region irregularity to have happened at or before the time of F layer attaining the peak height, late onset of ESF indicates the genesis of irregularities to have happened westward of Sriharikota. The fact that the peak h'F values were remarkably different in the three categories indicates a zonal variation of eastward electric field and postsunset height rise of F layer. The relative magnitude of the F layer height rise in the three different categories over Sriharikota has also been found to be significantly different than that over Thumba, an equatorial (magnetic) station located ~360 km westward of Sriharikota longitude. This scenario points toward the existence of a large-scale zonal standing wave in the F layer and its important role in F region instability process. Results presented in the manuscript have been discussed in the light of current understanding on the large-scale wave structure.

  11. Time variant cross correlation to assess residence time of water and implication for hydraulics of a sink-rise karst system

    NASA Astrophysics Data System (ADS)

    Bailly-Comte, V.; Martin, Jonathan B.; Screaton, E. J.

    2011-05-01

    Transport rates and residence time in the subsurface are critical parameters for understanding water-rock interactions for efficient contaminant remediation. This paper presents a methodology for assessing flow and transit time of water through hydrological systems, with specific applications to karst systems and implication for hydraulics of a conduit system surrounded by a porous and permeable intergranular matrix. A time variant cross-correlation function analysis is applied to bivariate time series that characterize mass transfer, assuming a stationary system using sliding windows of various sizes. We apply the method to 1 year long temperature records in the Santa Fe River (north central Florida) measured at (1) the River Sink, where all the incoming surface water drains into a sinkhole, (2) Sweetwater Lake, where the river resurges into a 500 m long karst window, and (3) the River Rise, where the water discharges from a first-magnitude karst spring. Results are compared with those obtained using specific conductivity. Estimated residence time ranges from less than 1 day during floods to more than 15 days during base flow within the 8000 m flow path between the River Sink and the River Rise. Results are used to characterize geometric, hydraulic, and hydrodynamic properties of this sink-rise system with strong matrix-conduit interactions. These properties are critical to the chemical and physical behavior of surface water-groundwater mixing. Our results also have direct implications for sampling strategies and hydrograph separation of many karst systems with different degrees and types of matrix porosity and permeability.

  12. Development of a novel voltage divider for measurement of sub-nanosecond rise time high voltage pulses

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Senthil, K.; Singh, S. K.; Kumar, Ranjeet; Sharma, Archana

    2016-02-01

    This paper is about the development of a copper sulphate based aqueous-electrolytic voltage divider for the measurement of high voltage pulses, 100 kV, with pulse widths of 1-2 ns and rise time <1 ns. Novel features are incorporated in the design of the divider, to meet the performance requirements for the application. Analytical calculations to justify design are described. Structural simulation of the divider is carried out using field wave simulation software to verify the effectiveness. A calibration procedure has been developed to calibrate the divider. Results obtained during calibration are subjected to statistical analysis to determine the confidence of measurement. Details of design, analysis, and simulation are described in this paper.

  13. Fault plane orientations of microearthquakes at Mt. Etna from the inversion of P-wave rise times

    NASA Astrophysics Data System (ADS)

    de Lorenzo, Salvatore; Giampiccolo, Elisabetta; Martinez-Arevalo, Carmen; Patanè, Domenico; Romeo, Annalisa

    2010-01-01

    A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 low-magnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002-2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the "true" fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies.

  14. A TRANSIT TIMING ANALYSIS OF NINE RISE LIGHT CURVES OF THE EXOPLANET SYSTEM TrES-3

    SciTech Connect

    Gibson, N. P.; Pollacco, D.; Simpson, E. K.; Barros, S.; Joshi, Y. C.; Todd, I.; Keenan, F. P.; Skillen, I.; Benn, C.; Christian, D.; Hrudkova, M.; Steele, I. A.

    2009-08-01

    We present nine newly observed transits of TrES-3, taken as part of a transit timing program using the RISE instrument on the Liverpool Telescope. A Markov-Chain Monte Carlo analysis was used to determine the planet-star radius ratio and inclination of the system, which were found to be R{sub p} /R {sub *} = 0.1664{sup +0.0011} {sub -0.0018} and i = 81.73{sup +0.13} {sub -0.04}, respectively, consistent with previous results. The central transit times and uncertainties were also calculated, using a residual-permutation algorithm as an independent check on the errors. A re-analysis of eight previously published TrES-3 light curves was conducted to determine the transit times and uncertainties using consistent techniques. Whilst the transit times were not found to be in agreement with a linear ephemeris, giving {chi}{sup 2} = 35.07 for 15 degrees of freedom, we interpret this to be the result of systematics in the light curves rather than a real transit timing variation. This is because the light curves that show the largest deviation from a constant period either have relatively little out-of-transit coverage or have clear systematics. A new ephemeris was calculated using the transit times and was found to be T{sub c} (0) = 2454632.62610 {+-} 0.00006 HJD and P = 1.3061864 {+-} 0.0000005 days. The transit times were then used to place upper mass limits as a function of the period ratio of a potential perturbing planet, showing that our data are sufficiently sensitive to have probed sub-Earth mass planets in both interior and exterior 2:1 resonances, assuming that the additional planet is in an initially circular orbit.

  15. Copernicus Rising

    NASA Astrophysics Data System (ADS)

    Rose, Michael A.

    2007-08-01

    Copernicus Rising began as a historical biography when it was first conceived, but as the writing progressed it quickly became a rather absurd play that took historical research and twisted it through the lens of my own wit, philosophy and personal affection for the characters. When working with historical figures--characters who existed in a very tangible way in our own history--the playwriting process opens a dialogue between different points in time and space. The difficulty lies in finding a unique and clear voice amongst the discordant personalities involved in this time and space overlap, both in the writing and production processes, in order to get to the heart of what the play is really all about. This thesis follows the journey of the play from its historical roots through the creation of an absurd journey both insides and outside time, space and the human mind. The first part of the thesis explains the beginnings of the concept and outlines much of the research and development that went into the play. The next part outlines the process of production and integrating the world on paper with that of moving bodies on stage. In the final part, post-production discussions and audience feedback sessions shape the play into the draft included in this thesis.

  16. A comparative study of Type II-P and II-L supernova rise times as exemplified by the case of LSQ13cuw

    NASA Astrophysics Data System (ADS)

    Gall, E. E. E.; Polshaw, J.; Kotak, R.; Jerkstrand, A.; Leibundgut, B.; Rabinowitz, D.; Sollerman, J.; Sullivan, M.; Smartt, S. J.; Anderson, J. P.; Benetti, S.; Baltay, C.; Feindt, U.; Fraser, M.; González-Gaitán, S.; Inserra, C.; Maguire, K.; McKinnon, R.; Valenti, S.; Young, D.

    2015-10-01

    We report on our findings based on the analysis of observations of the Type II-L supernova LSQ13cuw within the framework of currently accepted physical predictions of core-collapse supernova explosions. LSQ13cuw was discovered within a day of explosion, hitherto unprecedented for Type II-L supernovae. This motivated a comparative study of Type II-P and II-L supernovae with relatively well-constrained explosion epochs and rise times to maximum (optical) light. From our sample of twenty such events, we find evidence of a positive correlation between the duration of the rise and the peak brightness. On average, SNe II-L tend to have brighter peak magnitudes and longer rise times than SNe II-P. However, this difference is clearest only at the extreme ends of the rise time versus peak brightness relation. Using two different analytical models, we performed a parameter study to investigate the physical parameters that control the rise time behaviour. In general, the models qualitatively reproduce aspects of the observed trends. We find that the brightness of the optical peak increases for larger progenitor radii and explosion energies, and decreases for larger masses. The dependence of the rise time on mass and explosion energy is smaller than the dependence on the progenitor radius. We find no evidence that the progenitors of SNe II-L have significantly smaller radii than those of SNe II-P. Appendices are available in electronic form at http://www.aanda.org

  17. Distinct Effect of Impact Rise Times on Immediate and Early Neuropathology After Brain Injury in Juvenile Rats

    PubMed Central

    Jayakumar, Archana; Pfister, Bryan J.; Santhakumar, Vijayalakshmi

    2015-01-01

    Traumatic brain injury (TBI) can occur from physical trauma from a wide spectrum of insults ranging from explosions to falls. The biomechanics of the trauma can vary in key features, including the rate and magnitude of the insult. Although the effect of peak injury pressure on neurological outcome has been examined in the fluid percussion injury (FPI) model, it is unknown whether differences in rate of rise of the injury waveform modify cellular and physiological changes after TBI. Using a programmable FPI device, we examined juvenile rats subjected to a constant peak pressure at two rates of injury: a standard FPI rate of rise and a faster rate of rise to the same peak pressure. Immediate postinjury assessment identified fewer seizures and relatively brief loss of consciousness after fast-rise injuries than after standard-rise injuries at similar peak pressures. Compared with rats injured at standard rise, fewer silver-stained injured neuronal profiles and degenerating hilar neurons were observed 4-6 hr after fast-rise FPI. However, 1 week postinjury, both fast- and standard-rise FPI resulted in hilar cell loss and enhanced perforant path-evoked granule cell field excitability compared with sham controls. Notably, the extent of neuronal loss and increase in dentate excitability were not different between rats injured at fast and standard rates of rise to peak pressure. Our data indicate that reduced cellular damage and improved immediate neurological outcome after fast rising primary concussive injuries mask the severity of the subsequent cellular and neurophysiological pathology and may be unreliable as a predictor of prognosis. PMID:24799156

  18. Investigation of the rise time and damping of spin excitations in Ni{sub 81}Fe{sub 19} thin films

    SciTech Connect

    Wu, J.; Hughes, N. D.; Moore, J. R.; Hicken, R. J.

    2001-06-01

    The rise and damping of spin excitations in three Ni{sub 81}Fe{sub 19} films of thickness 50, 500, and 5000 Aa have been studied with an optical pump{endash}probe technique in which the sample is pumped with an optically triggered magnetic field pulse. The motion of the magnetization was described by the uniform mode solution of the Landau{endash}Lifshitz{endash}Gilbert equation. The rise time of the pulsed field within the film was smallest in the 50 Aa sample and was generally greater when the pulsed field was perpendicular to the film plane. The damping constant was smallest in the 500 Aa sample. The variations in the rise time and damping are attributed to the presence of eddy currents and structural disorder in the films. Under certain excitation conditions a second mode was observed in the 5000 Aa sample which we believe to be a magnetostatic surface mode. {copyright} 2001 American Institute of Physics.

  19. Summary of Sonic Boom Rise Times Observed During FAA Community Response Studies over a 6-Month Period in the Oklahoma City Area

    NASA Technical Reports Server (NTRS)

    Maglieri, Domenic J.; Sothcott, Victor E.

    1990-01-01

    The sonic boom signature data acquired from about 1225 supersonic flights, over a 6-month period in 1964 in the Oklahoma City area, was enhanced with the addition of data relating to rise times and total signature duration. These later parameters, not available at the time of publication of the original report on the Oklahoma City sonic boom exposures, are listed in tabular form along with overpressure, positive impulse, positive duration, and waveform category. Airplane operating information along with the surface weather observations are also included. Sonic boom rise times include readings to the 1/2, 3/4, and maximum overpressure values. Rise time relative probabilities for various lateral locations from the ground track of 0, 5, and 10 miles are presented along with the variation of rise times with flight altitude. The tabulated signature data, along with corresponding airplane operating conditions and surface and upper level atmospheric information, are also available on electronic files to provide it in the format for more efficient and effective utilization.

  20. From RISING to the DESPEC fast-timing project within NUSTAR at FAIR: sub-nanosecond nuclear timing spectroscopy with LaBr3 scintillators.

    PubMed

    Regan, P H

    2012-07-01

    This paper summarises a presentation given at the IRRMA8 conference in June 2011 which reviewed briefly the topic of current research studies in the evolution of nuclear structure with changing proton and neutron numbers. A short review of relevant contemporary spectroscopic studies of the structure of nuclei with highly exotic N/Z ratios using projectile fragmentation and fission reactions is given, together with an overview of some of the physics research aims to be attacked using the proposed Decay Spectroscopy (DESPEC) LaBr3 Fast-Timing gamma-ray array for the NUSTAR project at the upcoming Facility for Anti-Proton and Ion Research (FAIR). Examples of recent results using both 'isomer' and β--delayed gamma-ray decay measurements with the Stopped RISING hyper-pure germanium array at GSI are summarised and used to highlight some of the fundamental physics studies which are expected to become available in this area of research in the coming decade. Examples of the performance of cerium-doped LaBr3 detectors from 'in-beam' test experiments are presented together with initial plans for the geometry of the planned multi-detector LaBr3(Ce) array for DESPEC. PMID:22285659

  1. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch.

    PubMed

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source. PMID:26521006

  2. Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch

    NASA Astrophysics Data System (ADS)

    Wu, Hanyu; Zhang, Xinjun; Sun, Tieping; Zeng, Zhengzhong; Cong, Peitian; Zhang, Shaoguo

    2015-10-01

    In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source.

  3. Time-resolved changes in equatorial x-ray diffraction and stiffness during rise of tetanic tension in intact length-clamped single muscle fibers.

    PubMed Central

    Cecchi, G; Griffiths, P J; Bagni, M A; Ashley, C C; Maeda, Y

    1991-01-01

    We report the first time-resolved x-ray diffraction studies on tetanized intact single muscle fibers of the frog. The 10, 11, 20, 21, 30, and Z equatorial reflections were clearly resolved in the relaxed fiber. The preparation readily withstood 100 1-s duration (0.4-s beam exposure) tetani at 4 degrees C (less than 4% decline of force and no deterioration in the 10, 11 equatorial intensity ratio at rest or during activation). Equatorial intensity changes (10 and 11) and fiber stiffness led tension (t1/2 lead 20 ms at 4 degrees C) during the tetanus rise and lagged during the isometric phase of relaxation. These findings support the existence of a low force cross-bridge state during the rise of tetanic tension and isometric relaxation that is not evident at the tetanus plateau. In "fixed end" tetani lattice expansion occurred with a time course similar to stiffness during the tetanus rise. During relaxation, lattice spacing increased slightly, while the sarcomere length remained isometric, but underwent large changes after the "shoulder" of tension. Under length clamp control, lattice expansion during the tetanus rise was reduced or abolished, and compression (2%) of the lattice was observed. A lattice compression is predicted by certain cross-bridge models of force generation (Schoenberg, M. 1980. Biophys. J. 30:51-68; Schoenberg, M. 1980. Biophys. J. 30:69-78). PMID:1873464

  4. Ciguatera Incidence in the US Virgin Islands Has Not Increased over a 30-Year Time Period Despite Rising Seawater Temperatures

    PubMed Central

    Radke, Elizabeth G.; Grattan, Lynn M.; Cook, Robert L.; Smith, Tyler B.; Anderson, Donald M.; Morris, J. Glenn

    2013-01-01

    Ciguatera fish poisoning is the most common marine food poisoning worldwide. It has been hypothesized that increasing seawater temperature will result in increasing ciguatera incidence. In St. Thomas, US Virgin Islands, we performed an island-wide telephone survey (N = 807) and a medical record review of diagnosed ciguatera cases at the emergency department of the sole hospital and compared these data with comparable data sources collected in 1980. Annual incidence from both recent data sources remained high (12 per 1,000 among adults in the telephone survey). However, the combined data sources suggest that incidence has declined by 20% or more or remained stable over 30 years, whereas seawater temperatures were increasing. Illness was associated with lower education levels, higher levels of fish consumption, and having previous episodes of ciguatera; population shifts from 1980 to 2010 in these factors could explain an incidence decline of approximately 3 per 1,000, obscuring effects from rising seawater temperature. PMID:23400575

  5. Anode initiated impulse breakdown in water: the dependence on pulse rise time for nanosecond and sub-nanosecond pulses and initiation mechanism based on electrostriction

    NASA Astrophysics Data System (ADS)

    Seepersad, Yohan; Fridman, Alexander; Dobrynin, Danil

    2015-10-01

    The effect of the voltage rise time on nanosecond and sub-nanosecond impulse breakdown of distilled water is studied. The dependence of anode initiated streamer inception on this parameter is shown to be more intricate than previously reported, particularly as it relates to mechanisms directly in the liquid phase. Dynamics of the emission phase for sub-nanosecond pulses with 600 ps rise time are presented to enable comparison with previous work on nanosecond initiation features. Schlieren imaging is also used to show the development of optical density perturbations and rarefactions as a result of electrostriction in the liquid which were previously found for nanosecond pulses as well. The mechanism of nanopore generation in the liquid due to fast impulses proposed by Shneider, Pekker and Fridman is used to explain the results.

  6. Picosecond transient absorption rise time for ultrafast tagging of the interaction of ionizing radiation with scintillating crystals in high energy physics experiments

    NASA Astrophysics Data System (ADS)

    Auffray, E.; Buganov, O.; Fedorov, A.; Korjik, M.; Mechinsky, V.; Tikhomirov, A.; Vasil'ev, A.; Lecoq, P.

    2014-07-01

    Here we report the first results of a search of a signature for picosecond time stamps of the interaction between ionizing particles and transparent crystalline media. The induced absorption with sub-picosecond rise time observed in a cerium fluoride scintillation single crystal under UV excitation is directly associated with the ionization of Ce3+ atoms in CeF3 crystals, and the very fast occurrence thereof can be used to generate picosecond-precise time stamps corresponding to the interaction of ionizing particles with the crystal in high energy physics experiments.

  7. Extended Time as a Testing Accommodation for Students with Reading Disabilities: Does a Rising Tide Lift All Ships?

    ERIC Educational Resources Information Center

    Lewandowski, Lawrence J.; Lovett, Benjamin J.; Rogers, Cynthia L.

    2008-01-01

    Testing accommodations have become a common component of services for students with disabilities at all levels of education. This study examined the effect of a common testing accommodation--extended time--on the reading comprehension test performance of high school students. Sixty-four students, half of whom had learning disabilities (LDs) in the…

  8. "Their Rising Voices": A Study of Civil Rights, Social Movements, and Advertising in the "New York Times."

    ERIC Educational Resources Information Center

    Ross, Susan Dente

    1998-01-01

    Contributes to scholarship on social movements, the strategic use of advertising, and journalism by documenting strategic use of advertising in the "New York Times" by the civil rights movement between 1955 and 1961. Finds that the ads framed the civil rights movement to prime the audience to receive radical messages from marginalized speakers.…

  9. Rising College Costs.

    ERIC Educational Resources Information Center

    USA Today, 1981

    1981-01-01

    Focuses on ways in which parents of school-age children can offset the rising costs of college, including encouraging students to get summer and part-time jobs, putting savings toward students' education in accounts in students' names to save taxes, investigating cooperative work/education plans, and investing in mutual funds. (DB)

  10. The importance of land hydrology changes in sea level rise on decadal time scales: results from 2002-2014 using GRACE

    NASA Astrophysics Data System (ADS)

    Reager, John; Gardner, Alex; Famiglietti, James; Wiese, David; Eicker, Annette; Lo, Min-Hui

    2016-04-01

    Climate-driven changes in land hydrology and their contributions to sea level rise have been absent from IPCC sea level budgets owing to challenges in observing global land water storage. In a review of recent and ongoing work, we show that recent advances in the measurement of time variable gravity from space using Gravity Recovery and Climate Experiment (GRACE) mission observations, combined with reconciled global glacier loss estimates, enable a disaggregation of continental water mass trends and a quantification of this climate-driven term. We find that between 2002 and 2014, can additional 3200 +/- 900 Gt of water was stored on land in snow, soils and groundwater, likely due to climate variability. This gain partially offset water losses from ice sheets, glaciers, and groundwater pumping, slowing the rate of sea level rise by 0.71 +/- 0.20 mm yr-1, and consistent with observations of slowing over the recent decade. We also discuss possible causes and contributors to these trends and their implications for decadal variability. These findings highlight the importance of climate-driven changes in hydrology when assigning attribution to decadal changes in sea level.

  11. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET.

    PubMed

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time (τd) and the number of photons detected (n'), i.e. CTR proportional variant √τd/n'. However, it is still an open question to what extent the scintillation rise time (τr) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the single photon time

  12. Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET

    NASA Astrophysics Data System (ADS)

    Gundacker, Stefan; Auffray, Etiennette; Pauwels, Kristof; Lecoq, Paul

    2016-04-01

    The coincidence time resolution (CTR) of scintillator based detectors commonly used in positron emission tomography is well known to be dependent on the scintillation decay time ({τd} ) and the number of photons detected ({{n}\\prime} ), i.e. CTR\\propto \\sqrt{{τd}/{{n}\\prime}} . However, it is still an open question to what extent the scintillation rise time ({τr} ) and other fast or prompt photons, e.g. Cherenkov photons, at the beginning of the scintillation process influence the CTR. This paper presents measurements of the scintillation emission rate for different LSO type crystals, i.e. LSO:Ce, LYSO:Ce, LSO:Ce codoped Ca and LGSO:Ce. For the various LSO-type samples measured we find an average value of 70 ps for the scintillation rise time, although some crystals like LSO:Ce codoped Ca seem to have a much faster rise time in the order of 20 ps. Additional measurements for LuAG:Ce and LuAG:Pr show a rise time of 535 ps and 251 ps, respectively. For these crystals, prompt photons (Cherenkov) can be observed at the beginning of the scintillation event. Furthermore a significantly lower rise time value is observed when codoping with calcium. To quantitatively investigate the influence of the rise time to the time resolution we measured the CTR with the same L(Y)SO samples and compared the values to Monte Carlo simulations. Using the measured relative light yields, rise- and decay times of the scintillators we are able to quantitatively understand the measured CTRs in our simulations. Although the rise time is important to fully explain the CTR variation for the different samples tested we determined its influence on the CTR to be in the order of a few percent only. This result is surprising because, if only photonstatistics of the scintillation process is considered, the CTR would be proportional to the square root of the rise time. The unexpected small rise time influence on the CTR can be explained by the convolution of the scintillation rate with the

  13. Development of the N1-P2 auditory evoked response to amplitude rise time and rate of formant transition of speech sounds.

    PubMed

    Carpenter, Allen L; Shahin, Antoine J

    2013-06-01

    We investigated the development of weighting strategies for acoustic cues by examining the morphology of the N1-P2 auditory evoked potential (AEP) to changes in amplitude rise time (ART) and rate of formant transition (RFT) of consonant-vowel (CV) pairs in 4-6-year olds and adults. In the AEP session, individuals listened passively to the CVs /ba/, /wa/, and a /ba/ with a superimposed slower-rising /wa/ envelope (/ba/(wa)). In the behavioral session, individuals listened to the same stimuli and judged whether they heard a /ba/ or /wa/. We hypothesized that a developmental shift in weighting strategies should be reflected in a change in the morphology of the N1-P2 AEP. In 6-year olds and adults, the N1-P2 amplitude at the vertex reflected a change in RFT but not in ART. In contrast, in the 4-5-year olds, the vertex N1-P2 did not show specificity to changes in ART or RFT. In all groups, the N1-P2 amplitude at channel C4 (right hemisphere) reflected a change in ART but not in RFT. Behaviorally, 6-year olds and adults predominately utilized RFT cues (classified /ba/(wa) as /ba/) during phonetic judgments, as opposed to 4-5-year olds which utilized both cues equally. Our findings suggest that both ART and RFT are encoded in the auditory cortex, but an N1-P2 shift toward the vertex following age 4-5 indicates a shift toward an adult-like weighting strategy, such that, to utilize RFT to a greater extent. PMID:23570734

  14. Melting Ice, Rising Seas

    NASA Video Gallery

    Sea level rise is an indicator that our planet is warming. Much of the world's population lives on or near the coast, and rising seas are something worth watching. Sea level can rise for two reason...

  15. Sonic-boom measurements in the focus region during the ascent of Apollo 17. [maximum positive overpressure, positive impulse, signature duration, and bow-shock rise time

    NASA Technical Reports Server (NTRS)

    Henderson, H. R.; Hilton, D. A.

    1974-01-01

    Sonic-boom pressure signatures recorded during the ascent phase of Apollo 17 are presented. The measurements were obtained onboard six U.S. Navy ships positioned along the ground track of the spacecraft vehicle in the area of expected focus resulting from the flight path and acceleration of the vehicle. Tracings of the measured signatures are presented along with values of the maximum positive overpressure, positive impulse, signature duration, and bowshock rise time. Also included are brief descriptions of the ships and their location, the deployment of the sonic-boom instrumentation, flight profiles and operating conditions for the launch vehicle and spacecraft, surface-weather and sea-state information at the measuring sites, and high-altitude weather information for the general measurement areas. Comparisons of the measured and predicted sonic-boom overpressures for the Apollo 17 mission are presented. The measured data are also compared with data from the Apollo 15 and 16 missions and data from flight test programs of various aircraft.

  16. Optimal battery charging, Part I: Minimizing time-to-charge, energy loss, and temperature rise for OCV-resistance battery model

    NASA Astrophysics Data System (ADS)

    Abdollahi, A.; Han, X.; Avvari, G. V.; Raghunathan, N.; Balasingam, B.; Pattipati, K. R.; Bar-Shalom, Y.

    2016-01-01

    In this paper we present a closed-form solution to the problem of optimally charging a Li-ion battery. A combination of three cost functions is considered as the objective function: time-to-charge (TTC), energy losses (EL), and a temperature rise index (TRI). First, we consider the cost function of the optimization problem as a weighted sum of TTC and EL. We show that the optimal charging strategy in this case is the well-known Constant Current-Constant Voltage (CC-CV) policy with the value of the current in the CC stage being a function of the ratio of weighting on TTC and EL and of the resistance of the battery. Then, we extend the cost function to a weighted sum of TTC, EL and TRI and derive an analytical solution for the problem. It is shown that the analytical solution can be approximated by a CC-CV with the value of current in the CC stage being a function of ratio of weighting on TTC and EL, resistance of the battery and the effective thermal resistance.

  17. Contemporary sea level rise.

    PubMed

    Cazenave, Anny; Llovel, William

    2010-01-01

    Measuring sea level change and understanding its causes has considerably improved in the recent years, essentially because new in situ and remote sensing observations have become available. Here we report on most recent results on contemporary sea level rise. We first present sea level observations from tide gauges over the twentieth century and from satellite altimetry since the early 1990s. We next discuss the most recent progress made in quantifying the processes causing sea level change on timescales ranging from years to decades, i.e., thermal expansion of the oceans, land ice mass loss, and land water-storage change. We show that for the 1993-2007 time span, the sum of climate-related contributions (2.85 +/- 0.35 mm year(-1)) is only slightly less than altimetry-based sea level rise (3.3 +/- 0.4 mm year(-1)): approximately 30% of the observed rate of rise is due to ocean thermal expansion and approximately 55% results from land ice melt. Recent acceleration in glacier melting and ice mass loss from the ice sheets increases the latter contribution up to 80% for the past five years. We also review the main causes of regional variability in sea level trends: The dominant contribution results from nonuniform changes in ocean thermal expansion. PMID:21141661

  18. Crustal structure in the ROSE area of the East Pacific Rise: One-dimensional travel time inversion of sonobuoys and expanded spread profiles

    NASA Astrophysics Data System (ADS)

    Vera, Emilio E.; Mutter, John C.

    1988-06-01

    We study the variability of the young oceanic crust as a function of age by analyzing 11 digitally recorded sonobuoys and three expanded spread profiles over 0.5-, 2.5-, and 4.5-m.y.-old oceanic crust. The data were collected during the Rivera Ocean Seismic Experiment at the East Pacific Rise between 11° and 13°N. We analyze the data within a one-dimensional travel time scheme using the tau-p method and travel time forward modeling. We perform the tau-p mapping by using a polynomial least squares technique that is fast and can be applied even to poor quality data as in this case. We do not see large changes in the velocity structure between 0.5-and 4.5-m.y.-old oceanic crust. The overall structure consists of a rapid increase in velocity from about 2.5-6 km/s within the uppermost 1 km of crust (layer 2A), a zone ≤1 km in thickness with little or no velocity gradient (layer 2B), a thin transition layer with a relatively rapid increase in velocity from about 6.2 to 7 km/s (layer 2C), and a thick nearly homogeneous basal layer with velocities around 7.2 km/s (layer 3). We find that the low velocities at the seafloor and large velocity gradients within the shallow crust can be explained by the hypothesis of large-scale cracks and their behavior under confining pressure. For the variation of velocity V versus depth below seafloor z, this hypothesis yields V = (V02 + Bz)1/2, a relationship that fits our solutions.

  19. Structural Theories and Race-Specific Drug Arrests: What Structural Factors Account for the Rise in Race-Specific Drug Arrests over Time?

    ERIC Educational Resources Information Center

    Parker, Karen F.; Maggard, Scott R.

    2005-01-01

    Studies examining the structural correlates of urban crime have generated a large body of research; however, few studies have linked the structural conditions to race-specific drug arrests. In this study, the authors examine the impact of urban disadvantage, social disorganization, and racial threat indicators on the rise in race-specific drug…

  20. Time-resolved photoluminescence from self-assembled Ge(Si) islands in multilayer SiGe/Si and SiGe/SOI structures

    SciTech Connect

    Yablonskiy, A. N. Baidakova, N. A.; Novikov, A. V.; Lobanov, D. N.

    2013-11-15

    The results of a study of the spectral and temporal characteristics of the photoluminescence (PL) from multilayer structures with self-assembled Ge(Si) islands grown on silicon and 'silicon-on-insulator' substrates in relation to temperature and the excitation-light wavelength are presented. A substantial increase in island-related PL intensity is observed for structures with Ge(Si) islands grown on silicon substrates upon an increase in temperature from 4 to 70 K. This increase is due to the diffusion of nonequilibrium carriers from the silicon substrate into the active layer with the islands. In this case, a slow component with a characteristic time of {approx}100 ns appears in the PL rise kinetics. At the same time, no slow component in the PL rise kinetics and no rise in the PL intensity with increasing temperature are observed for structures grown on 'silicon-on-insulator' substrates, in which the active layer with the islands is insulated from the silicon substrate. It is found that absorption of the excitation light in the islands and SiGe wetting layers mainly contributes to the excitation of the PL signal from the islands under sub-bandgap optical pump conditions.

  1. Ground potential rise monitor

    DOEpatents

    Allen, Zachery W.; Zevenbergen, Gary A.

    2012-04-03

    A device and method for detecting ground potential rise (GPR) comprising positioning a first electrode and a second electrode at a distance from each other into the earth. The voltage of the first electrode and second electrode is attenuated by an attenuation factor creating an attenuated voltage. The true RMS voltage of the attenuated voltage is determined creating an attenuated true RMS voltage. The attenuated true RMS voltage is then multiplied by the attenuation factor creating a calculated true RMS voltage. If the calculated true RMS voltage is greater than a first predetermined voltage threshold, a first alarm is enabled at a local location. If user input is received at a remote location acknowledging the first alarm, a first alarm acknowledgment signal is transmitted. The first alarm acknowledgment signal is then received at which time the first alarm is disabled.

  2. The rising risks of rising tides

    SciTech Connect

    Hanson, H.; Lindh, G.

    1996-12-31

    The erosion of beaches, flooding of agricultural land, and intrusion of saltwater into coastal streams could become a reality if temperatures climb. Over the past century, sea levels have risen 4 to 6 inches. Now, the Intergovernmental panel on Climate Change (IPCC) predicts that sea levels will rise between 8 and 28 inches by 2070, say Hans Hanson, associate professor emeritus in the Department of Water Resources Engineering at the University of Lund in Sweden. Coastal communities, which harbor more than half the world`s population, are poorly equipped to combat the threat of encroaching waters. {open_quotes}Few public officials have developed comprehensive strategies to address the potential consequences of sea-level rise,{close_quotes} the authors say. In response to the lack of long-term strategies to address the potential consequences of sea-level rise,{close_quotes} the authors say. In response to the lack of long-term strategies, the IPCC has recommended that coastal nations implement coastal-zone management plans by 2000. {open_quotes}Low-lying islands and high-use, developed coastal areas... face an urgent need to develop strategies for coping with sea-level rise,{close_quotes} the authors conclude.

  3. Systematic investigation of effects of exciton–acoustic-phonon scattering on photoluminescence rise times of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells

    SciTech Connect

    Nakayama, Masaaki Ohno, Tatsuya; Furukawa, Yoshiaki

    2015-04-07

    We have systematically investigated the photoluminescence (PL) dynamics of free excitons in GaAs/Al{sub 0.3}Ga{sub 0.7}As single quantum wells, focusing on the energy relaxation process due to exciton–acoustic-phonon scattering under non-resonant and weak excitation conditions as a function of GaAs-layer thickness from 3.6 to 12.0 nm and temperature from 30 to 50 K. The free exciton characteristics were confirmed by observation that the PL decay time has a linear dependence with temperature. We found that the free exciton PL rise rate, which is the reciprocal of the rise time, is inversely linear with the GaAs-layer thickness and linear with temperature. This is consistent with a reported theoretical study of the exciton–acoustic-phonon scattering rate in the energy relaxation process in quantum wells. Consequently, it is conclusively verified that the PL rise rate is dominated by the exciton–acoustic-phonon scattering rate. In addition, from quantitative analysis of the GaAs-layer thickness and temperature dependences, we suggest that the PL rise rate reflects the number of exciton–acoustic-phonon scattering events.

  4. Acronical Risings and Settings

    NASA Astrophysics Data System (ADS)

    Hockey, Thomas A.

    2012-01-01

    A concept found in historical primary sources, and useful in contemporary historiography, is the acronical rising and setting of stars (or planets). Topocentric terms, they provide information about a star's relationship to the Sun and thus its visibility in the sky. Yet there remains ambiguity as to what these two phrases actually mean. "Acronical” is said to have come from the Greek akros ("point,” "summit,” or "extremity") and nux ("night"). While all sources agree that the word is originally Greek, there are alternate etymologies for it. A more serious difficulty with acronical rising and setting is that there are two competing definitions. One I call the Poetical Definition. Acronical rising (or setting) is one of the three Poetical Risings (or Settings) known to classicists. (The other two are cosmical rising/setting, discussed below, and the more familiar helical rising/setting.) The term "poetical" refers to these words use in classical poetry, e. g., that of Columella, Hesiod, Ovid, Pliny the Younger, and Virgil. The Poetical Definition of "acronical” usually is meant in this context. The Poetical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun sets, it sets acronically. In contrast with the Poetical Definition, there also is what I call the Astronomical Definition. The Astronomical Definition is somewhat more likely to appear in astronomical, mathematical, or navigational works. When the Astronomical Definition is recorded in dictionaries, it is often with the protasis "In astronomy, . . . ." The Astronomical Definition of "acronical” is as follows: When a star rises as the Sun sets, it rises acronically. When a star sets as the Sun rises, it sets acronically. I will attempt to sort this all out in my talk.

  5. Tharsis Rise Graben

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 22 May 2002) The Science This image is located in the northwestern portion of the Tharsis Rise at about 12 N and 125 W (235 E). What is immediately noticeable in this image is the series of linear features that are called graben. These features are associated with crustal extension which results in a series of up and down blocks of crust that run perpendicular to the direction of the extension. Images of Mars have shown a large number of these tectonic features concentrated on or near the Tharsis region. The Tharsis region is an enormous bulge that causes major tectonic disruptions across the planet when it tries to settle down from its height and reach equilibrium with the rest of the planet. The graben in this image display a number of preferential directions indicating that the crustal stresses that caused the graben have changed over time. By examining the cross-cutting relationships between the features, it is possible to reassemble the history of the area. The Story Now, if you thought that Mars was almost perfectly round, think again! The red planet has a large bulge sticking out from it called Tharsis. Almost 3,000 miles across, this enormous region rises almost four miles above the average radius of the planet. That's quite a bulge! Since Tharsis the land of the largest volcanoes in the solar system, it may have been formed by both the uplift of land from tectonic action and the build-up of lava flows. Tharsis can cause some pretty major tectonic disruptions across the planet when it tries to settle down from its height and reach a better equilibrium with the rest of the planet. In this image, located in the northwestern portion of the Tharsis Rise, a whole lot of lowered features stripe the landscape. They are called grabens, and formed when the crust of the planet was stretched tectonically. This kind of crustal extension (or stretching) tends to form a series of up-and-down blocks of crust that run perpendicular to the direction of the crustal

  6. Antarctic ice rise formation, evolution, and stability

    NASA Astrophysics Data System (ADS)

    Favier, Lionel; Pattyn, Frank

    2015-06-01

    Antarctic ice rises originate from the contact between ice shelves and one of the numerous topographic highs emerging from the edge of the continental shelf. While investigations of the Raymond effect indicate their millennial-scale stability, little is known about their formation and their role in ice shelf stability. Here we present for the first time the simulation of an ice rise using the BISICLES model. The numerical results successfully reproduce several field-observable features, such as the substantial thinning downstream of the ice rise and the successive formation of a promontory and ice rise with stable radial ice flow center, showing that ice rises are formed during the ice sheet deglaciation. We quantify the ice rise buttressing effect, found to be mostly transient, delaying grounding line retreat significantly but resulting in comparable steady state positions. We demonstrate that ice rises are key in controlling simulations of Antarctic deglaciation.

  7. Perceptual Temporal Asymmetry Associated with Distinct ON and OFF Responses to Time-Varying Sounds with Rising versus Falling Intensity: A Magnetoencephalography Study.

    PubMed

    Zhang, Yang; Cheng, Bing; Koerner, Tess K; Schlauch, Robert S; Tanaka, Keita; Kawakatsu, Masaki; Nemoto, Iku; Imada, Toshiaki

    2016-01-01

    This magnetoencephalography (MEG) study investigated evoked ON and OFF responses to ramped and damped sounds in normal-hearing human adults. Two pairs of stimuli that differed in spectral complexity were used in a passive listening task; each pair contained identical acoustical properties except for the intensity envelope. Behavioral duration judgment was conducted in separate sessions, which replicated the perceptual bias in favour of the ramped sounds and the effect of spectral complexity on perceived duration asymmetry. MEG results showed similar cortical sites for the ON and OFF responses. There was a dominant ON response with stronger phase-locking factor (PLF) in the alpha (8-14 Hz) and theta (4-8 Hz) bands for the damped sounds. In contrast, the OFF response for sounds with rising intensity was associated with stronger PLF in the gamma band (30-70 Hz). Exploratory correlation analysis showed that the OFF response in the left auditory cortex was a good predictor of the perceived temporal asymmetry for the spectrally simpler pair. The results indicate distinct asymmetry in ON and OFF responses and neural oscillation patterns associated with the dynamic intensity changes, which provides important preliminary data for future studies to examine how the auditory system develops such an asymmetry as a function of age and learning experience and whether the absence of asymmetry or abnormal ON and OFF responses can be taken as a biomarker for certain neurological conditions associated with auditory processing deficits. PMID:27527227

  8. Processing time using Datatrieve-11, clunks, and FORTRAN

    SciTech Connect

    Horning, R.R.; Goode, W.E.

    1983-01-01

    Although Datatrieve-11 processes dates with 100-ns resolution using clunks, it has no provision for processing time. This paper describes a set of Datatrieve-11 procedures and FORTRAN-callable subroutines for handling time, as well as dates, expressed in clunks. Although the FORTRAN-callable subroutines use RMS modules, these modules can be extracted from the appropriate RMS library, allowing FORTRAN programs to be linked to an FCS library instead of to RMS.

  9. Global sea level rise

    SciTech Connect

    Douglas, B.C. )

    1991-04-15

    Published values for the long-term, global mean sea level rise determined from tide gauge records exhibit considerable scatter, from about 1 mm to 3 mm/yr. This disparity is not attributable to instrument error; long-term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year. Instead, the differing estimates of global sea level rise appear to be in large part due to authors' using data from gauges located at convergent tectonic plate boundaries, where changes of land elevation give fictitious sea level trends. In addition, virtually all gauges undergo subsidence or uplift due to postglacial rebound (PGR) from the last deglaciation at a rate comparable to or greater than the secular rise of sea level. Modeling PGR by the ICE-3G model of Tushingham and Peltier (1991) and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records. The value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880-1980 is 1.8 mm/yr {plus minus} 0.1. This result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sea level and that many old tide gauge records are of very high quality.

  10. High speed electrostatic photomultiplier tube for the 1.06 micrometer wavelength. Cup and slat dynode chain combined with flat cathode and coax output produces 0.25 nsec rise time

    NASA Technical Reports Server (NTRS)

    Sparks, S. D.

    1973-01-01

    The Varian cup and slat dynode chain was modified to have a flat cathode. These modifications were incorporated in an all-electrostatic photomultiplier tube having a rise time of 0.25 n sec. The tube delivered under the contract had a flat S-20 opaque cathode with a useful diameter of 5 mm. The design of the tube is such that a III to V cathode support is mounted in place of the existing cathode substrate. This cathode support is designed to accept a transferred III to V cathode and maintain the cathode surface in the same position as the S-20 photocathode.

  11. Simple approximations for estimating quickly the motion and timing of salt diapir rise, overhang development, and associated thermal anomalies using present-day observations: Case history from the Gulf of Mexico and Danish North Sea

    SciTech Connect

    Lerche, I. ); Thomsen, R.O. )

    1993-09-01

    Estimates of the upward motion of salt, due solely to buoyancy forces, through deposited and depositing sedimentary cover can be split into several parts: the critical thickness of sedimentary cover necessary to cause an underlying salt to become buoyant; the critical thickness of sedimentary cover necessary for a salt diapir to reach the sediment mudline in the absence of an impeding pressure of competent sediments opposing salt rise and in the absence of significant overpressure (both differential impedance and differential overpressure will slow the rise of the salt to the mudline); the effective speed of motion of the salt through the nonimpeding sediments during the salt's buoyant-ascent phase; current observed salt-top depth below mudline versus nonimpeded predicted salt-top depth leading to (a) minimum estimate of mechanical strength of competent resistive layers, and (b) an approximate estimate of buoyancy pressure of salt attempting to penetrate the resistive cover layer; uplift estimate of the overlying competent sediments because of the buoyancy pressure, in relation to observed uplift, leading to an estimate of salt-diapir rise speed since reaching the impeding formation; timing estimates of [open quotes]mushroom cap[close quotes] development of salt since emplacement of the resistive overlying layer and an estimate of the lateral competence of sedimentary beds ahead of the mushroom-salt sheet cap as a consequence of the observed mushroom extent; an estimate of evolving thermal anomalies around the dynamic salt/sediment system as a consequence of high-salt thermal conductivity. Such simple rough estimation methods are important in assessing the local and regional factors influencing the dynamic, thermal, and hydrocarbon retention factors in basinal sediments influenced by salt. Examples from the Gulf of Mexico and the Danish North Sea illustrate how to use both seismic and/or downhole data to perform the simple estimates.

  12. Sea Level Rise in Tuvalu

    NASA Astrophysics Data System (ADS)

    Lin, C. C.; Ho, C. R.; Cheng, Y. H.

    2012-04-01

    Most people, especially for Pacific Islanders, are aware of the sea level change which may caused by many factors, but no of them has deeper sensation of flooding than Tuvaluan. Tuvalu, a coral country, consists of nine low-lying islands in the central Pacific between the latitudes of 5 and 10 degrees south, has the average elevation of 2 meters (South Pacific Sea Level and Climate Monitoring Project, SPSLCMP report, 2006) up to sea level. Meanwhile, the maximum sea level recorded was 3.44m on February 28th 2006 that damaged Tuvaluan's property badly. Local people called the flooding water oozes up out of the ground "King Tide", that happened almost once or twice a year, which destroyed the plant, polluted their fresh water, and forced them to colonize to some other countries. The predictable but uncontrollable king tide had been observed for a long time by SPSLCMP, but some of the uncertainties which intensify the sea level rise need to be analyzed furthermore. In this study, a span of 18 years of tide gauge data accessed from Sea Level Fine Resolution Acoustic Measuring Equipment (SEAFRAME) are compared with the satellite altimeter data accessed from Archiving Validation and Interpretation of Satellite Data in Oceanography (AVISO). All above are processed under the limitation of same time and spatial range. The outcome revealed a 9.26cm difference between both. After the tide gauge data shifted to the same base as altimeter data, the results showed the unknown residuals are always positive under the circumstances of the sea level rise above 3.2m. Apart from uncertainties in observing, the residual reflected unknown contributions. Among the total case number of sea level rise above 3.2m is 23 times, 22 of which were recorded with oceanic warm eddy happened simultaneously. The unknown residual seems precisely matched with oceanic warm eddies and illustrates a clear future approach for Tuvaluan to care for.

  13. Rising beyond elastocapillarity.

    PubMed

    Holmes, Douglas P; Brun, P-T; Pandey, Anupam; Protière, Suzie

    2016-06-14

    We consider the elastocapillary rise between swellable structures using a favorable solvent. We characterize the dynamic deformations and resulting equilibrium configurations for various beams. Our analysis reveals the importance of the spacing between the two beams, and the elastocapillary length lec, which prescribes the relative magnitude of surface tension and bending stiffness in the system. In particular, we rationalize the transition between coalescence-dominated, bending-dominated, and swelling-dominated regimes, and enumerate the subtle interfacial mechanisms at play in the ratcheting of a fluid droplet trapped between the curling beams. PMID:27076278

  14. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  15. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

    1998-10-13

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

  16. Understanding Sea-Level Rise and Variability

    NASA Astrophysics Data System (ADS)

    Anderson, John

    2011-05-01

    The debate about climate change lingers, fueled by the complexity of weather patterns around the Earth. The oceans filter spatial and temporal changes in temperature, yielding an undisputable record of warming and expansion that manifests as accelerated sea level rise. The rate of rise in historical time is nearly 6 times the average rate for the past 4000 years. Documentation of this accelerated rise, discussion of its causes and impacts, and descriptions of the methods used to measure sea level rise are provided in this compilation of 12 papers authored by some of the leading experts in the field. The book reads more like a textbook than an edited volume, a strategy seldom achieved in edited volumes.

  17. Four-dimensional visualization of rising microbubbles

    NASA Astrophysics Data System (ADS)

    Jung, Ji Won; Jeon, Hyung Min; Pyo, Jaeyeon; Lim, Jae-Hong; Weon, Byung Mook; Kohmura, Yoshiki; Ishikawa, Tetsuya; Je, Jung Ho

    2014-05-01

    Four-dimensional imaging, which indicates imaging in three spatial dimensions as a function of time, provides useful evidence to investigate the interactions of rising bubbles. However, this has been largely unexplored for microbubbles, mostly due to problems associated with strong light scattering and shallow depth of field in optical imaging. Here, tracking x-ray microtomography is used to visualize rising microbubbles in four dimensions. Bubbles are tracked by moving the cell to account for their rise velocity. The sizes, shapes, time-dependent positions, and velocities of individual rising microbubbles are clearly identified, despite substantial overlaps between bubbles in the field of view. Our tracking x-ray microtomography affords opportunities for understanding bubble-bubble (or particle) interactions at microscales - important in various fields such as microfluidics, biomechanics, and floatation.

  18. Four-dimensional visualization of rising microbubbles

    NASA Astrophysics Data System (ADS)

    Je, Jung Ho; Jung, Ji Won; Pyo, Jaeyeon; Lim, Jae-Hong

    2014-11-01

    Four-dimensional imaging, which indicates imaging in three spatial dimensions as a function of time, provides useful evidence to investigate the interactions of rising bubbles. However, this has been largely unexplored for microbubbles, mostly due to problems associated with strong light scattering and shallow depth of field in optical imaging. Here, we developed tracking x-ray microtomography that is capable of visualizing rising microbubbles in four dimensions. Bubbles are tracked by moving the in-situ cell to account for their rise velocity. The sizes, shapes, time-dependent positions, and velocities of individual rising microbubbles are clearly identified, despite substantial overlaps between bubbles in the field of view. Our tracking x-ray microtomography affords opportunities for understanding bubble-bubble (or particle) interactions at microscales - important in various fields such as microfluidics, biomechanics, and floatation.

  19. Was the economic crisis 1997-1998 responsible for rising suicide rates in East/Southeast Asia? A time-trend analysis for Japan, Hong Kong, South Korea, Taiwan, Singapore and Thailand.

    PubMed

    Chang, Shu-Sen; Gunnell, David; Sterne, Jonathan A C; Lu, Tsung-Hsueh; Cheng, Andrew T A

    2009-04-01

    In 1997-1998 a widespread economic crisis hit the economies of many East/Southeast Asian countries; its impact on suicide rates across the region has not been systematically documented. We investigated the impact of the Asian economic crisis (1997-1998) on suicide in Japan, Hong Kong, South Korea, Taiwan, Singapore and Thailand. Suicide and population data for the period 1985-2006 were extracted from the World Health Organisation's mortality database and Taiwanese mortality statistics. Sex-specific age-standardised suicide rates for people aged 15years or above were analysed using joinpoint regression. Trends in divorce, marriage, unemployment, gross domestic product (GDP) per capita and alcohol consumption were compared with trends in suicide rates graphically and using time-series analysis. Suicide mortality decreased in the late 1980s and early 1990s but subsequently increased markedly in all countries except Singapore, which had steadily declining suicide rates throughout the study period. Compared to 1997, male rates in 1998 rose by 39% in Japan, 44% in Hong Kong and 45% in Korea; rises in female rates were less marked. Male rates also rose in Thailand, but accurate data were incomplete. The economic crisis was associated with 10,400 more suicides in 1998 compared to 1997 in Japan, Hong Kong and Korea. Similar increases in suicide rates were not seen in Taiwan and Singapore, the two countries where the economic crisis had a smaller impact on GDP and unemployment. Time-series analyses indicated that some of the crisis's impact on male suicides was attributable to increases in unemployment. These findings suggest an association of the Asian economic crisis with a sharp increase in suicide mortality in some, but not all, East/Southeast Asian countries, and that these increases were most closely associated with rises in unemployment. PMID:19200631

  20. Ground potential rise monitor

    DOEpatents

    Allen, Zachery Warren; Zevenbergen, Gary Allen

    2012-07-17

    A device and method for detecting ground potential rise (GPR) comprising a first electrode, a second electrode, and a voltage attenuator. The first electrode and the second electrode are both electrically connected to the voltage attenuator. A means for determining the presence of a dangerous ground potential is connected to the voltage attenuator. The device and method further comprises a means for enabling one or more alarms upon the detection of the dangerous ground potential. Preferably, a first transmitter/receiver is connected to the means for enabling one or more alarms. Preferably, a second transmitter/receiver, comprising a button, is electromagnetically connected to the first transmitter/receiver. Preferably, the means for determining the presence of a dangerous ground potential comprises a means for determining the true RMS voltage at the output of the voltage attenuator, a transient detector connected to the output of the voltage attenuator, or a combination thereof.

  1. Rapid sea-level rise

    NASA Astrophysics Data System (ADS)

    Cronin, Thomas M.

    2012-11-01

    Several global and regional factors contribute to observed sea-level change along any particular coast. Global processes include changes in ocean mass (glacio-eustasy from ice melt), ocean volume (steric effects), viscoelastic land movements (glacioisostatic adjustment GIA), and changes in terrestrial water storage. Regional processes, often connected to steric and glacial changes, include changes in ocean circulation (Meridional Overturning Circulation [MOC]), glacial melting, local GIA, regional subsidence and others. Paleoclimate, instrumental and modeling studies show that combinations of these factors can cause relatively rapid rates of sea-level rise exceeding 3 mm yr-1 over various timescales along particular coasts. This paper discusses patterns and causes of sea-level rise with emphasis on paleoclimatological records. It then addresses the hypothesis of late Holocene (pre-20th century) sea-level stability in light of paleoclimatic evidence, notably from reconstructions of sea-surface temperature and glacial activity, for significant climate and sea-level variability during this time. The practical difficulties of assessing regional sea-level (SL) patterns at submillennial timescales will be discussed using an example from the eastern United States.

  2. Arrested Bubble Rise in a Narrow Tube

    NASA Astrophysics Data System (ADS)

    Lamstaes, Catherine; Eggers, Jens

    2016-06-01

    If a long air bubble is placed inside a vertical tube closed at the top it can rise by displacing the fluid above it. However, Bretherton found that if the tube radius, R, is smaller than a critical value Rc=0.918 ℓ_c , where ℓ_c=√{γ /ρ g} is the capillary length, there is no solution corresponding to steady rise. Experimentally, the bubble rise appears to have stopped altogether. Here we explain this observation by studying the unsteady bubble motion for Rrise in infinite time remains very small, giving the appearance of arrested motion.

  3. The rise of graphene

    NASA Astrophysics Data System (ADS)

    Geim, A. K.; Novoselov, K. S.

    2007-03-01

    Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

  4. The rise of graphene.

    PubMed

    Geim, A K; Novoselov, K S

    2007-03-01

    Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications. PMID:17330084

  5. Measurement of DNA Translocation Dynamics in a Solid-State Nanopore at 100 ns Temporal Resolution.

    PubMed

    Shekar, Siddharth; Niedzwiecki, David J; Chien, Chen-Chi; Ong, Peijie; Fleischer, Daniel A; Lin, Jianxun; Rosenstein, Jacob K; Drndić, Marija; Shepard, Kenneth L

    2016-07-13

    Despite the potential for nanopores to be a platform for high-bandwidth study of single-molecule systems, ionic current measurements through nanopores have been limited in their temporal resolution by noise arising from poorly optimized measurement electronics and large parasitic capacitances in the nanopore membranes. Here, we present a complementary metal-oxide-semiconductor (CMOS) nanopore (CNP) amplifier capable of low noise recordings at an unprecedented 10 MHz bandwidth. When integrated with state-of-the-art solid-state nanopores in silicon nitride membranes, we achieve an SNR of greater than 10 for ssDNA translocations at a measurement bandwidth of 5 MHz, which represents the fastest ion current recordings through nanopores reported to date. We observe transient features in ssDNA translocation events that are as short as 200 ns, which are hidden even at bandwidths as high as 1 MHz. These features offer further insights into the translocation kinetics of molecules entering and exiting the pore. This platform highlights the advantages of high-bandwidth translocation measurements made possible by integrating nanopores and custom-designed electronics. PMID:27332998

  6. High current, 0.5-MA, fast, 100-ns, linear transformer driver experiments

    NASA Astrophysics Data System (ADS)

    Mazarakis, Michael G.; Fowler, William E.; Kim, Alexander A.; Sinebryukhov, Vadim A.; Rogowski, Sonrisa T.; Sharpe, Robin A.; McDaniel, Dillon H.; Olson, Craig L.; Porter, John L.; Struve, Kenneth W.; Stygar, William A.; Woodworth, Joseph R.

    2009-05-01

    The linear transformer driver (LTD) is a new method for constructing high current, high-voltage pulsed accelerators. The salient feature of the approach is switching and inductively adding the pulses at low voltage straight out of the capacitors through low inductance transfer and soft iron core isolation. Sandia National Laboratories are actively pursuing the development of a new class of accelerator based on the LTD technology. Presently, the high current LTD experimental research is concentrated on two aspects: first, to study the repetition rate capabilities, reliability, reproducibility of the output pulses, switch prefires, jitter, electrical power and energy efficiency, and lifetime measurements of the cavity active components; second, to study how a multicavity linear array performs in a voltage adder configuration relative to current transmission, energy and power addition, and wall plug to output pulse electrical efficiency. Here we report the repetition rate and lifetime studies performed in the Sandia High Current LTD Laboratory. We first utilized the prototype ˜0.4-MA, LTD I cavity which could be reliably operated up to ±90-kV capacitor charging. Later we obtained an improved 0.5-MA, LTD II version that can be operated at ±100kV maximum charging voltage. The experimental results presented here were obtained with both cavities and pertain to evaluating the maximum achievable repetition rate and LTD cavity performance. The voltage adder experiments with a series of double sized cavities (1 MA, ±100kV) will be reported in future publications.

  7. Capillary rise kinetics of some building materials.

    PubMed

    Karoglou, M; Moropoulou, A; Giakoumaki, A; Krokida, M K

    2005-04-01

    The presence of water in masonry is one of the main factors in deterioration. Capillary rise is the most usual mechanism of water penetration into building materials. In this study the kinetics of the capillary rise phenomenon was studied for various building materials: four stones, two bricks, and six plasters. A first-order kinetic model was proposed, in which the equilibrium moisture height derived from Darcy law. The capillary height time constant found to be strongly affected by the material characteristics. Moreover, the capillary height time constant can be predicted if the average pore radius of the materials is known. PMID:15752811

  8. Capillary Rise in Porous Media.

    PubMed

    Lago, Marcelo; Araujo, Mariela

    2001-02-01

    Capillary rise experiments were performed in columns filled with glass beads and Berea sandstones, using visual methods to register the advance of the water front. For the glass bead filled columns, early time data are well fitted by the Washburn equation. However, in the experiments, the advancing front exceeded the predicted equilibrium height. For large times, an algebraic behavior of the velocity of the front is observed (T. Delker et al., Phys. Rev. Lett. 76, 2902 (1996)). A model for studying the capillary pressure evolution in a regular assembly of spheres is proposed and developed. It is based on a quasi-static advance of the meniscus with a piston-like motion and allows us to estimate the hydraulic equilibrium height, with values very close to those obtained by fitting early time data to a Washburn equation. The change of regime is explained as a transition in the mechanism of advance of the meniscus. On the other hand, only the Washburn regime was observed for the sandstones. The front velocity was fitted to an algebraical form with an exponent close to 0.5, a value expected from the asymptotic limit of the Washburn equation. Copyright 2001 Academic Press. PMID:11161488

  9. The Silver Lining in Rising Health Costs.

    ERIC Educational Resources Information Center

    McDowell, Don

    2001-01-01

    Discusses the emotional, financial, and structural reasons that health care costs in the United States, and therefore for colleges, continue to rise at staggering rates. Asserts that colleges must build health care cost reality into budget strategy, and level with constituents that there will not be a solution for the cost explosion any time soon.…

  10. Calculation of Temperature Rise in Calorimetry.

    ERIC Educational Resources Information Center

    Canagaratna, Sebastian G.; Witt, Jerry

    1988-01-01

    Gives a simple but fuller account of the basis for accurately calculating temperature rise in calorimetry. Points out some misconceptions regarding these calculations. Describes two basic methods, the extrapolation to zero time and the equal area method. Discusses the theoretical basis of each and their underlying assumptions. (CW)

  11. States' Budgets Reflect Rising Tax Collections

    ERIC Educational Resources Information Center

    Hoff, David J.

    2005-01-01

    Many state budgets are reaping the benefits of tax revenues that are rising faster than at any time since the economic slowdown ended. Overall tax collections by states rose by 11.7 percent in the first quarter of 2005, giving the legislatures extra cash to shore up school aid, increase teacher pay, and finance new initiatives such as full-day…

  12. HiRISE: The People's Camera

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.; Eliason, E.; Gulick, V. C.; Spinoza, Y.; Beyer, R. A.; HiRISE Team

    2010-12-01

    The High Resolution Imaging Science Experiment (HiRISE) camera, orbiting Mars since 2006 on the Mars Reconnaissance Orbiter (MRO), has returned more than 17,000 large images with scales as small as 25 cm/pixel. From it’s beginning, the HiRISE team has followed “The People’s Camera” concept, with rapid release of useful images, explanations, and tools, and facilitating public image suggestions. The camera includes 14 CCDs, each read out into 2 data channels, so compressed images are returned from MRO as 28 long (up to 120,000 line) images that are 1024 pixels wide (or binned 2x2 to 512 pixels, etc.). This raw data is very difficult to use, especially for the public. At the HiRISE operations center the raw data are calibrated and processed into a series of B&W and color products, including browse images and JPEG2000-compressed images and tools to make it easy for everyone to explore these enormous images (see http://hirise.lpl.arizona.edu/). Automated pipelines do all of this processing, so we can keep up with the high data rate; images go directly to the format of the Planetary Data System (PDS). After students visually check each image product for errors, they are fully released just 1 month after receipt; captioned images (written by science team members) may be released sooner. These processed HiRISE images have been incorporated into tools such as Google Mars and World Wide Telescope for even greater accessibility. 51 Digital Terrain Models derived from HiRISE stereo pairs have been released, resulting in some spectacular flyover movies produced by members of the public and viewed up to 50,000 times according to YouTube. Public targeting began in 2007 via NASA Quest (http://marsoweb.nas.nasa.gov/HiRISE/quest/) and more than 200 images have been acquired, mostly by students and educators. At the beginning of 2010 we released HiWish (http://www.uahirise.org/hiwish/), opening HiRISE targeting to anyone in the world with Internet access, and already more

  13. On Capillary Rise and Nucleation

    ERIC Educational Resources Information Center

    Prasad, R.

    2008-01-01

    A comparison of capillary rise and nucleation is presented. It is shown that both phenomena result from a balance between two competing energy factors: a volume energy and a surface energy. Such a comparison may help to introduce nucleation with a topic familiar to the students, capillary rise. (Contains 1 table and 3 figures.)

  14. RISE: Service and Learning Combine.

    ERIC Educational Resources Information Center

    Taylor, Rosemarye T.; Peterson, Deborah S.

    2003-01-01

    RISE (Reading Intervention Sans Expense) is a one-on-one reading intervention that involves maximizing human resources, not expending dollars. Tutors are high school students enrolled in a community service learning course who are trained in guided reading. Research suggests that RISE is an effective and efficient intervention that impacts all of…

  15. Choices for a Rising Generation

    ERIC Educational Resources Information Center

    Obama, Barack

    2008-01-01

    This article presents an essay by the 2008 Democratic Party Presidential Nominee. This essay focuses on the role of the rising generation in bringing about real change in America. The author contends that, at this historic moment, Americans must ask their rising generation to serve their country as Americans always have--by working on a political…

  16. A flexible time recording and time correlation analysis system

    NASA Astrophysics Data System (ADS)

    Shenhav, Nathan J.; Leiferman, Gabriel; Segal, Yitzhak; Notea, Amos

    1983-02-01

    A system was developed to digitize and record the time intervals between detection event pulses, feed to its input channels from a detection device. The accumulated data is transferred continuously in real time to a dise through a PDP 11/34 minicomputer. Even though the system was designed for a specific scope, i.e., the comparative study of passive neutron nondestructive assay methods. It can be characterized by its features as a general purpose time series recorder. The time correlation analysis is performed by software after completion of the data accumulation. The digitizing clock period is selectable and any value, larger than a minimum of 100 ns may be selected. Bursts of up to 128 events with a frequency up to 10 MHz may be recorded. With the present recorder-minicomputer combination, the maximal average recording frequency is 40 kHz.

  17. Crustal Thickness and Moho Character of the Fast-Spreading East Pacific Rise Between 9º37.5'N and 9º57'N From Poststack and Prestack Time Migrated 3D MCS data

    NASA Astrophysics Data System (ADS)

    Nedimovic, M. R.; Aghaei, O.; Carbotte, S. M.; Carton, H. D.; Canales, J. P.

    2014-12-01

    We measured crustal thickness and mapped Moho transition zone (MTZ) character over an 880 km2 section of the fast-spreading East Pacific Rise (EPR) using the first full 3D multichannel seismic (MCS) dataset collected across a mid-ocean ridge (MOR). The 9°42'-9°57'N area was initially investigated using 3D poststack time migration, which was followed by application of 3D prestack time migration (PSTM) to the whole dataset. This first attempt at applying 3D PSTM to MCS data from a MOR environment resulted in the most detailed reflection images of a spreading center to date. MTZ reflections are for the first time imaged below the ridge axis away from axial discontinuities indicating that Moho is formed at zero age at least at some sections of the MOR system. The average crustal thickness and crustal velocity derived from PSTM are 5920±320 m and 6320±290 m/s, respectively. The average crustal thickness varies little from Pacific to Cocos plate suggesting mostly uniform crustal production in the last ~180 Ka. However, the crust thins by ~400 m from south to north. The MTZ reflections were imaged within ~92% of the study area, with ~66% of the total characterized by impulsive reflections interpreted to originate from a thin MTZ and 26% characterized by diffusive reflections interpreted to originate from a thick MTZ. The MTZ is dominantly diffusive at the southern (9°37.5'-9°40'N) and northern (9°51'-9°57'N) ends of the study area, and it is impulsive in the central region (9°42'-9°51'N). No data were collected between 9°40'N and 9°42'N. More efficient mantle melt extraction is inferred within the central region with greater proportion of the lower crust accreted from the axial magma lens than within the northern and southern sections. This along-axis variation in the crustal accretion style may be caused by interaction between the melt sources for the ridge and the local seamounts, which are present within the northern and southern survey sections. Third

  18. The rising bubble technique for discharge measurements

    NASA Astrophysics Data System (ADS)

    Luxemburg, W.; Hilgersom, K.; van Eekelen, M.

    2010-12-01

    The rising bubble technique is an elegant method to determine the full discharge of a river or a canal in a short moment of time. The method is not new [Sargent, 1982], but hardly applied so far. The method applies air bubbles released from the bottom of a river or canal. While the bubbles rise to the surface they are dragged along by the current. The deeper the stream and the faster the current the longer will be the distance they are dragged along. The horizontal displacement L, of the bubbles can be observed at the surface of the stream. To obtain a discharge, the rising velocity vr, of the bubble is required additionally. When the rising velocity is assumed constant the discharge per unit width amounts to q= Lvr. Placing a tube on the bottom of the stream and releasing bubbles at regular intervals results in a complete discharge profile. The ongoing research is focusing on factors affecting the rising velocity, solving practicalities in applying the method in the field and how modern image processing techniques can enhance determining in a glance the distance travelled by the bubbles. Surfacing of air bubbles in a canal

  19. Measurement of the front-end dead-time of the LHCb muon detector and evaluation of its contribution to the muon detection inefficiency

    NASA Astrophysics Data System (ADS)

    Anderlini, L.; Anelli, M.; Archilli, F.; Auriemma, G.; Baldini, W.; Bencivenni, G.; Bizzeti, A.; Bocci, V.; Bondar, N.; Bonivento, W.; Bochin, B.; Bozzi, C.; Brundu, D.; Cadeddu, S.; Campana, P.; Carboni, G.; Cardini, A.; Carletti, M.; Casu, L.; Chubykin, A.; Ciambrone, P.; Dané, E.; De Simone, P.; Falabella, A.; Felici, G.; Fiore, M.; Fontana, M.; Fresch, P.; Furfaro, E.; Graziani, G.; Kashchuk, A.; Kotriakhova, S.; Lai, A.; Lanfranchi, G.; Loi, A.; Maev, O.; Manca, G.; Martellotti, G.; Neustroev, P.; Oldeman, R. G. C.; Palutan, M.; Passaleva, G.; Penso, G.; Pinci, D.; Polycarpo, E.; Saitta, B.; Santacesaria, R.; Santimaria, M.; Santovetti, E.; Saputi, A.; Sarti, A.; Satriano, C.; Satta, A.; Schmidt, B.; Schneider, T.; Sciascia, B.; Sciubba, A.; Siddi, B. G.; Tellarini, G.; Vacca, C.; Vazquez-Gomez, R.; Vecchi, S.; Veltri, M.; Vorobyev, A.

    2016-04-01

    A method is described which allows to deduce the dead-time of the front-end electronics of the LHCb muon detector from a series of measurements performed at different luminosities at a bunch-crossing rate of 20 MHz. The measured values of the dead-time range from ~ 70 ns to ~ 100 ns. These results allow to estimate the performance of the muon detector at the future bunch-crossing rate of 40 MHz and at higher luminosity.

  20. Surface Tension and Capillary Rise

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1972-01-01

    Discussion of the shortcomings of textbook explanations of surface tension, distinguishing between concepts of tension and capillary rise. The arguments require only a clear understanding of Newtonian mechanics, notably potential energy. (DF)

  1. Rising Food Prices: Who's Responsible?

    ERIC Educational Resources Information Center

    Brown, Lester R.

    1973-01-01

    Rise in food prices can be partially attributed to the high food consumption level throughout Europe and North America, coupled with failure to evolve systems for more production of cattle, soybeans, and fisheries at lower cost. (PS)

  2. Late Noachian development of the Coprates rise, Mars

    NASA Technical Reports Server (NTRS)

    Tanaka, Kenneth L.; Schultz, Richard A.

    1991-01-01

    The Coprates rise forms a 900 km long, north to northeast trending ridge south of Coprates Chasma between long. 56 and 60 degs. Radar and stereo photogrammetric data indicate that the rise is 2 to 4 km above a neighboring trough to the east. The break in slope between the rise and this trough is well defined topographically and in Viking images. In turn, the trough is bordered to the to the east at long. 52 deg by a much gentler rise. West of the Coprates rise, the terrain dips about 0.2 deg to roughly long. 75 deg. The rise and flanking highs were previously interpreted to be tilted fault blocks formed by either Tharsis tectonism or an ancient impact. Results are now reported of a preliminary geologic study that documents Late Noachian growth of the Coprates rise as a asymmetric fold. More comprehensive work will lead to a mechanical analysis of the kinematic development of the rise. It is concluded that the Coprate rise formed during the Late Noachian by 2 to 4 km of asymmetric uplift (steeper on its east flank). The timing is inconsistent with an origin by an early impact, but it coincides in time with early Tharsis centered radial faulting at Syria Planum.

  3. High-efficiency and compact semiconductor lasers with monolithically integrated switches for generation of high-power nanosecond pulses in time-of-flight (TOF) systems

    NASA Astrophysics Data System (ADS)

    Slipchenko, Sergey; Podoskin, Aleksandr; Soboleva, Olga; Zakharov, Maxim S.; Bakhvalov, Kirill; Romanovich, Dmitrii; Pikhtin, Nikita; Tarasov, Il`ya; Bagaev, Timur; Ladugin, Maxim; Marmalyuk, Aleksandr; Simakov, Vladimir

    2016-03-01

    We present a new approach based on the integration of the functions of a high-efficiency current switch and a laser emitter into a single heterostructure as elements of time-of-flight (TOF) systems. The approach being developed employs the effect of an electrical bistability, which occurs in the general case in thyristor structures. We report recent results obtained in a study of the dynamic electrical and optical characteristics of the pulsed sources we developed. An effective generation of 2- to 100-ns laser pulses at a wavelength of 905 nm is demonstrated. The possibility of generating laser pulses shorter than 1 ns is considered. The maximum peak power reached values of 7 and 50 W for 10- and 100-ns pulses, respectively.

  4. The Rise of Online Learning

    ERIC Educational Resources Information Center

    Umpstead, Bruce

    2009-01-01

    This article discusses the rise of online learning and describes how educators in Michigan are doing their part to harness the power of online learning to transform today's high school students into lifelong learners, a key component of students' long-term success in the global economy. The author urges schools to prepare for the growing demand in…

  5. Probability of sea level rise

    SciTech Connect

    Titus, J.G.; Narayanan, V.K.

    1995-10-01

    The report develops probability-based projections that can be added to local tide-gage trends to estimate future sea level at particular locations. It uses the same models employed by previous assessments of sea level rise. The key coefficients in those models are based on subjective probability distributions supplied by a cross-section of climatologists, oceanographers, and glaciologists.

  6. Capillary Rise in a Wedge

    ERIC Educational Resources Information Center

    Piva, M.

    2009-01-01

    In introductory-level physics courses, the concept of surface tension is often illustrated using the example of capillary rise in thin tubes. In this paper the author describes experiments conducted using a planar geometry created with two small plates forming a thin wedge. The distribution of the fluid entering the wedge can be studied as a…

  7. Post-Cromerian rise in sea level

    SciTech Connect

    Olausson, E.

    1992-03-01

    The intensified cooling in the northern hemisphere during the Elsterian-Saalian ice ages (isotopic stages 22-6) resulted in a reduction of the Antarctic ice sheet by 10-15 x 106 km3, equal to a rise in sea level by about 40 m. This rise in sea level changed the hydrography of the Black Sea during the late Pleistocene warmer times, caused anoxic conditions in the eastern Mediterranean during the corresponding warming-up phases, and enhanced water transport of less saline water from the Pacific into the Arctic Ocean (the present sill depth of the Bering Strait is about 50 m). The increased supply of less saline water strengthened the halocline in the Arctic Ocean, increasing the sea ice there and, by higher albedo, its cooling effect on the adjacent continents.

  8. Falling and Rising in Water

    ERIC Educational Resources Information Center

    Mohazzabi, Pirooz

    2010-01-01

    When an object is immersed in a liquid and released, it may sink to the bottom or rise to the surface and float. If the object's density is greater than that of the liquid, it sinks. If the object's density is less than the density of the liquid, it floats. In the special case when the object's density matches the density of the liquid, it will…

  9. Temperature rise and wear of sliding contact of alloy steels

    NASA Astrophysics Data System (ADS)

    Goswami, Arindam Roy; Sardar, Santanu; Karmakar, Santanu Kumar

    2016-07-01

    The tribo-failure of machine elements under relative sliding velocities is greatly affected by frictional heating and resultant contact temperature rise. Nevertheless, the tribo-failure of automotive components is a combined effect of mechanical, thermal and chemical phenomena. Over the decades, there have been developed a number of different mathematical models for predicting surface temperature rise at sliding contact under different geometries of asperity contacts and operating conditions. The experimental investigation is still relevant today to find out the surface temperature rise at sliding contact along with the outcomes of friction and wear under various operating conditions for real time applications. The present work aims at finding average surface temperature rise at different sliding velocities, normal loads with different surface roughness experimentally. It also involves to prepare two different rough surfaces of alloy steels and to study their influences in the process of generating contact temperature rise under a given operating conditions.

  10. Martian Heat on the Rise

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph shows that the atmospheric temperatures above the surface of Mars at Gusev Crater, Mars Exploration Rover Spirit's landing site, fluctuate to a significant degree. The color red denotes warmer temperatures, while blue is cooler. The red and yellow waves of color represent thermals, or pockets of heat, which rise and fall across the surface. These data, acquired by the rover's miniature thermal emission spectrometer, help scientists understand how the bottom layer of air closest to the surface behaves and interacts with global winds.

  11. Drainage in a rising foam.

    PubMed

    Yazhgur, Pavel; Rio, Emmanuelle; Rouyer, Florence; Pigeonneau, Franck; Salonen, Anniina

    2016-01-21

    Rising foams created by continuously blowing gas into a surfactant solution are widely used in many technical processes, such as flotation. The prediction of the liquid fraction profile in such flowing foams is of particular importance since this parameter controls the stability and the rheology of the final product. Using drift flux analysis and recently developed semi-empirical expressions for foam permeability and osmotic pressure, we build a model predicting the liquid fraction profile as a function of height. The theoretical profiles are very different if the interfaces are considered as mobile or rigid, but all of our experimental profiles are described by the model with mobile interfaces. Even the systems with dodecanol are well known to behave as rigid in forced drainage experiments. This is because in rising foams the liquid fraction profile is fixed by the flux at the bottom of the foam. Here the foam is wet with higher permeability and the interfaces are not in equilibrium. These results demonstrate once again that it is not only the surfactant system that controls the mobility of the interface, but also the hydrodynamic problem under consideration. For example liquid flow through the foam during generation or in forced drainage is intrinsically different. PMID:26554500

  12. Diagnostics from three rising submillimeter bursts

    NASA Astrophysics Data System (ADS)

    Zhou, Ai-Hua; Li, Jian-Ping; Wang, Xin-Dong

    2016-02-01

    In this paper we investigate three novel rising submillimeter (THz) bursts that occurred sequentially in Super Active Region NOAA 10486. The average rising rate of the flux density above 200 GHz is only 20 sfu GHz-1 (corresponding to spectral index α of 1.6) for the THz spectral components of the 2003 October 28 and November 4 bursts, but it attained values of 235 sfu GHz-1 (α = 4.8) in the 2003 November 2 burst. The steeply rising THz spectrum can be produced by a population of highly relativistic electrons with a low-energy cutoff of 1 MeV, but it only requires a low-energy cutoff of 30 keV for the two slowly rising THz bursts, via gyrosynchrotron (GS) radiation based on our numerical simulations of burst spectra in the magnetic dipole field case. The electron density variation is much larger in the THz source than in the microwave (MW) source. It is interesting that the THz source radius decreased by 20%-50% during the decay phase for the three events, but the MW source increased by 28% for the 2003 November 2 event. In the paper we will present a formula that can be used to calculate the energy released by ultrarelativistic electrons, taking the relativistic correction into account for the first time. We find that the energy released by energetic electrons in the THz source exceeds that in the MW source due to the strong GS radiation loss in the THz range, although the modeled THz source area is 3-4 orders smaller than the modeled MW source one. The total energies released by energetic electrons via the GS radiation in radio sources are estimated, respectively, to be 5.2 × 1033, 3.9 × 1033 and 3.7 × 1032 erg for the October 28, November 2 and 4 bursts, which are 131, 76 and 4 times as large as the thermal energies of 2.9 × 1031, 2.1 × 1031 and 5.2 × 1031 erg estimated from soft X-ray GOES observations.

  13. Parkinson's Rates Rising Among American Men

    MedlinePlus

    ... fullstory_159464.html Parkinson's Rates Rising Among American Men Smoking is known to help shield against the ... disease may be on the rise for U.S. men over the past three decades, and the trend ...

  14. Large Topographic Rises on Venus: Implications for Mantle Upwelling

    NASA Technical Reports Server (NTRS)

    Stofan, Ellen R.; Smrekar, Suzanne E.; Bindschandler, Duane L.; Senske, David A.

    1995-01-01

    Topographic rises on Venus have been identified that are interpreted to be the surface manifestation of mantle upwellings. These features are classified into groups based on their dominant morphology. Atla and Beta Regiones are classified as rift-dominated, Dione, western Eistla, Bell, and Imdr Regiones as volcano-dominated, and Themis, eastern Eistla, and central Eistla Regiones as corona-dominated. At several topographic rises, geologic indicators were identified that may provide evidence of uplifted topography (e.g., volcanic flow features trending upslope). We assessed the minimum contribution of volcanic construction to the topography of each rise, which in general represents less than 5% of the volume of the rise, similar to the volumes of edifices at terrestrial hotspot swells. The total melt volume at each rise is approximated to be 10(exp 4) - 10(exp 6) cu km. The variations in morphology, topography, and gravity signatures at topographic rises are not interpreted to indicate variations in stage of evolution of a mantle upwelling. Instead, the morphologic variations between the three classes of topographic rises are interpreted to indicate the varying influences of lithospheric structure, plume characteristics, and regional tectonic environment. Within each class, variations in topography, gravity, and amount of volcanism may be indicative of differing stages of evolution. The similarity between swell and volcanic volumes for terrestrial and Venusian hotspots implies comparable time-integrated plume strengths for individual upwellings on the two planets.

  15. Pulsar timing sensitivity to very-low-frequency gravitational waves

    SciTech Connect

    Jenet, Fredrick A.; Armstrong, J. W.; Tinto, Massimo

    2011-04-15

    We compute the sensitivity, constrained by instrumental, propagation, and other fundamental noises, of pulsar timing to very-low-frequency gravitational waves (GWs). Reaching predicted GW signal strengths will require suppression of time-of-arrival fluctuations caused by interstellar plasma turbulence and a reduction of white rms timing noise to < or approx. 100 ns. Assuming negligible intrinsic pulsar rotational noise, perfect time transfer from time standard to observatory, and stable pulse profiles, the resulting single-pulsar signal-to-noise ratio=1 sensitivity is limited by terrestrial time standards at h{sub rms}{approx}2x10{sup -16} [f/ (1 cycle/year)]-1/2 for f<3x10{sup -8} Hz, where f is the Fourier frequency and a bandwidth of 1 cycle/(10 years) is assumed. Since this sensitivity is comparable to predicted GW signal levels, a reliable detection will require substantial signal-to-noise ratio improvement via pulsar timing array.

  16. Pulsar timing sensitivity to very-low-frequency gravitational waves

    NASA Astrophysics Data System (ADS)

    Jenet, Fredrick A.; Armstrong, J. W.; Tinto, Massimo

    2011-04-01

    We compute the sensitivity, constrained by instrumental, propagation, and other fundamental noises, of pulsar timing to very-low-frequency gravitational waves (GWs). Reaching predicted GW signal strengths will require suppression of time-of-arrival fluctuations caused by interstellar plasma turbulence and a reduction of white rms timing noise to ≲100ns. Assuming negligible intrinsic pulsar rotational noise, perfect time transfer from time standard to observatory, and stable pulse profiles, the resulting single-pulsar signal-to-noiseratio=1 sensitivity is limited by terrestrial time standards at hrms˜2×10-16[f/(1cycle/year)]-1/2 for f<3×10-8Hz, where f is the Fourier frequency and a bandwidth of 1 cycle/(10 years) is assumed. Since this sensitivity is comparable to predicted GW signal levels, a reliable detection will require substantial signal-to-noise ratio improvement via pulsar timing array.

  17. A composition analyzer for microparticles using a spark ion source. [using time of flight spectrometers

    NASA Technical Reports Server (NTRS)

    Auer, S. O.; Berg, O. E.

    1975-01-01

    Iron microparticles were fired onto a capacitor-type microparticle detector which responded to an impact with a spark discharge. Ion currents were extracted from the spark and analyzed in a time-of-flight mass spectrometer. The mass spectra showed the element of both detector and particle materials. The total extracted ion currents was typically 10A within a period of 100ns, indicating very efficient vaporization of the particle and ionization of the vapor. Potential applications include research on cosmic dust, atmospheric aerosols and cloud droplets, particles ejected by rocket or jet engines, by machining processes, or by nuclear bomb explosions.

  18. Peniotron oscillations in rising sun cavity

    SciTech Connect

    Gallagher, D.; Richards, J.; Scafuri, F.; Armstrong, C.

    1995-12-31

    For the first time ever, peniotron oscillations have been observed from a peniotron oscillator operating at the f=4f{sub c} harmonic at 90 GHz and in a rising-sun magnetron-type waveguide circuit. The experiment was designed to achieve proof of principle at low power for the rising-sun circuit. The beam voltage and current were 9 kV and 0.3 A, respectively. Preliminary results show 65% beam transmission to the collector. The output power achieved was 5 watts. Output power was observed for beam voltages from 7 to over 9 kV. Performance optimization will be achieved by magnetic tuning and shimming. Also to improve on the output power, greater field stability and control of the magnetic field shape will be necessary. Computer controlled power supplies for each of the individual magnetic coils were placed on order. Presented will be the cold-test and optimized hot-test data and how they correlate to simulated performance to determine beam quality. Presented also will be a description of the gun, circuit and RF window, as well as a high power experiment planned for later this year.

  19. Stochastic secular trends in sea level rise

    NASA Astrophysics Data System (ADS)

    Ocaña, Victor; Zorita, Eduardo; Heimbach, Patrick

    2016-04-01

    Global mean sea level (GMSL) has been rising since (at least) the nineteenth century and the rate of rise may be increasing. Several studies that attempt to explain the long-term trend of GMSL during the instrumental record share the common assumption that this trend is deterministic in nature and different from natural variations. Here we show that the trend can alternatively be explained, at least in part, as being caused by random variations within the coupled ocean-atmosphere-cryosphere system, and hence not having a deterministic origin. These random trends, which add to externally forced changes (e.g., through anthropogenic climate change), are a consequence of the integrated character of GMSL, which is the cumulative addition of temporal contributions that exhibit random character, and whose integration results in GMSL variations with persistence on decadal-centennial time scales. The generation of trends by integration of random stationary noise (i.e., even in a constant climate) is a robust and fundamental feature of stochastically forced systems with memory. The integrated character of GMSL results in an intrinsic difficulty in distinguishing internal from externally forced trends.

  20. Large Volcanic Rises on Venus

    NASA Technical Reports Server (NTRS)

    Smrekar, Suzanne E.; Kiefer, Walter S.; Stofan, Ellen R.

    1997-01-01

    Large volcanic rises on Venus have been interpreted as hotspots, or the surface manifestation of mantle upwelling, on the basis of their broad topographic rises, abundant volcanism, and large positive gravity anomalies. Hotspots offer an important opportunity to study the behavior of the lithosphere in response to mantle forces. In addition to the four previously known hotspots, Atla, Bell, Beta, and western Eistla Regiones, five new probable hotspots, Dione, central Eistla, eastern Eistla, Imdr, and Themis, have been identified in the Magellan radar, gravity and topography data. These nine regions exhibit a wider range of volcano-tectonic characteristics than previously recognized for venusian hotspots, and have been classified as rift-dominated (Atla, Beta), coronae-dominated (central and eastern Eistla, Themis), or volcano-dominated (Bell, Dione, western Eistla, Imdr). The apparent depths of compensation for these regions ranges from 65 to 260 km. New estimates of the elastic thickness, using the 90 deg and order spherical harmonic field, are 15-40 km at Bell Regio, and 25 km at western Eistla Regio. Phillips et al. find a value of 30 km at Atla Regio. Numerous models of lithospheric and mantle behavior have been proposed to interpret the gravity and topography signature of the hotspots, with most studies focusing on Atla or Beta Regiones. Convective models with Earth-like parameters result in estimates of the thickness of the thermal lithosphere of approximately 100 km. Models of stagnant lid convection or thermal thinning infer the thickness of the thermal lithosphere to be 300 km or more. Without additional constraints, any of the model fits are equally valid. The thinner thermal lithosphere estimates are most consistent with the volcanic and tectonic characteristics of the hotspots. Estimates of the thermal gradient based on estimates of the elastic thickness also support a relatively thin lithosphere (Phillips et al.). The advantage of larger estimates of

  1. High resolution rainfall measurements around a high rise building

    NASA Astrophysics Data System (ADS)

    de Jong, Stijn; van de Giesen, Nick; Hut, Rolf

    2010-05-01

    A number of disdrometers (acoustic rain gauge) has been placed around a high rise building on a place where variation in spatial distribution of precipitation is expected, to show the advantage of high resolution rainfall measurements in a urban area. The standard recommendation for the placement of a rain gauge is that the gauge is positioned at a distance corresponding to two to four times the height of any nearby obstruction to obtain a measurement that is representative for the surrounding area. In an urban area it is almost impossible to find a location that suits this recommendation. Rain measurements in urban area with a high spatial resolution are desired, to obtain a better understanding of urban hydrology, but costs may be prohibitive. A low cost disdrometer has been developed to make it affordable to perform rain measurements with a very high spatial and temporal resolution. The disdrometer is tested around a high rise building on the Delft University of Technology campus. The faculty of Electrical Engineering, Mathematics and Computer Science (EWI) on the campus of Delft University of Technology consists of a high rise building of 90 meters and a low rise building of 15 meters. Sensors are placed on the low rise building to measure the impact of the high rise building on the spatial distribution of precipitation. In addition to the disdrometer, two other methods are used to measure precipitation differences around the high rise building. Tipping bucket rain gauges have been placed on two elevator shaft housings on the low rise building, of which one is situated in the shadow of the high rise building. Simultaneously, runoff from the elevator shafts is measured. A comparison of the different methods will be presented.

  2. The Rise of Statistical Mechanics

    NASA Astrophysics Data System (ADS)

    Cercignani, Carlo

    The atomic theory of matter is reviewed from the times of the early greeks until the times of Boltzmann and Gibbs. The modern kinetic theory of gases including the Boltzmann equation is discussed from a historical point of view.

  3. Pulsating proton aurora caused by rising tone Pc1 waves

    NASA Astrophysics Data System (ADS)

    Nomura, R.; Shiokawa, K.; Omura, Y.; Ebihara, Y.; Miyoshi, Y.; Sakaguchi, K.; Otsuka, Y.; Connors, M.

    2016-02-01

    We found rising tone emissions with a dispersion of ˜1 Hz per several tens of seconds in the dynamic spectrum of a Pc1 geomagnetic pulsation (Pc1) observed on the ground. These Pc1 rising tones were successively observed over ˜30 min from 0250 UT on 14 October 2006 by an induction magnetometer at Athabasca, Canada (54.7°N, 246.7°E, magnetic latitude 61.7°N). Simultaneously, a Time History of Events and Macroscale Interactions during Substorms panchromatic (THEMIS) all-sky camera detected pulsations of an isolated proton aurora with a period of several tens of seconds, ˜10% variations in intensity, and fine structures of 3° in magnetic longitudes. The pulsations of the proton aurora close to the zenith of ATH have one-to-one correspondences with the Pc1 rising tones. This suggests that these rising tones scatter magnetospheric protons intermittently at the equatorial region. The radial motion of the magnetospheric source, of which the isolated proton aurora is a projection, can explain the central frequency increase of Pc1, but not the shorter period (tens of seconds) frequency increase of ˜1 Hz in Pc1 rising tones. We suggest that EMIC-triggered emissions generate the frequency increase of Pc1 rising tones on the ground and that they also cause the Pc1 pearl structure, which has a similar characteristic time.

  4. Geochemistry and age of Shatsky, Hess, and Ojin Rise seamounts: Implications for a connection between the Shatsky and Hess Rises

    NASA Astrophysics Data System (ADS)

    Tejada, Maria Luisa G.; Geldmacher, Jörg; Hauff, Folkmar; Heaton, Daniel; Koppers, Anthony A. P.; Garbe-Schönberg, Dieter; Hoernle, Kaj; Heydolph, Ken; Sager, William W.

    2016-07-01

    Shatsky Rise in the Northwest Pacific is the best example so far of an oceanic plateau with two potential hotspot tracks emanating from it: the linear Papanin volcanic ridge and the seamounts comprising Ojin Rise. Arguably, these hotspot tracks also project toward the direction of Hess Rise, located ∼1200 km away, leading to speculations that the two plateaus are connected. Dredging was conducted on the massifs and seamounts around Shatsky Rise in an effort to understand the relationship between these plateaus and associated seamounts. Here, we present new 40Ar/39Ar ages and trace element and Nd, Pb, and Hf isotopic data for the recovered dredged rocks and new trace elements and isotopic data for a few drill core samples from Hess Rise. Chemically, the samples can be subdivided into plateau basalt-like tholeiites and trachytic to alkalic ocean-island basalt compositions, indicating at least two types of volcanic activity. Tholeiites from the northern Hess Rise (DSDP Site 464) and the trachytes from Toronto Ridge on Shatsky's TAMU massif have isotopic compositions that overlap with those of the drilled Shatsky Rise plateau basalts, suggesting that both Rises formed from the same mantle source. In contrast, trachytes from the southern Hess Rise (DSDP Site 465A) have more radiogenic Pb isotopic ratios that are shifted toward a high time-integrated U/Pb (HIMU-type mantle) composition. The compositions of the dredged seamount samples show two trends relative to Shatsky Rise data: one toward lower 143Nd/144Nd but similar 206Pb/204Pb ratios, the other toward similar 143Nd/144Nd but more radiogenic 206Pb/204Pb ratios. These trends can be attributed to lower degrees of melting either from lower mantle material during hotspot-related transition to plume tail or from less refractory shallow mantle components tapped during intermittent deformation-related volcanism induced by local tectonic extension between and after the main volcanic-edifice building episodes on Shatsky

  5. Temperature rise in superfluid helium pumps

    NASA Technical Reports Server (NTRS)

    Kittel, Peter

    1988-01-01

    The temperature rise of a fountain effect pump (FEP) and of a centrifugal pump (CP) are compared. Calculations and estimates presented here show that under the operating conditions expected during the resupply of superfluid helium in space, a centrifugal pump will produce a smaller temperature rise than will a fountain effect pump. The temperature rise for the FEP is calculated assuming an ideal pump, while the temperature rise of the CP is estimated from the measured performance of a prototype pump. As a result of this smaller temperature rise and of the different operating characteristics of the two types of pumps, transfers will be more effective using a centrifugal pump.

  6. Temperature rise in superfluid helium pumps

    SciTech Connect

    Kittel, P.

    1988-07-01

    The temperature rise of a fountain effect pump (FEP) and of a centrifugal pump (CP) are compared. Calculations and estimates presented here show that under the operating conditions expected during the resupply of superfluid helium in space, a centrifugal pump will produce a smaller temperature rise than will a fountain effect pump. The temperature rise for the FEP is calculated assuming an ideal pump, while the temperature rise of the CP is estimated from the measured performance of a prototype pump. As a result of this smaller temperature rise and of the different operating characteristics of the two types of pumps, transfers will be more effective using a centrifugal pump.

  7. Influence of Resistance Method on Motor Winding Temperature Rise Measurement

    NASA Astrophysics Data System (ADS)

    Beges, G.

    2011-12-01

    The objective of this article is presentation of influences when measuring the motor winding temperature rise in the scope of safety testing of electrical appliances, with respect to conformity assessment. The temperature measurement in testing is one of the most defined fields of measurement, but it is very important how the measurement is performed. Standards only describe that the resistance method shall be used for determination of the temperature rise (heating) of the winding. The temperature rise is defined as the average temperature rise of the windings above the ambient (surrounding) temperature, at the specified load of the unit under test. It is not explicitly defined how to approach this measurement when using cooling characteristics of the winding for determination of the temperature rise. Since the extrapolation curve is used, the procedure is also very important to obtain a result as accurate as possible. It is important that measurement results and their associated uncertainties are correctly evaluated, and on that basis, appropriate conclusions of conformity of the product with specifications are made. The resistance method influence on the motor winding temperature rise measurement is a case study in this article. The article focuses on the measurement of the temperature rise of electrical motors used in electrical appliances according to the standard EN 60335-1, clause 11 (2002) (identical as standard IEC 60335-1, 2001). In this article, the influencing parameters are analyzed when measuring the temperature rise of electromotor winding. As a case study, concrete measurements are presented. The optimal time after which the performer has to start measurement of the cooling characteristics is analyzed, since the motors are typically mounted deep into appliances. Especially for a collector motor winding, it takes some time for a performer to be able to connect the measuring instrument to collector's lamellas because this contact has an important

  8. Slow-rise and Fast-rise Phases of an Erupting Solar Filament and Flare Emission Onset

    NASA Technical Reports Server (NTRS)

    Sterling, Alphonse C.; Moore, Ronald L.

    2005-01-01

    We observe the eruption of an active-region solar filament of 1998 July 11 using high time cadence and high spatial resolution EUV observations from the TRACE satellite, along with soft X-ray images from the soft X-ray telescope (SXT) on the Yohkoh satellite, hard X-ray fluxes from the BATSE instrument on the Compton Gamma Ray Observatory (CGRO) satellite and from the hard X-ray telescope (HXT) on Yohkoh, and ground-based magnetograms. We concentrate on the initiation of the eruption in an effort to understand the eruption mechanism. Prior to eruption the filament undergoes slow upward movement in a "slow rise" phase with an approximately constant velocity of about 15 km/s that lasts about 10 min. It then erupts in a "fast-rise" phase, accelerating to a velocity of about 200 km/s in about 5 min, and then decelerating to approximately 150 km/s over the next 5 min. EUV brightenings begin about concurrent with the start of the filament's slow rise, and remain immediately beneath the rising filament during the slow rise; initial soft X-ray brightenings occur at about the same time and location. Strong hard X-ray emission begins after the onset of the fast rise, and does not peak until the filament has traveled to a substantial altitude (to a height about equal to the initial length of the erupting filament) beyond its initial location. Additional information is available in the original extended abstract.

  9. Time?

    NASA Astrophysics Data System (ADS)

    Amoroso, Richard L.

    2013-09-01

    The concept of time in the `clockwork' Newtonian world was irrelevant; and has generally been ignored until recently by several generations of physicists since the implementation of quantum mechanics. We will set aside the utility of time as a property relating to physical calculations of events relating to a metrics line element or as an aspect of the transformation of a particles motion/interaction in a coordinate system or in relation to thermodynamics etc., i.e. we will discard all the usual uses of time as a concept used to circularly define physical parameters in terms of other physical parameters; concentrating instead on time as an aspect of the fundamental cosmic topology of our virtual reality especially as it inseparably relates to the nature and role of the observer in natural science.

  10. Thermal lens measurements in liquids on a submicrosecond time scale

    SciTech Connect

    Isak, S. J.; Komorowski, S. J.; Merrow, C. N.; Poston, P. E.; Eyring, E. M.

    1989-03-01

    The use of the thermal lens method is shown to be quite suitable for kinetic studies of quenching on a submicrosecond time scale. The lower limit of time resolution that can be achieved is determined by the acoustic transit time, /tau//sub /ital a//, in the medium. A thermal lens signal with a 100-ns time constant due to the quenched triplet state of benzophenone is readily measured. The thermal lens method is superior to the photoacoustic (PA) method in the breadth of the accessible time range, and in the significantly fewer measurements required to obtain accurate data, including no requirement for a reference sample; it is also less sensitive to geometrical and laser power requirements than is the PA method.

  11. Explaining the Paleoproterozoic Rise of O2

    NASA Astrophysics Data System (ADS)

    Anbar, A. D.; Rye, R.; Kaufman, A. J.

    2001-12-01

    The Paleoproterozoic rise of atmospheric O2 is not understood. Geochemical evidence indicates pO2 \\leq 5 x 10-4 atm before ~ 2.2 Ga and >= 0.03 atm by 2.0 Ga [1]. Most models of this rapid oxygenation account for the timing in an ad hoc manner. In contrast, we suggest oxygenation was driven by rising solar luminosity, a hypothesis consistent with emerging geochemical evidence. Solar luminosity was { ~} 80 % of present value 2.75 Ga. Climate models indicate that pCO2 > 0.2 atm was required before 2.75 Ga if CO2 alone accounted for greenhouse enhancement that averted global glaciation [2]. Paleosols reveal pCO2 <= 10-1.4 atm between 2.75 and 2.2 Ga [3]. This constraint may extend earlier [4]. Given insufficient CO2, CH4 likely helped maintain surface temperature. pCH4 > 10-4 atm would have been adequate 2.75 Ga; Methanogens could sustain this level as long as pO2 was negligible [5]. Atmospheric CH4 and O2 are incompatible. If CH4 was a critical greenhouse gas, increases in pO2 caused global cooling. Temperature and photosynthetic O2 production are probably positively correlated between 273 and 300 K. Combined, these effects constituted a negative feedback on pO2: Excess O2 production cooled the surface, decreasing O2 production until pCH4 was restored. Methanogenesis was decoupled from this feedback as the bulk of Archean methanogens presumably lived in the deep ocean, insulated from surface temperature. Hence, the CH4 greenhouse acted as a cap on pO2 in the Archean. This cap would have eased as rising solar luminosity permitted "titration" of CH4 by increased O2 production; pO2 increased slowly as pCH4 decreased. This feedback suppressed pO2 until solar luminosity allowed the CO2-H2O greenhouse to maintain equable temperatures without appreciable CH4. This threshold was crossed { ~} 2.5 to 2.0 Ga [2], explaining Paleoproterozoic oxygenation. As Earth approached the threshold the CH4 buffer shrank and the likelihood of the feedback being temporarily overwhelmed by

  12. The Rise of the CISO

    ERIC Educational Resources Information Center

    Gale, Doug

    2007-01-01

    The late 1980s was an exciting time to be a CIO in higher education. Computing was being decentralized as microcomputers replaced mainframes, networking was emerging, and the National Science Foundation Network (NSFNET) was introducing the concept of an "internet" to hundreds of thousands of new users. Security wasn't much of an issue; the big…

  13. INFRARED METHOD FOR PLUME RISE VISUALIZATION AND MEASUREMENT

    EPA Science Inventory

    An infrared video camera and recording system were used to record near-source plume rise from a low turbine stack on an oil-gathering center at Prudhoe Bay, Alaska. he system provided real-time, continuous visualization of the plume using a color monitor while the images were rec...

  14. Excitation of a single atom with exponentially rising light pulses.

    PubMed

    Aljunid, Syed Abdullah; Maslennikov, Gleb; Wang, Yimin; Dao, Hoang Lan; Scarani, Valerio; Kurtsiefer, Christian

    2013-09-01

    We investigate the interaction between a single atom and optical pulses in a coherent state with a controlled temporal envelope. In a comparison between a rising exponential and a square envelope, we show that the rising exponential envelope leads to a higher excitation probability for fixed low average photon numbers, in accordance with a time-reversed Weisskopf-Wigner model. We characterize the atomic transition dynamics for a wide range of the average photon numbers and are able to saturate the optical transition of a single atom with ≈50 photons in a pulse by a strong focusing technique. PMID:25166660

  15. Excitation of a Single Atom with Exponentially Rising Light Pulses

    NASA Astrophysics Data System (ADS)

    Aljunid, Syed Abdullah; Maslennikov, Gleb; Wang, Yimin; Dao, Hoang Lan; Scarani, Valerio; Kurtsiefer, Christian

    2013-09-01

    We investigate the interaction between a single atom and optical pulses in a coherent state with a controlled temporal envelope. In a comparison between a rising exponential and a square envelope, we show that the rising exponential envelope leads to a higher excitation probability for fixed low average photon numbers, in accordance with a time-reversed Weisskopf-Wigner model. We characterize the atomic transition dynamics for a wide range of the average photon numbers and are able to saturate the optical transition of a single atom with ≈50 photons in a pulse by a strong focusing technique.

  16. Recovery Time Measurements of Silicon Photomultipliers Using a Pulsed Laser

    NASA Astrophysics Data System (ADS)

    Gruber, L.; Brunner, S. E.; Curceanu, C.; Marton, J.; Romero Vidal, A.; Scordo, A.; Suzuki, K.; Vazquez, O. D.

    We performed an experimental study to determine the pixel recovery time of various Multi Pixel Photon Counters (MPPCs) in order to characterize their rate capability and double-hit resolution. The recovery time constant and its dependence on the operating voltage has been evaluated by measuring the photosensor response to two consecutive laser pulses with varying relative time differences of a few ns (2-3 ns) up to some 100 ns using a waveform analysis technique. A Monte Carlo simulation tool is being developed to model the MPPC recovery process and interpret experimental data. In this context, the influence of after-pulsing, cross-talk and dark-noise on the recovery process can be studied.

  17. The rise of model protozoa.

    PubMed

    Montagnes, David; Roberts, Emily; Lukeš, Julius; Lowe, Chris

    2012-04-01

    It is timely to evaluate the role of protozoa as model organisms given their diversity, abundance and versatility as well as the economic and ethical pressures placed on animal-based experimentation. We first define the term model organism and then examine through examples why protozoa make good models. Our examples reflect major issues including evolution, ecology, population and community biology, disease, the role of organelles, ageing, space travel, toxicity and teaching. We conclude by recognising that although protozoa may in some cases not completely mimic tissue- or whole-animal-level processes, they are extremely flexible and their use should be embraced. Finally, we offer advice on obtaining emergent model protozoa. PMID:22342867

  18. Fertility postponement is largely due to rising educational enrolment

    PubMed Central

    Bhrolcháin, Máire Ní; Beaujouan, Éva

    2012-01-01

    The rise in educational enrolment is often cited as a possible cause of the trend to later childbearing in developed societies but direct evidence of its contribution to the aggregate change in fertility tempo is scarce. We show that rising enrolment, resulting in later ages at the end of education, accounts for a substantial part of the upward shift in the mean age at first birth in the 1980s and 1990s in Britain and in France. The postponement of first birth over that period has two components: a longer average period of enrolment and a post-enrolment component that is also related to educational level. The relationship between rising educational participation and the move to later fertility timing is almost certainly causal. Our findings therefore suggest that fertility tempo change is rooted in macro-economic and structural forces rather than in the cultural domain. PMID:22889178

  19. Timescales for detecting a significant acceleration in sea level rise

    PubMed Central

    Haigh, Ivan D.; Wahl, Thomas; Rohling, Eelco J.; Price, René M.; Pattiaratchi, Charitha B.; Calafat, Francisco M.; Dangendorf, Sönke

    2014-01-01

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records. PMID:24728012

  20. Timescales for detecting a significant acceleration in sea level rise.

    PubMed

    Haigh, Ivan D; Wahl, Thomas; Rohling, Eelco J; Price, René M; Pattiaratchi, Charitha B; Calafat, Francisco M; Dangendorf, Sönke

    2014-01-01

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records. PMID:24728012

  1. Timescales for detecting a significant acceleration in sea level rise

    NASA Astrophysics Data System (ADS)

    Haigh, Ivan D.; Wahl, Thomas; Rohling, Eelco J.; Price, René M.; Pattiaratchi, Charitha B.; Calafat, Francisco M.; Dangendorf, Sönke

    2014-04-01

    There is observational evidence that global sea level is rising and there is concern that the rate of rise will increase, significantly threatening coastal communities. However, considerable debate remains as to whether the rate of sea level rise is currently increasing and, if so, by how much. Here we provide new insights into sea level accelerations by applying the main methods that have been used previously to search for accelerations in historical data, to identify the timings (with uncertainties) at which accelerations might first be recognized in a statistically significant manner (if not apparent already) in sea level records that we have artificially extended to 2100. We find that the most important approach to earliest possible detection of a significant sea level acceleration lies in improved understanding (and subsequent removal) of interannual to multidecadal variability in sea level records.

  2. Fertility postponement is largely due to rising educational enrolment.

    PubMed

    Ní Bhrolcháin, Máire; Beaujouan, Eva

    2012-11-01

    The rise in educational enrolment is often cited as a possible cause of the trend to later childbearing in developed societies but direct evidence of its contribution to the aggregate change in fertility tempo is scarce. We show that rising enrolment, resulting in later ages at the end of education, accounts for a substantial part of the upward shift in the mean age at first birth in the 1980s and 1990s in Britain and in France. The postponement of first birth over that period has two components: a longer average period of enrolment and a post-enrolment component that is also related to educational level. The relationship between rising educational participation and the move to later fertility timing is almost certainly causal. Our findings therefore suggest that fertility tempo change is rooted in macro-economic and structural forces rather than in the cultural domain. PMID:22889178

  3. Preferential amplification of rising versus falling frequency whistler mode signals

    NASA Astrophysics Data System (ADS)

    Li, J. D.; Harid, V.; Spasojevic, M.; Gołkowski, M.; Inan, U. S.

    2015-01-01

    Analysis of ground-based ELF/VLF observations of injected whistler mode waves from the 1986 Siple Station experiment demonstrates the preferential magnetospheric amplification of rising over descending frequency-time ramps. From examining conjugate region receptions of ±1 kHz/s frequency-time ramps, we find that rising ramps generate an average total power 1.9 times higher than that of falling frequency ramps when both are observed during a transmission. And in 17% of receptions, only rising ramps are observed above the noise floor. Furthermore, the amplification ratio inversely correlates with the noise and total signal power. Using a narrowband Vlasov-Maxwell numerical simulation, we explore the preferential amplification due to differences in linear growth rate as a function of frequency, relative to the frequency which maximizes the linear growth rate for a given anisotropy, and in nonlinear phase trapping. These results contribute to the understanding of magnetospheric wave amplification and the preference for structured rising elements in chorus.

  4. RADIOACTIVELY POWERED RISING LIGHT CURVES OF TYPE Ia SUPERNOVAE

    SciTech Connect

    Piro, Anthony L.

    2012-11-10

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first Almost-Equal-To 0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X {sub 56} Almost-Equal-To (4-6) Multiplication-Sign 10{sup -2} of {sup 56}Ni distributed between a depth of Almost-Equal-To 10{sup -2} and 0.3 M {sub Sun} below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  5. Radioactively Powered Rising Light Curves of Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Piro, Anthony L.

    2012-11-01

    The rising luminosity of the recent, nearby supernova 2011fe shows a quadratic dependence with time during the first ≈0.5-4 days. In addition, studies of the composite light curves formed from stacking together many Type Ia supernovae (SNe Ia) have found similar power-law indices for the rise, but may also show some dispersion that may indicate diversity. I explore what range of power-law rises are possible due to the presence of radioactive material near the surface of the exploding white dwarf (WD). I summarize what constraints such a model places on the structure of the progenitor and the distribution and velocity of ejecta. My main conclusion is that for the inferred explosion time for SN 2011fe, its rise requires an increasing mass fraction X 56 ≈ (4-6) × 10-2 of 56Ni distributed between a depth of ≈10-2 and 0.3 M ⊙ below the WD's surface. Radioactive elements this shallow are not found in simulations of a single C/O detonation. Scenarios that may produce this material include helium-shell burning during a double-detonation ignition, a gravitationally confined detonation, and a subset of deflagration to detonation transition models. In general, the power-law rise can differ from quadratic depending on the details of the velocity, density, and radioactive deposition gradients in a given event. Therefore, comparisons of this work with observed bolometric rises of SNe Ia would place strong constraints on the properties of the shallow outer layers, providing important clues for identifying the elusive progenitors of SNe Ia.

  6. Airport cleanup rises above problems

    SciTech Connect

    Pressly, N.; Lucas, B.; Frumer, B.; Roth, R.

    1996-07-01

    Engineers used a treatment combination to improve the in-situ bioremediation system`s efficiency in removing underground fuel leaks at JFK Airport. John F. Kennedy International Airport, in New York City, on Jamaica Bay, has an above-ground storage capacity of about 32 million gallons of jet fuel, which flow through about 50 miles of high-pressure underground pipe to the central terminal area. EAch terminal`s fuel hydrant system was the major source os subsurface contamination at the site. The site is covered by 1 to 1.5 feet of reinforced concrete pavement. Liquid phase jet fuel (free product) was measured on the water table with true thickness ranging from less than 1 inch to 1 foot. After analysis of core samples, contamination was found adsorbed to the soil with maximum levels at the water table. This article describes the clean up, covering the following topics: microbial conditions during system operation; above-ground treatment challenges: free product emulsification, presence of biomass; evaluation of enhancements: dissolved air floatation, coagulation and flocculation, retention time adjustments; conclusions.

  7. Ampicillin: rise fall and resurgence.

    PubMed

    Kaushik, Dwarikadhish; Mohan, Mudit; Borade, Dhammraj M; Swami, Onkar C

    2014-05-01

    Antimicrobial resistance (AMR) is a global problem. AMR has posed new challenges in treatment of infectious diseases. Antimicrobials are losing efficacy due to development of resistant pathogens. It has lead to re-emergence of certain infectious diseases. Treatment of such diseases has undergone changes with use of alternative antimicrobials and drug combinations. Pathogens are likely to develop resistance to alternative antimicrobials also and risk of infections with nonexistent treatment is real. Salmonella showed widespread resistant to ampicillin which resulted in use of alternative antimicrobials like fluroquinolones and cephalosporins in the treatment of enteric fever in last two decades. Unfortunately there are growing reports of resistance to these antimicrobials. Interestingly there are numerous reports of ampicillin regaining activity against Salmonella. Speculatively lack of exposure of Salmonella to ampicillin for long time resulted in the loss of plasmid mediated resistance in the pathogen. There may have been emergence of de novo ampicillin susceptible strains. This is assuring in the era where problem of AMR is compounded by the scarcity of new antimicrobial development. PMID:24995206

  8. Measurement of Temperature Rise of Quartz Plate during Synchrotron Radiation Irradiation Using Infrared Camera

    NASA Astrophysics Data System (ADS)

    Chiba, Akira; Oizumi, Hiroaki; Yamanashi, Hiromasa; Hoko, Hiromasa; Nishiyama, Iwao; Ogawa, Tarou; Okazaki, Shinji

    2002-01-01

    The temperature rise of an attenuator under synchrotron radiation irradiation was measured with an infrared (IR) camera containing an InSb detection device. Since the measured value changes with the emissivity of the measured sample, in measurement by thermography, calibration is required. In order to determine the actual temperature rise, calibration of the IR camera was performed using a hot plate as a heat source under the same geometrical arrangement as the double quartz plates with a sapphire window. The calibrated temperature rise is three times higher than the temperature rise observed with the IR camera. The calibrated temperature rise is in agreement with temperature rise predicted by simulation. As a result, it is predicted that the temperature rise of the attenuator is 119°C at a beam current of 500 mA.

  9. The Rise of a Giant

    NASA Astrophysics Data System (ADS)

    2006-12-01

    European astronomy has received a tremendous boost with the decision from ESO's governing body to proceed with detailed studies for the European Extremely Large Telescope. This study, with a budget of 57 million euro, will make it possible to start, in three years time, the construction of an optical/infrared telescope with a diameter around 40m that will revolutionise ground-based astronomy. The chosen design is based on a revolutionary concept specially developed for a telescope of this size. "The decision by the ESO Council to go ahead with the design study for an European Extremely Large Telescope is a very exciting one for European astronomy,", said Richard Wade, President of the ESO Council. "Today is a great day because the ESO Council has authorised us to go forward with the final design of the next flagship telescope of ESO,", says Catherine Cesarsky, ESO's Director General. ESO PR Photo 46/06 ESO PR Photo 46/06 The European Extremely Large Telescope (Artist's Impression) Since the end of last year, ESO has been working together with its user community of European astronomers and astrophysicists to define the new giant telescope needed by the middle of the next decade [1]. More than one hundred astronomers from all European countries have been involved throughout 2006, helping the ESO Project Offices to produce a novel concept, in which performance, cost, schedule and risk were carefully evaluated. This fast pace has also been possible thanks to early conceptual studies in Europe (such as the ESO OWL and the EURO-50 studies) and research and development done in collaboration with a large number of European institutes and high-tech industries to develop critical enabling technologies within the framework of the EU FP6 programme and with significant contributions from all partners. Provisionally dubbed E-ELT for the European Extremely Large Telescope, ESO's innovative concept was presented in detail two weeks ago to more than 250 European astronomers at a

  10. The rising light curves of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Firth, R. E.; Sullivan, M.; Gal-Yam, A.; Howell, D. A.; Maguire, K.; Nugent, P.; Piro, A. L.; Baltay, C.; Feindt, U.; Hadjiyksta, E.; McKinnon, R.; Ofek, E.; Rabinowitz, D.; Walker, E. S.

    2015-02-01

    We present an analysis of the early, rising light curves of 18 Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory and the La Silla-QUEST variability survey. We fit these early data flux using a simple power law (f(t) = α × tn) to determine the time of first light (t0), and hence the rise time (trise) from first light to peak luminosity, and the exponent of the power-law rise (n). We find a mean uncorrected rise time of 18.98 ± 0.54 d, with individual supernova (SN) rise times ranging from 15.98 to 24.7 d. The exponent n shows significant departures from the simple `fireball model' of n = 2 (or f(t) ∝ t2) usually assumed in the literature. With a mean value of n = 2.44 ± 0.13, our data also show significant diversity from event to event. This deviation has implications for the distribution of 56Ni throughout the SN ejecta, with a higher index suggesting a lesser degree of 56Ni mixing. The range of n found also confirms that the 56Ni distribution is not standard throughout the population of SNe Ia, in agreement with earlier work measuring such abundances through spectral modelling. We also show that the duration of the very early light curve, before the luminosity has reached half of its maximal value, does not correlate with the light-curve shape or stretch used to standardize SNe Ia in cosmological applications. This has implications for the cosmological fitting of SN Ia light curves.

  11. Drivers of Pontocaspian Biodiversity Rise and Demise

    NASA Astrophysics Data System (ADS)

    Wesselingh, Frank; Flecker, Rachel; Wilke, Thomas; Leroy, Suzanne; Krijgsman, Wout; Stoica, Marius

    2015-04-01

    In the past two million years, the region of the Black Sea Basin, Caspian Basin and adjacent Anatolia and the Balkans were the stage of the evolution of a unique brackish water fauna, the so-called Pontocaspian fauna. The fauna is the result of assembly of genera with a Paratethyan origin and Anatolian origins during the Early Pleistocene. The rapid diversification of the Pontocaspian fauna is the result of the very dynamic nature of the lakes (the Caspian Sea is technically a lake) and seas in the region in the past two million years. In most times the various lake basins were isolated (like today), but in other episodes connections existed. Regional and global climate as well as the regional tectonic regimes were main drivers of lake basin evolution. Over the past 80 years a major biodiversity crisis is hitting the Pontocaspian faunas due to environmental degradation, pollution and invasive species. In the new EU-ETN PRIDE (Drivers of Pontocaspian Biodiversity Rise and Demise)we will be documenting the geological context of past diversifications and turnover events. We present examples of rapid turnover (biodiversity crises) in the Quaternary, assess driving forces and draw implications for the nature of the current human-mediated biodiversity crisis in the region.

  12. Time-of-flight neutral particle analyzer and calibration

    SciTech Connect

    Harris, W. S.; Garate, E. P.; Heidbrink, W. W.; McWilliams, R.; Roche, T.; Trask, E.; Zhang Yang

    2008-10-15

    A time-of-flight diagnostic has been implemented on the Irvine field reversed configuration (IFRC) to obtain an energy distribution function from charge-exchanged neutral hydrogen. The diagnostic includes a 13 cm radius slotted disk rotating at 165 Hz in vacuum which chops the emitted neutrals at a rate of 26 kHz. In situ timing verification was performed with a dc xenon discharge lamp with an uncertainty less than 100 ns for a 38 {mu}s chopping period. Energy calibration was accomplished with a singly ionized lithium source in the range of 300-1500 eV, achieving an average energy uncertainty, {delta}E/E, of 0.11. The diagnostic has measured neutrals in the range of 20-80 eV from the IFRC and the corresponding energy distribution function has been obtained.

  13. Parkinson's Rates Rising Among American Men

    MedlinePlus

    ... news/fullstory_159464.html Parkinson's Rates Rising Among American Men Smoking is known to help shield against ... from an otherwise very positive health trend among American men over the past few decades: A steep ...

  14. Rising Blood Sugar Hitting More Obese Adults

    MedlinePlus

    ... https://medlineplus.gov/news/fullstory_159853.html Rising Blood Sugar Hitting More Obese Adults To curb diabetes, researchers ... HealthDay News) -- Among obese American adults, control of blood sugar is worsening, leading to more diabetes and heart ...

  15. Colon Cancer Rising in People Under 50

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_159004.html Colon Cancer Rising in People Under 50 Incidence up ... TUESDAY, May 24, 2016 (HealthDay News) -- Although overall colon cancer rates are declining, the rates among Americans ...

  16. Colon Cancer Rising in People Under 50

    MedlinePlus

    ... fullstory_159004.html Colon Cancer Rising in People Under 50 Incidence up more than 10 percent in ... cancer rates are declining, the rates among Americans under 50 have jumped more than 11 percent in ...

  17. As Fitness Levels Rise, Diabetes Risk Drops

    MedlinePlus

    ... medlineplus.gov/news/fullstory_158889.html As Fitness Levels Rise, Diabetes Risk Drops But change requires dedication ... TUESDAY, May 17, 2016 (HealthDay News) -- A higher level of heart-lung fitness may reduce your risk ...

  18. As Fitness Levels Rise, Diabetes Risk Drops

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_158889.html As Fitness Levels Rise, Diabetes Risk Drops But change ... of the overall population, the study author's explained. "As this benefit remained significant even when adjusting for ...

  19. Obesity Rates Rising Among Women: CDC

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_159239.html Obesity Rates Rising Among Women: CDC Though a major ... are another group that continues to struggle with obesity. "Obesity remains a public health concern," said Cynthia ...

  20. Biogenic Methane and the Rise of Oxygen

    NASA Technical Reports Server (NTRS)

    Catling, David; McKay, Christopher

    2001-01-01

    Oxygenic photosynthesis does not make the rise of oxygen inevitable. What is required is that reductant and oxygen be separated and permanently segregated. The usual picture for Earth is that oxygenic photosynthesis split CO2 into carbon and oxygen, with the carbon buried in sediments and the oxygen mostly taken up by oxides of iron and sulfur. The relatively small atmospheric reservoir of O2 is regulated by the carbon burial rate, reaction with volcanic and metamorphic gases, and oxidation of reduced carbon released as old sediments weather. Absent from this picture is a distinction between the Archean and modern times: on average, carbon burial fluxes would have been matched by oxygen losses then as now. Separation of reductant from oxidant is only provisional. No net oxidation of the continents occurs, and so no change of diagenetic, metamorphic, or volcanic gases is expected. Nor would any change in oxidative weathering be expected. Something more than carbon burial is required to make the Archean different. The escape of hydrogen to space permanently separates the reductant from the oxidant. Hydrogen escape is widely believed to have led to the present highly oxidized states of Mars and Venus. Hydrogen escape has usually been thought small for Archaean Earth, because water vapor is cold-trapped at the troposphere and thus held to levels of a few ppmv in the stratosphere. This cold trapping renders hydrogen escape negligible. However, methane is not cold trapped, and its expected abundance in the Archaean, given low oxygen levels and a biogenic source, would have been high, probably more than 100 times present. At such levels methane would have driven geologically significant levels of hydrogen escape. Additional information is contained in the original extended abstract.

  1. CRISM/HiRISE Correlative Spectroscopy

    NASA Astrophysics Data System (ADS)

    Seelos, F. P.; Murchie, S. L.; McGovern, A.; Milazzo, M. P.; Herkenhoff, K. E.

    2011-12-01

    The Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and High Resolution Imaging Science Experiment (HiRISE) are complementary investigations with high spectral resolution and broad wavelength coverage (CRISM ~20 m/pxl; ~400 - 4000 nm, 6.55 nm sampling) and high spatial resolution with broadband color capability (HiRISE ~25 cm/pxl; ~500, 700, 900 nm band centers, ~200-300 nm FWHM). Over the course of the MRO mission it has become apparent that spectral variations in the IR detected by CRISM (~1000 nm - 4000 nm) sometimes correlate spatially with visible and near infrared 3-band color variations observed by HiRISE. We have developed a data processing procedure that establishes a numerical mapping between HiRISE color and CRISM VNIR and IR spectral data and provides a statistical evaluation of the uncertainty in the mapping, with the objective of extrapolating CRISM-inferred mineralogy to the HiRISE spatial scale. The MRO mission profile, spacecraft capabilities, and science planning process emphasize coordinated observations - the simultaneous observation of a common target by multiple instruments. The commonalities of CRISM/HiRISE coordinated observations present a unique opportunity for tandem data analysis. Recent advances in the systematic processing of CRISM hyperspectral targeted observations account for gimbal-induced photometric variations and transform the data to a synthetic nadir acquisition geometry. The CRISM VNIR (~400 nm - 1000 nm) data can then be convolved to the HiRISE Infrared, Red, and Blue/Green (IRB) response functions to generate a compatible CRISM IRB product. Statistical evaluation of the CRISM/HiRISE spatial overlap region establishes a quantitative link between the data sets. IRB spectral similarity mapping for each HiRISE color spatial pixel with respect to the CRISM IRB product allows a given HiRISE pixel to be populated with information derived from the coordinated CRISM observation

  2. Rising Sea Levels: Truth or Scare?

    ERIC Educational Resources Information Center

    Peacock, Alan

    2007-01-01

    When "ITV News" ran an item that shocked the author, about rising sea levels that will have caused the entire evacuation of the islands by the end of this year, he began to wonder whether the Pacific Ocean is really rising as fast as this. The media reporting of such things can be a double-edged sword. On the one hand, it brought to the author's…

  3. Subsidence and Relative Sea-level Rise in Threatened Deltas

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Higgins, S.

    2014-12-01

    In determining the risk lowland deltaic topography, as threatened by sea level rise and land subsidence, a number of important processes must be evaluated. Sea level rise is a global process but with local manifestations. Asian deltas have been experiencing higher rates of sea level rise due to the steric impact on dynamic (ocean) topography. Other large scale geophysical impacts on relative sea level at the local scale include the isostatic and flexural response to Holocene sea level history, Holocene sediment loads, and in former ice sheet zones --- glacial rebound. Tectonism does play a role on relative sea level rise, particularly in South America where the Eastern coastline, particularly Argentina, is rising relative to regional sea levels. Subsidence is impacted by both natural ground compaction, and accelerated compaction due to, for example, peat oxidation that often has a human driver (e.g. swamp reclammation). Subsidence is also impacted by the extraction of deeper deposits of petroleum and water. Rates of delta subsidence vary widely, depending on the magnitude of the anthropogenic driver, from a few mm/y to 100's of mm/y. Ground water withdrawal is the dominant reason behind much of the world's coastal subsidence, with important exceptions. On average subsidence rates (all causes) now contribute to local sea level innundations at rates four times faster then sea level is rising. New technologies, particularly InSAR and GPS methods, can often pin point the local cause (e.g. water withdrawl for agriculture versus for aquaculture). Subsurface soil or rock heterogeneity, and other very local geological patterns such as historical river pathways, also influence the temporal and spatial patterns associated with delta subsidence.

  4. Nothing But MORB at Shatsky Rise

    NASA Astrophysics Data System (ADS)

    Natland, J. H.

    2013-12-01

    I compare basaltic rocks and glasses obtained by IODP Expedition 324 drilling at Shatsky Rise, a Jurassic Large Igneous Province in the northwestern Pacific, to mid-ocean ridge basalts (MORB) from the Indian Ocean and East Pacific Rise. Data are compositions in Sano et al (2012) and electron-probe microanalyses of spinel and clinopyroxene. Although several different basalt types were obtained from Shatsky Rise, they all have counterparts along modern spreading ridges, namely depleted (normal, or N-type) and enriched (E-type) MORB plus one extremely depleted type, here termed 'truly depleted'. The latter is similar to eastern Pacific basalts from small intra-transform spreading segments (e.g., Siqueiros fracture zone) and near-ridge seamounts. Basalts from Shatsky Rise are mainly strongly differentiated ferrobasalts; some appear to have mixed with or assimilated small amounts of silicic differentiates and with E-MORB. Similar processes also occur along the East Pacific Rise (9N, Endeavor Deep, Pacific-Antarctic East Pacific Rise). Some clinopyroxene crystals occur in gabbro clots at one site. The textures and mineral compositions resemble those of gabbro cumulates at Hess Deep, eastern Pacific. Spinel compositions from two sites, including in 'truly depleted' basalt, are similar to those in strongly depleted picritic basalt from Siqueiros Fracture Zone, except that they crystallized at lower temperature. Petrogenetic models suggest slightly lower temperatures and smaller degrees of partial melting for all parental Shatsky basalts than for either the N-type or depleted (D-type) MORB of Gale et al (2013). Those with smaller extents of melting resemble basalts from the very slowly spreading and deeply rifted Southwest Indian Ridge near the Indian Ocean triple junction. In summary, Shatsky Rise basalts in all respects resemble those of modern spreading ridges, but mostly to the East Pacific Rise. Compositions of mantle sources were similar; conditions of partial melting

  5. Numerical model for atmospheric contaminant cloud rise scenarios

    NASA Astrophysics Data System (ADS)

    Kanarska, Yuliya; Lomov, Ilya; Antoun, Tarabay; Glenn, Lewis

    2007-11-01

    Our numerical approach includes fluid mechanical model which is the combination of a compressible GEODYN code and a Low Mach code (LMC). The first one is an explicit code and it is intended to simulate early stages of nuclear explosions up to 15 s. The second one is an implicit code based on a pressure projection method and it is intended to simulate subsequent cloud rise events up to few hours. We perform series of cloud rise scenarios ranging from idealized bubble rise problem to realistic air bursts. We analyze effects of compressible dynamics and different turbulent parameterizations on the cloud evolution. It is found that in a realistic configuration interaction of a reflected shock wave from the ground with a fireball affects significantly cloud evolution in contrast to idealized bubble rise simulations. We show that by providing initial source from compressible GEODYN code, later times flow evolution can be successfully simulated with fast and efficient LMC code. Finally, we develop formalism for tracer particles and their fallout and present some preliminary results.

  6. Exhaust cloud rise and growth for Apollo Saturn engines.

    NASA Technical Reports Server (NTRS)

    Susko, M.; Kaufman, J. W.

    1973-01-01

    Empirical and analytical results have been reduced from time-lapse photographs of exhaust clouds during the launch of Apollo 10, 14, 15, and 16 from the Kennedy Space Center. Theoretical predictions of the buoyant cloud rise and growth compare very favorably to actual measurements. The mathematical model predicts with engineering accuracy the terminal altitude and size of the clouds. A principal input to MSFC's multilayer diffusion model is top height of the exhaust cloud. It is this characteristic dimension that is the main subject of this report. An interesting occurrence during launch is the formation of bimodal exhaust cloud which is due to the north-south oriented flame trench directly beneath the base of the vehicle. This study has added considerable information on engine exhaust cloud rise and growth which is essential to the study of atmospheric dispersal in time and space.

  7. Sea Level Rise in Santa Clara County

    NASA Technical Reports Server (NTRS)

    Milesi, Cristina

    2005-01-01

    Presentation by Cristina Milesi, First Author, NASA Ames Research Center, Moffett Field, CA at the "Meeting the Challenge of Sea Level Rise in Santa Clara County" on June 19, 2005 Santa Clara County, bordering with the southern portion of the San Francisco Bay, is highly vulnerable to flooding and to sea level rise (SLR). In this presentation, the latest sea level rise projections for the San Francisco Bay will be discussed in the context of extreme water height frequency and extent of flooding vulnerability. I will also present preliminary estimations of levee requirements and possible mitigation through tidal restoration of existing salt ponds. The examples will draw mainly from the work done by the NASA Climate Adaptation Science Investigators at NASA Ames.

  8. Visualizing Sea Level Rise with Augmented Reality

    NASA Astrophysics Data System (ADS)

    Kintisch, E. S.

    2013-12-01

    Looking Glass is an application on the iPhone that visualizes in 3-D future scenarios of sea level rise, overlaid on live camera imagery in situ. Using a technology known as augmented reality, the app allows a layperson user to explore various scenarios of sea level rise using a visual interface. Then the user can see, in an immersive, dynamic way, how those scenarios would affect a real place. The first part of the experience activates users' cognitive, quantitative thinking process, teaching them how global sea level rise, tides and storm surge contribute to flooding; the second allows an emotional response to a striking visual depiction of possible future catastrophe. This project represents a partnership between a science journalist, MIT, and the Rhode Island School of Design, and the talk will touch on lessons this projects provides on structuring and executing such multidisciplinary efforts on future design projects.

  9. Who Gets a Mentor? A Longitudinal Assessment of the Rising Star Hypothesis

    ERIC Educational Resources Information Center

    Singh, Romila; Ragins, Belle Rose; Tharenou, Phyllis

    2009-01-01

    This study assessed the rising star hypothesis, which proposes that individuals who are on the fast track to career success are more likely to gain mentors than others. The study used a sample of employees who had never been mentored and examined the relationship between rising star attributes measured at Time 1 and the attainment of a mentor a…

  10. Rising prostate-specific antigen values during neoadjuvant androgen deprivation therapy: The importance of monitoring

    SciTech Connect

    Niblock, Paddy; Pickles, Tom . E-mail: tpickles@bccancer.bc.ca

    2006-05-01

    Purpose: To assess the impact of a rising prostate-specific antigen (PSA) level in patients receiving neoadjuvant androgen deprivation therapy (N-ADT) before external beam radiotherapy for prostate cancer. Methods and Materials: From prospectively collected data, we identified 182 patients who received between 3 and 12 months of N-ADT before definitive external beam radiotherapy and who had at least three PSA readings during the neoadjuvant period. One hundred fifty patients had PSA values that continued to fall (Non-Rise group), but 32 had a PSA value that started to rise (Rise group). The two groups were compared by Mann-Whitney U and Pearson chi-square tests. Kaplan-Meier and log-rank analyses were performed for time to treatment failure, cause-specific survival (CSS), and overall survival (OS). Results: The median follow-up was 62.5 months for the Non-Rise group and 53 months for the Rise group. Patients who sustained a PSA rise during the N-ADT period had a shorter time to PSA relapse (p = 0.013), poorer CSS (p = 0.027), and poorer OS (p = 0.03). Multivariate analysis confirms the significance of a PSA rise during the N-ADT period for CSS (p = 0.035) and OS (p = 0.038). Conclusions:: A subset of patients treated with N-ADT develop a rising PSA profile that likely represents early androgen resistance. They have significantly worse outcome.

  11. Large lateral photovoltaic effect with ultrafast relaxation time in SnSe/Si junction

    NASA Astrophysics Data System (ADS)

    Wang, Xianjie; Zhao, Xiaofeng; Hu, Chang; Zhang, Yang; Song, Bingqian; Zhang, Lingli; Liu, Weilong; Lv, Zhe; Zhang, Yu; Tang, Jinke; Sui, Yu; Song, Bo

    2016-07-01

    In this paper, we report a large lateral photovoltaic effect (LPE) with ultrafast relaxation time in SnSe/p-Si junctions. The LPE shows a linear dependence on the position of the laser spot, and the position sensitivity is as high as 250 mV mm-1. The optical response time and the relaxation time of the LPE are about 100 ns and 2 μs, respectively. The current-voltage curve on the surface of the SnSe film indicates the formation of an inversion layer at the SnSe/p-Si interface. Our results clearly suggest that most of the excited-electrons diffuse laterally in the inversion layer at the SnSe/p-Si interface, which results in a large LPE with ultrafast relaxation time. The high positional sensitivity and ultrafast relaxation time of the LPE make the SnSe/p-Si junction a promising candidate for a wide range of optoelectronic applications.

  12. HIGH RISE OR LOW RISE. A STUDY OF DECISION FACTORS IN RESIDENCE HALLS PLANNING.

    ERIC Educational Resources Information Center

    Educational Facilities Labs., Inc., New York, NY.

    THE PURPOSE OF THIS REPORT IS TO SERVE COLLEGE OFFICIALS, HOUSING ADMINISTRATORS, PLANNING GROUPS AND ARCHITECTS BY FOCUSING ON THE DECISION FACTORS WHICH RELATE TO HIGH-RISE AND LOW-RISE STUDENT HOUSING. DECISION FACTORS INCLUDE--(1) LAND USE IMPLICATIONS, (2) SITE REQUIREMENTS--BUILDING CODES, SUB-SOIL CONSIDERATIONS, NATURAL TERRAIN,…

  13. How To Attack Rising Energy Costs.

    ERIC Educational Resources Information Center

    Fickes, Michael

    2001-01-01

    Presents manufacturer and engineer suggestions on how schools can solve their rising energy costs in the face of more demanding classroom needs placing greater demands of Heating and air conditioning ventilation systems. The use of CO2 sensors, boiler technology and two-pipe systems are explored. (GR)

  14. Obesity Rates Rising Among Women: CDC

    MedlinePlus

    ... news/fullstory_159239.html Obesity Rates Rising Among Women: CDC Though a major health concern, little has changed, expert says To use the sharing features on this page, please enable JavaScript. (*this news ... June 7, 2016 (HealthDay News) -- More American women than ever are obese, while the number of ...

  15. The Rise of School-Supporting Nonprofits

    ERIC Educational Resources Information Center

    Nelson, Ashlyn Aiko; Gazley, Beth

    2014-01-01

    This paper examines voluntary contributions to public education via charitable school foundations, booster clubs, parent teacher associations, and parent teacher organizations. We use panel data on school-supporting charities with national coverage from 1995 to 2010, which we geocode and match to school districts. We document the meteoric rise of…

  16. The Rise of the Digital Public Library

    ERIC Educational Resources Information Center

    McKendrick, Joseph

    2012-01-01

    There is a growing shift to digital offerings among public libraries. Libraries increasingly are fulfilling roles as technology hubs for their communities, with high demand for technology and career development training resources. Ebooks and other digital materials are on the rise, while print is being scaled back. More libraries are turning to…

  17. Rising Tides: Faculty Expectations of Library Websites

    ERIC Educational Resources Information Center

    Nicol, Erica Carlson; O'English, Mark

    2012-01-01

    Looking at 2003-2009 LibQUAL+ responses at research-oriented universities in the United States, faculty library users report a significant and consistent rise in desires and expectations for library-provided online tools and websites, even as student user groups show declining or leveling expectations. While faculty, like students, also report…

  18. Tuition Rising: Why College Costs So Much.

    ERIC Educational Resources Information Center

    Ehrenberg, Ronald G.

    This book explores the causes of tuition inflation, using Cornell University (New York) as a prototypical institution. There are 9 sections with 20 chapters. Section 1, "Setting the Stage," includes (1) "Why Do Costs Keep Rising at Selective Private Colleges and Universities?" and (2) "Who Is In Charge of the University?" Section 2, "Wealth and…

  19. Sea Level Rise National Coastal Property Model

    EPA Science Inventory

    The impact of sea level rise on coastal properties depends critically on the human response to the threat, which in turn depends on several factors, including the immediacy of the risk, the magnitude of property value at risk, options for adapting to the threat and the cost of th...

  20. Agriculture waste and rising CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Currently, there are many uncertainties concerning agriculture’s role in global environmental change including the effects of rising atmospheric CO2 concentration. A viable and stable world food supply depends on productive agricultural systems, but environmental concerns within agriculture have to...

  1. Rising Political Consciousness: Transformational Learning in Malaysia.

    ERIC Educational Resources Information Center

    Kamis, Mazalan; Muhamad, Mazanah

    As part of a larger study (not discussed) ten educated Malaysian citizens were interviewed to find whether their rising political consciousness, over a ten year period (1988-1999), indicated that their transformation was influenced by their culture. The subjects were between 35-45 years old, married, with an average of four children. All were…

  2. Project RISE: Workplace Literacy Education in Context.

    ERIC Educational Resources Information Center

    Beder, Hal; And Others

    A reflective self-assessment process was used to evaluate Project RISE, a 1-year, federally funded workplace literacy project. The goal of the evaluation was to help staff understand their collective experience in a way that might help them to serve their clients more effectively in the future. A list of the most critical problems faced by staff…

  3. Sea Level Rise Coastal Property Model

    EPA Science Inventory

    The impact of sea level rise on coastal properties depends critically on the human response to the threat, which in turn depends on several factors, including the immediacy of the risk, the magnitude of property value at risk, options for adapting to the threat and the cost of th...

  4. Rising atmospheric carbon dioxide and crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The increase in carbon dioxide concentration in the earth's atmosphere and its potential effect on atmospheric temperature is a major concern. Changes in global environment will have major effects for natural and agricultural ecosystems. Plants have been directly affected by rising atmospheric CO2...

  5. Relative Deprivation, Rising Expectations, and Black Militancy

    ERIC Educational Resources Information Center

    Abeles, Ronald P.

    1976-01-01

    Investigates the role of relative deprivation (RD) and rising expectations (RE) as mediating variables between social structure and black militancy through secondary analyses of survey data of blacks living in Cleveland and Miami in the late 1960s. Alternative explanations and implications derived from the present data and the theories for the…

  6. Impact of sea-level rise assessed

    NASA Astrophysics Data System (ADS)

    Coastal erosion, flooding of low-lying coastal areas, disruption of ecosystems, probable population relocation, and economic loss are some consequences of projected relative sea-level rise. The term includes both the rise anticipated to result from global warming and other factors, and the rise from local tectonic subsidence. Some specific sites were discussed at the annual meeting of the American Association for the Advancement of Science, held in Washington, D.C., February 14-19.In comparing the New York City and eastern Mediterranean coasts, Victor Goldsmith of Hunter College, New York, presented a case for stabilization versus retreat of coastal areas, dependent on the geologic terrane and on the degree of development. The 578-mile New York City coastline is considered “hard,” meaning some sort of cement structure, such as roads, jetties, or piers, separates the water from the coast. It is also an area of many beaches that are not natural, but that have been built up and maintained by the process of sand nourishment over the past 50 years. The Rockaway peninsula, for example, has received more than 12 million cubic yards of sand between 1926 and 1962 in response to the measured sea-level rise of 30 cm in the last 100 years from downwarping of the wide continental shelf, said Goldsmith. Because land is highly developed and expensive in this area, retreat is not a practical option. Goldsmith suggests that the effects of on-going sea-level rise, at rates of about 1 foot per century, can be offset by continued hardening of the New York City coastline and beach nourishment where necessary.

  7. Impact of sea-level rise assessed

    NASA Astrophysics Data System (ADS)

    Coastal erosion, flooding of low-lying coastal areas, disruption of ecosystems, probable population relocation, and economic loss are some consequences of projected relative sea-level rise. The term includes both the rise anticipated to result from global warming and other factors, and the rise from local tectonic subsidence. Some specific sites were discussed at the annual meeting of the American Association for the Advancement of Science, held in Washington, D.C., February 14-19.In comparing the New York City and eastern Mediterranean coasts, Victor Goldsmith of Hunter College, New York, presented a case for stabilization versus retreat of coastal areas, dependent on the geologic terrane and on the degree of development. The 578-mile New York City coastline is considered "hard," meaning some sort of cement structure, such as roads, jetties, or piers, separates the water from the coast. It is also an area of many beaches that are not natural, but that have been built up and maintained by the process of sand nourishment over the past 50 years. The Rockaway peninsula, for example, has received more than 12 million cubic yards of sand between 1926 and 1962 in response to the measured sea-level rise of 30 cm in the last 100 years from downwarping of the wide continental shelf, said Goldsmith. Because land is highly developed and expensive in this area, retreat is not a practical option. Goldsmith suggests that the effects of on-going sea-level rise, at rates of about 1 foot per century, can be offset by continued hardening of the New York City coastline and beach nourishment where necessary.

  8. Updating Maryland's sea-level rise projections

    USGS Publications Warehouse

    Boesch, Donald F.; Atkinson, Larry P.; Boicourt, William C.; Boon, John D.; Cahoon, Donald R.; Dalrymple, Robert A.; Ezer, Tal; Horton, Benjamin P.; Johnson, Zoe P.; Kopp, Robert E.; Li, Ming; Moss, Richard H.; Parris, Adam; Sommerfield, Christopher K.

    2013-01-01

    With its 3,100 miles of tidal shoreline and low-lying rural and urban lands, “The Free State” is one of the most vulnerable to sea-level rise. Historically, Marylanders have long had to contend with rising water levels along its Chesapeake Bay and Atlantic Ocean and coastal bay shores. Shorelines eroded and low-relief lands and islands, some previously inhabited, were inundated. Prior to the 20th century, this was largely due to the slow sinking of the land since Earth’s crust is still adjusting to the melting of large masses of ice following the last glacial period. Over the 20th century, however, the rate of rise of the average level of tidal waters with respect to land, or relative sea-level rise, has increased, at least partially as a result of global warming. Moreover, the scientific evidence is compelling that Earth’s climate will continue to warm and its oceans will rise even more rapidly. Recognizing the scientific consensus around global climate change, the contribution of human activities to it, and the vulnerability of Maryland’s people, property, public investments, and natural resources, Governor Martin O’Malley established the Maryland Commission on Climate Change on April 20, 2007. The Commission produced a Plan of Action that included a comprehensive climate change impact assessment, a greenhouse gas reduction strategy, and strategies for reducing Maryland’s vulnerability to climate change. The Plan has led to landmark legislation to reduce the state’s greenhouse gas emissions and a variety of state policies designed to reduce energy consumption and promote adaptation to climate change.

  9. Is the detection of accelerated sea level rise imminent?

    PubMed Central

    Fasullo, J. T.; Nerem, R. S.; Hamlington, B.

    2016-01-01

    Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade. PMID:27506974

  10. Is the detection of accelerated sea level rise imminent?

    NASA Astrophysics Data System (ADS)

    Fasullo, J. T.; Nerem, R. S.; Hamlington, B.

    2016-08-01

    Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred. This masking arose largely from a recovery in ocean heat content through the mid to late 1990 s subsequent to major heat content reductions in the years following the eruption. A consequence of this finding is that barring another major volcanic eruption, a detectable acceleration is likely to emerge from the noise of internal climate variability in the coming decade.

  11. Rising income and the subjective well-being of nations.

    PubMed

    Diener, Ed; Tay, Louis; Oishi, Shigehiro

    2013-02-01

    We explored whether rising income in nations is associated with increasing subjective well-being (SWB), with several advances over earlier work. Our methods are improved in that across time, the same well-being questions were asked in the same order, and we employed broad and equivalent representative samples over time from a large number of nations. We also assessed psychosocial factors that might mediate the relation of income and SWB. We found that changes in household income were associated with concomitant changes in life evaluations, positive feelings, and negative feelings. The effects of gross domestic product (GDP) change were weaker and significant only for life evaluations, perhaps because GDP was a less certain index of the standard of living of the average household. The association of income and SWB is more likely to occur when the average person's material welfare accompanies rising income, when people become more satisfied with their finances, and when people become more optimistic about their futures. People did not adapt to the income rises during the period of years we studied, in that income rises produced SWB increases that did not return to earlier levels. It appears that previous researchers failed to come to agreement because of the small sample sizes of the nations, the inconsistent methods across years and surveys, and the lack of measures of potential mediating variables. Analyses of income relative to people in one's nation and between-nation slopes together suggest that income standards are now largely global, with little effect of national social comparison. PMID:23106249

  12. Estimating Hardness from the USDC Tool-Bit Temperature Rise

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Sherrit, Stewart

    2008-01-01

    A method of real-time quantification of the hardness of a rock or similar material involves measurement of the temperature, as a function of time, of the tool bit of an ultrasonic/sonic drill corer (USDC) that is being used to drill into the material. The method is based on the idea that, other things being about equal, the rate of rise of temperature and the maximum temperature reached during drilling increase with the hardness of the drilled material. In this method, the temperature is measured by means of a thermocouple embedded in the USDC tool bit near the drilling tip. The hardness of the drilled material can then be determined through correlation of the temperature-rise-versus-time data with time-dependent temperature rises determined in finite-element simulations of, and/or experiments on, drilling at various known rates of advance or known power levels through materials of known hardness. The figure presents an example of empirical temperature-versus-time data for a particular 3.6-mm USDC bit, driven at an average power somewhat below 40 W, drilling through materials of various hardness levels. The temperature readings from within a USDC tool bit can also be used for purposes other than estimating the hardness of the drilled material. For example, they can be especially useful as feedback to control the driving power to prevent thermal damage to the drilled material, the drill bit, or both. In the case of drilling through ice, the temperature readings could be used as a guide to maintaining sufficient drive power to prevent jamming of the drill by preventing refreezing of melted ice in contact with the drill.

  13. DETECTING MASSIVE GRAVITONS USING PULSAR TIMING ARRAYS

    SciTech Connect

    Lee, Kejia; Kramer, Michael; Jenet, Fredrick A.; Price, Richard H.; Wex, Norbert

    2010-10-20

    At the limit of weak static fields, general relativity becomes Newtonian gravity with a potential field that falls off as inverse distance rather than a theory of Yukawa-type fields with a finite range. General relativity also predicts that the speed of disturbances of its waves is c, the vacuum light speed, and is non-dispersive. For these reasons, the graviton, the boson for general relativity, can be considered to be massless. Massive gravitons, however, are features of some alternatives to general relativity. This has motivated experiments and observations that, so far, have been consistent with the zero-mass graviton of general relativity, but further tests will be valuable. A basis for new tests may be the high sensitivity gravitational wave (GW) experiments that are now being performed and the higher sensitivity experiments that are being planned. In these experiments, it should be feasible to detect low levels of dispersion due to non-zero graviton mass. One of the most promising techniques for such a detection may be the pulsar timing program that is sensitive to nano-Hertz GWs. Here, we present some details of such a detection scheme. The pulsar timing response to a GW background with the massive graviton is calculated, and the algorithm to detect the massive graviton is presented. We conclude that, with 90% probability, massless gravitons can be distinguished from gravitons heavier than 3 x 10{sup -22} eV (Compton wavelength {lambda}{sub g} = 4.1 x 10{sup 12} km), if bi-weekly observation of 60 pulsars is performed for 5 years with a pulsar rms timing accuracy of 100 ns. If 60 pulsars are observed for 10 years with the same accuracy, the detectable graviton mass is reduced to 5 x 10{sup -23} eV ({lambda}{sub g} = 2.5 x 10{sup 13} km); for 5 year observations of 100 or 300 pulsars, the sensitivity is respectively 2.5 x 10{sup -22} ({lambda}{sub g} = 5.0 x 10{sup 12} km) and 10{sup -22} eV ({lambda}{sub g} = 1.2 x 10{sup 13} km). Finally, a 10 year

  14. Precision Time Transfer and Obit Determination Using Laser Ranging to Lunar Reconnaissance Orbiter

    NASA Astrophysics Data System (ADS)

    Mao, D.; Barker, M. K.; Clarke, C. B.; Golder, J. E.; Hoffman, E.; Horvath, J. E.; Mazarico, E.; Mcgarry, J.; Neumann, G. A.; Torrence, M. H.; Rowlands, D. D.; Skillman, D.; Smith, D. E.; Sun, X.; Zuber, M. T.

    2011-12-01

    Since the commissioning of LRO in June, 2009, one-way laser ranging (LR) to Lunar Reconnaissance Orbiter (LRO) has been conducted successfully from NASA's Next Generation Satellite Laser Ranging System (NGSLR) at Goddard Geophysical and Astronomical observatory (GGAO) in Greenbelt, Maryland. With the support of the International Laser Ranging Service (ILRS), ten international satellite laser ranging (SLR) ground stations have participated in this experiment and over 1200 hours of ranging data have been collected. In addition to supplementing the precision orbit determination (POD) of LRO, LR is able to perform time transfer between the ground station and the spacecraft clocks. The LRO clock oscillator is stable to 1 part in 10^{12} over several hours, and as stable for much longer periods after correcting for a long-term drift rate and an aging rate. With a precisely-determined LRO ephemeris, the oscillator-determined laser pulse receive time can be differenced with ground station clock transmit times using H-maser and GPS-steered Rb oscillators as references. Simultaneous ranging to LRO among 2, 3, or 4 ground stations has made it possible for relative time transfer among the participating LR stations. Results have shown about 100 ns difference between some LR stations and the primary NGSLR station. At present, the time transfer accuracy is limited to 100 ns at NGSLR. However, an All-View GPS receiver has been installed, which, in combination with a H-maser, is expected to improve the accuracy to 1 ns r.m.s. at NGSLR. Results of new ranging and time transfer experiments using the new time base will be reported. The ability to use LR for time transfer validates the selection of a commercially-supplied, oven-controlled crystal oscillator on board LRO for one-way laser ranging.The increased clock accuracy also provides stronger orbit constraints for LRO POD. The improvements due to including LR data in the LRO POD will be presented.

  15. The sitting and rising test for assessing people with chronic stroke

    PubMed Central

    Ng, Shamay S.M.; Fong, Shirley S.M.; Chan, Wayne L.S.; Hung, Ben K.Y.; Chung, Ricci K.S.; Chim, Tina H.T.; Kwong, Patrick W.H.; Liu, Tai-Wa; Tse, Mimi M.Y.; Chung, Raymond C.K.

    2016-01-01

    [Purpose] To investigate the inter-rater and test-retest reliability of the sitting-rising test (SRT), the correlations of sitting-rising test scores with measures of strength, balance, community integration and quality of life, as well as the cut-off score which best discriminates people with chronic stroke from healthy older adults were investigated. [Subjects and Methods] Subjects with chronic stroke (n=30) and healthy older adults (n=30) were recruited. The study had a cross-sectional design, and was carried out in a university rehabilitation laboratory. Sitting-rising test performance was scored on two occasions. Other measurements included ankle dorsiflexor and plantarflexor strength, the Fugl-Meyer assessment, the Berg Balance Scale, the timed up and go test, the five times sit-to-stand test, the limits of stability test, and measures of quality of health and community integration. [Results] Sitting-rising test scores demonstrated good to excellent inter-rater and test-retest reliabilities (ICC=0.679 to 0.967). Sitting-rising test scores correlated significantly with ankle strength, but not with other test results. The sitting-rising test showed good sensitivity and specificity. A cut-off score of 7.8 best distinguished healthy older adults from stroke subjects. [Conclusions] The sitting-rising test is a reliable and sensitive test for assessing the quality of sitting and rising movements. Further studies with a larger sample are required to investigate the test’s validity. PMID:27390398

  16. Coastal subsidence and relative sea level rise

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Galloway, Devin L.

    2014-01-01

    Subsurface fluid-pressure declines caused by pumping of groundwater or hydrocarbons can lead to aquifer-system compaction and consequent land subsidence. This subsidence can be rapid, as much as 30 cm per year in some instances, and large, totaling more than 13 m in extreme examples. Thus anthropogenic subsidence may be the dominant contributor to relative sea-level rise in coastal environments where subsurface fluids are heavily exploited. Maximum observed rates of human-induced subsidence greatly exceed the rates of natural subsidence of unconsolidated sediments (~0.1–1 cm yr−1) and the estimated rates of ongoing global sea-level rise (~0.3 cm yr−1).

  17. Does senescence give rise to disease?

    PubMed

    Carnes, Bruce A; Staats, David O; Sonntag, William E

    2008-12-01

    The distinctions between senescence and disease are blurred in the literature of evolutionary biology, biodemography, biogerontology and medicine. Theories of senescence that have emerged over the past several decades are based on the concepts that organisms are a byproduct of imperfect structural designs built with imperfect materials and maintained by imperfect processes. Senescence is a complex mixture of processes rather than a monolithic process. Senescence and disease have overlapping biological consequences. Senescence gives rise to disease, but disease does not give rise to senescence. Current data indicate that treatment of disease can delay the age of death but there are no convincing data that these interventions alter senescence. An understanding of these basic tenets suggests that there are biological limits to duration of life and the life expectancy of populations and reveal biological domains where the development of interventions and/or treatments may modulate senescence. PMID:18977242

  18. Hurricanes, sea level rise, and coastal change

    USGS Publications Warehouse

    Sallenger,, Asbury H., Jr.

    2011-01-01

    Sixteen hurricanes have made landfall along the U.S. east and Gulf coasts over the past decade. For most of these storms, the USGS with our partners in NASA and the U.S. Army Corps of Engineers have flown before and after lidar missions to detect changes in beaches and dunes. The most dramatic changes occurred when the coasts were completely submerged in an inundation regime. Where this occurred locally, a new breach was cut, like during Hurricane Isabel in North Carolina. Where surge inundated an entire island, the sand was stripped off leaving marshy outcrops behind, like during Hurricane Katrina in Louisiana. Sea level rise together with sand starvation and repeated hurricane impacts could increase the probabilities of inundation and degrade coasts more than sea level rise alone.

  19. Bubble growth and rise in soft sediments

    NASA Astrophysics Data System (ADS)

    Boudreau, Bernard P.; Algar, Chris; Johnson, Bruce D.; Croudace, Ian; Reed, Allen; Furukawa, Yoko; Dorgan, Kelley M.; Jumars, Peter A.; Grader, Abraham S.; Gardiner, Bruce S.

    2005-06-01

    The mechanics of uncemented soft sediments during bubble growth are not widely understood and no rheological model has found wide acceptance. We offer definitive evidence on the mode of bubble formation in the form of X-ray computed tomographic images and comparison with theory. Natural and injected bubbles in muddy cohesive sediments are shown to be highly eccentric oblate spheroids (disks) that grow either by fracturing the sediment or by reopening preexisting fractures. In contrast, bubbles in soft sandy sediment tend to be spherical, suggesting that sand acts fluidly or plastically in response to growth stresses. We also present bubble-rise results from gelatin, a mechanically similar but transparent medium, that suggest that initial rise is also accomplished by fracture. Given that muddy sediments are elastic and yield by fracture, it becomes much easier to explain physically related phenomena such as seafloor pockmark formation, animal burrowing, and gas buildup during methane hydrate melting.

  20. Rising temperatures place cities at risk

    SciTech Connect

    Tickell, C.

    1996-12-31

    This article focuses on vulerability of urban areas as the global temperature rises and the climate changes. Basic resources - food, water, building materials, and fuel - must be brought in; the external resource base is being depleted as a result of deforestation; disposal of wastes both toxic and not is an added stress; and health effected by air and water pollution is vulnerable. This article discusses these aspects along with the sociology of urban areas in our current world. Historical prospectives are included.

  1. Igneous rocks of the East Pacific Rise

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1964-01-01

    The apical parts of large volcanoes along the East Pacific Rise (islands and seamounts) are encrusted with rocks of the alkali volcanic suite (alkali basalt, andesine- and oligoclase-andesite, and trachyte). In contrast, the more submerged parts of the Rise are largely composed of a tholeiitic basalt which has low concentrations of K, P, U, Th, Pb, and Ti. This tholeiitic basalt is either the predominant or the only magma generated in the earth's mantle under oceanic ridges and rises. It is at least 1000-fold more abundant than the alkali suite, which is probably derived from tholeiitic basalt by magmatic differentiation in and immediately below the larger volcanoes. Distinction of oceanic tholeiites from almost all continental tholeiites is possible on the simple basis of total potassium content, with the discontinuity at 0.3 to 0.5 percent K2O by weight. Oceanic tholeiites also are readily distinguished from some 19 out of 20 basalts of oceanic islands and seamount cappings by having less than 0.3 percent K2O by weight and more than 48 percent SiO2. Deep drilling into oceanic volcanoes should, however, core basalts transitional between the oceanic tholeiites and the presumed derivative alkali basalts.The composition of the oceanic tholeiites suggests that the mantle under the East Pacific Rise contains less than 0.10 percent potassium oxide by weight; 0.1 part per million of uranium and 0.4 part of thorium; a potassium:rubidium ratio of about 1200 and a potassium: uranium ratio of about 104.

  2. The Darwin Rise: A Cretaceous superswell?

    NASA Astrophysics Data System (ADS)

    McNutt, M. K.; Winterer, E. L.; Sager, W. W.; Natland, J. H.; Ito, G.

    1990-07-01

    The Japanese Guyots, Wake Guyots, and Mid-Pacific Mountains are part of a broad area of Cretaceous volcanism in the western Pacific termed the “Darwin Rise.” Based on Seabeam bathymetric data we classify these drowned volcanic islands as: type “A,” those that advanced to the atoll stage before final submergence; type “B,” those that drowned at the barrier reef stage; and type “V,” those with little or no reef material on their volcanic summits. Widespread evidence for karst topography extending to depths of 200 m on the summits of A and B guyots sheds new light on events leading to the synchronous extinction of reefs on the Darwin Rise in the mid-Cretaceous. We propose that after the formation of the reefs on the A and B guyots, the entire region was elevated at approximately the Aptian-Albian boundary (113 Ma) to form a superswell similar to that existing now in French Polynesia. The type V guyots formed on this anomalously shallow lithosphere. The demise of the reefs was the direct result of the rise of this superswell, although climate factors may have prevented reef recolonization following its later subsidence.

  3. Claritas rise, Mars: Pre-Tharsis magmatism?

    USGS Publications Warehouse

    Dohm, J.M.; Anderson, R.C.; Williams, J.-P.; Ruiz, J.; McGuire, P.C.; Buczkowski, D.L.; Wang, R.; Scharenbroich, L.; Hare, T.M.; Connerney, J.E.P.; Baker, V.R.; Wheelock, S.J.; Ferris, J.C.; Miyamoto, H.

    2009-01-01

    Claritas rise is a prominent ancient (Noachian) center of tectonism identified through investigation of comprehensive paleotectonic information of the western hemisphere of Mars. This center is interpreted to be the result of magmatic-driven activity, including uplift and associated tectonism, as well as possible hydrothermal activity. Coupled with its ancient stratigraphy, high density of impact craters, and complex structure, a possible magnetic signature may indicate that it formed during an ancient period of Mars' evolution, such as when the dynamo was in operation. As Tharsis lacks magnetic signatures, Claritas rise may pre-date the development of Tharsis or mark incipient development, since some of the crustal materials underlying Tharsis and older parts of the magmatic complex, respectively, could have been highly resurfaced, destroying any remanent magnetism. Here, we detail the significant characteristics of the Claritas rise, and present a case for why it should be targeted by the Mars Odyssey, Mars Reconnaissance Orbiter, and Mars Express spacecrafts, as well as be considered as a prime target for future tier-scalable robotic reconnaissance. ?? 2009 Elsevier B.V.

  4. A new Lagrangian method for modelling the buoyant plume rise

    NASA Astrophysics Data System (ADS)

    Alessandrini, Stefano; Ferrero, Enrico; Anfossi, Domenico

    2013-10-01

    A new method for the buoyant plume rise computation is proposed. Following Alessandrini and Ferrero (Phys A 388:1375-1387, 2009) a scalar transported by the particles and representing the temperature difference between the plume and the environment air is introduced. As a consequence, no more particles than those inside the plume have to be released to simulate the entrainment of the background air temperature. A second scalar, the vertical plume velocity, is assigned to each particle. In this way the entrainment is properly simulated and the plume rise is calculated from the local property of the flow. The model has been tested against data from two laboratory experiments in neutral and stable stratified flows. The comparison shows a good agreement. Then, we tested our new model against literature analytical formulae in a simple uniform neutral atmosphere, considering either the case of a single plume or the one of two plumes from adjacent stacks combining during the rising stage. Finally, a comparison of the model against an atmospheric tracer experiment (Bull Run), characterized by vertically non-homogeneous fields (wind velocity, temperature, velocity standard deviations and time scales), was performed. All the tests confirmed the satisfactory performance of the model.

  5. Dynamics of rising bubble inside a viscosity-stratified medium

    NASA Astrophysics Data System (ADS)

    Tripathi, Manoj; Premlata, A. R.; Sahu, Kirti

    2015-11-01

    The rising bubble dynamics in an unconfined quiescent viscosity-stratified medium has been numerically investigated. This is frequently encountered in industrial as well as natural phenomena. In spite of the large number of studies carried out on bubbles and drops, very few studies have examined the influence of viscosity stratification on bubble rise dynamics. To the best of our knowledge, none of them have isolated the effects of viscosity-stratification alone, even though it is known to influence the dynamics extensively, which is the main objective of the present study. By conducting time-dependent simulations, we present a library of bubble shapes in the Gallilei and the Eötvös numbers plane. Our results demonstrate some counter-intuitive phenomena for certain range of parameters due to the presence of viscosity stratification in the surrounding fluid. We found that in a linearly increasing viscosity medium, for certain values of parameters, bubble undergoes large deformation by forming an elongated skirt, while the skirt tends to physically separate the wake region from the rest of the surrounding fluid. This peculiar dynamics is attributed to the migration of less viscous fluid that is carried in the wake of the bubble as it rises, and thereby creating an increase.

  6. Propagation of solutes and pressure into aquifers following river stage rise

    NASA Astrophysics Data System (ADS)

    Welch, Chani; Cook, Peter G.; Harrington, Glenn A.; Robinson, Neville I.

    2013-09-01

    Water level rises associated with river flow events induce both pressure and solute movement into adjacent aquifers at vastly different rates. We present a simple analytical solution that relates the travel time and travel distance of solutes into an aquifer following river stage rise to aquifer properties. Combination with an existing solution for pressure propagation indicates that the ratio of solute to pressure travel times is proportional to the ratio of the volume of water stored in the aquifer before the river stage rise and the volume added by the stage rise and is independent of hydraulic conductivity. Two-dimensional numerical simulations of an aquifer slice perpendicular to a river demonstrate that the solutions are broadly applicable to variably saturated aquifers and partially penetrating rivers. The solutions remain applicable where river stage rise and fall occur, provided that regional hydraulic gradients are low and the duration of the river stage rise is less than pressure and solute travel times to the observation point in the aquifer. Consequently, the solutions provide new insight into the relationships between aquifer properties and distance and time of solute propagation and, in some cases, may be used to estimate system characteristics. Travel time metrics obtained for a flood event in the Cockburn River in eastern Australia using electrical conductivity measurements enabled estimates of aquifer properties and a lateral extent of river-aquifer mixing of 25 m. A detailed time series of any soluble tracer with distinctly different concentrations in river water and groundwater may be used.

  7. 21 CFR 137.185 - Enriched self-rising flour.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 2 2011-04-01 2011-04-01 false Enriched self-rising flour. 137.185 Section 137... Cereal Flours and Related Products § 137.185 Enriched self-rising flour. Enriched self-rising flour... of ingredients, prescribed for self-rising flour by § 137.180, except that: (a) It contains in...

  8. 21 CFR 137.185 - Enriched self-rising flour.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 2 2014-04-01 2014-04-01 false Enriched self-rising flour. 137.185 Section 137... Cereal Flours and Related Products § 137.185 Enriched self-rising flour. Enriched self-rising flour... of ingredients, prescribed for self-rising flour by § 137.180, except that: (a) It contains in...

  9. 21 CFR 137.185 - Enriched self-rising flour.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Enriched self-rising flour. 137.185 Section 137... Cereal Flours and Related Products § 137.185 Enriched self-rising flour. Enriched self-rising flour... of ingredients, prescribed for self-rising flour by § 137.180, except that: (a) It contains in...

  10. 21 CFR 137.185 - Enriched self-rising flour.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 2 2012-04-01 2012-04-01 false Enriched self-rising flour. 137.185 Section 137... Cereal Flours and Related Products § 137.185 Enriched self-rising flour. Enriched self-rising flour... of ingredients, prescribed for self-rising flour by § 137.180, except that: (a) It contains in...

  11. Education And Public Outreach With MRO's High Resolution Imaging Science Experiment (HiRISE).

    NASA Astrophysics Data System (ADS)

    Gulick, V. C.; McEwen, A.

    2005-12-01

    The HiRISE team is planning an innovative education and public outreach program with a variety of formal and informal educational activities. These include educator workshops, large-scale displays of HiRISE images at museums and planetariums, and opportunities for students and the general public to suggest HiRISE image observations and to participate in data analysis via the internet. Additionally, HiRISE team members have committed to spending at least 5% of their time in outreach activities and to coordinating local EP/O activities in their regions. The centerpiece of the E/PO program is HiRISE's interactive website called HiWeb (http://marsoweb.nasa.nasa.gov/hirise). HiRISE's public website will provide user-friendly web tools for students, team members, and the general public to suggest target locations for HiRISE imaging. HiWeb will provide interactive viewing and analysis of HiRISE images in context with other available Mars data. Web events, involving participation by team members, will inform students and interested members of the public of HiRISE capabilities and science goals and provide support for submitting good image suggestions. Curriculum modules and activities will focus on Mars geology, the image suggestion process and working with digital image data. We will also provide online opportunities for student and public participation in data analysis to create databases of geologic features (gullies, boulders, craters, wind streaks, etc.) present in the HiRISE images. Educator workshops will be held each year at or near the institution of HiRISE team members. Workshop background materials and instructions for all hands-on activities will be placed on HiWeb to facilitate sharing of information with other educators and the general public.

  12. PERSPECTIVE: The tripping points of sea level rise

    NASA Astrophysics Data System (ADS)

    Hecht, Alan D.

    2009-12-01

    coastal management in which options for shore protection or retreats are clearly identified and where economic, ecosystem and social impacts can be clearly evaluated. At stake are both the future of wetlands that provide important ecosystem services and the safety and sustainability of our coastal communities. This is a huge challenge requiring adequate data, long-term planning, federal-state cooperation, and integration of environmental laws. The time is at hand to assess a business-as-usual response to sea level rise or to explore a more holistic and integrated approach. President Obama has said: `The threat from climate change is serious, it is urgent, and it is growing. Our generation's response to this challenge will be judged by history, for if we fail to meet it—boldly, swiftly, and together—we risk consigning future generations to an irreversible catastrophe' [3]. Though the President was talking about action to reduce emissions of greenhouse gases, cooperation to address the consequences of rising sea level and changing climate is just as urgent. References [1] Titus J G et al 2009 State and local governments plan for development of most land vulnerable to rising sea level along the US Atlantic coast Environ. Res. Lett. 4 044008 [2] US Global Change Research Program 2009 Global Climate Change Impacts in the United States (June 2009) [3] www.whitehouse.gov/the_press_office/Remarks-by-the-President-at-UN-Secretary-General-Ban-Ki-moons-Climate-Change-Summit/

  13. How much more global warming and sea level rise?

    PubMed

    Meehl, Gerald A; Washington, Warren M; Collins, William D; Arblaster, Julie M; Hu, Aixue; Buja, Lawrence E; Strand, Warren G; Teng, Haiyan

    2005-03-18

    Two global coupled climate models show that even if the concentrations of greenhouse gases in the atmosphere had been stabilized in the year 2000, we are already committed to further global warming of about another half degree and an additional 320% sea level rise caused by thermal expansion by the end of the 21st century. Projected weakening of the meridional overturning circulation in the North Atlantic Ocean does not lead to a net cooling in Europe. At any given point in time, even if concentrations are stabilized, there is a commitment to future climate changes that will be greater than those we have already observed. PMID:15774757

  14. The rise flank trails left by migrating offsets of the equatorial East Pacific Rise axis

    SciTech Connect

    Lonsdale, P. )

    1989-01-10

    Sea Beam and magnetic surveys of the young (<1 Ma) rise flank around nontransform rise crest offsets at 5.5{degree}N, 4.9{degree}N, 3.4{degree}, 2.0{degree}N, and 2.8{degree}S mapped distinctive trails of obliquely lineated, highly magnetic crust that spreads from the characteristically curving overlapping rift zones. A Deep Tow survey around the small (1.5 km) 3.9{degree}N offset and the large (27 km) 2.0{degree}N offset provided more detailed infromation on the formation of crust in the offset trails, and of the structure of tectoniclly modified crust at interrift rise crest sites. Patches of interrift crust, which forms deep overlap basins at medium size offsets and basins and plateaus of rotated abyssal hills at large offsets, are periodically shed from the axial zone, together with abandoned portions of overlapped rift zone, to become important elements of the rise flank trails. The oblique aximuths of the paired 'fracture zone' trails that diverge from the rise crest offsets show that most have migrated along the rise crest at average speeds of 25-125 mm/yr. Net movement of the 27-km 2.8{degree}S offset has been slower, with alternating periods of rapid northward and southward migration. Information on the migration history of the surveyed offsets was supplemented by inferring the migration direction of another eight offsets on the equatorial East Pacific Rise (EPR) whose trails were less throughly mapped. Most offsets of the southern Pacific-Cocos boundary have migrated south, and most on the northern Pacific-Nazca boundary have migrated south, and most on the northern Pacific-Nazca boundary have migrated north; the patterns are not readily explained by the inferred distribution of mantle upwellings along the EPR axis.

  15. Laser-induced photoelectrochemistry. Time-resolved coulostatic-flash studies of cadmium sulfide electrodes

    SciTech Connect

    Richardson, J.H.; Perone, S.P.; Deutscher, S.B.

    1981-02-19

    Coulostatic-flash irradiation of semiconductor-liquid-junction cells with a pulsed laser source permits time-resolved measurements of photopotential transients in the nanosecond time domain. The transients observed with CdS electrodes are unusual in that they exhibit wavelength and solution dependence. Both fast (10 ns) and slow (approx. 100 ns) transients are observed in various aqueous electrolytes with irradiation near the band gap. Similar results in nonaqueous solution and with CdSe suggest that these transient photopotentials are related to processes within the semiconductor itself. A much slower (approx. 1 ..mu..s) transient is observed in polysulfide solution with irradiation in the ultraviolet; it is suggested that this transient photopotential is due to light absorption by polysulfide.

  16. Temperature Rises In Pumps For Superfluid Helium

    NASA Technical Reports Server (NTRS)

    Kittel, Peter

    1990-01-01

    Report discusses increases in temperature of superfluid helium in centrifugal and fountain-effect pumps. Intended for use in transfers of superfluid helium in outer space. Increases in temperature significantly affect losses during transfers and are important in selection of temperatures of supply tanks. Purpose of study, increase in temperature in fountain-effect pump calculated on basis of thermodynamic considerations, starting from assumption of ideal pump. Results of recent tests of ceramic material intended for use in such pumps support this assumption. Overall, centrifugal pumps more effective because it produces smaller rise in temperature.

  17. Rising river flows and glacial mass balance in central Karakoram

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Biswajit; Khan, Asif

    2014-05-01

    Field observations and geodetic measurements suggest that in the central part of the Karakoram Mountains, glaciers are either stable or expanding since 1990, in sharp contrast to glacier retreats that are prevalent in the Himalayas and adjoining high-altitude terrains of central Asia. Decreased discharge in the rivers originating from Karakoram is cited as a supporting evidence of this somewhat anomalous phenomenon. Here, in contrary to those citations, we show that, river discharge during the melting season of the glaciers in central Karakoram has increased from 1985 to 2010. We have implemented a sophisticated statistical procedure involving non-parametric tests combined with a benchmark smoothing technique that has proven to be a powerful method for empirical trend analysis to remove the stochastic component from the trend component in a time series. Melt water from winter snows is the dominant constituent of June and July flows. Glacial melts predominantly contribute to August and partially to September flows, which are controlled by monsoonal snowfall too at elevations approximately >3500 m. For all four summer months, flows increased from 1985 to 2000. August flows, which actually reflect the states of the glaciers, have continued to rise steadily after 2000 at the same rate as those did for the period 1985-2000. However, the rising trends of June and July flows changed to slightly declining trends from 2000 to 2010. These trends most likely indicate drop in winter snowfall over Karakoram and do not provide direct indications about the states of the glaciers. The rising trend of August discharge is due to change in glacial storage at a steadily decreasing rate of approximately 0.04-0.05 mm/day/year for the period 1985-2010. This rate is nearly equal to the rate of increase in precipitation during the summer months over Karakoram Mountains in recent decades as determined from the ERA-40 and GPCP precipitation datasets. Thereby, this is most plausibly, why the

  18. Measuring temperature rise during orthopaedic surgical procedures.

    PubMed

    Manoogian, Sarah; Lee, Adam K; Widmaier, James C

    2016-09-01

    A reliable means for measuring temperatures generated during surgical procedures is needed to recommend best practices for inserting fixation devices and minimizing the risk of osteonecrosis. Twenty four screw tests for three surgical procedures were conducted using the four thermocouples in the bone and one thermocouple in the screw. The maximum temperature rise recorded from the thermocouple in the screw (92.7±8.9°C, 158.7±20.9°C, 204.4±35.2°C) was consistently higher than the average temperature rise recorded in the bone (31.8±9.3°C, 44.9±12.4°C, 77.3±12.7°C). The same overall trend between the temperatures that resulted from three screw insertion procedures was recorded with significant statistical analyses using either the thermocouple in the screw or the average of several in-bone thermocouples. Placing a single thermocouple in the bone was determined to have limitations in accurately comparing temperatures from different external fixation screw insertion procedures. Using the preferred measurement techniques, a standard screw with a predrilled hole was found to have the lowest maximum temperatures for the shortest duration compared to the other two insertion procedures. Future studies evaluating bone temperature increase need to use reliable temperature measurements for recommending best practices to surgeons. PMID:27246667

  19. Gas-rise velocities during kicks

    SciTech Connect

    White, D.B. )

    1991-12-01

    This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is caused by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.

  20. Quantitative effect of initial current rise on pumping the double-pulsed copper chloride laser

    NASA Technical Reports Server (NTRS)

    Vetter, A. A.

    1977-01-01

    The laser energy at optimum time delay of a double-pulsed CuCl laser was experimentally determined to be a logarithmic function of the initial current rise of the pumping pulse over the total circuit inductance range 1 to 12 microhenrys. The minimum delay was found to decrease with initial current rise, which implies that faster rising current pulses are more efficient at pumping copper atoms from the ground state to the upper laser level because lasing threshold occurs with a higher population in the lower laser level.

  1. Initiation of the Slow-Rise and Fast-Rise Phases of an Erupting Solar Filament by Localized Emerging Magnetic Field via Microflaring

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.; Harra, L. K.

    2006-01-01

    EUV data from EIT show that a filament of 2001 February 28 underwent a slow-rise phase lasting about 6 hrs, before rapidly erupting in a fast-rise phase. Concurrent images in soft X-rays (SXRs) from Yohkoh/SXT show that a series of three microflares, prominent in SXT images but weak in EIT approx.195 Ang EUV images, occurred near one end of the filament. The first and last microflares occurred respectively in conjunction with the start of the slow-rise phase and the start of the fast-rise phase, and the second microflare corresponded to a kink in the filament trajectory. Beginning within 10 hours of the start of the slow rise, new magnetic flux emerged at the location of the microflaring. This localized new flux emergence and the resulting microflares, consistent with reconnection between the emerging field and the sheared sigmoid core magnetic field holding the filament, apparently caused the slow rise of this field and the transition to explosive eruption. For the first time in such detail, the observations show this direct action of localized emerging flux in the progressive destabilization of a sheared core field in the onset of a coronal mass ejection (CME). Similar processes may have occurred in other recently-studied events, NASA supported this work through NASA SR&T and SEC GI grants.

  2. Temperature and velocity measurements of a rising thermal plume

    NASA Astrophysics Data System (ADS)

    Cagney, Neil; Newsome, William H.; Lithgow-Bertelloni, Carolina; Cotel, Aline; Hart, Stanley R.; Whitehead, John A.

    2015-03-01

    The three-dimensional velocity and temperature fields surrounding an isolated thermal plume in a fluid with temperature-dependent viscosity are measured using Particle-Image Velocimetry and thermochromatic liquid crystals, respectively. The experimental conditions are relevant to a plume rising through the mantle. It is shown that while the velocity and the isotherm surrounding the plume can be used to visualize the plume, they do not reveal the finer details of its structure. However, by computing the Finite-Time Lyapunov Exponent fields from the velocity measurements, the material lines of the flow can be found, which clearly identify the shape of the plume head and characterize the behavior of the flow along the plume stem. It is shown that the vast majority of the material in the plume head has undergone significant stretching and originates from a wide region very low in the fluid domain, which is proposed as a contributing factor to the small-scale isotopic variability observed in ocean-island basalt regions. Lastly, the Finite-Time Lyapunov Exponent fields are used to calculate the steady state rise velocity of the thermal plume, which is found to scale linearly with the Rayleigh number, in contrast to some previous work. The possible cause and the significance of these conflicting results are discussed, and it is suggested that the scaling relationship may be affected by the temperature-dependence of the fluid viscosity in the current work.

  3. AN ESTIMATE OF THE DETECTABILITY OF RISING FLUX TUBES

    SciTech Connect

    Birch, A. C.; Braun, D. C.; Fan, Y.

    2010-11-10

    The physics of the formation of magnetic active regions (ARs) is one of the most important problems in solar physics. One main class of theories suggests that ARs are the result of magnetic flux that rises from the tachocline. Time-distance helioseismology, which is based on measurements of wave propagation, promises to allow the study of the subsurface behavior of this magnetic flux. Here, we use a model for a buoyant magnetic flux concentration together with the ray approximation to show that the dominant effect on the wave propagation is expected to be from the roughly 100 m s{sup -1} retrograde flow associated with the rising flux. Using a B-spline-based method for carrying out inversions of wave travel times for flows in spherical geometry, we show that at 3 days before emergence the detection of this retrograde flow at a depth of 30 Mm should be possible with a signal-to-noise level of about 8 with a sample of 150 emerging ARs.

  4. Temperature rise and safety considerations for radiation force ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Herman, Bruce A.; Harris, Gerald R.

    2002-11-01

    Current models for estimating temperature increase during ultrasound exposure calculate the steady-state rise, using time-averaged acoustic output, as the worst case for safety consideration. While valid for the typically very short (microsecond) pulses used by conventional diagnostic techniques, this analysis does not necessarily correspond to a worst case scenario for the longer pulses or pulse bursts used by a new method, radiation force imaging. Radiation force imaging, employing ultrasound pulse durations up to hundreds of milliseconds, produces and detects motion in solid tissue or acoustic streaming in fluids via a high intensity beam. Models that calculate the transient temperature rise from these pulses are developed for both the bone at focus and soft tissue cases. Based on accepted time-temperature dose criteria, it is shown that for pulse lengths and intensities utilized by this technique, temperature may increase to levels that raise safety concerns for bone at the focus of the ultrasound beam. Also, the impact on this modality of the current U.S. Food and Drug Administration output limits for diagnostic ultrasound devices is discussed.

  5. Cloud rise model for radiological dispersal devices events

    NASA Astrophysics Data System (ADS)

    Sharon, Avi; Halevy, Itzhak; Sattinger, Daniel; Yaar, Ilan

    2012-07-01

    As a part of the preparedness and response to possible radiological terror events, it is important to model the evolution of the radioactive cloud immediately after its formation, as a function of time, explosive quantity and local meteorological conditions. One of the major outputs of a cloud rise models is the evaluation of cloud top height, which is an essential input for most of the succeeding atmospheric dispersion models. This parameter strongly affects the radiological consequences of the event. Most of the cloud rise models used today, have been developed according to experiments were large quantities of explosives were used, within the range of hundreds of kilograms of TNT. The majority of these models, however, fail to address Radiological Dispersion Devices (RDD) events, which are typically characterized by smaller amounts of TNT. In this paper, a new, semi-empirical model that describes the vertical evolution of the cloud up to its effective height as a function of time, explosive quantity, atmospheric stability and horizontal wind speed, is presented. The database for this model is taken from five sets of experiments done in Israel during 2006-2009 under the "Green Field" (GF) project, using 0.25-100 kg of TNT.

  6. Sea-level rise and coastal wetlands.

    PubMed

    Blankespoor, Brian; Dasgupta, Susmita; Laplante, Benoit

    2014-12-01

    This paper seeks to quantify the impact of a1-m sea-level rise on coastal wetlands in 86 developing countries and territories. It is found that approximately 68 % of coastal wetlands in these countries are at risk. A large percentage of this estimated loss is found in Europe and Central Asia, East Asia, and the Pacific, as well as in the Middle East and North Africa. A small number of countries will be severely affected. China and Vietnam(in East Asia and the Pacific), Libya and Egypt (in the Middle East and North Africa), and Romania and Ukraine (in Europe and Central Asia) will bear most losses. In economic terms, the loss of coastal wetlands is likely to exceed $703 million per year in 2000 US dollars. PMID:24659473

  7. HiRISE observations of gas sublimation-driven activity

    NASA Astrophysics Data System (ADS)

    Thomas, N.; Hansen, C. J.; Portyankina, G.; Russell, P. S.; Bridges, N. T.

    2009-04-01

    The High Resolution Imaging Science Experiment (HiRISE) onboard Mars Reconnaissance Orbiter (MRO) has been used to monitor the seasonal evolution of several regions at high southern latitudes and, in particular, the geyser-like activity which may result from the process described by Kieffer [JGR, 112, 8005, 2007] involving translucent CO2 ice. Here, we mostly concentrate on observations of the Inca City (81S, 296E) region. The observations indicate rapid on-set of activity at the beginning of southern spring with activity initiating before HiRISE can obtain adequately illuminated images (Ls < 174 at Inca City). Most sources became active within the subsequent 8 weeks. Activity is indicated by the production of dark deposits surrounded by brighter bluer deposits which probably arise from the freezing out of vented CO2 [Titus et al., AGU Abstract P41A-0188, 2007]. These deposits originate from araneiform structures (spiders), stones on ridges, cracks on slopes, and along linear cracks in the slab ice on flatter surfaces. The type of activity observed can often be explained qualitatively by considering the local topography. Some dark fans were observed to shorten enormously in length on a timescale of 18 days. We consider this to be strong evidence that emission was in progress at the time of HiRISE image acquisition. The orientations of surficial deposits were mostly topographically controlled in Inca City in 2007. The deposition of dark material also appeared to be influenced by local topography suggesting that the ejection from the vents was at low velocity (<10 m/s) and that a ground-hugging flow type process (a sort of "cryo-fumarole") may have been occurring. The presentation will illustrate the above features and make a first comparison between activity separated by one full Martian year. Our first observations indicate a stronger influence of wind in 2009.

  8. Numerical Investigation of Microgravity Tank Pressure Rise Due to Boiling

    NASA Technical Reports Server (NTRS)

    Hylton, Sonya; Ibrahim, Mounir; Kartuzova, Olga; Kassemi, Mohammad

    2015-01-01

    The ability to control self-pressurization in cryogenic storage tanks is essential for NASAs long-term space exploration missions. Predictions of the tank pressure rise in Space are needed in order to inform the microgravity design and optimization process. Due to the fact that natural convection is very weak in microgravity, heat leaks into the tank can create superheated regions in the liquid. The superheated regions can instigate microgravity boiling, giving rise to pressure spikes during self-pressurization. In this work, a CFD model is developed to predict the magnitude and duration of the microgravity pressure spikes. The model uses the Schrage equation to calculate the mass transfer, with a different accommodation coefficient for evaporation at the interface, condensation at the interface, and boiling in the bulk liquid. The implicit VOF model was used to account for the moving interface, with bounded second order time discretization. Validation of the models predictions was carried out using microgravity data from the Tank Pressure Control Experiment, which flew aboard the Space Shuttle Mission STS-52. Although this experiment was meant to study pressurization and pressure control, it underwent boiling during several tests. The pressure rise predicted by the CFD model compared well with the experimental data. The ZBOT microgravity experiment is scheduled to fly on February 2016 aboard the ISS. The CFD model was also used to perform simulations for setting parametric limits for the Zero-Boil-Off Tank (ZBOT) Experiments Test Matrix in an attempt to avoid boiling in the majority of the test runs that are aimed to study pressure increase rates during self-pressurization. *Supported in part by NASA ISS Physical Sciences Research Program, NASA HQ, USA

  9. Dynamics of rising bubble inside a viscosity-stratified medium

    NASA Astrophysics Data System (ADS)

    Premlata, A. R.; Tripathi, Manoj Kumar; Sahu, Kirti Chandra

    2015-07-01

    The rising bubble dynamics in an unconfined quiescent viscosity-stratified medium has been numerically investigated. This is frequently encountered in industrial as well as natural phenomena. In spite of the large number of studies carried out on bubbles and drops, very few studies have examined the influence of viscosity stratification on bubble rise dynamics. To the best of our knowledge, none of them have isolated the effects of viscosity-stratification alone, even though it is known to influence the dynamics extensively, which is the main objective of the present study. By conducting time-dependent simulations, we present a library of bubble shapes in the Galilei and the Eötvös numbers plane. Our results demonstrate some counter-intuitive phenomena for certain range of parameters due to the presence of viscosity stratification in the surrounding fluid. We found that in a linearly increasing viscosity medium, for certain values of parameters, bubble undergoes large deformation by forming an elongated skirt, while the skirt tends to physically separate the wake region from the rest of the surrounding fluid. This peculiar dynamics is attributed to the migration of less viscous fluid that is carried in the wake of the bubble as it rises, and thereby creating an increasingly larger viscosity contrast between the fluid occupied in the wake region and the surrounding fluid, unlike that observed in a constant viscosity medium. It is also observed that the effect of viscosity stratification is qualitatively different for different regimes of the dimensionless parameters. In future, it will be interesting to investigate this problem in three-dimensions.

  10. Flare Emission Onset in the Slow-Rise and Fast-Rise Phases of an Erupting Solar Filament Observed with TRACE

    NASA Technical Reports Server (NTRS)

    Sterling, A. C.; Moore, R. L.

    2005-01-01

    We observe the eruption of an active-region solar filament of 1998 July 11 using high time cadence and high spatial resolution EUV observations from the TRACE sareiii'ce, along with soft X-ray images from the soft X-ray telescope (SXT) on the Yohkoh satellite, hard X-ray fluxes from the BATSE instrument on the (CGRO) satellite and from the hard X-ray telescope (HXT) on Yohkoh, and ground-based magnetograms. We concentrate on the initiation of the eruption in an effort to understand the eruption mechanism. First the filament undergoes slow upward movement in a "slow rise" phase with an approximately constant velocity of approximately 15 km/s that lasts about 10-min, and then it erupts in a "fast-rise" phase, reaching a velocity of about 200 km/s in about 5-min, followed by a period of deceleration. EUV brightenings begin just before the start of the filament's slow rise, and remain immediately beneath the rising filament during the slow rise; initial soft X-ray brightenings occur at about the same time and location. Strong hard X-ray emission begins after the onset of the fast rise, and does not peak until the filament has traveled a substantial altitude (to a height about equal to the initial length of the erupting filament) beyond its initial location. Our observations are consistent with the slow-rise phase of the eruption resulting from the onset of "tether cutting" reconnection between magnetic fields beneath the filament, and the fast rise resulting from an explosive increase in the reconnection rate or by catastrophic destabilization of the overlying filament-carrying fields. About two days prior to the event new flux emerged near the location of the initial brightenings, and this recently- emerged flux could have been a catalyst for initiating the tether-cutting reconnection. With the exception of the initial slow rise, our findings qualitatively agree with the prediction for erupting-flux-rope height as a function of time in a model discussed by Chen

  11. 46 CFR 111.20-5 - Temperature rise.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Temperature rise. 111.20-5 Section 111.20-5 Shipping... REQUIREMENTS Transformer Construction, Installation, and Protection § 111.20-5 Temperature rise. (a) The temperature rise, based on an ambient temperature of 40 degrees C, must not exceed the following: (1)...

  12. 46 CFR 111.20-5 - Temperature rise.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Temperature rise. 111.20-5 Section 111.20-5 Shipping... REQUIREMENTS Transformer Construction, Installation, and Protection § 111.20-5 Temperature rise. (a) The temperature rise, based on an ambient temperature of 40 degrees C, must not exceed the following: (1)...

  13. 46 CFR 111.20-5 - Temperature rise.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Temperature rise. 111.20-5 Section 111.20-5 Shipping... REQUIREMENTS Transformer Construction, Installation, and Protection § 111.20-5 Temperature rise. (a) The temperature rise, based on an ambient temperature of 40 degrees C, must not exceed the following: (1)...

  14. 46 CFR 111.20-5 - Temperature rise.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Temperature rise. 111.20-5 Section 111.20-5 Shipping... REQUIREMENTS Transformer Construction, Installation, and Protection § 111.20-5 Temperature rise. (a) The temperature rise, based on an ambient temperature of 40 degrees C, must not exceed the following: (1)...

  15. 46 CFR 111.20-5 - Temperature rise.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Temperature rise. 111.20-5 Section 111.20-5 Shipping... REQUIREMENTS Transformer Construction, Installation, and Protection § 111.20-5 Temperature rise. (a) The temperature rise, based on an ambient temperature of 40 degrees C, must not exceed the following: (1)...

  16. Cyclic fractionation processes beneath the Shatsky Rise oceanic plateau

    NASA Astrophysics Data System (ADS)

    Husen, A.; Almeev, R. R.; Holtz, F.

    2013-12-01

    Our understanding of the magma ascent, storage and differentiation beneath large igneous provinces (LIPs) is still under debate. Mainly two competing models are explaining the formation of LIPs: 1) the arrival of a deep sourced mantle plume in the lithosphere, and 2) decompression melting of unusually fusible mantle beneath fast-spreading ridges. The Shatsky Rise oceanic plateau is a unique opportunity to discuss this problem because its tectonic evolution along the Pacific-Farallon-Izanagi triple junction is well known. We examined samples recovered during IODP Expedition 324 at the Tamu Massif, one of three massifs of the Shatsky Rise. In general, the Shatsky Rise glasses are tholeiitic basalts containing 5 to 8.7 wt% MgO. Compared to MORB, the glass compositions are high in FeO (Fe8: 10.3) and low in SiO2 and Na2O (Na8: 1.9), indicating high amounts of partial melting at great depth. The CaO/Al2O3 ratios in the Tamu Massif evolved glasses are higher respectively to MORB indicating low pressure cotectic fractionation. In general, the basaltic glasses from Shatsky Rise show differentiation trends similar to those of other oceanic plateaus, as e.g. Ontong Java and Kerguelen. Pressures and temperatures of magma storage were estimated for 40 naturally quenched glasses (5-6.5 wt% MgO) along a drilled profile of 150 m length. Based on the glass major element compositions (electron microprobe) and glass H2O contents (infrared spectroscopy), we simulated the conditions of multiple saturation (Liq+Ol+Pl+Cpx) using the COMAGMAT program. The calculated pressures range from 240 MPa to 1 atm and the calculated temperatures range from 1150 to 1100 °C, indicating polybaric crystallization in a shallow magma reservoir. As a result, along the drilled profile, we identified two complete cycles of magma injection in the reservoir with subsequent fractionation and eruption followed by a time of magmatic inactivity. The most magnesian samples of the Shatsky Rise were drilled at Ori

  17. The Effect of Temperature Rise in a Fine Blanking Tool

    NASA Astrophysics Data System (ADS)

    Kim, Su-Hyun; Kang, JeongJin; Lee, Dong-Jae; Lee, Kwan-Young; Kim, Heon-Young; Kim, Hyung-Jong

    2007-05-01

    This study was performed to investigate the influence of the tool temperature rise in a fine blanking process. It is known that most of the plastic deformation energy changes into heat and the heat raises tool temperature increasingly in the continual fine blanking process. Real-time measurement of the temperature distribution on the tool surfaces was carried out using a thermal infrared camera. Finite element analysis for the fine blanking process considering the heat transfer and thermal expansion was also performed, and the result was compared with the experimental data. It is found that the tool temperature rises rapidly within one minute (20 to 30 strokes) from the beginning of the continual process and thereafter increases very slowly. It is thought that the increase of tool temperature affects the decrease tendency of fracture zone in blanked workpiece. The phenomena could be properly predicted using finite element method and it is expected that effective information for the design and manufacture of die in a fine blanking process could be given through finite element analysis.

  18. Mangrove Sedimentation and Response to Relative Sea-Level Rise.

    PubMed

    Woodroffe, C D; Rogers, K; McKee, K L; Lovelock, C E; Mendelssohn, I A; Saintilan, N

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics. PMID:26407146

  19. Mangrove Sedimentation and Response to Relative Sea-Level Rise

    NASA Astrophysics Data System (ADS)

    Woodroffe, C. D.; Rogers, K.; McKee, K. L.; Lovelock, C. E.; Mendelssohn, I. A.; Saintilan, N.

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions, related primarily to elevation and hydroperiod, influence mangrove distributions; this review considers how these distributions change over time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks, and tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas measurements made using surface elevation tables and marker horizons provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in a continuing decline in their extent throughout the tropics. *

  20. Mangrove sedimentation and response to relative sea-level rise

    USGS Publications Warehouse

    Woodroffe, CD; Rogers, K.; Mckee, Karen L.; Lovelock, CE; Mendelssohn, IA; Saintilan, N.

    2016-01-01

    Mangroves occur on upper intertidal shorelines in the tropics and subtropics. Complex hydrodynamic and salinity conditions influence mangrove distributions, primarily related to elevation and hydroperiod; this review considers how these adjust through time. Accumulation rates of allochthonous and autochthonous sediment, both inorganic and organic, vary between and within different settings. Abundant terrigenous sediment can form dynamic mudbanks; tides redistribute sediment, contrasting with mangrove peat in sediment-starved carbonate settings. Sediments underlying mangroves sequester carbon, but also contain paleoenvironmental records of adjustments to past sea-level changes. Radiometric dating indicates long-term sedimentation, whereas Surface Elevation Table-Marker Horizon measurements (SET-MH) provide shorter perspectives, indicating shallow subsurface processes of root growth and substrate autocompaction. Many tropical deltas also experience deep subsidence, which augments relative sea-level rise. The persistence of mangroves implies an ability to cope with moderately high rates of relative sea-level rise. However, many human pressures threaten mangroves, resulting in continuing decline in their extent throughout the tropics.

  1. Microbial geochemistry in rising plumes of two hydrothermal vents at the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Dick, G.; Breier, J. A.; Toner, B. M.; Sheik, C.; Cron, B. R.; Li, M.; Reed, D. C.; Anantharaman, K.; Baker, B. J.; Jain, S.; Klausmeier, C. A.; Jiang, H.; German, C. R.; Seewald, J.; Sylva, S. P.; McDermott, J. M.; Bennett, S. A.

    2012-12-01

    Slow and ultraslow spreading ridges comprise ~50% of the global ridge-axis length and are thus relevant to the impact of hydrothermal activity on global ocean biogeochemistry. These ridges host ultramafic vent systems with reducing chemical environments that yield hydrothermal fluids rich in methane, hydrogen, and organic carbon, thus providing energy sources to biological communities relevant to the origin and early evolution of life on Earth and the potential for life on other planets. Microbial-geochemical interactions are also important for understanding how deep-sea hydrothermal vents impact ocean biogeochemistry, especially in hydrothermal plumes, where vent fluids stimulate chemosynthetic microbial communities and microbes influence the oceanic fate of hydrothermally-sourced elements. Many critical processes occur in the rising portion of hydrothermal plumes, which are dynamic and challenging to sample. To address these questions and challenges, we developed methods for the in situ collection and preservation of paired microbiology and geochemical samples from rising hydrothermal plumes. Samples were collected with ROV Jason from two hydrothermal vent systems, Von Damm and Beebe, which are in close proximity to each other on the Mid Cayman Rise yet are quite distinct in terms of chemistry, temperature, and depth. Bulk geochemistry, spatially-resolved spectroscopy, and molecular microbiological approaches were applied to yield some of the first views into the dynamic biotic and abiotic processes operative in rising hydrothermal plumes from an ultra-slow spreading system. Results indicate that the Cayman plumes are enriched in hydrogen, sulfur, and methane-utilizing microorganisms relative to background deep Caribbean seawater. Clear differences were observed between near-vent samples, which were dominated by seafloor-derived organisms, and samples from the upper buoyant or non-buoyant plume. These Cayman plume microbes are distinct from those observed in

  2. Northern east Pacific rise: Magnetic anomaly and bathymetric framework

    SciTech Connect

    Klitgord, K.D.; Mammerickx, J.

    1982-08-10

    The oceanic crust in the eastern Pacific between 7/sup 0/N and 30/sup 0/N and east of 127/sup 0/W contains a fairly complete history of the spreading centers associated with the East Pacific Rise since 25 m.y. B.P. (late Oligocene). In this paper, we have summarized the seafloor spreading magnetic-anomaly data and the bathymetric data that reflect the record of this technique history. The well-defined magnetic lineations north of the Clarion fracture zone, in the mouth of the Gulf of California, and on the east flank of the East Pacific Rise (EPR) are carefully examined and used to provide a guide for interpreting the spreading pattern between the Clarion and Clipperton fracture zones, southward of the Rivera fracture zone over the Mathematician Ridge, and over the entire EPR east of the Mathematician Ridge between the Rivera and Siqueiros fracture zones. The bathymetric data provide a trace of the fracture zone pattern in each of the above mentioned areas. The fracture zone bathymetry and the seafloor spreading magnetc lineations on the EPR south of the Rivera fracture zone have a distinctive fanning pattern caused by close poles of rotation and plate boundary reorganizations. All these data provide a good record of the plate reorganizations in the middle Miocene at magnetic anomaly 5A time (12.5 to 11 m.y. B.P.), in the late Miocene at a magnetic anomaly 3'--4 time (6.5 m.y. B.P.), and in the Pliocene at magnetic anomaly 2'--3 time (3.5 m.y.B.P.). Several abandoned spreading centers, including the Mathematician Ridge, were left behind as a result of these reorganizations. The Mathematician Ridge is shown to be a set of ridges and trough whose origin is related to the tectonics activity associated with each of the above mentioned reorganizations since anomaly 5A.

  3. China's rising hydropower demand challenges water sector.

    PubMed

    Liu, Junguo; Zhao, Dandan; Gerbens-Leenes, P W; Guan, Dabo

    2015-01-01

    Demand for hydropower is increasing, yet the water footprints (WFs) of reservoirs and hydropower, and their contributions to water scarcity, are poorly understood. Here, we calculate reservoir WFs (freshwater that evaporates from reservoirs) and hydropower WFs (the WF of hydroelectricity) in China based on data from 875 representative reservoirs (209 with power plants). In 2010, the reservoir WF totaled 27.9 × 10(9) m(3) (Gm(3)), or 22% of China's total water consumption. Ignoring the reservoir WF seriously underestimates human water appropriation. The reservoir WF associated with industrial, domestic and agricultural WFs caused water scarcity in 6 of the 10 major Chinese river basins from 2 to 12 months annually. The hydropower WF was 6.6 Gm(3) yr(-1) or 3.6 m(3) of water to produce a GJ (10(9) J) of electricity. Hydropower is a water intensive energy carrier. As a response to global climate change, the Chinese government has promoted a further increase in hydropower energy by 70% by 2020 compared to 2012. This energy policy imposes pressure on available freshwater resources and increases water scarcity. The water-energy nexus requires strategic and coordinated implementations of hydropower development among geographical regions, as well as trade-off analysis between rising energy demand and water use sustainability. PMID:26158871

  4. Rising Expectations: Access to Biomedical Information

    PubMed Central

    Lindberg, D. A. B.; Humphreys, B. L.

    2008-01-01

    Summary Objective To provide an overview of the expansion in public access to electronic biomedical information over the past two decades, with an emphasis on developments to which the U.S. National Library of Medicine contributed. Methods Review of the increasingly broad spectrum of web-accessible genomic data, biomedical literature, consumer health information, clinical trials data, and images. Results The amount of publicly available electronic biomedical information has increased dramatically over the past twenty years. Rising expectations regarding access to biomedical information were stimulated by the spread of the Internet, the World Wide Web, advanced searching and linking techniques. These informatics advances simplified and improved access to electronic information and reduced costs, which enabled inter-organizational collaborations to build and maintain large international information resources and also aided outreach and education efforts The demonstrated benefits of free access to electronic biomedical information encouraged the development of public policies that further increase the amount of information available. Conclusions Continuing rapid growth of publicly accessible electronic biomedical information presents tremendous opportunities and challenges, including the need to ensure uninterrupted access during disasters or emergencies and to manage digital resources so they remain available for future generations. PMID:18587496

  5. Iraqi crude exports may rise further

    SciTech Connect

    Not Available

    1980-12-08

    Iraq will soon start exporting crude oil through a 550 mi, 500,000 bbl/day capacity pipeline from Iraq to Banias, Syria, on the Mediterranean. Iraq has already been transporting a reported 400,000 bbl/day in a 700,000 bbl/day capacity pipeline that goes to Dortyol, Turk., on the Mediterranean. Iraq's theoretical export capacity will soon reach 1.2 million bbl/day (compared with 3.2 million bbl/day before the war), assuming that the facilities are undamaged. Iran has been exporting some crude from its Kharg Island terminal, presumably by Iranian boat to the Lavan Island terminal at the southern end of the gulf, where it would be transported along with crude from offshore fields in the area. The exports apparently had been large enough to keep spot-market prices from rising much above the $40/bbl level, and in Dec. 1980, the spot-market prices eased to just under the $40 mark. Indonesia has raised the premium on its Sumatran light crude by $1/bbl, bringing the total to $35.20. Other producers have not yet raised their prices correspondingly. The agenda of the Dec. 1980 price-fixing meeting in Indonesia (assuming it takes place as planned) is discussed.

  6. Enhancing capillary rise on a rough surface

    NASA Astrophysics Data System (ADS)

    Chow, Melissa; Wexler, Jason; Jacobi, Ian; Stone, Howard

    2014-11-01

    Liquid-infused surfaces have been proposed as a robust alternative to traditional air-cushioned superhydrophobic surfaces. However, if these surfaces are held vertically the lubricating oil can drain from the surface, and cause the surface to lose its novel properties. To examine this failure mode, we measure the drainage from a surface with model roughness that is scaled-up to allow for detailed measurements. We confirm that the bulk fluid drains from the surface until it reaches the level of the capillary rise height, although the detailed dynamics vary even in simple surface geometries. We then test different substrate architectures to explore how the roughness can be designed to retain greater amounts of oil. Supported under MRSEC NSF DMR 0819860 (PI: Prof. N. Phuan Ong) REU Site Grant: NSF DMR-1156422 (PI: Prof. Mikko Haataja), PREM CSUN Prime # NSF 1205734 and ONR MURI Grants N00014-12-1-0875 and N00014-12-1-0962 (Program Manager Dr. Ki-Han Kim).

  7. Capillary rise in a tilted Taylor-Hauksbee cell

    NASA Astrophysics Data System (ADS)

    Medina, Abraham; Klapp, Jaime; Torres Victoria, Ayax Hernando; Peralta Lopez, Salomon; Jara Hernandez, Aydet

    2015-11-01

    The penetration of a wetting liquid in the narrow gap between two tilted plates making a small angle among them is analyzed in the framework of the lubrication approximation. At the beginning of the process, the liquid rises independently at different distances from the line of intersection of the plates. The maximum height of the liquid initially increases as a power law of time, where the exponent is dependent on the angle of inclination of the plates and is attained at a point that reaches the line of intersection only after a certain time. At later times, the motion of the liquid is confined to a thin layer around the line of intersection whose height increases again as a power law of time and the exponent of the power law is a function of the angle of inclination. The thickness of the film decreases as the inverse of the power law of time. The evolution of the liquid surface is computed numerically and compared with the results of simple experiments.

  8. Developing a Coastal Risk Indicator for Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Masters, D. S.; Nerem, R.

    2012-12-01

    Coastal sea level rise is one the most important potential environmental risks. Multiple satellite altimeters flying on the same repeat orbit track have allowed estimation of global mean sea level for the past 20 years, and the time series has yielded information about the average rate of sea level increase over that time. Due to the duration, consistency, and inter-calibration of the altimeter measurements, the time series is now considered a climate record. The time series has also shown the strong dependence of sea level on interannual signals such as the ENSO and the NAO. But the most important sea level effects of climate change will be felt on the regional and local scales. At these smaller scales, local effects due to topography, tides, earth deformation (glacial isostatic adjustment (GIA), subsidence, etc.), and storm surges must also be considered when estimating the risks of sea level change to coastal communities. Recently, work has begun to understand the methods applicable to estimating the risks of expected sea level change to coastal communities (Strauss et al., 2012; Tebaldi et al., 2012). Tebaldi et al (2012) merged the expected global mean sea level increase from the semi-empirical model of Vermeer and Rahmstorf (2009) with historical local tide gauges to predict increases in storm surge risk posed by increasing sea level. In this work, we will further explore the currently available data and tools that can potentially be used to provide a sea level climate change indicator and local risk assessment along US coasts. These include global and regional sea level trends from the satellite altimetry climate record, in situ tide gauge measurements and the historical extremes at each location, local tide and storm surge models, topographic surveys of vulnerable coastlines, GIA models, and measurements of local subsidence and crustal deformation rates. We will also evaluate methods to estimate the increased risk to communities from sea level change

  9. Particle dynamics in the rising plume at Piccard Hydrothermal Field, Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Estapa, M. L.; Breier, J. A.; German, C. R.

    2015-09-01

    Processes active in rising hydrothermal plumes, such as precipitation, particle aggregation, and biological growth, affect particle size distributions and can exert important influences on the biogeochemical impact of submarine venting of iron to the oceans and their sediments. However, observations to date of particle size distribution within these systems are both limited and conflicting. In a novel buoyant hydrothermal plume study at the recently discovered high-temperature (398°C) Piccard Hydrothermal Field, Mid-Cayman Rise, we report optical measurements of particle size distributions (PSDs). We describe the plume PSD in terms of a simple, power-law model commonly used in studies of upper and coastal ocean particle dynamics. Observed PSD slopes, derived from spectral beam attenuation and laser diffraction measurements, are among the highest found to date anywhere in the ocean and ranged from 2.9 to 8.5. Beam attenuation at 650 nm ranged from near zero to a rarely observed maximum of 192 m-1 at 3.5 m above the vent. We did not find large (>100 μm) particles that would settle rapidly to the sediments. Instead, beam attenuation was well-correlated to total iron, suggesting the first-order importance of particle dilution, rather than precipitation or dissolution, in the rising plume at Piccard. Our observations at Piccard caution against the assumption of rapid deposition of hydrothermal, particulate metal fluxes, and illustrate the need for more particle size and composition measurements across a broader range of sites, globally.

  10. Rising dough and baking bread at the Australian synchrotron

    NASA Astrophysics Data System (ADS)

    Mayo, S. C.; McCann, T.; Day, L.; Favaro, J.; Tuhumury, H.; Thompson, D.; Maksimenko, A.

    2016-01-01

    Wheat protein quality and the amount of common salt added in dough formulation can have a significant effect on the microstructure and loaf volume of bread. High-speed synchrotron micro-CT provides an ideal tool for observing the three dimensional structure of bread dough in situ during proving (rising) and baking. In this work, the synchrotron micro-CT technique was used to observe the structure and time evolution of doughs made from high and low protein flour and three different salt additives. These experiments showed that, as expected, high protein flour produces a higher volume loaf compared to low protein flour regardless of salt additives. Furthermore the results show that KCl in particular has a very negative effect on dough properties resulting in much reduced porosity. The hundreds of datasets produced and analysed during this experiment also provided a valuable test case for handling large quantities of data using tools on the Australian Synchrotron's MASSIVE cluster.

  11. Contribution of Groundwater Depletion to Global Mean Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Lambinicio, A.; An, K.; Reager, J. T.; Druffel-Rodriguez, R. E.; Richey, A. S.; Famiglietti, J. S.; Rodell, M.

    2012-12-01

    The contribution of groundwater depletion to Global Mean Sea Level Rise (GMSLR) is an important topic and source of great uncertainty in the GMSLR budget. This research uses gridded GRACE Tellus satellite data to quantify changes in total land water storage, including those of groundwater. Global Land Data Assimilation System land components such as soil moisture, canopy moisture, and snow, are subtracted from the GRACE data to isolate the groundwater component. The resulting trends show that most continents are gaining in groundwater storage, which is consistent with GRACE-based estimates of zero-to-increasing changes in total land water. Results indicate a negative contribution to GMSLR for the GRACE time period, which is in contrast to the positive contribution identified in recent studies.

  12. Computational Fluid Dynamics of rising droplets

    SciTech Connect

    Wagner, Matthew; Francois, Marianne M.

    2012-09-05

    The main goal of this study is to perform simulations of droplet dynamics using Truchas, a LANL-developed computational fluid dynamics (CFD) software, and compare them to a computational study of Hysing et al.[IJNMF, 2009, 60:1259]. Understanding droplet dynamics is of fundamental importance in liquid-liquid extraction, a process used in the nuclear fuel cycle to separate various components. Simulations of a single droplet rising by buoyancy are conducted in two-dimensions. Multiple parametric studies are carried out to ensure the problem set-up is optimized. An Interface Smoothing Length (ISL) study and mesh resolution study are performed to verify convergence of the calculations. ISL is a parameter for the interface curvature calculation. Further, wall effects are investigated and checked against existing correlations. The ISL study found that the optimal ISL value is 2.5{Delta}x, with {Delta}x being the mesh cell spacing. The mesh resolution study found that the optimal mesh resolution is d/h=40, for d=drop diameter and h={Delta}x. In order for wall effects on terminal velocity to be insignificant, a conservative wall width of 9d or a nonconservative wall width of 7d can be used. The percentage difference between Hysing et al.[IJNMF, 2009, 60:1259] and Truchas for the velocity profiles vary from 7.9% to 9.9%. The computed droplet velocity and interface profiles are found in agreement with the study. The CFD calculations are performed on multiple cores, using LANL's Institutional High Performance Computing.

  13. The rise and fall of gluten!

    PubMed

    Aziz, Imran; Branchi, Federica; Sanders, David S

    2015-08-01

    Mankind has existed for 2·5 million years but only in the last 10,000 years have we been exposed to wheat. Wheat was first cultivated in the Fertile Crescent (South Western Asia) with a farming expansion that lasted from about 9000BC to 4000BC. Thus it could be considered that wheat (and gluten) is a novel introduction to man's diet! Prior to 1939 the rationing system had already been devised. This led to an imperative to try to increase agricultural production. Thus it was agreed in 1941 that there was a need to establish a Nutrition Society. The very roots of the society were geared towards necessarily increasing the production of wheat. This goal was achieved and by the end of the 20th century, global wheat output had expanded 5-fold. Perhaps as a result the epidemiology of coeliac disease (CD) or gluten sensitive enteropathy has changed. CD is a state of heightened immunological responsiveness to ingested gluten in genetically susceptible individuals. CD now affects 1 % or more of all adults, for which the treatment is a strict lifelong gluten-free diet. However, there is a growing body of evidence to show that a far greater proportion of individuals without coeliac disease are taking a gluten-free diet of their own volition. This clinical entity has been termed non-coeliac gluten sensitivity (NCGS), although the condition is fraught with complexities due to overlap with other gluten-based constituents that can also trigger similar clinical symptoms. This review will explore the relationship between gluten, the rising prevalence of modern coeliac disease, and the new entity of NCGS along with its associated uncertainties. PMID:25686620

  14. A Hydro-marsh equilibrium model for marsh system response to Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Alizad, K.; Hagen, S. C.; Morris, J. T.; Bacopoulos, P.

    2013-12-01

    In this study, an integrated model to assess the effect of sea level rise on salt marsh systems is presented. It is based on a coupled two-dimensional hydrodynamic model and a parametric marsh model. The model shows marsh productivity as a function of mean high water (MHW), mean low water (MLW), and the elevation of the marsh platform. MHW and MLW are the mean high and low water levels over a tidal record and the marsh platform elevation is the elevation of the thick and smooth piled up sediments and biomass that support the productivity of the marsh. MHW and MLW throughout a river and tidal creeks are determined by time varying tides resulting from the two-dimensional hydrodynamic model. In order to calculate accurate biomass productivity, and MHW and MLW elevations, a digital elevation model (DEM) representing the marsh table elevation and tidal creeks with high accuracy is necessary (Hagen et al., 2013). There are optimum ranges for relative sea level rise (RSLR), mean sea level (MSL), and depth of inundation for salt marshes to increase productivity. Because of the constantly changing MSL, the marsh always adjusts itself to a new equilibrium (Morris, et al., 2002). In the marsh model, the sediment accretion rate, which is a function of the marsh productivity, is considered. The tidal record is calculated by the hydrodynamic model and the DEM is adjusted by incorporating the accretion rate over a period of time, provided by the marsh model. Then, the new tidal record is assessed by running the hydrodynamic model, considering sea level rise with the new marsh table elevations. Using the new tidal record, the marsh productivity is simulated. This process can be divided into short time steps to capture changes in the rate of sea level rise. For example, a 68 cm sea level rise over 63 years can be split into five- or ten- year periods to have a linear trend for sea level rise in each period. The model is examined for the lower St. Johns River and Apalachicola River

  15. Influence of early rising on performance in tasks requiring attention and memory.

    PubMed

    Kumaran, V Shankar; Raghavendra, Bhat Ramachandra; Manjunath, Nandi Krishnamurthy

    2012-01-01

    Rising early in the morning has been a prescribed discipline of ancient Indian tradition. While there are no scientific studies comparing early rising volitionally versus circumstantially, selected studies on the latter (rising forcefully) have shown negative impact on an individual's peroformance. Hence the present study was undertaken to assess the influence of early rising (during Brahma-muhurtha) on tasks requiring attention and the ability to recall. Fifty four normal healthy male volunteers, with ages ranging from 16-22 years from a residential school were selected. They were randomly allocated to two groups (Brahma-muhurtha and control). They were assessed on day 1, day 10 and day 20 of the intervention, using a digit letter substitution task and verbal and spatial memory task. The Brahma-muhurtha group were asked to rise before 4:30 am in the morning based on the traditional Indian astrological calculations, while the control group were allowed to wake up just before 7 am which was their regular timing for waking. Brahma-muhurtha group after 20 days showed a significant improvement in the net scores for digit letter substitution task as well as scores for verbal and spatial memory tasks. The control group also showed an improvement in the memory task but not in the task requiring attentional processes. The present study suggests that rising early in the morning as described in ancient Indian tradition influences the process of attention and can improve the ability to recall. PMID:23781653

  16. SEA-LEVEL RISE. Sea-level rise due to polar ice-sheet mass loss during past warm periods.

    PubMed

    Dutton, A; Carlson, A E; Long, A J; Milne, G A; Clark, P U; DeConto, R; Horton, B P; Rahmstorf, S; Raymo, M E

    2015-07-10

    Interdisciplinary studies of geologic archives have ushered in a new era of deciphering magnitudes, rates, and sources of sea-level rise from polar ice-sheet loss during past warm periods. Accounting for glacial isostatic processes helps to reconcile spatial variability in peak sea level during marine isotope stages 5e and 11, when the global mean reached 6 to 9 meters and 6 to 13 meters higher than present, respectively. Dynamic topography introduces large uncertainties on longer time scales, precluding robust sea-level estimates for intervals such as the Pliocene. Present climate is warming to a level associated with significant polar ice-sheet loss in the past. Here, we outline advances and challenges involved in constraining ice-sheet sensitivity to climate change with use of paleo-sea level records. PMID:26160951

  17. Population dynamics of Hawaiian seabird colonies vulnerable to sea-level rise.

    PubMed

    Hatfield, Jeff S; Reynolds, Michelle H; Seavy, Nathaniel E; Krause, Crystal M

    2012-08-01

    Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-level rise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-level rise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-level rise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sea level rises 1 m and 28% if sea level rises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-level rise, but seawalls and habitat restoration may mitigate the effects of sea-level rise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sea levels rise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds. PMID:22624702

  18. Population dynamics of Hawaiian seabird colonies vulnerable to sea-level rise

    USGS Publications Warehouse

    Hatfield, Jeff S.; Reynolds, Michelle H.; Seavy, Nathaniel E.; Krause, Crystal M.

    2012-01-01

    Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-level rise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-level rise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-level rise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sea level rises 1 m and 28% if sea level rises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-level rise, but seawalls and habitat restoration may mitigate the effects of sea-level rise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sea levels rise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds.

  19. Rise velocity of an air bubble in porous media: Theoretical studies

    NASA Astrophysics Data System (ADS)

    Corapcioglu, M. Yavuz; Cihan, Abdullah; Drazenovic, Mirna

    2004-04-01

    The rise velocity of injected air phase from the injection point toward the vadose zone is a critical factor in in-situ air sparging operations. It has been reported in the literature that air injected into saturated gravel rises as discrete air bubbles in bubbly flow of air phase. The objective of this study is to develop a quantitative technique to estimate the rise velocity of an air bubble in coarse porous media. The model is based on the macroscopic balance equation for forces acting on a bubble rising in a porous medium. The governing equation incorporates inertial force, added mass force, buoyant force, surface tension and drag force that results from the momentum transfer between the phases. The momentum transfer terms take into account the viscous as well as the kinetic energy losses at high velocities. Analytical solutions are obtained for steady, quasi-steady, and accelerated bubble rise velocities. Results show that air bubbles moving up through a porous medium equilibrate after a short travel time and very short distances of rise. It is determined that the terminal rise velocity of a single air bubble in an otherwise water saturated porous medium cannot exceed 18.5 cm/s. The theoretical model results compared favorably with the experimental data reported in the literature. A dimensional analysis conducted to study the effect of individual forces indicates that the buoyant force is largely balanced by the drag force for bubbles with an equivalent radius of 0.2-0.5 cm. With increasing bubble radius, the dimensionless number representing the effect of the surface tension force decreases rapidly. Since the total inertial force is quite small, the accelerated bubble rise velocity can be approximated by the terminal velocity.

  20. Outer Rise Faulting And Mantle Serpentinization

    NASA Astrophysics Data System (ADS)

    Ranero, C. R.; Phipps Morgan, J.; McIntosh, K.; Reichert, C.

    Dehydration of serpentinized mantle of the downgoing slab has been proposed to cause both intermediate depth earthquakes (50-300 km) and arc volcanism at sub- duction zones. It has been suggested that most of this serpentinization occurs beneath the outer rise; where normal faulting earthquakes due to bending cut > 20 km deep into the lithosphere, allowing seawater to reach and react with underlying mantle. However, little is known about flexural faulting at convergent margins; about how many normal faults cut across the crust and how deeply they penetrate into the man- tle; about the true potential of faults as conduits for fluid flow and how much water can be added through this process. We present evidence that pervasive flexural faulting may cut deep into the mantle and that the amount of faulting vary dramatically along strike at subduction zones. Flexural faulting increases towards the trench axis indicat- ing that active extension occurs in a broad area. Multibeam bathymetry of the Pacific margin of Costa Rica and Nicaragua shows a remarkable variation in the amount of flexural faulting along the incoming ocean plate. Several parameters seem to control lateral variability. Off south Costa Rica thick crust of the Cocos Ridge flexes little, and little to no faulting develops near the trench. Off central Costa Rica, normal thick- ness crust with magnetic anomalies striking oblique to the trench displays small offset faults (~200 m) striking similar to the original seafloor fabric. Off northern Costa Rica, magnetic anomalies strike perpendicular to the trench axis, and a few ~100m-offset faults develop parallel to the trench. Further north, across the Nicaraguan margin, magnetic anomalies strike parallel to the trench and the most widespread faulting de- velops entering the trench. Multichannel seismic reflection images in this area show a pervasive set of trenchward dipping reflections that cross the ~6 km thick crust and extend into the mantle to depths of at

  1. Swarm dynamics may give rise to Lévy flights

    PubMed Central

    Reynolds, Andrew M.; Ouellette, Nicholas T.

    2016-01-01

    “Continuous-time correlated random walks” are now gaining traction as models of scale-finite animal movement patterns because they overcome inherent shortcomings with the prevailing paradigm - discrete random walk models. Continuous-time correlated random walk models are founded on the classic Langevin equation that is driven by purely additive noise. The Langevin equation is, however, changed fundamentally by the smallest of multiplicative noises. The inclusion of such noises gives rise to Lévy flights, a popular but controversial model of scale-free movement patterns. Multiplicative noises have not featured prominently in the literature on biological Lévy flights, being seen, perhaps, as no more than a mathematical contrivance. Here we show how Langevin equations driven by multiplicative noises and incumbent Lévy flights arise naturally in the modelling of swarms. Model predictions find some support in three-dimensional, time-resolved measurements of the positions of individual insects in laboratory swarms of the midge Chironomus riparius. We hereby provide a new window on Lévy flights as models of movement pattern data, linking patterns to generative processes. PMID:27465971

  2. The social values at risk from sea-level rise

    SciTech Connect

    Graham, Sonia; Barnett, Jon; Fincher, Ruth; Hurlimann, Anna; Mortreux, Colette; Waters, Elissa

    2013-07-15

    Analysis of the risks of sea-level rise favours conventionally measured metrics such as the area of land that may be subsumed, the numbers of properties at risk, and the capital values of assets at risk. Despite this, it is clear that there exist many less material but no less important values at risk from sea-level rise. This paper re-theorises these multifarious social values at risk from sea-level rise, by explaining their diverse nature, and grounding them in the everyday practices of people living in coastal places. It is informed by a review and analysis of research on social values from within the fields of social impact assessment, human geography, psychology, decision analysis, and climate change adaptation. From this we propose that it is the ‘lived values’ of coastal places that are most at risk from sea-level rise. We then offer a framework that groups these lived values into five types: those that are physiological in nature, and those that relate to issues of security, belonging, esteem, and self-actualisation. This framework of lived values at risk from sea-level rise can guide empirical research investigating the social impacts of sea-level rise, as well as the impacts of actions to adapt to sea-level rise. It also offers a basis for identifying the distribution of related social outcomes across populations exposed to sea-level rise or sea-level rise policies.

  3. Demographic responses to sea level rise in California

    SciTech Connect

    Constable, A. |; Van Arsdol, M.D. Jr.; Sherman, D.J.; Wang, J.; McMullin-Messier, P.A.; Rollin, L.

    1996-12-31

    Human consequences of sea level rise in California coastal counties reflect increasing population densities. Populations of coastal counties potentially affected by sea level rise are projected to increase from 26.2 million persons in 1990 to 63.3 million persons in 2040. Urbanization dominates Los Angeles and the South Coast and San Francisco Bay and Delta regions. California shoreline populations subject to potential disruption impacts of sea level rise are increasing rapidly. Enhanced risk zones for sea level rise are specified for the Oxnard Plain of Ventura County on the south coast of California. Four separate sea level rise scenarios are considered: (1) low (sea level rise only); (2) moderate (adding erosion); (3) high (adding erosion and storm surges); and (4) a maximum case, a 3 m enhanced risk zone. Population impacts are outlined for the 3 m zone. More serious impacts from storm surges are expected than from sea level rise and erosion. Stakeholders who support or oppose policies which may expose populations to sea level rise include energy, commercial, financial, industrial, public agency, private interest and governmental organizations. These organizations respond to extreme events from differing positions. Vested interests determine the degree of mitigation employed by stakeholders to defer impacts of sea level rise.

  4. Projections of Rapidly Rising Temperatures over Africa Under Low Mitigation

    NASA Technical Reports Server (NTRS)

    Engelbrecht, Francois; Adegoke, Jimmy; Bopape, Mary-Jane; Naidoo, Mogesh; Garland, Rebecca; Thatcher, Marcus; McGregor, John; Katzfe, Jack; Werner, Micha; Ichoku, Charles; Gatebe, Charles

    2015-01-01

    An analysis of observed trends in African annual-average near-surface temperatures over the last five decades reveals drastic increases, particularly over parts of the subtropics and central tropical Africa. Over these regions, temperatures have been rising at more than twice the global rate of temperature increase. An ensemble of high-resolution downscalings, obtained using a single regional climate model forced with the sea-surface temperatures and sea-ice fields of an ensemble of global circulation model (GCM) simulations, is shown to realistically represent the relatively strong temperature increases observed in subtropical southern and northern Africa. The amplitudes of warming are generally underestimated, however. Further warming is projected to occur during the 21st century, with plausible increases of 4-6 C over the subtropics and 3-5 C over the tropics by the end of the century relative to present-day climate under the A2 (a low mitigation) scenario of the Special Report on Emission Scenarios. High impact climate events such as heat-wave days and high fire-danger days are consistently projected to increase drastically in their frequency of occurrence. General decreases in soil-moisture availability are projected, even for regions where increases in rainfall are plausible, due to enhanced levels of evaporation. The regional downscalings presented here, and recent GCM projections obtained for Africa, indicate that African annual-averaged temperatures may plausibly rise at about 1.5 times the global rate of temperature increase in the subtropics, and at a somewhat lower rate in the tropics. These projected increases although drastic, may be conservative given the model underestimations of observed temperature trends. The relatively strong rate of warming over Africa, in combination with the associated increases in extreme temperature events, may be key factors to consider when interpreting the suitability of global mitigation targets in terms of African

  5. Rise, stagnation, and rise of Danish women’s life expectancy

    PubMed Central

    Lindahl-Jacobsen, Rune; Rau, Roland; Jeune, Bernard; Canudas-Romo, Vladimir; Lenart, Adam; Christensen, Kaare; Vaupel, James W.

    2016-01-01

    Health conditions change from year to year, with a general tendency in many countries for improvement. These conditions also change from one birth cohort to another: some generations suffer more adverse events in childhood, smoke more heavily, eat poorer diets, etc., than generations born earlier or later. Because it is difficult to disentangle period effects from cohort effects, demographers, epidemiologists, actuaries, and other population scientists often disagree about cohort effects’ relative importance. In particular, some advocate forecasts of life expectancy based on period trends; others favor forecasts that hinge on cohort differences. We use a combination of age decomposition and exchange of survival probabilities between countries to study the remarkable recent history of female life expectancy in Denmark, a saga of rising, stagnating, and now again rising lifespans. The gap between female life expectancy in Denmark vs. Sweden grew to 3.5 y in the period 1975–2000. When we assumed that Danish women born 1915–1945 had the same survival probabilities as Swedish women, the gap remained small and roughly constant. Hence, the lower Danish life expectancy is caused by these cohorts and is not attributable to period effects. PMID:27035998

  6. Comment [on “Sea level rise shown to drive coastal erosion”

    NASA Astrophysics Data System (ADS)

    Pilkey, Orrin H.; Young, Robert S.; Bush, David M.

    Leatherman et al. [2000] (Eos, Trans., AGU, February 8, 2000, p.55) affirm that global eustatic sea-level rise is driving coastal erosion. Furthermore, they argue that the long-term average rate of shoreline retreat is 150 times the rate of sea-level rise. This rate, they say, is more than a magnitude greater than would be expected from a simple response to sea-level rise through inundation of the shoreline. We agree that sea-level rise is the primary factor causing shoreline retreat in stable coastal areas.This is intuitive. We also believe, however, that the Leatherman et al. [2000] study has greatly underestimated the rate of coastal recession along most low slope shorelines. Slopes along the North Carolina continental shelf/coastal plain approach 10,000:1. To us, this suggests that we should expect rates of shoreline recession 10,000 times the rate of sea-level rise through simple inundation of the shoreline.

  7. Comment [on “Sea level rise shown to drive coastal erosion”

    USGS Publications Warehouse

    Pilkey, Orrin H.; Young, Robert S.; Bush, David M.

    2000-01-01

    Leatherman et al. [2000] (Eos, Trans., AGU, February 8, 2000, p.55) affirm that global eustatic sea-level rise is driving coastal erosion. Furthermore, they argue that the long-term average rate of shoreline retreat is 150 times the rate of sea-level rise. This rate, they say, is more than a magnitude greater than would be expected from a simple response to sea-level rise through inundation of the shoreline. We agree that sea-level rise is the primary factor causing shoreline retreat in stable coastal areas.This is intuitive. We also believe, however, that the Leatherman et al. [2000] study has greatly underestimated the rate of coastal recession along most low slope shorelines. Slopes along the North Carolina continental shelf/coastal plain approach 10,000:1. To us, this suggests that we should expect rates of shoreline recession 10,000 times the rate of sea-level rise through simple inundation of the shoreline.

  8. Is School Bullying Really on the Rise?

    ERIC Educational Resources Information Center

    Rigby, Ken; Smith, Peter K.

    2011-01-01

    Whether bullying in schools is increasing, as is widely believed, was investigated drawing upon empirical studies undertaken in a wide range of countries in which findings had been published describing its prevalence at different points in time between 1990 and 2009. Results do not support the view that reported bullying in general has increased…

  9. Rescuing Education: The Rise of Experiential Learning

    ERIC Educational Resources Information Center

    McKenzie, Malcolm

    2013-01-01

    The term "experiential education" can be--and has been--applied to a wide range of educational programming. Malcolm McKenzie's working definition of experiential education is this: it promotes learning through direct experience, often outside the classroom, at times not directly related to academic courses, frequently not graded,…

  10. The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey

    SciTech Connect

    Hayden, Brian T.; Garnavich, Peter M.; Kessler, Richard; Frieman, Joshua A.; Jha, Saurabh W.; Bassett, Bruce; Cinabro, David; Dilday, Benjamin; Kasen, Daniel; Marriner, John; Nichol, Robert C.; /Portsmouth U., ICG /Baltimore, Space Telescope Sci. /Johns Hopkins U.

    2010-01-01

    We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single 'stretch' correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a '2-stretch' fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 {+-} 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink (2007) from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, t{sub r} - t{sub f} {approx}< 2 days and t{sub r} - t{sub f} > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our

  11. High tides and rising seas: Potential effects on estuarine waterbirds

    USGS Publications Warehouse

    Erwin, R.M.; Sanders, G.M.; Prosser, D.J.; Cahoon, D.R.

    2006-01-01

    Coastal waterbirds are vulnerable to water-level changes especially under predictions of accelerating sea-level rise and increased storm frequency in the next century. Tidal and wind-driven fluctuations in water levels affecting marshes, their invertebrate communities, and their dependent waterbirds are manifested in daily, monthly, seasonal, annual, and supra-annual (e.g., decadal or 18.6-yr) periodicities. Superimposed on these cyclic patterns is a long-term (50-80 yr) increase in relative sea-level rise that varies from about 2-4 + mm/yr along the Atlantic coastline. At five study sites selected on marsh islands from Cape Cod, Massachusetts to coastal Virginia, we monitored marsh elevation changes and flooding, tide variations over time, and waterbird use. We found from long-term marsh core data that marsh elevations at three of five sites may not be sufficient to maintain pace with current sea-level rise. Results of the short-term (3-4 yr) measures using surface elevation tables suggest a more dramatic difference, with marsh elevation change at four of five sites falling below relative sea-level rise. In addition, we have found a significant increase (in three of four cases) in the rate of surface marsh flooding in New Jersey and Virginia over the past 70-80 yr during May-July when waterbirds are nesting on or near the marsh surface. Short-term, immediate effects of flooding will jeopardize annual fecundity of many species of concern to federal and state agencies, most notably American Black Duck (Anas rubripes), Nelson's Sharp-tailed Sparrow (Ammodramus nelsoni), Saltmarsh Sharp-tailed Sparrow (A. caudacutus), Seaside Sparrow (A. maritima), Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens), Black Rail (Laterallus jamaicensis), Forster's Tern (Sterna forsteri). Gull-billed Tern (S. nilotica), Black Skimmer (Rynchops niger), and American Oystercatcher (Haemotopus palliatus). Forster's Terns are probably most at risk given the large proportion of their

  12. High tides and rising seas: potential effects on estuarine waterbirds

    USGS Publications Warehouse

    Erwin, R.M.; Sanders, G.M.; Prosser, D.J.; Cahoon, D.R.

    2006-01-01

    Coastal waterbirds are vulnerable to water-level changes especially under predictions of accelerating sea-level rise and increased storm frequency in the next century. Tidal and wind-driven fluctuations in water levels affecting marshes, their invertebrate communities, and their dependent waterbirds are manifested in daily, monthly, seasonal, annual, and supra-annual (e.g., decadal or 18.6-yr) periodicities. Superimposed on these cyclic patterns is a long-term (50?80 yr) increase in relative sea-level rise that varies from about 2?4 + mm/yr along the Atlantic coastline. At five study sites selected on marsh islands from Cape Cod, Massachusetts to coastal Virginia, we monitored marsh elevation changes and flooding, tide variations over time, and waterbird use. We found from longterm marsh core data that marsh elevations at three of five sites may not be sufficient to maintain pace with current sea-level rise. Results of the short-term (3?4 yr) measures using surface elevation tables suggest a more dramatic difference, with marsh elevation change at four of five sites falling below relative sea-level rise. In addition, we have found a significant increase (in three of four cases) in the rate of surface marsh flooding in New Jersey and Virginia over the past 70?80 yr during May?July when waterbirds are nesting on or near the marsh surface. Short-term, immediate effects of flooding will jeopardize annual fecundity of many species of concern to federal and state agencies, most notably American Black Duck (Anas rubripes), Nelson?s Sharp-tailed Sparrow (Ammodramus nelsoni), Saltmarsh Sharp-tailed Sparrow (A. caudacutus), Seaside Sparrow (A. maritima), Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens), Black Rail (Laterallus jamaicensis), Forster?s Tern (Sterna forsteri), Gull-billed Tern (S. nilotica), Black Skimmer (Rynchops niger), and American Oystercatcher (Haemotopus palliatus). Forster?s Terns are probably most at risk given the large proportion of their

  13. Rising levels of atmospheric oxygen and evolution of Nrf2.

    PubMed

    Gacesa, Ranko; Dunlap, Walter C; Barlow, David J; Laskowski, Roman A; Long, Paul F

    2016-01-01

    In mammals, the master transcription regulator of antioxidant defences is provided by the Nrf2 protein. Phylogenetic analyses of Nrf2 sequences are used here to derive a molecular clock that manifests persuasive evidence that Nrf2 orthologues emerged, and then diverged, at two time points that correlate with well-established geochemical and palaeobiological chronologies during progression of the 'Great Oxygenation Event'. We demonstrate that orthologues of Nrf2 first appeared in fungi around 1.5 Ga during the Paleoproterozoic when photosynthetic oxygen was being absorbed into the oceans. A subsequent significant divergence in Nrf2 is seen during the split between fungi and the Metazoa approximately 1.0-1.2 Ga, at a time when oceanic ventilation released free oxygen to the atmosphere, but with most being absorbed by methane oxidation and oxidative weathering of land surfaces until approximately 800 Ma. Atmospheric oxygen levels thereafter accumulated giving rise to metazoan success known as the Cambrian explosion commencing at ~541 Ma. Atmospheric O2 levels then rose in the mid Paleozoic (359-252 Ma), and Nrf2 diverged once again at the division between mammals and non-mammalian vertebrates during the Permian-Triassic boundary (~252 Ma). Understanding Nrf2 evolution as an effective antioxidant response may have repercussions for improved human health. PMID:27297177

  14. Rising levels of atmospheric oxygen and evolution of Nrf2

    PubMed Central

    Gacesa, Ranko; Dunlap, Walter C.; Barlow, David J.; Laskowski, Roman A.; Long, Paul F.

    2016-01-01

    In mammals, the master transcription regulator of antioxidant defences is provided by the Nrf2 protein. Phylogenetic analyses of Nrf2 sequences are used here to derive a molecular clock that manifests persuasive evidence that Nrf2 orthologues emerged, and then diverged, at two time points that correlate with well-established geochemical and palaeobiological chronologies during progression of the ‘Great Oxygenation Event’. We demonstrate that orthologues of Nrf2 first appeared in fungi around 1.5 Ga during the Paleoproterozoic when photosynthetic oxygen was being absorbed into the oceans. A subsequent significant divergence in Nrf2 is seen during the split between fungi and the Metazoa approximately 1.0–1.2 Ga, at a time when oceanic ventilation released free oxygen to the atmosphere, but with most being absorbed by methane oxidation and oxidative weathering of land surfaces until approximately 800 Ma. Atmospheric oxygen levels thereafter accumulated giving rise to metazoan success known as the Cambrian explosion commencing at ~541 Ma. Atmospheric O2 levels then rose in the mid Paleozoic (359–252 Ma), and Nrf2 diverged once again at the division between mammals and non-mammalian vertebrates during the Permian-Triassic boundary (~252 Ma). Understanding Nrf2 evolution as an effective antioxidant response may have repercussions for improved human health. PMID:27297177

  15. The decline and rise of the medical school applicant pool.

    PubMed

    Kassebaum, D G; Szenas, P L

    1995-04-01

    The authors characterize the demographic changes that transpired with the decline and rise of the medical school applicant pool over the past decade, and describe the variations in academic antecedents, attrition, and graduation rates of students matriculated during that time. Data over the ten-year cycle, derived from the AAMC's Student and Applicant Information Management System (SAIMS), were examined in the context of published education and employment statistics. The contraction and expansion of the applicant pool were related to changes in the number and pattern of undergraduate majors and to changes in the employment conditions for college-educated youth. Furthermore, a significant part of the variations in size of the applicant pool is an artifact of changes in the number of repeat applications. Matriculants' pre-medical grades and MCAT scores dropped slightly during the period of applicant decline, and rebounded as admission committees were able to exercise greater selection when the pool expanded. The attrition of medical students rose and fell during this time, but the changes were small and of little discrete influence on graduation rates during the period. The downturn and rebound in applications over the past decade appear to be more related to cycles in the employment market for college graduates than to applicants' perceptions of unfavorable/favorable conditions in medical education and practice. PMID:7718069

  16. The Formation of the Rising Generation under the Conditions of Social Differentiation in Russia

    ERIC Educational Resources Information Center

    Shabunova, A.

    2008-01-01

    The transformations in Russian society that took place in the late twentieth century and early twenty-first century led to a rapid rise in social and economic differentiation. According to official data, the income gap between the 10 percent most-well-off and the 10 percent least-well-off families (the capital coefficient) rose to 14.8 times in…

  17. Application of a rising plate meter to estimate forage yield on dairy farms in Pennsylvania

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately assessing pasture forage yield is necessary for producers who want to budget feed expenses and make informed pasture management decisions. Clipping and weighing forage from a known area is a direct method to measure pasture forage yield, however it is time consuming. The rising plate mete...

  18. Application of a rising plate meter to estimate forage yield on dairy farms in PA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately assessing pasture forage yield is necessary for producers who want to budget feed expenses and make informed pasture management decisions. Clipping and weighing forage from a known area is a direct method to measure pasture forage yield, however it is time consuming. The rising plate mete...

  19. Near-simultaneous great earthquakes at Tongan megathrust and outer rise in September 2009.

    PubMed

    Beavan, J; Wang, X; Holden, C; Wilson, K; Power, W; Prasetya, G; Bevis, M; Kautoke, R

    2010-08-19

    The Earth's largest earthquakes and tsunamis are usually caused by thrust-faulting earthquakes on the shallow part of the subduction interface between two tectonic plates, where stored elastic energy due to convergence between the plates is rapidly released. The tsunami that devastated the Samoan and northern Tongan islands on 29 September 2009 was preceded by a globally recorded magnitude-8 normal-faulting earthquake in the outer-rise region, where the Pacific plate bends before entering the subduction zone. Preliminary interpretation suggested that this earthquake was the source of the tsunami. Here we show that the outer-rise earthquake was accompanied by a nearly simultaneous rupture of the shallow subduction interface, equivalent to a magnitude-8 earthquake, that also contributed significantly to the tsunami. The subduction interface event was probably a slow earthquake with a rise time of several minutes that triggered the outer-rise event several minutes later. However, we cannot rule out the possibility that the normal fault ruptured first and dynamically triggered the subduction interface event. Our evidence comes from displacements of Global Positioning System stations and modelling of tsunami waves recorded by ocean-bottom pressure sensors, with support from seismic data and tsunami field observations. Evidence of the subduction earthquake in global seismic data is largely hidden because of the earthquake's slow rise time or because its ground motion is disguised by that of the normal-faulting event. Earthquake doublets where subduction interface events trigger large outer-rise earthquakes have been recorded previously, but this is the first well-documented example where the two events occur so closely in time and the triggering event might be a slow earthquake. As well as providing information on strain release mechanisms at subduction zones, earthquakes such as this provide a possible mechanism for the occasional large tsunamis generated at the Tonga

  20. 40 CFR Appendix Vi to Part 266 - Stack Plume Rise

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 28 2012-07-01 2012-07-01 false Stack Plume Rise VI Appendix VI to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Pt. 266, App. VI Appendix VI to Part 266—Stack Plume Rise Flow rate (m3/s) Exhaust Temperature...

  1. 40 CFR Appendix Vi to Part 266 - Stack Plume Rise

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 27 2014-07-01 2014-07-01 false Stack Plume Rise VI Appendix VI to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Pt. 266, App. VI Appendix VI to Part 266—Stack Plume Rise Flow rate (m3/s) Exhaust Temperature...

  2. 40 CFR Appendix Vi to Part 266 - Stack Plume Rise

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Stack Plume Rise VI Appendix VI to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Pt. 266, App. VI Appendix VI to Part 266—Stack Plume Rise Flow rate (m3/s) Exhaust Temperature...

  3. 40 CFR Appendix Vi to Part 266 - Stack Plume Rise

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 27 2011-07-01 2011-07-01 false Stack Plume Rise VI Appendix VI to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Pt. 266, App. VI Appendix VI to Part 266—Stack Plume Rise Flow rate (m3/s) Exhaust Temperature...

  4. Origin of Corona-Dominated Topographic Rises on Venus

    NASA Technical Reports Server (NTRS)

    Smrekar, S.; Stofan, E.

    1999-01-01

    Both large-scale mantel upwellings, comparable to terrestrial hotspots on Earth, and smaller scale mantel upwellings, known as coronae, occur on Venus. Corona-dominated rises have many of the characteristics of large scale mantle upwellings, or hotspots, such as broad topographic rises greater than 1000km in diameter and large positive gravity anomalies.

  5. 40 CFR Appendix Vi to Part 266 - Stack Plume Rise

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 28 2013-07-01 2013-07-01 false Stack Plume Rise VI Appendix VI to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... FACILITIES Pt. 266, App. VI Appendix VI to Part 266—Stack Plume Rise Flow rate (m3/s) Exhaust Temperature...

  6. RISE Evaluation and Development System: Student Learning Objectives Handbook

    ERIC Educational Resources Information Center

    Indiana Department of Education, 2016

    2016-01-01

    With the help of teachers and leaders throughout the state, the Indiana Department of Education has developed an optional model teacher evaluation system named RISE. Whether corporations choose to adopt RISE or a model of their own, the department's goal is to assist corporations in developing or adopting models that both comply with IC 20-28-11.5…

  7. Lower bounds to future sea-level rise

    NASA Astrophysics Data System (ADS)

    Zecca, Antonio; Chiari, Luca

    2012-12-01

    Sea-level rise is among the most important changes expected as a consequence of anthropogenic global warming. Climate model-based projections made until the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC) yield a 21st century rise spanning nearly 20-60 cm. However, it is known that current climate models are likely to underestimate sea-level change in response to rapid climatic variations. Recent alternative semi-empirical approaches predict a much higher sea-level rise than the IPCC AR4 projections. Nevertheless, the underway depletion of conventional fossil fuels might, at least in principle, constrain future fossil CO2 emissions and, in turn, affect also the extent of sea-level rise. Here we project 2000-2200 sea-level rise with a semi-empirical method coupled to a simple climate model that is run under a range of fossil-fuel exhaustion scenarios. We find that, in spite of fossil-fuel depletion, sea level is predicted to rise by at least ~ 80 cm at the end of this century and is expected to continue rising for at least the next two hundred years. The present results support the need for prompt and substantial emission cuts in order to slow down future sea-level rise and implement adaptation measures.

  8. The New Woman in "The Sun Also Rises"

    ERIC Educational Resources Information Center

    Yu, Xiaoping

    2010-01-01

    Hemingway is a famous American writer and a spokesman of the Lost Generation. His life attitude of the characters in the novels influenced the whole world. His first masterpiece "The Sun Also Rises" contributes a lot to the rise of feminism and make the world began to be familiar with a term: The New Woman through the portrayal of Brett.…

  9. Estuaries May Face Increased Parasitism as Sea Levels Rise

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-12-01

    Invertebrates in estuaries could be at a greater risk of parasitism as climate change causes sea levels to rise. A new paper published 8 December in Proceedings of the National Academy of Sciences of the United States of America (doi:10.1073/pnas.1416747111) describes how rapid sea level rise in the Holocene affected the population of parasitic flatworms called trematodes.

  10. The Rise of Conservatism since World War II.

    ERIC Educational Resources Information Center

    Carter, Dan T.

    2003-01-01

    Discusses the rise of the conservatism movement in the United States since World War II. States that laissez-faire capitalism and the rise of communism contributed to the popularity of conservatism in the United States. Focuses on the role of U.S. Presidents, such as Richard Nixon and Ronald Reagan. (CMK)

  11. Cenozoic seismic stratigraphy of the SW Bermuda Rise

    SciTech Connect

    Mountain, G.S.; Driscoll, N.W.; Miller, K.G.

    1985-01-01

    The seismic Horizon A-Complex (Tucholke, 1979) readily explains reflector patterns observed along the western third of the Bermuda Rise; farther east, basement is much more rugged and gravity flows shed from local topographic highs complicate the stratigraphy. Distal turbidites on the southwestern Bermuda Rise onlap reflector A* from the west, suggesting early Paleocene mass wasting of the North American margin. Locally erosive bottom currents cut into the middle Eocene section of the SW Bermuda Rise; these northward flowing currents preceded those that formed reflector Au along the North American margin near the Eocene-Oligocene boundary. Southward flowing currents swift enough to erode the sea floor and to form reflector Au did not reach as far east as the SW Bermuda Rise. Instead, the main effect of these Au currents was to pirate sediment into contour-following geostrophic flows along the North American margin and to deprive the deep basin and the Bermuda Rise of sediment transported down-slope. Consequently, post-Eocene sediments away from the margin are fine-grained muds. Deposition of these muds on the SW Bermuda Rise was controlled by northward flowing bottom currents. The modern Hatteras Abyssal Plain developed in the late Neogene as turbidites once again onlapped the SW Bermuda Rise. Today, these deposits extend farthest east in fracture zone valleys and in the swales between sediment waves. Northward flowing currents continue at present to affect sediment distribution patterns along the western edge of the Bermuda Rise.

  12. The rise and fall of Luz

    SciTech Connect

    Shinnar, R. )

    1993-01-01

    In the search for renewable power the United States has established tax credits for power plants that use solar or wind energy. These tax credits are, of course, eventually paid by the taxpayers and must be justified by the politicians. And there's the rub. When a solar plant becomes big, the taxpayers' contribution grows so large that politicians have a hard time justifying it. The experience of Luz describes how this company's success in building solar plants inevitably led to its demise. It brings into question whether we're serious in the pursuit of solar power or whether we merely pay lip service.

  13. Mars reconnaissance orbiter's high resolution imaging science experiment (HiRISE)

    USGS Publications Warehouse

    McEwen, A.S.; Eliason, E.M.; Bergstrom, J.W.; Bridges, N.T.; Hansen, C.J.; Delamere, W.A.; Grant, J. A.; Gulick, V.C.; Herkenhoff, K. E.; Keszthelyi, L.; Kirk, R.L.; Mellon, M.T.; Squyres, S. W.; Thomas, N.; Weitz, C.M.

    2007-01-01

    The HiRISE camera features a 0.5 m diameter primary mirror, 12 m effective focal length, and a focal plane system that can acquire images containing up to 28 Gb (gigabits) of data in as little as 6 seconds. HiRISE will provide detailed images (0.25 to 1.3 m/pixel) covering ???1% of the Martian surface during the 2-year Primary Science Phase (PSP) beginning November 2006. Most images will include color data covering 20% of the potential field of view. A top priority is to acquire ???1000 stereo pairs and apply precision geometric corrections to enable topographic measurements to better than 25 cm vertical precision. We expect to return more than 12 Tb of HiRISE data during the 2-year PSP, and use pixel binning, conversion from 14 to 8 bit values, and a lossless compression system to increase coverage. HiRISE images are acquired via 14 CCD detectors, each with 2 output channels, and with multiple choices for pixel binning and number of Time Delay and Integration lines. HiRISE will support Mars exploration by locating and characterizing past, present, and future landing sites, unsuccessful landing sites, and past and potentially future rover traverses. We will investigate cratering, volcanism, tectonism, hydrology, sedimentary processes, stratigraphy, aeolian processes, mass wasting, landscape evolution, seasonal processes, climate change, spectrophotometry, glacial and periglacial processes, polar geology, and regolith properties. An Internet Web site (HiWeb) will enable anyone in the world to suggest HiRISE targets on Mars and to easily locate, view, and download HiRISE data products. Copyright 2007 by the American Geophysical Union.

  14. Frictional temperature rise in a sliding physisorbed monolayer of Kr/graphene

    NASA Astrophysics Data System (ADS)

    Walker, M.; Jaye, C.; Krim, J.; Cole, Milton W.

    2012-10-01

    A quartz crystal microbalance (QCM) with a graphene/Ni(111) electrode has been used to probe frictional heating effects in Kr monolayers sliding on the microbalance electrode in response to its oscillatory motion. The temperatures of the sliding Kr monolayers are observed to rise approximately 13 K higher than their static counterparts, but show surprisingly little dependence on oscillation amplitude. Although counterintuitive, the observation can be explained by noting that the Kr surface residence times are limited, which effectively caps how much the temperature can rise.

  15. Chemostratigraphy at DSDP Sites 386 (Bermuda Rise) and 144 (Demerara Rise), Implications for Euxinic Conditions During OAE-2

    NASA Astrophysics Data System (ADS)

    Horst, P. A.; Maurrasse, F. J.; Sinninghe-Damsté, J. S.; Sandler, A.

    2008-05-01

    Chemostratigraphic studies of DSDP Site 386 on the Bermuda Rise and Site 144 on the Demerara Rise indicate that euxinic conditions developed at these deep-water sites during the time interval that corresponds to Oceanic Anoxic Event 2 (OAE 2). The data show a large increase in Fe/Al ratios, and dispersed pyrite aggregates (Site 386 Core 43, Section 3). Such findings at these deep oceanic sites are compatible with earlier studies showing that sediments in euxinic settings display increases in Fe/Al ratios due to the scavenging of dissolved Fe, and is also in agreement with previous Pr/Ph ratio of <1 (Simoneit, 1979). This study further shows that OM, previously believed to show bimodal distribution, which was used to argue in support of turbidity currents at Site 386 as transport mechanism for some of the OM, is predominantly derived from marine phytoplankton and cyanobacteria showing low thermal stress, supporting in situ derivation. Elemental analyses at Site 386 also show that relatively high Sr/CaO ratios are present before and after OAE 2, indicating an increased contribution of biogenic carbonates, but not during the C/T boundary event. When Cr is plotted against Al2O3 in conjunction with a solid line representing the Cr/Al2O3 ratio in average shale, half of the samples fall above and half fall below this line. The values that plot above this line are all from Cores 47, 44, 43, and 42, which contain higher TOC. Their strong Cr enrichment with respect to the average shale can be indicative of an algal source of the OM, as this biota preferentially concentrates Cr. Competitive exclusion due to dominance of opportunistic prokaryotic blooms in combination with oxygen depletion can be invoked to explain the conditions that developed and were unfavorable to most other organisms throughout the water column during OAE 2. Sediments from DSDP Site 144 also reveal increased molecular fossils indicative of green sulfur bacteria, which are further characteristic of euxinic

  16. The rise and fall of Golgi's school.

    PubMed

    Mazzarello, Paolo

    2011-01-01

    The Camillo Golgi's school of Histology and General Pathology in Pavia played an important role in the development of medical-biological studies in Italy in the period after Unification of the state. Founded around 1880 when Golgi (1843-1926) began to wield power at the University of Pavia, the school soon became famous for the distinctive morphological basis of its studies. Many of its staff members made important discoveries and won international acclaim. The school however went into decline after 1910 because of its rigid adherence to the morphological approach that had characterized its golden years at a time when the international scientific world was developing other fundamental methodological criteria for medical-biological studies. PMID:20594993

  17. Rise in landing-related skydiving fatalities.

    PubMed

    Hart, Christian L; Griffith, James D

    2003-10-01

    The purpose was to assess whether adoption of potentially dangerous skydiving gear and skydiving practices has led to an increase in fatalities. Beginning in the early 1990s, civilian skydivers began to utilize high performance parachutes that fly much faster and are much more responsive than older style parachutes. Also, skydivers began to fly these parachutes in a more aggressive manner. An analysis of data from the 507 skydiving fatalities in the USA between 1986 and 2001 indicated that this shift toward high performance parachutes and aggressive flying techniques was temporally associated with an increase in parachute-landing deaths. During the same time period, the total number of fatalities remained fairly stable. PMID:14620223

  18. Rising temperatures reduce global wheat production

    NASA Astrophysics Data System (ADS)

    Asseng, S.; Ewert, F.; Martre, P.; Rötter, R. P.; Lobell, D. B.; Cammarano, D.; Kimball, B. A.; Ottman, M. J.; Wall, G. W.; White, J. W.; Reynolds, M. P.; Alderman, P. D.; Prasad, P. V. V.; Aggarwal, P. K.; Anothai, J.; Basso, B.; Biernath, C.; Challinor, A. J.; de Sanctis, G.; Doltra, J.; Fereres, E.; Garcia-Vila, M.; Gayler, S.; Hoogenboom, G.; Hunt, L. A.; Izaurralde, R. C.; Jabloun, M.; Jones, C. D.; Kersebaum, K. C.; Koehler, A.-K.; Müller, C.; Naresh Kumar, S.; Nendel, C.; O'Leary, G.; Olesen, J. E.; Palosuo, T.; Priesack, E.; Eyshi Rezaei, E.; Ruane, A. C.; Semenov, M. A.; Shcherbak, I.; Stöckle, C.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Thorburn, P. J.; Waha, K.; Wang, E.; Wallach, D.; Wolf, J.; Zhao, Z.; Zhu, Y.

    2015-02-01

    Crop models are essential tools for assessing the threat of climate change to local and global food production. Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature. Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 °C to 32 °C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each °C of further temperature increase and become more variable over space and time.

  19. Rising Temperatures Reduce Global Wheat Production

    NASA Technical Reports Server (NTRS)

    Asseng, S.; Ewert, F.; Martre, P.; Rötter, R. P.; Lobell, D. B.; Cammarano, D.; Kimball, B. A.; Ottman, M. J.; Wall, G. W.; White, J. W.; Reynolds, M. P.; Alderman, P. D.; Prasad, P. V. V.; Aggarwal, P. K.; Anothai, J.; Basso, B.; Biernath, C.; Challinor, A. J.; De Sanctis, G.; Doltra, J.; Fereres, E.; Garcia-Vila, M.; Gayler, S.; Hoogenboom, G.; Hunt, L. A.; Izaurralde, R. C.; Jabloun, M.; C. D. Jones,; Kersebaum, K. C.; Koehler, A-K.; Müller, C.; Naresh Kumar, S.; Nendel, C.; O’Leary, G.; Olesen, J. E.; Palosuo, T.; Priesack, E.; Eyshi Rezaei, E.; Ruane, A. C.; Semenov, M. A.; Shcherbak, I.; Stöckle, C.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Thorburn, P. J.; Waha, K.; Wang, E.; Wallach, D.; Wolf, J.; Zhao, Z.; Zhu, Y.

    2015-01-01

    Crop models are essential tools for assessing the threat of climate change to local and global food production. Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature. Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 degrees C to 32? degrees C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each degree C of further temperature increase and become more variable over space and time.

  20. [Burnout: rising interest phenomenon in stressful workplace].

    PubMed

    Della Valle, E; De Pascale, G; Cuccaro, A; Di Mare, M; Padovano, L; Carbone, U; Farinaro, E

    2006-01-01

    Many stressful situations, particularly strong and long time lasting, can induce the burnout syndrome. The definition "burnout" refers to emotional and exhausting conditions related to working environment. Since 70'ties, many studies, have focused on this topic, have assessed that this condition is much more frequent in some particular professional categories: teachers, physicians, nurses, social workers, policemen, judges (the so-called helping professions). The main syndrome characteristics are: physical and emotional fatigue, depersonalization, frustration for unsuccessful professional realization and reduced personal accomplishment in competence and productivity with decreasing critical sense towards working field. The Maslach Burnout Inventory (MBI) has been the most popular instrument for measuring burnout in medical research. The coherence of many studies results on helping professions in different countries, leads to the conclusion that basically burnout is a psycho-social phenomenon of international relevance. These studies have also identified personal, relational and environmental risk factors susceptible to prevention. PMID:16649514

  1. Relative outcomes of climate change mitigation related to global temperature versus sea-level rise

    NASA Astrophysics Data System (ADS)

    Meehl, Gerald A.; Hu, Aixue; Tebaldi, Claudia; Arblaster, Julie M.; Washington, Warren M.; Teng, Haiyan; Sanderson, Benjamin M.; Ault, Toby; Strand, Warren G.; White, James B.

    2012-08-01

    There is a common perception that, if human societies make the significant adjustments necessary to substantively cut emissions of greenhouse gases, global temperature increases could be stabilized, and the most dangerous consequences of climate change could be avoided. Here we show results from global coupled climate model simulations with the new representative concentration pathway mitigation scenarios to 2300 to illustrate that, with aggressive mitigation in two of the scenarios, globally averaged temperature increase indeed could be stabilized either below 2 °C or near 3 °C above pre-industrial values. However, even as temperatures stabilize, sea level would continue to rise. With little mitigation, future sea-level rise would be large and continue unabated for centuries. Though sea-level rise cannot be stopped for at least the next several hundred years, with aggressive mitigation it can be slowed down, and this would buy time for adaptation measures to be adopted.

  2. Comment [on “Sea level rise shown to drive coastal erosion”

    USGS Publications Warehouse

    Sallenger,, Asbury H., Jr.; Morton, Robert; Fletcher, Charles; Thieler, E. Robert; Howd, Peter

    2000-01-01

    In a recent article (Eos, Trans., AGU, February 8, 2000, p.55), Leatherman et al. [2000] state that they have confirmed an association between sea-level rise and coastal erosion. Applying their results to the New Jersey, Delaware, and Maryland coasts and using a projected sea-level rise, the authors predict that by 2050 the shoreline will recede 60 m, about two times the average beach width. However, Leatherman et al. [2000] have not convincingly quantified a relationship between sea-level rise and shoreline erosion.We do not agree with their rationale for subsetting their data, and they have not considered other explanations for a background erosion along the U.S. east coast. Furthermore, their future projections are not supported by their analyses.

  3. Radiometric Calibration of Mars HiRISE High Resolution Imagery Based on Fpga

    NASA Astrophysics Data System (ADS)

    Hou, Yifan; Geng, Xun; Xing, Shuai; Tang, Yonghe; Xu, Qing

    2016-06-01

    Due to the large data amount of HiRISE imagery, traditional radiometric calibration method is not able to meet the fast processing requirements. To solve this problem, a radiometric calibration system of HiRISE imagery based on field program gate array (FPGA) is designed. The montage gap between two channels caused by gray inconsistency is removed through histogram matching. The calibration system is composed of FPGA and DSP, which makes full use of the parallel processing ability of FPGA and fast computation as well as flexible control characteristic of DSP. Experimental results show that the designed system consumes less hardware resources and the real-time processing ability of radiometric calibration of HiRISE imagery is improved.

  4. Method for Assessing Impacts of Global Sea Level Rise on Navigation Gate Operations

    NASA Astrophysics Data System (ADS)

    Obrien, P. S.; White, K. D.; Friedman, D.

    2015-12-01

    Coastal navigation infrastructure may be highly vulnerable to changing climate, including increasing sea levels and altered frequency and intensity of coastal storms. Future gate operations impacted by global sea level rise will pose unique challenges, especially for structures 50 years and older. Our approach is to estimate future changes in gate operational frequency based on a bootstrapping method to forecast future water levels. A case study will be presented to determine future changes in frequency of operations over the next 100 years. A statistical model in the R programming language was developed to apply future sea level rise projections using the three sea level rise scenarios prescribed by USACE Engineer Regulation ER 1100-2-8162. Information derived from the case study will help forecast changes in operational costs caused by increased gate operations and inform timing of decisions on adaptation measures.

  5. Estimating Temperature Rise Due to Flashlamp Heating Using Irreversible Temperature Indicators

    NASA Technical Reports Server (NTRS)

    Koshti, Ajay M.

    1999-01-01

    One of the nondestructive thermography inspection techniques uses photographic flashlamps. The flashlamps provide a short duration (about 0.005 sec) heat pulse. The short burst of energy results in a momentary rise in the surface temperature of the part. The temperature rise may be detrimental to the top layer of the part being exposed. Therefore, it is necessary to ensure the nondestructive nature of the technique. Amount of the temperature rise determines whether the flashlamp heating would be detrimental to the part. A direct method for the temperature measurement is to use of an infrared pyrometer that has much shorter response time than the flash duration. In this paper, an alternative technique is given using the irreversible temperature 'indicators. This is an indirect technique and it measures the temperature rise on the irreversible temperature indicators and computes the incident heat flux. Once the heat flux is known, the temperature rise on the part can be computed. A wedge shaped irreversible temperature indicator for measuring the heat flux is proposed. A procedure is given to use the wedge indicator.

  6. Dynamical Suppression of Sea Level Rise Along the Eastern Boundary of the North Pacific

    NASA Astrophysics Data System (ADS)

    Bromirski, P. D.; Miller, A. J.; Flick, R. E.

    2011-12-01

    Long-term changes in global mean sea level (MSL) rise have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm-surge flooding, and coastal development. Altimetry since 1993 indicates that global MSL rise has increased about 50% above the 20th century rise rate, from 2 to 3 mm/yr. At the same time, both tide gauge measurements and altimetry indicate virtually no increase in mean sea level height (SLH) along the Pacific coast of North America during the satellite epoch. Analyses of wind stress patterns indicates that the dynamical steric response of North Pacific eastern boundary ocean circulation to a dramatic change in wind stress curl, that occurred after the mid-1970's regime shift, can account for the suppression of regional sea level rise along the U.S. West Coast since 1980, modulating the canonical SLH response expected along the eastern boundary during the warm phase of the PDO. Alarmingly, mean wind stress curl over the North Pacific recently reached levels not observed since before the mid-1970's regime shift. This change in wind stress patterns may be foreshadowing a PDO regime shift, causing an associated persistent change in wind stress curl that may result in a concomitant resumption of sea level rise along the West Coast to global rates.

  7. The importance of plume rise on the concentrations and atmospheric impacts of biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Walter, Carolin; Freitas, Saulo R.; Kottmeier, Christoph; Kraut, Isabel; Rieger, Daniel; Vogel, Heike; Vogel, Bernhard

    2016-07-01

    We quantified the effects of the plume rise of biomass burning aerosol and gases for the forest fires that occurred in Saskatchewan, Canada, in July 2010. For this purpose, simulations with different assumptions regarding the plume rise and the vertical distribution of the emissions were conducted. Based on comparisons with observations, applying a one-dimensional plume rise model to predict the injection layer in combination with a parametrization of the vertical distribution of the emissions outperforms approaches in which the plume heights are initially predefined. Approximately 30 % of the fires exceed the height of 2 km with a maximum height of 8.6 km. Using this plume rise model, comparisons with satellite images in the visible spectral range show a very good agreement between the simulated and observed spatial distributions of the biomass burning plume. The simulated aerosol optical depth (AOD) with data of an AERONET station is in good agreement with respect to the absolute values and the timing of the maximum. Comparison of the vertical distribution of the biomass burning aerosol with CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) retrievals also showed the best agreement when the plume rise model was applied. We found that downwelling surface short-wave radiation below the forest fire plume is reduced by up to 50 % and that the 2 m temperature is decreased by up to 6 K. In addition, we simulated a strong change in atmospheric stability within the biomass burning plume.

  8. Sea-Level Rise Impacts on Hudson River Marshes

    NASA Astrophysics Data System (ADS)

    Hooks, A.; Nitsche, F. O.

    2015-12-01

    The response of tidal marshes to increasing sea-level rise is uncertain. Tidal marshes can adapt to rising sea levels through vertical accretion and inland migration. Yet tidal marshes are vulnerable to submergence if the rate of sea-level rise exceeds the rate of accretion and if inland migration is limited by natural features or development. We studied how Piermont and Iona Island Marsh, two tidal marshes on the Hudson River, New York, would be affected by sea-level rise of 0.5m, 1m, and 1.5m by 2100. This study was based on the 2011-2012 Coastal New York LiDAR survey. Using GIS we mapped sea-level rise projections accounting for accretion rates and calculated the submerged area of the marsh. Based on the Hudson River National Estuarine Research Reserve Vegetation 2005 dataset, we studied how elevation zones based on vegetation distributions would change. To evaluate the potential for inland migration, we assessed land cover around each marsh using the National Land Cover Database 2011 Land Cover dataset and examined the slope beyond the marsh boundaries. With an accretion rate of 0.29cm/year and 0.5m of sea-level rise by 2100, Piermont Marsh would be mostly unchanged. With 1.5m of sea-level rise, 86% of Piermont Marsh would be flooded. For Iona Island Marsh with an accretion rate of 0.78cm/year, sea-level rise of 0.5m by 2100 would result in a 4% expansion while 1.5m sea-level rise would cause inundation of 17% of the marsh. The results indicate that Piermont and Iona Island Marsh may be able to survive rates of sea-level rise such as 0.5m by 2100 through vertical accretion. At rates of sea-level rise like 1.5m by 2100, vertical accretion cannot match sea-level rise, submerging parts of the marshes. High elevations and steep slopes limit Piermont and Iona Island Marsh's ability to migrate inland. Understanding the impacts of sea-level rise on Piermont and Iona Island Marsh allows for long-term planning and could motivate marsh conservation programs.

  9. Online Citizen Science with Clickworkers & MRO HiRISE E/PO

    NASA Astrophysics Data System (ADS)

    Gulick, V. C.; Deardorff, G.; Kanefsky, B.; HiRISE Science Team

    2010-12-01

    contributors. In HiRISE Clickworkers, over a dozen different geologic features have been identified on over 57,000 image tiles. A key objective of Clickworkers has been to break up work into manageable chunks so that people can contribute a few minutes at a time and their work all adds up. Our HiRISE Student Image Challenges (http://quest.nasa.gov), another online citizen science project, provide educators and students a virtual science team experience. Registered participants are given access to HiWeb, the HiRISE team’s image suggestion facility to submit their image suggestions. Once the images are returned, students browse, pan and zoom through their acquired images online and at full resolution before they are released to the public (http://marsoweb.nas.nasa.gov/HiRISE/quest/). Students fill out a report form summarizing the key results of their image analysis and with the help of a HiRISE team member write a caption for their image. The image is posted on the HiRISE image release website along with the caption, with credit to the suggesting class and school. HiWish, HiRISE’s public image suggestion website (see McEwen et al., this mtg.), provides a simpler interface for the public at large to submit HiRISE images. HiWish also provides a list of recently submitted image requests.

  10. Flooded Dark Matter and S level rise

    NASA Astrophysics Data System (ADS)

    Randall, Lisa; Scholtz, Jakub; Unwin, James

    2016-03-01

    Most dark matter models set the dark matter relic density by some interaction with Standard Model particles. Such models generally assume the existence of Standard Model particles early on, with the dark matter relic density a later consequence of those interactions. Perhaps a more compelling assumption is that dark matter is not part of the Standard Model sector and a population of dark matter too is generated at the end of inflation. This democratic assumption about initial conditions does not necessarily provide a natural value for the dark matter relic density, and furthermore superficially leads to too much entropy in the dark sector relative to ordinary matter. We address the latter issue by the late decay of heavy particles produced at early times, thereby associating the dark matter relic density with the lifetime of a long-lived state. This paper investigates what it would take for this scenario to be compatible with observations in what we call Flooded Dark Matter (FDM) models and discusses several interesting consequences. One is that dark matter can be very light and furthermore, light dark matter is in some sense the most natural scenario in FDM as it is compatible with larger couplings of the decaying particle. A related consequence is that the decay of the field with the smallest coupling and hence the longest lifetime dominates the entropy and possibly the matter content of the Universe, a principle we refer to as "Maximum Baroqueness". We also demonstrate that the dark sector should be colder than the ordinary sector, relaxing the most stringent free-streaming constraints on light dark matter candidates. We will discuss the potential implications for the core-cusp problem in a follow-up paper. The FDM framework will furthermore have interesting baryogenesis implications. One possibility is that dark matter is like the baryon asymmetry and both are simultaneously diluted by a late entropy dump. Alternatively, FDM is compatible with an elegant non

  11. Effects of sea level rise on deltaic coastal marshlands, Mississippi River deltaic plain

    SciTech Connect

    Ramsey, K.E.; Penland, S. ); Roberts, H.H.; Coleman, J.M. )

    1990-05-01

    Low-relief deltaic coastal plains commonly experience land loss because of the cumulative effects of natural and human-induced processes. Although it is difficult to separate the individual factors within the overall process, interplay between these factors can result in a rate of relative sea level rise greater than the natural rate of coastal-plain aggradation that causes land loss. Between 1956 and 1978, about 11,400 and 2,490 ha of marsh were lost in east Texas and Mississippi, respectively. Louisiana's loss was 18,755 ha. Relative sea level rise over the last 65 yr has averaged 0.23 cm/yr in the Gulf and as much as 1-1.5 cm/yr in the delta plain. The Environmental Protection Agency predicts the rate of sea level rise to increase over the next century. Rates of relative sea level rise for the Gulf of Mexico are expected to increase from 0.23-1.5 cm/yr to 0.6-3.7 cm/yr. The current rate of relative sea level rise and land loss in the subsiding Mississippi delta is a response that can be expected for many US coastal areas over the next century. With the predicted change, the Mississippi River delta complex will experience dramatically increased rates of land loss. Isles Dernieres will disappear by the year 2000, and Plaquemines and Terrebonne marshes will be gone between 2020 and 2080. Based on the lowest predicted sea level rise rate, by the year 2100, the delta plain could be reduced from 150.9 {times} 10{sup 3} ha to 29.8 x 10{sup 3} ha or to 4.9 {times} 10{sup 3} ha if calculations are based on the highest rate.

  12. The contribution of sea-level rise to flooding in large river catchments

    NASA Astrophysics Data System (ADS)

    Thiele-Eich, I.; Hopson, T. M.; Gilleland, E.; Lamarque, J.; Hu, A.; Simmer, C.

    2012-12-01

    Climate change is expected to both impact sea level rise as well as flooding. Our study focuses on the combined effect of climate change on upper catchment precipitation as well as on sea-level rise at the river mouths and the impact this will have on river flooding both at the coast and further upstream. We concentrate on the eight catchments of the Amazonas, Congo, Orinoco, Ganges/Brahmaputra/Meghna, Mississippi, St. Lawrence, Danube and Niger rivers. To assess the impact of climate change, upper catchment precipitation as well as monthly mean thermosteric sea-level rise at the river mouth outflow are taken from the four CCSM4 1° 20th Century ensemble members as well as from six CCSM4 1° ensemble members for the RCP scenarios RCP8.5, 6.0, 4.5 and 2.6. Continuous daily time series for average catchment precipitation and discharge are available for each of the catchments. To arrive at a future discharge time series, we used these observations to develop a simple statistical hydrological model which can be applied to the modelled future upper catchment precipitation values. The analysis of this surrogate discharge time series alone already yields significant changes in flood return levels as well as flood duration. Using the geometry of the river channel, the backwater effect of sea-level rise is incorporated in our analysis of both flood frequencies and magnitudes by calculating the effective additional discharge due to the increase in water level at the river mouth outflow, as well as its tapering impact upstream. By combining these effects, our results focus on the merged impact of changes in extreme precipitation with increases in river height due to sea-level rise at the river mouths. Judging from our preliminary results, the increase in effective discharge due to sea-level rise cannot be neglected when discussing late 21st century flooding in the respective river basins. In particular, we find that especially in countries with low elevation gradient, flood

  13. Rising CO2 concentrations affect settlement behaviour of larval damselfishes

    NASA Astrophysics Data System (ADS)

    Devine, B. M.; Munday, P. L.; Jones, G. P.

    2012-03-01

    Reef fish larvae actively select preferred benthic habitat, relying on olfactory, visual and acoustic cues to discriminate between microhabitats at settlement. Recent studies show exposure to elevated carbon dioxide (CO2) impairs olfactory cue recognition in larval reef fishes. However, whether this alters the behaviour of settling fish or disrupts habitat selection is unknown. Here, the effect of elevated CO2 on larval behaviour and habitat selection at settlement was tested in three species of damselfishes (family Pomacentridae) that differ in their pattern of habitat use: Pomacentrus amboinensis (a habitat generalist), Pomacentrus chrysurus (a rubble specialist) and Pomacentrus moluccensis (a live coral specialist). Settlement-stage larvae were exposed to current-day CO2 levels or CO2 concentrations that could occur by 2100 (700 and 850 ppm) based on IPCC emission scenarios. First, pair-wise choice tests were performed using a two-channel flume chamber to test olfactory discrimination between hard coral, soft coral and coral rubble habitats. The habitat selected by settling fish was then compared among treatments using a multi-choice settlement experiment conducted overnight. Finally, settlement timing between treatments was compared across two lunar cycles for one of the species, P. chrysurus. Exposure to elevated CO2 disrupted the ability of larvae to discriminate between habitat odours in olfactory trials. However, this had no effect on the habitats selected at settlement when all sensory cues were available. The timing of settlement was dramatically altered by CO2 exposure, with control fish exhibiting peak settlement around the new moon, whereas fish exposed to 850 ppm CO2 displaying highest settlement rates around the full moon. These results suggest larvae can rely on other sensory information, such as visual cues, to compensate for impaired olfactory ability when selecting settlement habitat at small spatial scales. However, rising CO2 could cause larvae

  14. Rise and Fall of the Regional Jet

    NASA Astrophysics Data System (ADS)

    Sedghi, Brian K.

    Over the course of more than two decades, the aviation industry has seen the introduction of the regional jet and witnessed the many operational benefits that it has presented airlines. Its future, however, hangs in the balance as record fuel prices and other economic and operational factors seem to threaten its existence in the capacity that it holds today. This research paper attempts to explore some of the factors that have both helped the regional jet find its place within the industry and also factors that have been linked to the threat against its future use. One of the two factors discussed in this paper will be the effect of fuel cost on the operational costs between a time that regional jets were considered viable and present day. The other will be the effect on market capacity that has been presented by the regional jet since its introduction more than two decades ago. In addition to these factors, other reasons for the potential discontinuation of the regional jet will be discussed including the effects of pilot unions on airline operations.

  15. Behavioural addiction-A rising tide?

    PubMed

    Chamberlain, Samuel R; Lochner, Christine; Stein, Dan J; Goudriaan, Anna E; van Holst, Ruth Janke; Zohar, Joseph; Grant, Jon E

    2016-05-01

    The term 'addiction' was traditionally used in relation to centrally active substances, such as cocaine, alcohol, or nicotine. Addiction is not a unitary construct but rather incorporates a number of features, such as repetitive engagement in behaviours that are rewarding (at least initially), loss of control (spiralling engagement over time), persistence despite untoward functional consequences, and physical dependence (evidenced by withdrawal symptoms when intake of the substance diminishes). It has been suggested that certain psychiatric disorders characterized by maladaptive, repetitive behaviours share parallels with substance addiction and therefore represent 'behavioural addictions'. This perspective has influenced the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which now has a category 'Substance Related and Addictive Disorders', including gambling disorder. Could other disorders characterised by repetitive behaviours, besides gambling disorder, also be considered 'addictions'? Potential examples include kleptomania, compulsive sexual behaviour, 'Internet addiction', trichotillomania (hair pulling disorder), and skin-picking disorder. This paper seeks to define what is meant by 'behavioural addiction', and critically considers the evidence for and against this conceptualisation in respect of the above conditions, from perspectives of aetiology, phenomenology, co-morbidity, neurobiology, and treatment. Research in this area has important implications for future diagnostic classification systems, neurobiological models, and novel treatment directions. PMID:26585600

  16. Numerical modeling of outer rise deformation in the Tonga subduction system: Coupling between outer rise deformation, slab weakening and plate velocities

    NASA Astrophysics Data System (ADS)

    Naliboff, J. B.; Billen, M. I.; Gerya, T.; Saunders, J. K.

    2012-12-01

    During subduction, bending and flexure of oceanic lithosphere generates a topographic bulge seaward of the trench known as the outer rise, which commonly exhibits extensional deformation attributed to slab pull forces and bending stresses. The resulting brittle and viscous deformation may play a significant role in long-term geodynamic processes by limiting the ability of subducted oceanic lithosphere to act as a stress guide driving surface plate motions through slab pull. Recent numerical studies provide varying estimates of slab pull's contribution to surface plate motions [e.g., van Summeren et al. 2012, Ghosh & Holt 2012], while observational constraints suggest old oceanic lithosphere may weaken by 3-4 orders of magnitude as it bends and descends beneath the overriding plate [Arredondo & Billen, 2012]. Preliminary numerical models of outer rise deformation during oceanic-continental convergence (40 Myr oceanic lithosphere) exhibit 10x-150x viscous weakening in the upper plate near the trench, with time-dependent variations related to both changes in slab depth and downgoing-overriding plate coupling (Naliboff et al., in prep). In order to more closely examine the relationship between outer rise deformation, geophysical observations and plate velocities, we consider 2D subduction models of the Tonga subduction system where flow will be strictly driven by upper mantle slab buoyancy as defined by the Slab1.0 model [Hayes et al. 2012]. The resulting subducting plate deformation patterns are compared to observations of outer rise faulting, elastic thickness measurements and outer rise seismicity. While keeping buoyancy forces fixed, we will examine the role of brittle rheology, hydration and downgoing-overriding plate coupling in patterns of subducting plate deformation. These results will provide improved physical understanding of the relationship between slab pull, plate velocities and downgoing plate weakening, and a basis for future work examining the role of

  17. The Import of the Cortisol Rise in Child Care Differs as a Function of Behavioral Inhibition

    ERIC Educational Resources Information Center

    Gunnar, Megan R.; Kryzer, Erin; Van Ryzin, Mark J.; Phillips, Deborah A.

    2011-01-01

    Children of ages 3 to 4.5 years (N = 107; 45 boys, 62 girls) were studied twice, 6 months apart, to examine whether the cortisol rise in child care at Time 1 (T1) was associated with (a) changes in anxious, vigilant behavior from T1 to Time 2 (T2) and (b) higher internalizing symptoms at T2. Controlling for measures of home environment and child…

  18. The rise of novelty in ecosystems.

    PubMed

    Radeloff, Volker C; Williams, John W; Bateman, Brooke L; Burke, Kevin D; Carter, Sarah K; Childress, Evan S; Cromwell, Kara J; Gratton, Claudio; Hasley, Andrew O; Kraemer, Benjamin M; Latzka, Alexander W; Marin-Spiotta, Erika; Meine, Curt D; Munoz, Samuel E; Neeson, Thomas M; Pidgeon, Anna M; Rissman, Adena R; Rivera, Ricardo J; Szymanski, Laura M; Usinowicz, Jacob

    2015-12-01

    Rapid and ongoing change creates novelty in ecosystems everywhere, both when comparing contemporary systems to their historical baselines, and predicted future systems to the present. However, the level of novelty varies greatly among places. Here we propose a formal and quantifiable definition of abiotic and biotic novelty in ecosystems, map abiotic novelty globally, and discuss the implications of novelty for the science of ecology and for biodiversity conservation. We define novelty as the degree of dissimilarity of a system, measured in one or more dimensions relative to a reference baseline, usually defined as either the present or a time window in the past. In this conceptualization, novelty varies in degree, it is multidimensional, can be measured, and requires a temporal and spatial reference. This definition moves beyond prior categorical definitions of novel ecosystems, and does not include human agency, self-perpetuation, or irreversibility as criteria. Our global assessment of novelty was based on abiotic factors (temperature, precipitation, and nitrogen deposition) plus human population, and shows that there are already large areas with high novelty today relative to the early 20th century, and that there will even be more such areas by 2050. Interestingly, the places that are most novel are often not the places where absolute changes are largest; highlighting that novelty is inherently different from change. For the ecological sciences, highly novel ecosystems present new opportunities to test ecological theories, but also challenge the predictive ability of ecological models and their validation. For biodiversity conservation, increasing novelty presents some opportunities, but largely challenges. Conservation action is necessary along the entire continuum of novelty, by redoubling efforts to protect areas where novelty is low, identifying conservation opportunities where novelty is high, developing flexible yet strong regulations and policies, and

  19. Coastal Impact Underestimated From Rapid Sea Level Rise

    NASA Astrophysics Data System (ADS)

    Anderson, John; Milliken, Kristy; Wallace, Davin; Rodriguez, Antonio; Simms, Alexander

    2010-06-01

    A primary effect of global warming is accelerated sea level rise, which will eventually drown low-lying coastal areas, including some of the world's most populated cities. Predictions from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) suggest that sea level may rise by as much as 0.6 meter by 2100 [Solomon et al., 2007]. However, uncertainty remains about how projected melting of the Greenland and Antarctic ice sheets will contribute to sea level rise. Further, considerable variability is introduced to these calculations due to coastal subsidence, especially along the northern Gulf of Mexico (see http://tidesandcurrents.noaa.gov/sltrends/sltrends.shtml).

  20. Oblique stepwise rise and growth of the Tibet plateau.

    PubMed

    Tapponnier, P; Zhiqin, X; Roger, F; Meyer, B; Arnaud, N; Wittlinger, G; Jingsui, Y

    2001-11-23

    Two end member models of how the high elevations in Tibet formed are (i) continuous thickening and widespread viscous flow of the crust and mantle of the entire plateau and (ii) time-dependent, localized shear between coherent lithospheric blocks. Recent studies of Cenozoic deformation, magmatism, and seismic structure lend support to the latter. Since India collided with Asia approximately 55 million years ago, the rise of the high Tibetan plateau likely occurred in three main steps, by successive growth and uplift of 300- to 500-kilometer-wide crustal thrust-wedges. The crust thickened, while the mantle, decoupled beneath gently dipping shear zones, did not. Sediment infilling, bathtub-like, of dammed intermontane basins formed flat high plains at each step. The existence of magmatic belts younging northward implies that slabs of Asian mantle subducted one after another under ranges north of the Himalayas. Subduction was oblique and accompanied by extrusion along the left lateral strike-slip faults that slice Tibet's east side. These mechanisms, akin to plate tectonics hidden by thickening crust, with slip-partitioning, account for the dominant growth of the Tibet Plateau toward the east and northeast. PMID:11721044

  1. Rise of Racetrack Memory! Domain Wall Spin-Orbitronics

    NASA Astrophysics Data System (ADS)

    Parkin, Stuart

    Memory-storage devices based on the current controlled motion of a series of domain walls (DWs) in magnetic racetracks promise performance and reliability beyond that of conventional magnetic disk drives and solid state storage devices (1). Racetracks that are formed from atomically thin, perpendicularly magnetized nano-wires, interfaced with adjacent metal layers with high spin-orbit coupling, give rise to domain walls that exhibit a chiral Néel structure (2). These DWs can be moved very efficiently with current via chiral spin-orbit torques (2,3). Record-breaking current-induced DW speeds exceeding 1,000 m/sec are found in synthetic antiferromagnetic structures (3) in which the net magnetization of the DWs is tuned to almost zero, making them ``invisible''. Based on these recent discoveries, Racetrack Memory devices have the potential to operate on picosecond timescales and at densities more than 100 times greater than other memory technologies. (1) S.S.P. Parkin et al., Science 320, 5873 (2008); S.S.P. Parkin and S.-H. Yang, Nat. Nano. 10, 195 (2015). (2) K.-S. Ryu metal. Nat. Nano. 8, 527 (2013). (3) S.-H. Yang, K.-S. Ryu and S.S.P. Parkin, Nat. Nano. 10, 221 (2015). (4). S.S.P. Parkin, Phys. Rev. Lett. 67, 3598 (1991).

  2. Measuring sand flux on Mars using HiRISE Images

    NASA Astrophysics Data System (ADS)

    Ayoub, F.; Bridges, N. T.; Avouac, J.; Leprince, S.; Lucas, A.; Mattson, S.

    2011-12-01

    As wind is the major agent of sediment transport on Mars, a quantitative estimate of aeolian processes is therefore essential to assess recent geological evolution and current climate. We adapted the Co-registration of Optically Sensed Image and Correlation (COSI-Corr) toolbox to the MRO HiRISE imager specifications to produce a dense map of the ripples migration on the surface of the Martian dunes on the Nili Patera area. The ripple migration rate, along with an estimate of the ripple height, were used to derive the sand flux, a key quantity that controls the style and rate of landscape evolution. Using the dunes shape, size, and height, which were extracted from a DEM of the dune field, we show that the dunes are near steady state, and we observe that dune migration rate varies inversely with size and position within the dune field. The time scale associated with the formation and evolution of the Nili Patera dune field, estimated from comparing the sand volume with the sand flux and the dunes migration rates with the length scale of the dune field, is on the order of 10s to 100s of thousands Earth years. However, sand fluxes at the dune crests are 0.7 - 4.8 m3 m-1 per Earth year, which is comparable to that of dunes in Victoria Valley, Antarctica. This implies that rates of landscape modification from aeolian abrasion on Mars may be comparable to that on Earth.

  3. Ventilation and infiltration in high-rise apartment buildings

    SciTech Connect

    Diamond, R.C.; Feustel, H.E.; Dickerhoff, D.J.

    1996-03-01

    Air flow, air leakage measurements and numerical simulations were made on a 13-story apartment building to characterize the ventilation rates for the individual apartments. Parametric simulations were performed for specific conditions, e.g., height, orientation, outside temperature and wind speed. Our analysis of the air flow simulations suggest that the ventilation to the individual units varies considerably. With the mechanical ventilation system disabled and no wind, units at the lower level of the building have adequate ventilation only on days with high temperature differences, while units on higher floors have no ventilation at all. Units facing the windward side will be over-ventilated when the building experiences wind directions between west and north. At the same time, leeward apartments did not experience any fresh air-because, in these cases, air flows enter the apartments from the corridor and exit through the exhaust shafts and the cracks in the facade. Even with the mechanical ventilation system operating, we found wide variation in the air flows to the individual apartments. In addition to the specific case presented here, these findings have more general implications for energy retrofits and health and comfort of occupants in high-rise apartment buildings.

  4. Scattering by infinitely rising one-dimensional potentials

    NASA Astrophysics Data System (ADS)

    Ferreira, E. M.; Sesma, J.

    2015-12-01

    Infinitely rising one-dimensional potentials constitute impenetrable barriers which reflect totally any incident wave. However, the scattering by such kind of potentials is not structureless: resonances may occur for certain values of the energy. Here we consider the problem of scattering by the members of a family of potentials Va(x) = - sgn(x) | x | a, where sgn represents the sign function and a is a positive rational number. The scattering function and the phase shifts are obtained from global solutions of the Schrödinger equation. For the determination of the Gamow states, associated to resonances, we exploit their close relation with the eigenvalues of the PT-symmetric Hamiltonians with potentials VaPT(x) = - i sgn(x) | x | a. Calculation of the time delay in the scattering at real energies is used to characterize the resonances. As an additional result, the breakdown of the PT-symmetry of the family of potentials VaPT for a < 3 may be conjectured.

  5. A Current Source Method For t(sub q) Measurement of Fast Switching Thyristors

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    2006-01-01

    A current source driven circuit has been constructed to measure the turn-off time (t(sub q)) of fast-switching SiC thyristors. This circuit operates from a single power supply and a dual channel pulse generator to provide adjustment of forward current, magnitude and duration of reverse applied voltage, and rate of rise of reapplied forward voltage. Values of t(sub q) down to 100 ns can be resolved.

  6. Nonlinear diffusion waves in high magnetic fields

    NASA Astrophysics Data System (ADS)

    Oreshkin, V. I.; Chaikovsky, S. A.; Labetskaya, N. A.; Datsko, I. M.; Rybka, D. V.; Ratakhin, N. A.; Khishchenko, K. V.

    2015-11-01

    The nonlinear diffusion of a magnetic field and the large-scale instabilities arising upon an electrical explosion of conductors in a superstrong (2-3 MG) magnetic field were investigated experimentally on the MIG high-current generator (up to 2.5 peak current, 100 ns current rise time). It was observed that in the nonlinear stage of the process, the wavelength of thermal instabilities (striations) increased with a rate of 1.5-3 km/s.

  7. Chopper system for time resolved experiments with synchrotron radiation

    SciTech Connect

    Cammarata, Marco; Eybert, Laurent; Ewald, Friederike; Reichenbach, Wolfgang; Wulff, Michael; Anfinrud, Philip; Schotte, Friedrich; Plech, Anton; Kong, Qingyu; Lorenc, Maciej; Lindenau, Bernd; Raebiger, Juergen; Polachowski, Stephan

    2009-01-15

    A chopper system for time resolved pump-probe experiments with x-ray beams from a synchrotron is described. The system has three parts: a water-cooled heatload chopper, a high-speed chopper, and a millisecond shutter. The chopper system, which is installed in beamline ID09B at the European Synchrotron Radiation Facility, provides short x-ray pulses for pump-probe experiments with ultrafast lasers. The chopper system can produce x-ray pulses as short as 200 ns in a continuous beam and repeat at frequencies from 0 to 3 kHz. For bunch filling patterns of the synchrotron with pulse separations greater than 100 ns, the high-speed chopper can isolate single 100 ps x-ray pulses that are used for the highest time resolution. A new rotor in the high-speed chopper is presented with a single pulse (100 ps) and long pulse (10 {mu}s) option. In white beam experiments, the heatload of the (noncooled) high-speed chopper is lowered by a heatload chopper, which absorbs 95% of the incoming power without affecting the pulses selected by the high speed chopper.

  8. Theoretical analysis for meniscus rise of a liquid contained between a flexible film and a solid wall

    NASA Astrophysics Data System (ADS)

    Di, Yana; Xu, Xianmin; Doi, Masao

    2016-02-01

    We study the dynamics of the meniscus rise of a liquid contained in a narrow gap between a flexible film and a solid wall. We show that the meniscus rises indefinitely expelling liquid from the gap region, and that the height of the rising front h(t) increases with time as h(t)\\propto t2/7 , while the gap distance e(t) decreases as e(t) \\propto t-3/7 . These results are consistent with the experiments of Cambau et al. (EPL, 96 (2011) 24001).

  9. Mars' Active Surface: Observing Changes with Orthorectified HiRISE Images

    NASA Astrophysics Data System (ADS)

    Mattson, S.; McEwen, A. S.; Ojha, L.; Bridges, N. T.; Kirk, R. L.; Howington-Kraus, E.; Mogk, N.

    2012-12-01

    Active processes on Mars have been observed and documented with high resolution images from orbit. The HiRISE camera, operating on MRO since 2006, acquires images of the surface of Mars at up to 25 cm pixel scale, and has stereo capability. The use of HiRISE stereo images to produce digital terrain models (DTMs) allows for orthorectification of the stereo pair and other images targeted over the same area. HiRISE DTMs typically have 1 or 2 m horizontal resolution with vertical precision on the order of 10's of cm. DTM production with HiRISE requires that the source stereo pair has similar lighting and minimal surface differences. However, there is no similar requirement for orthorectifying other images taken of the same area. Changes on the surface can then be measured accurately in the orthoimages as topographic distortions have been minimized. Time sequences of surface changes can be constructed from a series of orthoimages, providing essential data for understanding their rate and magnitude. Some of the current areas of study using HiRISE DTMs and orthoimages include recurring slope lineae (RSL) (McEwen et al., Science 333, 740, 2011), dune and ripple migration (Bridges et al., Nature 485, 339, 2012), seasonal frost changes, and gully activity. In some cases, DTMs from before and after significant surface movement can be compared to measure volumetric changes. The demand for HiRISE DTMs and orthoimages has led to advances in techniques for their production and analysis. Improved image processing and terrain editing tools result in better DTMs and orthoimages, as well as minimize the time required to produce them. We present here ongoing work to refine these techniques and develop new methods for generating orthoimage sequences, including orthorectification of the HiRISE 3-band color strip. Results are illustrated using series of orthoimages over dunes, RSL sites and other areas of Martian surface activity. HiRISE DTMs and orthoimages are released to the Planetary

  10. Book Review: Venus Rising: Cultural Astronomy in Southern Africa

    NASA Astrophysics Data System (ADS)

    Snedegar, K.

    2014-10-01

    Book review: Dr Peter G. Alcock's important new publication, Venus Rising: South African Astronomical Beliefs, Customs and Observations. See also articles by Alcock, P.G. and Labuscagne, L. in the next issue.

  11. Most Americans Support Rise in Legal Smoking Age

    MedlinePlus

    ... 159148.html Most Americans Support Rise in Legal Smoking Age Survey finds wide support in all regions ... survey finds most Americans support pushing the legal smoking age even higher. Across all regions of the ...

  12. U.S. Maternal Death Rate Is Rising

    MedlinePlus

    ... medlineplus.gov/news/fullstory_160299.html U.S. Maternal Death Rate Is Rising Up 27 percent since 2000 ... study. Between 2000 and 2014, the nation's maternal death rate rose by almost 27 percent, researchers found. ...

  13. Flat as a Pancake? Exploring Rising in Baked Goods.

    ERIC Educational Resources Information Center

    Journal of Chemical Education, 2000

    2000-01-01

    Presents an activity that can be used for acid-base chemistry, everyday chemistry, or food chemistry. Investigates the rising in baked goods. Includes both instructor information and student activity sheets. (YDS)

  14. 9. REYNOLDS AVENUE BRIDGE, ROAD VIEW. NOTE THE GRADE RISES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. REYNOLDS AVENUE BRIDGE, ROAD VIEW. NOTE THE GRADE RISES OVER TRACKS DUE TO INCREASED LOCOMOTIVE SIZES. SEVERAL MONUMENTS WERE MOVED TO FACILITATE THIS. VIEW NE. - Gettysburg National Military Park Tour Roads, Gettysburg, Adams County, PA

  15. Shaping of the continental rise by deep geostrophic contour currents.

    PubMed

    Heezen, B C; Hollister, C D; Ruddiman, W F

    1966-04-22

    Geostrophic contour-following bottom currents involved in the deep thermohaline circulation of the world ocean appear to be the principal agents which control the shape of the continental rise and other sediment bodies. PMID:17815077

  16. Abortion Rates Rising in Zika-Affected Countries, Study Shows

    MedlinePlus

    ... news/fullstory_159500.html Abortion Rates Rising in Zika-Affected Countries, Study Shows Brazil, Ecuador have seen ... News) -- Fears over birth defects from mosquito-borne Zika may be driving up abortion rates in Latin ...

  17. Abortion Rates Rising in Zika-Affected Countries, Study Shows

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_159500.html Abortion Rates Rising in Zika-Affected Countries, Study Shows ... from mosquito-borne Zika may be driving up abortion rates in Latin American countries affected by the ...

  18. View facing south, near Structure 515, of Transmission Line rising ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View facing south, near Structure 51-5, of Transmission Line rising out of Marias River Valley - Havre Rainbow Transmission Line, Havre City to Great Falls vicinity, Montana, Great Falls, Cascade County, MT

  19. The rise of the bank infomediary in health care.

    PubMed

    Casillas, John

    2008-08-01

    Banks are evolving in four key areas that collectively comprise the rise of a "bank infomediary": Efficient administrative processing; Medical Internet; Health information broker; Community care platform. PMID:18709871

  20. Dynamics of Bubbles Rising in Finite and Infinite Media

    SciTech Connect

    C.C. Maneri; P.F. Vassallo

    2000-10-27

    The dynamic behavior of single bubbles rising in quiescent liquid Suva (R134a) in a duct has been examined through the use of a high speed video system. Size, shape and velocity measurements obtained with the video system reveal a wide variety of characteristics for the bubbles as they rise in both finite and infinite media. This data, coupled with previously published data for other working fluids, has been used to assess and extend a rise velocity model given by Fan and Tsuchiya. As a result of this assessment, a new rise velocity model has been developed which maintains the physically consistent characteristics of the surface tension in the distorted bubbly regime. In addition, the model is unique in that it covers the entire range of bubble sizes contained in the spherical, distorted and planar slug regimes.

  1. Sea-Level Projections from the SeaRISE Initiative

    NASA Technical Reports Server (NTRS)

    Nowicki, Sophie; Bindschadler, Robert

    2011-01-01

    SeaRISE (Sea-level Response to Ice Sheet Evolution) is a community organized modeling effort, whose goal is to inform the fifth IPCC of the potential sea-level contribution from the Greenland and Antarctic ice sheets in the 21st and 22nd century. SeaRISE seeks to determine the most likely ice sheet response to imposed climatic forcing by initializing an ensemble of models with common datasets and applying the same forcing to each model. Sensitivity experiments were designed to quantify the sea-level rise associated with a change in: 1) surface mass balance, 2) basal lubrication, and 3) ocean induced basal melt. The range of responses, resulting from the multi-model approach, is interpreted as a proxy of uncertainty in our sea-level projections. http://websrv.cs .umt.edu/isis/index.php/SeaRISE_Assessment.

  2. The East Pacific Rise: An Active Not Passive Spreading System

    NASA Astrophysics Data System (ADS)

    Rowley, D. B.; Rowan, C. J.; Forte, A. M.; Moucha, R.; Grand, S. P.; Simmons, N. A.

    2011-12-01

    Traditional plate tectonic interpretations of mid-oceanic ridges regard spreading as an entirely passive phenomenon. From this one would assume that the oceanic ridges will move over the mantle in response to the geodynamics of the diverging plates, and do not remain fixed spatially over any protracted period of time. An analysis of the kinematics of ridge motions in the Indo-Atlantic hotspot frame of reference since 83 Ma generally supports this view, with the notable exception of the East Pacific Rise (EPR). The Pacific-Nazca/Farallon segment of the EPR north of Easter Island (27°S) is oriented essentially N-S, and has produced more than 9500km of E-W spreading in the past 80 Ma, making it the dominant ridge in the world's plate system over this interval of time. Yet despite the large amount of E-W divergence, the spreading center has maintained its longitudinal position to within <±250 km of the current ridge axis. Global mantle convective flow modeling indicates that the EPR, unlike any other extensive segment of the mid-oceanic ridge system, is underlain by an active upwelling system extending from the core-mantle boundary to the surface. We suggest that the lack of E-W motion of the EPR apparent from the kinematics is a consequence of these mantle dynamics; this ridge is thus not behaving as a passive plate boundary, but is actively and directly linked to, and controlled by, whole mantle upwelling. This observation overturns the notion that ridges are always entirely passive features of the plate system. Subduction of the northern EPR beneath western North America has thus resulted in the overriding of an active upwelling system that has contributed significantly to the evolution of Basin and Range kinematics and superimposed dynamics, including significant contributions from dynamic topography.

  3. Field Monitoring of Column Shortenings in a High-Rise Building during Construction

    PubMed Central

    Choi, Se Woon; Kim, Yousok; Kim, Jong Moon; Park, Hyo Seon

    2013-01-01

    The automatic monitoring of shortenings of vertical members in high-rise buildings under construction is a challenging issue in the high-rise building construction field. In this study, a practical system for monitoring column shortening in a high-rise building under construction is presented. The proposed monitoring system comprises the following components: (1) a wireless sensing system and (2) the corresponding monitoring software. The wireless sensing system comprises the sensors and energy-efficient wireless sensing units (sensor nodes, master nodes, and repeater nodes), which automate the processes for measuring the strains of vertical members and transmitting the measured data to the remote server. The monitoring software enables construction administrators to monitor real-time data collected by the server via an Internet connection. The proposed monitoring system is applied to actual 66-floor and 72-floor high-rise buildings under construction. The system enables automatic and real-time measurements of the shortening of vertical members, which can result in more precise construction. PMID:24284768

  4. Adapting to Rising Sea Level: A Florida Perspective

    NASA Astrophysics Data System (ADS)

    Parkinson, Randall W.

    2009-07-01

    Global climate change and concomitant rising sea level will have a profound impact on Florida's coastal and marine systems. Sea-level rise will increase erosion of beaches, cause saltwater intrusion into water supplies, inundate coastal marshes and other important habitats, and make coastal property more vulnerable to erosion and flooding. Yet most coastal areas are currently managed under the premise that sea-level rise is not significant and the shorelines are static or can be fixed in place by engineering structures. The new reality of sea-level rise and extreme weather due to climate change requires a new style of planning and management to protect resources and reduce risk to humans. Scientists must: (1) assess existing coastal vulnerability to address short term management issues and (2) model future landscape change and develop sustainable plans to address long term planning and management issues. Furthermore, this information must be effectively transferred to planners, managers, and elected officials to ensure their decisions are based upon the best available information. While there is still some uncertainty regarding the details of rising sea level and climate change, development decisions are being made today which commit public and private investment in real estate and associated infrastructure. With a design life of 30 yrs to 75 yrs or more, many of these investments are on a collision course with rising sea level and the resulting impacts will be significant. In the near term, the utilization of engineering structures may be required, but these are not sustainable and must ultimately yield to "managed withdrawal" programs if higher sea-level elevations or rates of rise are forthcoming. As an initial step towards successful adaptation, coastal management and planning documents (i.e., comprehensive plans) must be revised to include reference to climate change and rising sea-level.

  5. Modeling the Rise of Fibril Magnetic Fields in Fully Convective Stars

    NASA Astrophysics Data System (ADS)

    Weber, Maria A.; Browning, Matthew K.

    2016-08-01

    Many fully convective stars exhibit a wide variety of surface magnetism, including starspots and chromospheric activity. The manner by which bundles of magnetic field traverse portions of the convection zone to emerge at the stellar surface is not especially well understood. In the solar context, some insight into this process has been gleaned by regarding the magnetism as consisting partly of idealized thin flux tubes (TFTs). Here we present the results of a large set of TFT simulations in a rotating spherical domain of convective flows representative of a 0.3 M ⊙ main-sequence star. This is the first study to investigate how individual flux tubes in such a star might rise under the combined influence of buoyancy, convection, and differential rotation. A time-dependent hydrodynamic convective flow field, taken from separate 3D simulations calculated with the anelastic equations, impacts the flux tube as it rises. Convective motions modulate the shape of the initially buoyant flux ring, promoting localized rising loops. Flux tubes in fully convective stars have a tendency to rise nearly parallel to the rotation axis. However, the presence of strong differential rotation allows some initially low-latitude flux tubes of moderate strength to develop rising loops that emerge in the near-equatorial region. Magnetic pumping suppresses the global rise of the flux tube most efficiently in the deeper interior and at lower latitudes. The results of these simulations aim to provide a link between dynamo-generated magnetic fields, fluid motions, and observations of starspots for fully convective stars.

  6. Rising motion of a bubble layer near a vertical wall

    NASA Astrophysics Data System (ADS)

    Dabiri, Sadegh; Bhuvankar, Pramod

    2015-11-01

    Bubbly flows in vertical pipes and channels form a wall-peak distribution of bubbles under certain conditions. The dynamics of the bubbles near the wall is different than in an unbounded liquid. Here we report the rising motion of bubbles in a liquid near a vertical wall. In a simulation of a bubbly flow in a periodic domain with a vertical wall on one side, an average pressure gradient is applied to the domain that balances the weight of the liquid phase. The upward flow is created by the rising motion of the bubbles. The bubbles are kept near the wall by the lateral lift force acting on them as a result of rising in a shear flow which is in turn generated by rising motion of bubbles. The rise velocity of the bubbles on the wall and the average rise velocity of the liquid depend on three dimensionless parameters, Archimedes number, Eotvos number, and the average volume fraction of bubbles near the wall. In the limit of small Eo, bubbles are nearly spherical and the dependency on Eo becomes negligible. In this limit, the scaling of the liquid Reynolds number with Archimedes number and the void fraction is presented.

  7. [Occasional temperature rises following streptokinase infusions. Animal experiment findings].

    PubMed

    Ronneberger, V H

    1975-04-01

    The mechanism of the rises in temperature which have been observed in the clinic during long-term infusions with streptokinase (SK, Streptase-R) was clarified in animal experiments. After pyrogenic substances had been excluded as the possible cause of this side-effect and no rises in temperature in normal rabbits during SK infusions had been observed, this effect was imitated in animals immunised with SK. A clear fever reaction could be induced. Control experiments with rabbits which had been sensitised with human albumin, confirmed the hypothesis that the rise in body temperature is caused by anaphylactic fever. Neutralisation of the SK antibodies prevents the rise in temperature. Injecting high-titre gamma-globulin solution from animals immunised with SK, cannot suppress the fever reaction; this also applies to antihistamine (pheniramine-p-aminosalicylate) and hydrocortisone acetate therapy. During the lysis of thrombi induced by thrombin in the ear veins of rabbits, a rise in body temperature is obtained during the SK infusion and during treatment with a thrombolytic gel. Untreated control animals also showed the same rise in temperature during thrombolysis. The possibility that the fever reaction is set off by components of the dissolving thrombus is also discussed. PMID:1174079

  8. Short Lived Climate Pollutants cause a Long Lived Effect on Sea-level Rise: Analyzing climate metrics for sea-level rise

    NASA Astrophysics Data System (ADS)

    Sterner, E.; Johansson, D. J.

    2013-12-01

    Climate change depends on the increase of several different atmospheric pollutants. While long term global warming will be determined mainly by carbon dioxide, warming in the next few decades will depend to a large extent on short lived climate pollutants (SLCP). Reducing emissions of SLCPs could contribute to lower the global mean surface temperature by 0.5 °C already by 2050 (Shindell et al. 2012). Furthermore, the warming effect of one of the most potent SLCPs, black carbon (BC), may have been underestimated in the past. Bond et al. (2013) presents a new best estimate of the total BC radiative forcing (RF) of 1.1 W/m2 (90 % uncertainty bounds of 0.17 to 2.1 W/m2) since the beginning of the industrial era. BC is however never emitted alone and cooling aerosols from the same sources offset a majority of this RF. In the wake of calls for mitigation of SLCPs it is important to study other aspects of the climate effect of SLCPs. One key impact of climate change is sea-level rise (SLR). In a recent study, the effect of SLCP mitigation scenarios on SLR is examined. Hu et al (2013) find a substantial effect on SLR from mitigating SLCPs sharply, reducing SLR by 22-42% by 2100. We choose a different approach focusing on emission pulses and analyse a metric based on sea level rise so as to further enlighten the SLR consequences of SLCPs. We want in particular to understand the time dynamics of SLR impacts caused by SLCPs compared to other greenhouse gases. The most commonly used physical based metrics are GWP and GTP. We propose and evaluate an additional metric: The global sea-level rise potential (GSP). The GSP is defined as the sea level rise after a time horizon caused by an emissions pulse of a forcer to the sea level rise after a time horizon caused by an emissions pulse of a CO2. GSP is evaluated and compared to GWP and GTP using a set of climate forcers chosen to cover the whole scale of atmospheric perturbation life times (BC, CH4, N2O, CO2 and SF6). The study

  9. Sea-level rise risks to coastal cities: what are the limits to adaptation?

    NASA Astrophysics Data System (ADS)

    Nicholls, R. J.; Reeder, T.; Brown, S.; Haigh, I. D.

    2015-12-01

    Understanding the consequence of sea-level rise for coastal cities has long lead times and huge political implications. Civilisation has emerged and developed during a period of several thousand years during which in geological terms sea level has been unusually stable. We have now moved out of this period raising important challenges for the future. In 2005 there were 136 coastal cities with a population exceeding one million people and a collective population of 400 million people. All these cities are threatened by flooding from the sea to varying degrees and these risks are increasing due to growing exposure (people and assets), rising sea levels due to climate change, and in some cities, significant coastal subsidence due to human agency (drainage and groundwater withdrawals from susceptible soils). City abandonment due to sea-level rise is widely discussed in the media, but most of the discussion is speculative. The limits to adaptation and abandonment of cities are not predictable in a formal sense - while the rise in mean sea level raises the likelihood of a catastrophic flood, extreme events are what cause damage and trigger a response, be it abandonment or a defence upgrade. Several types of potential adaptation limits can be recognised: (1) physical/engineering limits; (2) economic/financial limits; and (3) socio-political limits. The latter two types of limits are much less understood, and yet issues such as loss of confidence rather than a simple engineering failure may be instrumental in the future of a coastal city. There are few studies which quantify the sea-level rise threshold at which cities will be challenged, especially for large rises exceeding a metre or more. Exceptions include London and the Thames Estuary and the Amsterdam and Rotterdam (the Netherlands) where adaptation to a rise of sea level of up to 4 m or more appears feasible. This lack of knowledge on sea-level rise thresholds for coastal cities is of concern, and similar

  10. Stress-induced rise in body temperature is repeatable in free-ranging Eastern chipmunks (Tamias striatus).

    PubMed

    Careau, Vincent; Réale, Denis; Garant, Dany; Speakman, John R; Humphries, Murray M

    2012-04-01

    In response to handling or other acute stressors, most mammals, including humans, experience a temporary rise in body temperature (T(b)). Although this stress-induced rise in T(b) has been extensively studied on model organisms under controlled environments, individual variation in this interesting phenomenon has not been examined in the field. We investigated the stress-induced rise in T(b) in free-ranging eastern chipmunks (Tamias striatus) to determine first if it is repeatable. We predicted that the stress-induced rise in T(b) should be positively correlated to factors affecting heat production and heat dissipation, including ambient temperature (T(a)), body mass (M(b)), and field metabolic rate (FMR). Over two summers, we recorded both T(b) within the first minute of handling time (T(b1)) and after 5 min of handling time (T(b5)) 294 times on 140 individuals. The mean ∆T(b) (T(b5) - T(b1)) during this short interval was 0.30 ± 0.02°C, confirming that the stress-induced rise in T(b) occurs in chipmunks. Consistent differences among individuals accounted for 40% of the total variation in ∆T(b) (i.e. the stress-induced rise in T(b) is significantly repeatable). We also found that the stress-induced rise in T(b) was positively correlated to T(a), M(b), and mass-adjusted FMR. These results confirm that individuals consistently differ in their expression of the stress-induced rise in T(b) and that the extent of its expression is affected by factors related to heat production and dissipation. We highlight some research constraints and opportunities related to the integration of this laboratory paradigm into physiological and evolutionary ecology. PMID:22076533

  11. Subpacket structures in EMIC rising tone emissions observed by the THEMIS probes

    NASA Astrophysics Data System (ADS)

    Nakamura, Satoko; Omura, Yoshiharu; Shoji, Masafumi; Nosé, Masahito; Summers, Danny; Angelopoulos, Vassilis

    2015-09-01

    We report subpacket structures found in electromagnetic ion cyclotron (EMIC) rising tone emissions observed by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes. We investigate three typical cases in detail. The first case shows a continuous single rising tone with four obvious subpackets, and the second case is characterized by a patchy emission with multiple subpackets triggered in a broadband frequency. The third case looks like a smooth rising tone without any obvious subpacket in the fast Fourier transform spectrum, while its amplitude contains small peaks with increasing frequencies. The degree of polarization of each subpacket is generally higher than 0.8 with a left-handed polarization, and the wave direction of the subpackets is typically field aligned. We show that the time evolution of the observed frequency and amplitude can be reproduced consistently by nonlinear growth theory. We also compare the observed time span of each subpacket structure with the theoretical trapping time for second-order cyclotron resonance. They are consistent, indicating that an individual subpacket is generated through a nonlinear wave growth process which excites an element in accordance with the theoretically predicted optimum amplitude.

  12. Future sea-level rise in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Galassi, Gaia; Spada, Giorgio

    2014-05-01

    Secular sea level variations in the Mediterranean Sea are the result of a number of processes characterized by distinct time scales and spatial patterns. Here we predict the future sea level variations in the Mediterranean Sea to year 2050 combining the contributions from terrestrial ice melt (TIM), glacial isostatic adjustment (GIA), and the ocean response (OR) that includes the thermal expansion and the ocean circulation contributions. The three contributions are characterized by comparable magnitudes but distinctly different sea-level fingerprints across the Mediterranean basin. The TIM component of future sea-level rise is taken from Spada et al. (2013) and it is mainly driven by the melt of small glaciers and ice caps and by the dynamic ice loss from Antarctica. The sea-level fingerprint associated with GIA is studied using two distinct models available from the literature: ICE-5G(VM2) (Peltier, 2004) and the ice model progressively developed at the Research School of Earth Sciences (RSES) of the National Australian University (KL05) (see Fleming and Lambeck, 2004 and references therein). Both the GIA and the TIM sea-level predictions have been obtained with the aid of the SELEN program (Spada and Stocchi, 2007). The spatially-averaged OR component, which includes thermosteric and halosteric sea-level variations, recently obtained using a regional coupled ocean-atmosphere model (Carillo et al., 2012), vary between 2 and 7 cm according to scenarios adopted (EA1B and EA1B2, see Meehl at al., 2007). Since the sea-level variations associated with TIM mainly result from the gravitational interactions between the cryosphere components, the oceans and the solid Earth, and long-wavelength rotational variations, they are characterized by a very smooth global pattern and by a marked zonal symmetry reflecting the dipole geometry of the ice sources. Since the Mediterranean Sea is located in the intermediate far-field of major ice sources, TIM sea-level changes have sub

  13. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    SciTech Connect

    Chakraborty, Manoneeta; Bhattacharyya, Sudip E-mail: sudip@tifr.res.in

    2014-09-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from 10 neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such a trend. Moreover, it is important to note that an opposite trend is not found in any of the bursts. The concave shape of the fractional amplitude profiles for all the bursts suggests latitude-dependent flame speeds, possibly due to the effects of the Coriolis force. We also systematically study the roles of low fractional amplitude and low count rate for non-detection and intermittent detections of rise oscillations, and attempt to understand them within the flame spreading scenario. Our results support a weak turbulent viscosity for flame spreading, and imply that burst rise oscillations originate from an expanding hot spot, thus making these oscillations a more reliable tool to constrain the neutron star equations of state.

  14. Fires and the rise and regulation of atmospheric oxygen

    NASA Astrophysics Data System (ADS)

    Lenton, T. M.

    2012-04-01

    When did oxygen first approach 21% of the atmosphere, and what regulates it there? These are enduring puzzles in Earth system science, and fire science provides a key part of the answers. The results of ignition experiments with natural fuels indicate that to start a fire requires at least 17% oxygen in the atmosphere. Thus, the appearance of charcoal in the fossil record around 420 million years ago in the Silurian Period indicates atmospheric oxygen was >17% then. Here we hypothesise that the first non-vascular plants, which began colonising the land surface around 50 million years beforehand (in the Ordovician Period), caused a rise in atmospheric oxygen concentration to a level >17% sufficient to support fires. We base this on weathering experiments with an analogue for the first non-vascular plants, and modelling with the COPSE model of the coupled phosphorus, carbon and oxygen biogeochemical cycles. The experiments reveal that a non-vascular plant (the moss Physcomitrella patens) hugely amplifies phosphorus weathering by a factor of up to 60. The modelling shows that early plant colonisation could hence have increased phosphorus supply to the ocean, fuelling photosynthetic production and organic carbon burial, which is the long-term source of oxygen to the atmosphere. Atmospheric oxygen is predicted to have risen through the late Ordovician and into the Silurian. Since 370 million years ago, the nearly continuous record of charcoal indicates that oxygen has remained above 17% of the atmosphere. At the same time, the continued persistence of forests means fires have never been so frequent as to prevent trees from regenerating, setting a contested upper limit on oxygen of around 30%. The restriction of oxygen variation within a factor of two suggests remarkable regulation, because the whole oxygen reservoir has been replaced over 100 times in this interval. Fires are a prime candidate for forming part of the regulating mechanism, and giving it a 'set point', as

  15. Rise to dominance of angiosperm pioneers in European Cretaceous environments.

    PubMed

    Coiffard, Clément; Gomez, Bernard; Daviero-Gomez, Véronique; Dilcher, David L

    2012-12-18

    The majority of environments are dominated by flowering plants today, but it is uncertain how this dominance originated. This increase in angiosperm diversity happened during the Cretaceous period (ca. 145-65 Ma) and led to replacement and often extinction of gymnosperms and ferns. We propose a scenario for the rise to dominance of the angiosperms from the Barremian (ca. 130 Ma) to the Campanian (ca. 84 Ma) based on the European megafossil plant record. These megafossil data demonstrate that angiosperms migrated into new environments in three phases: (i) Barremian (ca. 130-125 Ma) freshwater lake-related wetlands; (ii) Aptian-Albian (ca. 125-100 Ma) understory floodplains (excluding levees and back swamps); and (iii) Cenomanian-Campanian (ca. 100-84 Ma) natural levees, back swamps, and coastal swamps. This scenario allows for the measured evolution of angiosperms in time and space synthesizing changes in the physical environment with concomitant changes in the biological environment. This view of angiosperm radiation in three phases reconciles previous scenarios based on the North American record. The Cretaceous plant record that can be observed in Europe is exceptional in many ways. (i) Angiosperms are well preserved from the Barremian to the Maastrichtian (ca. 65 Ma). (ii) Deposits are well constrained and dated stratigraphically. (iii) They encompass a full range of environments. (iv) European paleobotany provides many detailed studies of Cretaceous floras for analysis. These factors make a robust dataset for the study of angiosperm evolution from the Barremian to the Campanian that can be traced through various ecosystems and related to other plant groups occupying the same niches. PMID:23213256

  16. Rise to dominance of angiosperm pioneers in European Cretaceous environments

    PubMed Central

    Coiffard, Clément; Gomez, Bernard; Daviero-Gomez, Véronique; Dilcher, David L.

    2012-01-01

    The majority of environments are dominated by flowering plants today, but it is uncertain how this dominance originated. This increase in angiosperm diversity happened during the Cretaceous period (ca. 145–65 Ma) and led to replacement and often extinction of gymnosperms and ferns. We propose a scenario for the rise to dominance of the angiosperms from the Barremian (ca. 130 Ma) to the Campanian (ca. 84 Ma) based on the European megafossil plant record. These megafossil data demonstrate that angiosperms migrated into new environments in three phases: (i) Barremian (ca. 130–125 Ma) freshwater lake-related wetlands; (ii) Aptian–Albian (ca. 125–100 Ma) understory floodplains (excluding levees and back swamps); and (iii) Cenomanian–Campanian (ca. 100–84 Ma) natural levees, back swamps, and coastal swamps. This scenario allows for the measured evolution of angiosperms in time and space synthesizing changes in the physical environment with concomitant changes in the biological environment. This view of angiosperm radiation in three phases reconciles previous scenarios based on the North American record. The Cretaceous plant record that can be observed in Europe is exceptional in many ways. (i) Angiosperms are well preserved from the Barremian to the Maastrichtian (ca. 65 Ma). (ii) Deposits are well constrained and dated stratigraphically. (iii) They encompass a full range of environments. (iv) European paleobotany provides many detailed studies of Cretaceous floras for analysis. These factors make a robust dataset for the study of angiosperm evolution from the Barremian to the Campanian that can be traced through various ecosystems and related to other plant groups occupying the same niches. PMID:23213256

  17. Color imaging of Mars by the High Resolution Imaging Science Experiment (HiRISE)

    USGS Publications Warehouse

    Delamere, W.A.; Tornabene, L.L.; McEwen, A.S.; Becker, K.; Bergstrom, J.W.; Bridges, N.T.; Eliason, E.M.; Gallagher, D.; Herkenhoff, K. E.; Keszthelyi, L.; Mattson, S.; McArthur, G.K.; Mellon, M.T.; Milazzo, M.; Russell, P.S.; Thomas, N.

    2010-01-01

    HiRISE has been producing a large number of scientifically useful color products of Mars and other planetary objects. The three broad spectral bands, coupled with the highly sensitive 14 bit detectors and time delay integration, enable detection of subtle color differences. The very high spatial resolution of HiRISE can augment the mineralogic interpretations based on multispectral (THEMIS) and hyperspectral datasets (TES, OMEGA and CRISM) and thereby enable detailed geologic and stratigraphic interpretations at meter scales. In addition to providing some examples of color images and their interpretation, we describe the processing techniques used to produce them and note some of the minor artifacts in the output. We also provide an example of how HiRISE color products can be effectively used to expand mineral and lithologic mapping provided by CRISM data products that are backed by other spectral datasets. The utility of high quality color data for understanding geologic processes on Mars has been one of the major successes of HiRISE. ?? 2009 Elsevier Inc.

  18. Tension between reducing sea-level rise and global warming through solar-radiation management

    NASA Astrophysics Data System (ADS)

    Irvine, P. J.; Sriver, R. L.; Keller, K.

    2012-02-01

    Geoengineering using solar-radiation management (SRM) is gaining interest as a potential strategy to reduce future climate change impacts. Basic physics and past observations suggest that reducing insolation will, on average, cool the Earth. It is uncertain, however, whether SRM can reduce climate change stressors such as sea-level rise or rates of surface air temperature change. Here we use an Earth system model of intermediate complexity to quantify the possible response of sea levels and surface air temperatures to projected climate forcings and SRM strategies. We find that SRM strategies introduce a potentially strong tension between the objectives to reduce (1) the rate of temperature change and (2) sea-level rise. This tension arises primarily because surface air temperatures respond faster to radiative forcings than sea levels. Our results show that the forcing required to stop sea-level rise could cause a rapid cooling with a rate similar to the peak business-as-usual warming rate. Furthermore, termination of SRM was found to produce warming rates up to five times greater than the maximum rates under the business-as-usual CO2 scenario, whereas sea-level rise rates were only 30% higher. Reducing these risks requires a slow phase-out of many decades and thus commits future generations.

  19. Mass and volume contributions to twentieth-century global sea level rise.

    PubMed

    Miller, Laury; Douglas, Bruce C

    2004-03-25

    The rate of twentieth-century global sea level rise and its causes are the subjects of intense controversy. Most direct estimates from tide gauges give 1.5-2.0 mm yr(-1), whereas indirect estimates based on the two processes responsible for global sea level rise, namely mass and volume change, fall far below this range. Estimates of the volume increase due to ocean warming give a rate of about 0.5 mm yr(-1) (ref. 8) and the rate due to mass increase, primarily from the melting of continental ice, is thought to be even smaller. Therefore, either the tide gauge estimates are too high, as has been suggested recently, or one (or both) of the mass and volume estimates is too low. Here we present an analysis of sea level measurements at tide gauges combined with observations of temperature and salinity in the Pacific and Atlantic oceans close to the gauges. We find that gauge-determined rates of sea level rise, which encompass both mass and volume changes, are two to three times higher than the rates due to volume change derived from temperature and salinity data. Our analysis supports earlier studies that put the twentieth-century rate in the 1.5-2.0 mm yr(-1) range, but more importantly it suggests that mass increase plays a larger role than ocean warming in twentieth-century global sea level rise. PMID:15042085

  20. Numerical Analysis of Temperature Rise in Tissue Using Electronically Focused Ultrasound

    NASA Astrophysics Data System (ADS)

    Saito, Yoshikazu; Tsuchiya, Takenobu; Endoh, Nobuyuki

    2006-05-01

    Recently, the use of higher power ultrasonic equipment has been extended to not only therapy but also diagnosis because the new diagnostic imaging techniques, such as Doppler color flow imaging and harmonic imaging, require a higher ultrasound power than conventional imaging techniques. It is very important to ensure the safety of temperature rise caused by the absorption of ultrasound energy in new ultrasonic imaging systems. In this two-dimensional finite difference time domain-heat conduction equation study, the temperature rise in tissue has been simulated at a focal point radiated by a phased array focused transducer, such as like a common B-mode imagine system. The center frequency of radiated wave pulses is 2.5 MHz and ISPTA=0.72 W/cm2. When the sound pulse repetition frequency (PRF) is changed from 100 to 400 kHz, the temperature rise in tissue at a focal point is proportional to the PRF. The maximum temperature rise in tissue has been simulated only at 0.0004 °C at a focal point of a transducer when PRF is 400 kHz.

  1. Scaling law for bubbles rising near vertical walls

    NASA Astrophysics Data System (ADS)

    Dabiri, Sadegh; Bhuvankar, Pramod

    2016-06-01

    This paper examines the rising motion of a layer of gas bubbles next to a vertical wall in a liquid in the presence of an upward flow parallel to the wall to help with the understanding of the fluid dynamics in a bubbly upflow in vertical channels. Only the region near the wall is simulated with an average pressure gradient applied to the domain that balances the weight of the liquid phase. The upward flow is created by the rising motion of the bubbles. The bubbles are kept near the wall by the lateral lift force acting on them as a result of rising in the shear layer near the wall. The rise velocity of the bubbles sliding on the wall and the average rise velocity of the liquid depend on three dimensionless parameters, Archimedes number, Ar, Eötvös number, Eo, and the average volume fraction of bubbles on the wall. In the limit of small Eo, bubbles are nearly spherical and the dependency on Eo becomes negligible. In this limit, the scaling of the liquid Reynolds number with Archimedes number and the void fraction is presented. A scaling argument is presented based on viscous dissipation analysis that matches the numerical findings. Viscous dissipation rates are found to be high in a thin film region between the bubble and the wall. A scaling of the viscous dissipation and steady state film thickness between the bubble and the wall with Archimedes number is presented.

  2. Rising sea level may cause decline of fringing coral reefs

    NASA Astrophysics Data System (ADS)

    Field, Michael E.; Ogston, Andrea S.; Storlazzi, Curt D.

    2011-08-01

    Coral reefs are major marine ecosystems and critical resources for marine diversity and fisheries. These ecosystems are widely recognized to be at risk from a number of stressors, and added to those in the past several decades is climate change due to anthropogenically driven increases in atmospheric concentrations of greenhouse gases. Most threatening to most coral reefs are elevated sea surface temperatures and increased ocean acidity [e.g., Kleypas et al., 1999; Hoegh-Guldberg et al., 2007], but sea level rise, another consequence of climate change, is also likely to increase sedimentary processes that potentially interfere with photosynthesis, feeding, recruitment, and other key physiological processes (Figure 1). Anderson et al. [2010] argue compellingly that potential hazardous impacts to coastlines from 21st-century sea level rise are greatly underestimated, particularly because of the rapid rate of rise. The Intergovernmental Panel on Climate Change estimates that sea level will rise in the coming century (1990-2090) by 2.2-4.4 millimeters per year, when projected with little contribution from melting ice [Meehl et al., 2007]. New studies indicate that rapid melting of land ice could substantially increase the rate of sea level rise [Grinsted et al., 2009; Milne et al., 2009].

  3. STS-53 Discovery, Orbiter Vehicle (OV) 103, rises into sky after KSC liftoff

    NASA Technical Reports Server (NTRS)

    1992-01-01

    STS-53 Discovery, Orbiter Vehicle (OV) 103, rises into the clear morning sky after liftoff from Kennedy Space Center (KSC) Launch Complex (LC) Pad 39A at 8:24:00 am (Eastern Standard Time (EST)). This profile view shows OV-103, riding atop the external tank (ET) and flanked by two solid rocket boosters. Exhaust plumes billow from the SRB skirts. The diamond shock effect is visible at the three space shuttle main engine (SSME) nozzles.

  4. Speculative Truth - Henry Cavendish, Natural Philosophy, and the Rise of Modern Theoretical Science

    NASA Astrophysics Data System (ADS)

    McCormmach, Russell

    2004-03-01

    With a never-before published paper by Lord Henry Cavendish, as well as a biography on him, this book offers a fascinating discourse on the rise of scientific attitudes and ways of knowing. A pioneering British physicist in the late 18th and early 19th centuries, Cavendish was widely considered to be the first full-time scientist in the modern sense. Through the lens of this unique thinker and writer, this book is about the birth of modern science.

  5. Study of temporal evolution of emission spectrum in a steeply rising submillimeter burst

    NASA Astrophysics Data System (ADS)

    Li, Jian-Ping; Zhou, Ai-Hua; Wang, Xin-Dong

    2016-01-01

    The temporal evolution of a spectrum during a steeply rising submillimeter (THz) burst that occurred on 2003 November 2 was investigated in detail for the first time. Observations show that the flux density of the THz spectrum increased steeply with frequency above 200 GHz. Their average rising rates reached a value of 235 sfu GHz-1 (corresponding to spectral index α of 4.8) during the burst. The flux densities reached about 4 000 and 70 000 sfu at 212 and 405 GHz at the maximum phase, respectively. The emissions at 405 GHz maintained such a continuous high level that they largely exceeded the peak values of the microwave (MW) spectra during the main phase. Our studies suggest that only energetic electrons with a low-energy cutoff of ˜1 MeV and number density of ˜106-108 cm-3 can produce such a strong and steeply rising THz component via gyrosynchrotron radiation based on numerical simulations of burst spectra in the case of a nonuniform magnetic field. The electron number density N, derived from our numerical fits to the THz temporal evolution spectra, increased substantially from 8 × 106 to 4 × 108 cm-3, i.e., the N value increased 50 times during the rise phase. During the decay phase it decreased to 7 × 107 cm-3, i.e., it decreased by about five times from the maximum phase. The total electron number decreased an order of magnitude from the maximum phase to the decay phase. Nevertheless, the variation in amplitude of N is only about one time in the MW emission source during this burst, and the total electron number did not decrease but increased by about 20% during the decay phase. Interestingly, we find that the THz source radius decreased by about 24% while the MW source radius, on the contrary, increased by 28% during the decay phase.

  6. Micro- and nano- second time scale, high power electrical wire explosions in water.

    NASA Astrophysics Data System (ADS)

    Grinenko, Alon; Efimov, Sergey; Sayapin, Arkadii; Fedotov, Alexander; Gurovich, Viktor; Krasik, Yakov

    2006-10-01

    Experimental and magneto-hydro-dynamic simulation results of micro- and nanosecond time scale underwater electrical Al, Cu and W wires explosions are presented. A capacitor bank with stored energy up to 6 kJ (discharge current up to 80 kA with 2.5 μs quarter period) was used in microsecond time scale experiments and water forming line generator with current amplitude up to 100 kA and pulse duration of 100 ns were used in nanosecond time scale experiments. Extremely high energy deposition of up to 60 times the atomization enthalpy was registered in nanosecond time scale explosions. A discharge channel evolution and surface temperature were analyzed by streak shadow imaging and using fast photo-diode with a set of interference filters, respectively. Microsecond time scale electrical explosion of cylindrical wire array showed extremely high pressure of converging shock waves at the axis, up to 0.2 MBar. A 1D and 2D magneto-hydro-dynamic simulation demonstrated good agreement with such experimental parameters as discharge channel current, voltage, radius, and temperature.

  7. Flexural ridges, trenches, and outer rises around coronae on Venus

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Schubert, Gerald

    1992-01-01

    Flexural signatures outboard of Venusian coronal rims are examined with the purpose of inferring the thickness of the planet's elastic lithosphere. Topographic profiles of several prominent coronae which display clear trench and outer rise signatures are presented. Via a thin elastic plate flexure model to characterize the shape of the trench and outer rise, Venusian flexures are found to be similar in both amplitude and wavelength to lithospheric flexures seaward of subduction zones on earth. It is shown that circumferential fractures are concentrated in areas where the topography is curved downward, in good agreement with the high tensile stress predicted by the flexure models. Two scenarios for the development of the ridge-trench-outer rise flexural topography and circumferential fractures of coronae are presented. The first scenario involves reheating and thermal subsidence of the lithosphere interior to the corona, while the second involves expansion of the corona interior and roll back of the subducting lithosphere exterior to the corona.

  8. Overestimation of marsh vulnerability to sea level rise

    NASA Astrophysics Data System (ADS)

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-03-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  9. Overestimation of marsh vulnerability to sea level rise

    USGS Publications Warehouse

    Kirwan, Matthew L.; Temmerman, Stijn; Skeehan, Emily E.; Guntenspergen, Glenn R.; Fagherazzi, Sergio

    2016-01-01

    Coastal marshes are considered to be among the most valuable and vulnerable ecosystems on Earth, where the imminent loss of ecosystem services is a feared consequence of sea level rise. However, we show with a meta-analysis that global measurements of marsh elevation change indicate that marshes are generally building at rates similar to or exceeding historical sea level rise, and that process-based models predict survival under a wide range of future sea level scenarios. We argue that marsh vulnerability tends to be overstated because assessment methods often fail to consider biophysical feedback processes known to accelerate soil building with sea level rise, and the potential for marshes to migrate inland.

  10. Modelling of Air Bubble Rising in Water and Polymeric Solution

    NASA Astrophysics Data System (ADS)

    Hassan, N. M. S.; Khan, M. M. K.; Rasul, M. G.; Subaschandar, N.

    2010-06-01

    This study investigates a Computational Fluid Dynamics (CFD) model for a single air bubble rising in water and xanthan gum solution. The bubble rise characteristics through the stagnant water and 0.05% xanthan gum solution in a vertical cylindrical column is modelled using the CFD code Fluent. Single air bubble rise dispersed into the continuous liquid phase has been considered and modelled for two different bubble sizes. Bubble velocity and vorticity magnitudes were captured through a surface-tracking technique i.e. Volume of Fluid (VOF) method by solving a single set of momentum equations and tracking the volume fraction of each fluid throughout the domain. The simulated results of the bubble flow contours at two different heights of the cylindrical column were validated by the experimental results and literature data. The model developed is capable of predicting the entire flow characteristics of different sizes of bubble inside the liquid column.

  11. Numerical simulation of rising bubble with chemical reaction

    NASA Astrophysics Data System (ADS)

    Sahu, Kirti; Tripathi, Manoj; Matar, Omar; Karapetsas, George

    2014-11-01

    The dynamics of a rising bubble under the action of gravity and in the presence of an exothermic chemical reaction at the interface is investigated via direct numerical simulation using Volume-of-Fluid (VOF) method. The product of the chemical reaction, and temperature rise due to the exothermic chemical reaction influence the local viscosity and surface tension near the interfacial region, which in turn give rise to many interesting dynamics. The flow is governed by continuity, Navier-Stokes equations along with the convection equation of the volume fraction of the outer fluid and the energy equation. The effects of the Bond, Damkohler, and Reynolds numbers, and of the dimensionless heat of reaction are investigated. The results of this parametric study will be presented at the meeting.

  12. The formation of ice rises, their dynamics and role in the deglaciation of the Antarctic ice sheet

    NASA Astrophysics Data System (ADS)

    Favier, Lionel; Pattyn, Frank

    2015-04-01

    Numerous underwater mountains emerge from the edge of the continental shelf around the Antarctic ice sheet. During the last deglaciation, those features gave birth to ice rises, each being small scale copies of a continental ice sheet characterised by an ice divide and a local flow going outwards embedded within the fringing ice shelves. The well-known millenium-scale stability of ice rises can be strong indicators for the past deglaciation termination. However, the interpretation of physical measurements of an ice rise is not straightforward due to unknown past ice dynamics. Here, using the Bisicles ice-sheet model, we investigate for the first time the formation of an ice rise on top of an underwater mountain during the retreat of an ideal Antarctic-like ice sheet (i.e., including both grounded and floating ice flow). Prior to the retreat, the underwater mountain is barely detectable from the ice surface geometry and velocity. During the ice sheet retreat, induced by an increase of the sea level, an ice divide develops quickly above the underwater mountain. Within a short period of hundreds of years, the ice rise adopts a thousand years stability along with two main features: (i) a shifted upstream position of the ice rise compared to the mountain underneath and (ii) a geometrical asymmetry of the ice rise showing a gentle slope upstream and a steep slope downstream. We also investigate the influence of a non uniform surface mass balance on the migration of the ice divide. Our results provide additional ice dynamical constraints to facilitate numerical reconstructions of the last deglacial history in Antarctica as we demonstrate that ice rises are stable, but transient features of the ice shelf, stabilizing fast outlet flow. The timing of pinning and unpinning therefore becomes crucial in simulating the episodes of slow and fast grounding line retreat, respectively.

  13. Combined Flux Compression and Plasma Opening Switch on the Saturn Pulsed Power Generator

    SciTech Connect

    Felber, Franklin S.; Waisman, Eduardo M.; Mazarakis, Michael G.

    2010-05-07

    A wire-array flux-compression cartridge installed on Sandia's Saturn pulsed power generator doubled the current into a 3-nH load to 6 MA and halved its rise time to 100 ns. The current into the load, however, was unexpectedly delayed by almost 1 {mu}s. Estimates of a plasma flow switch acting as a long-conduction-time opening switch are consistent with key features of the power compression. The results suggest that microsecond-conduction-time plasma flow switches can be combined with flux compression both to amplify currents and to sharpen pulse rise times in pulsed power drivers.

  14. Whole mantle shear structure beneath the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    Melbourne, Timothy I.; Helmberger, Donald V.

    2002-09-01

    We model broadband seismograms containing triplicated S, S2, and S3 along with ScS to produce a pure path one-dimensional model extending from the crust to the core-mantle boundary beneath the East Pacific Rise. We simultaneously model all body wave shapes and amplitudes, thereby eliminating depth-velocity ambiguities. The data consist of western North American broadband recordings of East Pacific Rise (EPR) affiliate transform events that form a continuous record section out to 82° and sample nearly the entire East Pacific Rise. The best fitting synthetics contain attenuation and small changes in lithospheric thickness needed to correct for variation in bounce point ages. The 660-km discontinuity is particularly well resolved and requires a steep gradient (4%), extending down to 745 km. We find no discernible variation in apparent depths of the 405- and 660-km discontinuities over ridge-orthogonal distances on the order of 1000 km (or 20 Ma lithosphere). Body waveform comparisons indicate that we can resolve discontinuity depths to less than ±10 km, providing an upper limit to transition zone topography. These depth estimates, in conjunction with the fan shot nature of the ray paths, lower the detection limit from S2 precursor analysis of the lateral length scale over which short-wavelength topographic variation could occur and indicate the sub-EPR Transition Zone and upper mantle are remarkably homogeneous. The lower mantle beneath the East Pacific Rise is well modeled by PREM, with the greatest variation occurring in ScS, reflecting strong heterogeneity along the core-mantle boundary. Together, these observations require that the East Pacific Rise spreading ridge cannot be actively supplied from the local lower mantle and that tomographically imaged lateral variation beneath the ridge likely reflects lateral smearing of outlying velocity gradients. Dynamically, the transition zone therefore appears vertically decoupled from the overlying East Pacific Rise

  15. Heliospheric Observations in the Rising Phase of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Jian, L. K.; Luhmann, J. G.; Russell, C. T.; Szabo, A.

    2012-12-01

    In solar cycle 24 (the beginning of year 2009 - present), the solar polar field started with a magnitude as weak as a half of initial field strength for previous solar cycles 21-23. As the cycle 24 rises, the solar polar field has been approaching its reversal very gradually, especially after January 2011. The approach speed is less than a half of previous cycles. The pace needs to increase for the Sun to reach the cycle maximum (field reversal) in 2013 as predicted. Consistent with the small sunspot number and weak solar field, the interplanetary magnetic field (IMF) and solar wind dynamic pressure at 1 AU are weaker than previous cycles, resulting in less geomagnetic activity. In addition, based on our long-term study of large-scale solar wind structures, including interplanetary CMEs (ICMEs), stream interaction regions (SIRs), and their associated shocks at 1 AU from 1995 to present, we have compared their properties in this rising phase with those of Cycle 23 and study their possible influence on geomagnetic activity. From 2009 to 2011, the ICME occurrence rate increases from 10 to 30 per year, not much less than the rising phase of cycle 23. However, these ICMEs are usually weaker and slower than last rising phase. The occurrence rate of SIRs decreases slightly from 2009 to 2011, similar to the rising phase of last cycle. As the sunspots show a north-south asymmetry, we will investigate the heliospheric response of this. By dividing the solar wind into positive (anti-sunward) and negative (sunward) sectors depending on the IMF polarity, we have compared the solar wind parameters of the two polarity sectors from the beginning of Solar Cycle 21 to present. The sector asymmetry is pronounced during the solar minimum 23/24. We will study how this asymmetry changes in the rising phase of cycle 24.

  16. Coastal flooding by tropical cyclones and sea-level rise.

    PubMed

    Woodruff, Jonathan D; Irish, Jennifer L; Camargo, Suzana J

    2013-12-01

    The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence. PMID:24305147

  17. Ore potential of the Marcus-Wake rise (Central Pacific)

    NASA Astrophysics Data System (ADS)

    Novikov, G. V.; Mel'nikov, M. E.; Lobkovsky, L. I.; Bogdanova, O. Yu.; Sorokhtin, N. O.

    2015-12-01

    The data on the geological structure of different guyots on the Marcus-Wake rise with cobalt-bearing Fe-Mn crusts are discussed. Crusts are represented by three-layer aggregates composed of one lower phosphatized (I-1) and two upper non-phosphatized (II and III) layers. Fe-vernadite and Mn-feroxygite are the major ore minerals in all studied crusts and their layers. Small contents of vernadite, asbolane-buserite, and goethite are registered. Crusts of guyots on the rise are characterized by a stable concentration of heavy and rare metals (Cotot, Ni, Cu, Zn, Pb, Mo, and Cd) independently of their latitudinal location.

  18. Accurately Determining the Risks of Rising Sea Level

    NASA Astrophysics Data System (ADS)

    Marbaix, Philippe; Nicholls, Robert J.

    2007-10-01

    With the highest density of people and the greatest concentration of economic activity located in the coastal regions, sea level rise is an important concern as the climate continues to warm. Subsequent flooding may potentially disrupt industries, populations, and livelihoods, particularly in the long term if the climate is not quickly stabilized [McGranahan et al., 2007; Tol et al., 2006]. To help policy makers understand these risks, a more accurate description of hazards posed by rising sea levels is needed at the global scale, even though the impacts in specific regions are better known.

  19. MRO HiRISE Observations of the Nucleus of Comet C/2013 A1 (Siding Spring)

    NASA Astrophysics Data System (ADS)

    McEwen, A. S.; Delamere, W. A.; Heyd, R.; Mattson, S.; Tamppari, L.; Zurek, R. W.; Schaller, C.; Block, K.; Polit, A. T.; Milkovich, S. M.; Hansen, C. J.; Thomas, N.; Cremonese, G.

    2014-12-01

    Comet C/2013 A1 (Siding Spring) will pass Mars at a distance of 131,000 ± 3,000 km on Oct 19, 2014. Mars Reconnaissance Orbiter (MRO) will observe the comet on multiple orbits within 2.5 days before and after closest approach. The HiRISE telescope has a 50 cm aperture and an instantaneous field of view of one micro-radian per pixel, so the best image will have a scale near 131 m/pixel. If imaging is successful (i.e., not too smeared) and if the nucleus is larger than ~200 m diameter, this will provide the first resolved images of the nucleus of a long-period comet. Previous resolved images cover the nuclei of short-period comets, whose surfaces have been processed by many close passes by the sun. The encounter velocity is 56 km/s, so the best observations of the nucleus are only possible a few hours near closest approach, as seen from portions of 3 MRO orbits. A total of 20 HiRISE observations are planned for these 3 orbits, with exposure times varying from 0.13 to 2.5 s to cover a range of potential brightness. The HiRISE CCDs are operated at much higher temperatures, 20-30C, than those used for astronomical observations, so the maximum exposure time is limited by dark current signal. HiRISE objectives are to measure the shape and dimensions of the nucleus, determine its albedo (currently unknown for long-period comets), measure the rotation period and axis, and observe the inner coma for bright jets or outbursts. The phase angles range from 90 to 107 degrees, which will make imaging the nucleus challenging. The fast relative motions and changing geometries of the comet and MRO also make it challenging to acquire unsmeared images, since the image must pass directly down the 128 lines used for time-delay integration (TDI). Although the comet's trajectory is probably well known (as nongravitational effects have not been detected), the exact timing is uncertain. Small timing errors could result in the image passing down the TDI rows at an angle, producing smeared

  20. What we have learned about Shatsky Rise Oceanic Plateau from IODP Expedition 324

    NASA Astrophysics Data System (ADS)

    Sano, T.; Sager, W. W.; Geldmacher, J.; Koppers, A. A.; Heydolph, K.; Almeev, R.; Hanyu, T.; Delacour, A.

    2012-12-01

    In fall 2009, Integrated Ocean Drilling Program (IODP) Expedition 324 drilled igneous cores at five sites (U1346 to U1350) to study the origin of Shatsky Rise oceanic plateau, one of the large igneous provinces of the Pacific Ocean. Since we are now three years post-cruise and seeing results of studies come to light, we present here what we have learned about Shatsky Rise. Located ~1500 km east of Japan, Shatsky Rise consists of three massifs, Tamu, Ori, and Shirshov, which were generated along the trace of a mid-ocean ridge triple junction during the latest Jurassic to Early Cretaceous times. Radiometric dating of cored basalts using the 40Ar/39Ar technique is turning out to be challenging due to low-K content of the basalts, but preliminary ages show that eruptions are age progressive across Shatsky Rise. Eruptions apparently began at the southwest, with Tamu Massif, then moved to the northeast with time. Geochemistry data indicate that four magma types exist on the plateau; namely normal, low-Ti, high-Nb, and U1349 types. The normal type constitute ~94% lava units of the oldest volcano (Tamu Massif) and the other three types comprise ~57% of samples from the younger Ori Massif, implying that geochemical compositions may have become heterogeneous with time. Phase equilibria modeling and our new experimental data both indicate the low pressure magma fractionation (<200-300MPa). Model calculations of immobile trace elements estimate that melting fraction of Shatsky Rise is similar to normal mid-ocean ridge basalt (N-MORB), but there is greater effect of residual garnet inferring the depth of melting is probably higher. Sr-Nd-Pb-Hf isotopic results for the normal, low-Ti, and U1349 type basalts are almost identical and fall within the N-MORB range, but the high-Nb type basalts have distinctly enriched compositions. The normal type basalts show uniform and lower 3He/4He than N-MORB, suggesting the presence of recycled material in the magma source of Shatsky Rise

  1. Non-linear shape oscillations of rising drops and bubbles: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Lalanne, Benjamin; Abi Chebel, Nicolas; Vejražka, Jiří; Tanguy, Sébastien; Masbernat, Olivier; Risso, Frédéric

    2015-12-01

    This paper focuses on shape-oscillations of a gas bubble or a liquid drop rising in another liquid. The bubble/drop is initially attached to a capillary and is released by a sudden motion of that capillary, resulting in the rise of the bubble/drop along with the oscillations of its shape. Such experimental conditions make difficult the interpretation of the oscillation dynamics with regard to the standard linear theory of oscillation because (i) amplitude of deformation is large enough to induce nonlinearities, (ii) the rising motion may be coupled with the oscillation dynamics, and (iii) clean conditions without residual surfactants may not be achieved. These differences with the theory are addressed by comparing experimental observation with numerical simulation. Simulations are carried out using Level-Set and Ghost-Fluid methods with clean interfaces. The effect of the rising motion is investigated by performing simulations under different gravity conditions. Using a decomposition of the bubble/drop shape into a series of spherical harmonics, experimental and numerical time evolutions of their amplitudes are compared. Due to large oscillation amplitude, non-linear couplings between the modes are evidenced from both experimental and numerical signals; modes of lower frequency influence modes of higher frequency, whereas the reverse is not observed. Nevertheless, the dominant frequency and overall damping rate of the first five modes are in good agreement with the linear theory. Effect of the rising motion on the oscillations is globally negligible, provided the mean shape of the oscillation remains close to a sphere. In the drop case, despite the residual interface contamination evidenced by a reduction in the terminal velocity, the oscillation dynamics is shown to be unaltered compared to that of a clean drop.

  2. Detecting anthropogenic footprints in sea level rise: the role of complex colored noise

    NASA Astrophysics Data System (ADS)

    Dangendorf, Sönke; Marcos, Marta; Müller, Alfred; Zorita, Eduardo; Jensen, Jürgen

    2015-04-01

    While there is scientific consensus that global mean sea level (MSL) is rising since the late 19th century, it remains unclear how much of this rise is due to natural variability or anthropogenic forcing. Uncovering the anthropogenic contribution requires profound knowledge about the persistence of natural MSL variations. This is challenging, since observational time series represent the superposition of various processes with different spectral properties. Here we statistically estimate the upper bounds of naturally forced centennial MSL trends on the basis of two separate components: a slowly varying volumetric (mass and density changes) and a more rapidly changing atmospheric component. Resting on a combination of spectral analyses of tide gauge records, ocean reanalysis data and numerical Monte-Carlo experiments, we find that in records where transient atmospheric processes dominate, the persistence of natural volumetric changes is underestimated. If each component is assessed separately, natural centennial trends are locally up to ~0.5 mm/yr larger than in case of an integrated assessment. This implies that external trends in MSL rise related to anthropogenic forcing might be generally overestimated. By applying our approach to the outputs of a centennial ocean reanalysis (SODA), we estimate maximum natural trends in the order of 1 mm/yr for the global average. This value is larger than previous estimates, but consistent with recent paleo evidence from periods in which the anthropogenic contribution was absent. Comparing our estimate to the observed 20th century MSL rise of 1.7 mm/yr suggests a minimum external contribution of at least 0.7 mm/yr. We conclude that an accurate detection of anthropogenic footprints in MSL rise requires a more careful assessment of the persistence of intrinsic natural variability.

  3. Rise dynamics of unsteady laboratory jets with implications for volcanic plumes

    NASA Astrophysics Data System (ADS)

    Chojnicki, K. N.; Clarke, A. B.; Phillips, J. C.; Adrian, R. J.

    2015-02-01

    Geophysical observations of discrete volcanic eruptions suggest their eruption rates vary rapidly in time. To learn how such variations may impact the initial stages of plume rise, we conducted a laboratory study of neutrally-buoyant jets generated by unsteady source conditions analogous to the volcanic case. Turbulent jets were generated by quickly injecting a finite volume of water into a large volume of still water. The mass injection rates evolved over time with a Gaussian-like history, producing jets with peak Reynolds numbers ranging from 104 to 105, consistent with values estimated for small, discrete eruptions. Except during very early and late times, jet heights show a logarithmic dependence on time; this trend contrasts with the power law dependence for jets produced by steady-state or instantaneous discharge conditions. We show that this logarithmic dependence is the similarity form appropriate for impulsive releases from a time-varying source, and found characteristic length and time scales that consolidate the non-dimensional jet heights, as functions of non-dimensional times, from a range of experimental conditions onto a single trend. The rise of unsteady volcanic plume fronts from short-duration eruptions (Mori and Burton, 2009; Patrick, 2007) show the same trend as that observed in the laboratory. Variations in mass eruption rate strongly influence the initial phases of plume rise and may impact related processes such as mixing, entrainment and eruption column collapse. Consequently, source unsteadiness must be accounted for in physical plume models before they will reliably estimate trajectory, dilution, and stability for volcanic plumes from discrete eruptions.

  4. Michael Young's "The Rise of the Meritocracy": A Philosophical Critique

    ERIC Educational Resources Information Center

    Allen, Ansgar

    2011-01-01

    This paper examines Michael Young's 1958 dystopia, "The Rise of the Meritocracy". In this book, the word "meritocracy" was coined and used in a pejorative sense. Today, however, meritocracy represents a positive ideal against which we measure the justice of our institutions. This paper argues that, when read in the twenty-first century, Young's…

  5. Pressure Rise Due to a Fire in an Enclosure

    NASA Technical Reports Server (NTRS)

    Atallah, Sami; deRis, John N.

    1969-01-01

    Can temperature and pressure rise resulting from a fast developing fire in an enclosure be predicted? Toward that end, the authors developed equations, the results of which were compared with the few available experimental data and with the Apollo accident pressure record.

  6. Whither Opportunity? Rising Inequality, Schools, and Children's Life Chances

    ERIC Educational Resources Information Center

    Duncan, Greg J., Ed.; Murnane, Richard, Ed.

    2011-01-01

    As the incomes of affluent and poor families have diverged over the past three decades, so too has the educational performance of their children. But how exactly do the forces of rising inequality affect the educational attainment and life chances of low-income children? In "Whither Opportunity?" a distinguished team of economists,…

  7. RETENTION BASIN. ERECTING REINFORCING STEEL FOR CONCRETE DECK. STACK RISES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    RETENTION BASIN. ERECTING REINFORCING STEEL FOR CONCRETE DECK. STACK RISES AT TOP LEFT. CAMERA FACES WEST. INL NEGATIVE NO. 2581. Unknown Photographer, 6/18/1951 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  8. PBF Cooling Tower detail. Camera facing southwest. Wood fill rises ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PBF Cooling Tower detail. Camera facing southwest. Wood fill rises from foundation piers of cold water basin. Photographer: Kirsh. Date: May 1, 1969. INEEL negative no. 69-2826 - Idaho National Engineering Laboratory, SPERT-I & Power Burst Facility Area, Scoville, Butte County, ID

  9. High-Rise Buildings versus Outdoor Thermal Environment in Chongqing

    PubMed Central

    Lu, Jun; Chen, Jin-hua; Tang, Ying; Feng, Yuan; Wang, Jin-sha

    2007-01-01

    This paper gives a brief description of the over quick urbanization since Chongqing, one of the biggest cities in China, has been a municipality directly under the Central Government in 1997, excessive development and exceeding increase of high-rise buildings because of its special geographical position which finally leads to the worsening of the urban outdoor thermal environment. Then, this paper makes a bright balance to the field measurement and simulated results of the wind speed field, temperature field of one multifunctional high-rise building in Chongqing university located in the city center, and the contrasted results validate the correctness of CFD in the outdoor thermal environmental simulation, expose the disadvantages of high-rise buildings on the aspects of blocking the wind field, decreasing wind speed which results in accumulation of the air-conditioning heat revolving around and periscian region where sunshine can not rip into. Finally, in order to improve the urban outdoor thermal environment near the high-rise buildings especially for the angle of natural ventilation, this paper simulates the wind environment in different architectural compositions and architectural layouts by CFD, and the simulated results show that freestyle and tower buildings which can guarantee the wind speed and take the air-conditioning heat away are much suitable and reasonable for the special Chongqing geography. These conclusions can also be used as a reference in other mountain cities, especially for the one with a great number of populations.

  10. The Rising Cost of Higher Education. APPA Thought Leaders 2013

    ERIC Educational Resources Information Center

    APPA: Association of Higher Education Facilities Officers, 2013

    2013-01-01

    The 2013 Thought Leaders Symposium, sponsored in part by DTZ, a UGL company, and Jacobs, focused on the topic of the rising cost of higher education. More than three dozen higher education leaders--including presidents, provosts, business officers, consultants, association executives, and facilities professionals--participated in a facilitated…

  11. The Milliken/Georgia Tech Rising Senior Summer Program.

    ERIC Educational Resources Information Center

    Agrawal, Pradeep K; Sommerfeld, Jude T.

    1987-01-01

    Describes the Rising Senior Program at the Georgia Institute of Technology, which is a cooperative education program designed to provide student interns with an opportunity to apply engineering principles to real problems related to the business interests of the Milliken textile manufacturing company. (TW)

  12. Thermodynamics of Capillary Rise: Why Is the Meniscus Curved?

    ERIC Educational Resources Information Center

    Henriksson, Ulf; Eriksson, Jan Christer

    2004-01-01

    The thermodynamics of capillary rise is explained as the gravitational elevation of the whole column of liquid caused by the positive connection between the liquid, and the solid wall of the capillary tube. The curvature of the meniscus is ascribed to the maintenance of a physiochemical balance throughout the gravitational column of liquid.

  13. RISING ATMOSPHERIC CO2 AND CARBON SEQUESTRATION IN FORESTS

    EPA Science Inventory

    Rising CO2 concentrations in the Earth's atmosphere could alter Earth's climate system, but it is thought that higher concentrations may improve plant growth by way of the fertilization effect. Forests, an important part of the Earth's carbon cycle, are postulated to sequester a...

  14. The January 13, 2007, Kuril Islands Outer Rise Earthquake

    NASA Astrophysics Data System (ADS)

    Polet, J.; Thio, H. K.

    2007-12-01

    We will present the results of an investigation of the January 13, 2007, Kuril Islands Mw=8.1 normal faulting outer rise earthquake that occurred in close proximity of an Mw=8.3 interplate event that took place two months earlier. Our primary interest is in determining the depth extent of its rupture process through the modeling of seismic waveforms and tsunami data. This earthquake was one of the greatest outer rise earthquakes of the past century and is certainly the best recorded. We will put this event in the context of a larger framework of worldwide outer rise earthquake occurrence in the past 35 years, using a catalog that we created by applying a search algorithm, based on earthquake mechanism in combination with local subduction zone geometry, to the Global CMT catalog. The January 13 earthquake was followed by a unproductive aftershock sequence and preceded by a significant number of events in the outer rise area following the Mw=8.3 interplate event of December 2006. We will also show the results of a basic analysis of the temporal and spatial characteristics of both of these sequences.

  15. Rising Cost of Gasoline Pinches Students at Rural Community Colleges

    ERIC Educational Resources Information Center

    Sander, Libby

    2008-01-01

    Aware of the increasing burden of fuel costs on their students, administrators of rural community colleges are looking for ways to help students stay on track with their studies even as their monthly transportation bills rise. Two common tactics are increasing the number of online courses and offering block scheduling that allows students to pack…

  16. The Rise and Fall of the Australian DBA

    ERIC Educational Resources Information Center

    Kortt, Michael A.; Pervan, Simon J; Hogan, Owen

    2016-01-01

    Purpose: The purpose of this paper is to identify and discuss the drivers behind the rise and fall of the Australian Doctor of Business Administration (DBA) and to assess its future. Design/methodology/approach: Data covering the period 1993-2013 was sourced from the Commonwealth Department of Education and Training to provide a comprehensive…

  17. Rising above the Gathering Storm, Revisited: Rapidly Approaching Category 5

    ERIC Educational Resources Information Center

    National Academies Press, 2010

    2010-01-01

    In the face of so many daunting near-term challenges, U.S. government and industry are letting the crucial strategic issues of U.S. competitiveness slip below the surface. Five years ago, the National Academies prepared "Rising Above the Gathering Storm," a book that cautioned: "Without a renewed effort to bolster the foundations of…

  18. Punishing Kids: The Rise of the "Boot Camp"

    ERIC Educational Resources Information Center

    Mills, Martin; Pini, Barbara

    2015-01-01

    This paper is concerned with the rise of 'the boot camp' as a means of addressing "the problem of troubled youth" in contemporary industrialised nations such as Australia and the UK. Drawing on a corpus of publicly available material including press releases and policy documents, media reports, and programme websites, the paper…

  19. The Secular Rise in IQ: Giving Heterosis a Closer Look

    ERIC Educational Resources Information Center

    Mingroni, Michael A.

    2004-01-01

    Although most discussions today start from the assumption that the secular rise in IQ must be environmental in origin, three reasons warrant giving the genetic phenomenon heterosis a closer look as a potential cause. First, it easily accounts for both the high heritability and low shared environmental effects seen in IQ, findings that are…

  20. The Rise of the Corporate Mind in Composition Teaching.

    ERIC Educational Resources Information Center

    Buckley, William K.

    Most discussions concerning whether literature should be taught in the composition classroom have concentrated on the pedagogical theories of learning how to write, instead of the economic and political reasons for the initial separation of the two disciplines. To help make people more employable in the rising service economy universities have…

  1. For Cancer Patients, Pain May Rise as Finances Dwindle

    MedlinePlus

    ... nih.gov/medlineplus/news/fullstory_157508.html For Cancer Patients, Pain May Rise as Finances Dwindle Suffering can escalate ... policy. More Health News on: Cancer--Living with Cancer Pain Stress Recent Health News Related MedlinePlus Health Topics ...

  2. Rising to the Challenge: Meaningful Assessment of Student Learning

    ERIC Educational Resources Information Center

    Association of Public and Land-grant Universities, 2010

    2010-01-01

    "Rising to the Challenge: Meaningful Assessment of Student Learning" was envisioned in response to a 2007 request for proposals from the U.S. Department of Education's Fund for Improvement of Post Secondary Education (FIPSE). FIPSE called for national, consortial contributions to improving the knowledge and abilities to assess student learning for…

  3. Effects of a rise in base level on graded streams

    SciTech Connect

    Dickfoss, P.V. . Geology Dept.)

    1994-04-01

    What changes take place in a longitudinal river profile due to a rise in base level would seem to be a fundamental question in geomorphology, however, little has been accomplished toward answering this question, and the prevailing views are contradictory. Most authors say that a river will adjust its entire profile in response to a rise in base level. This misconception appears to have started in Elmo G. Harris' 1901 article, Effects of Dams and Like Obstructions in Silt-bearing Streams. The hypothesis became popular after publication of J. Hoover Mackin's classic 1948 paper, Concept of the Graded River. In the section Rise of Base Level'' Mackin explained that ''...the only generalization that can be made is that the new profile will be everywhere adjusted to the new prevailing conditions.'' Although Mackin's idea was a conceptual one, the concept has subsequently been taken literally. Contrary to this perception, the small amount of work that has been completed shows rivers will adjust their profiles only a short distance upstream from reservoir level. This may be due to the adjustment becoming infinitesimally small upstream and grading into the original profile so that the adjustment upstream is negligible. Unfortunately the misconception of stream aggradation in response to a rise in base level has prevailed for over 90 years and is widespread in the literature. Many textbooks, both introductory and advanced, from 1971 to the present, and some of the leading names in geomorphology have accepted the misconception without question.

  4. 21 CFR 137.180 - Self-rising flour.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., self-rising wheat flour, is an intimate mixture of flour, sodium bicarbonate, and one or more of the... sufficient quantity to neutralize the sodium bicarbonate. The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used. Subject to...

  5. 21 CFR 137.180 - Self-rising flour.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., self-rising wheat flour, is an intimate mixture of flour, sodium bicarbonate, and one or more of the... sufficient quantity to neutralize the sodium bicarbonate. The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used. Subject to...

  6. 21 CFR 137.180 - Self-rising flour.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., self-rising wheat flour, is an intimate mixture of flour, sodium bicarbonate, and one or more of the... sufficient quantity to neutralize the sodium bicarbonate. The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used. Subject to...

  7. 21 CFR 137.180 - Self-rising flour.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., self-rising wheat flour, is an intimate mixture of flour, sodium bicarbonate, and one or more of the... sufficient quantity to neutralize the sodium bicarbonate. The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used. Subject to...

  8. 21 CFR 137.180 - Self-rising flour.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., self-rising wheat flour, is an intimate mixture of flour, sodium bicarbonate, and one or more of the... sufficient quantity to neutralize the sodium bicarbonate. The combined weight of such acid-reacting substance and sodium bicarbonate is not more than 4.5 parts to each 100 parts of flour used. Subject to...

  9. Exhaust cloud rise and diffusion in the atmosphere

    NASA Technical Reports Server (NTRS)

    Chandler, M. W.; Chu, R. T.; Thayer, S. D.

    1971-01-01

    Analytical approach develops physical-mathematical model of rocket engine exhaust cloud rise, growth, and diffusion. Analytic derivations and resultant model apply to hot exhaust cloud study or industrial stack plumes, making work results applicable to air pollution. Model formulations apply to all exhaust cloud types and various atmospheric conditions.

  10. Reconsidering Low-Rising Intonation in American English.

    ERIC Educational Resources Information Center

    Levis, John M.

    2002-01-01

    Sought to determine whether two low-rising intonation contours should be accepted as distinct patterns in American English, alongside three other widely accepted contours. Dialogues varying only in their intonation contour were presented in a random order to 47 speakers of Midwestern American English. Subjects interpreted the meaning of the…

  11. Knowledge Work: The Rise of the Office Economy. Full Report.

    ERIC Educational Resources Information Center

    Doyle, Leonie; Kurth, Brian; Kerr, Ella

    The rise of the office economy and its impact on vocational education and training (VET) in Australia were examined by replicating the methodology used in Carnevale and Rose's U.S. study on the impact of the new office economy. Both studies took a functional approach to analyzing economic activities and the work force and focused primarily on…

  12. Managing Problems of Acceptability through High Rise-Fall Repetitions

    ERIC Educational Resources Information Center

    Benjamin, Trevor; Walker, Traci

    2013-01-01

    This article examines one of the ways in which matters of truth, appropriateness, and acceptability are raised and managed within the course of everyday conversation. Using the methodology of conversation analysis, we show that by repeating what another participant has said and doing so with a high rise-fall intonation contour, a speaker claims…

  13. Whither Opportunity? Rising Inequality, Schools, and Children's Life Chances

    ERIC Educational Resources Information Center

    Duncan, Greg J., Ed.; Murnane, Richard, Ed.

    2011-01-01

    As the incomes of affluent and poor families have diverged over the past three decades, so too has the educational performance of their children. But how exactly do the forces of rising inequality affect the educational attainment and life chances of low-income children? In "Whither Opportunity?" a distinguished team of economists, sociologists,…

  14. The rise (and fall?) of parental vaccine hesitancy

    PubMed Central

    Gowda, Charitha; Dempsey, Amanda F

    2013-01-01

    Parental vaccine hesitancy is a growing problem affecting the health of children and the larger population. This article describes the evolution of the vaccine hesitancy movement and the individual, vaccine-specific and societal factors contributing to this phenomenon. In addition, potential strategies to mitigate the rising tide of parent vaccine reluctance and refusal are discussed. PMID:23744504

  15. 11. Buttress rising above stream bed elevation. Concrete mixing plant ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Buttress rising above stream bed elevation. Concrete mixing plant is at right, west tower and placement tower boom are visible. Photographer unknown, November 24, 1926. Source: Ralph Pleasant. - Waddell Dam, On Agua Fria River, 35 miles northwest of Phoenix, Phoenix, Maricopa County, AZ

  16. Colleges' Debt Is Fed by Rising Bond Rates

    ERIC Educational Resources Information Center

    Wolverton, Brad

    2008-01-01

    Dozens of colleges and universities, including some of the country's wealthiest institutions, are facing a sharp rise in interest payments on a whopping mound of debt. About a third of the nearly 300 private institutions rated by Moody's Investors Service are financing more than half their debt with variable-rate bonds, some of whose rates have…

  17. Direct effects of rising atmospheric carbon dioxide on crop yields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rising atmospheric carbon dioxide concentration (CO2) in this century will alter crop yield quantity and quality. It is important to understand the magnitude of the expected changes and the mechanisms involved in crop responses to elevated CO2 in order to adapt our food systems to the committed chan...

  18. Suppressing the Morning Rise in Cortisol Impairs Free Recall

    ERIC Educational Resources Information Center

    Rimmele, Ulrike; Meier, Flurina; Lange, Tanja; Born, Jan

    2010-01-01

    Elevated glucocorticoid levels impair memory retrieval. We investigated whether retrieval under naturally elevated glucocorticoid levels, i.e., during the morning rise in cortisol can be improved by suppressing cortisol. In a crossover study 16 men retrieved emotional and neutral texts and pictures (learned 3 d earlier) 30 min after morning…

  19. Biogeochemical Modeling of the Second Rise of Atmospheric Oxygen

    NASA Astrophysics Data System (ADS)

    Smith, M.; Catling, D. C.; Claire, M.

    2014-12-01

    The second rise of atmospheric oxygen (~600 Ma) marked an increase of atmospheric pO2 from a poorly constrained value of 0.1% < pO2 < 10% of present atmospheric level (PAL) in the early and mid Proterozoic to >10%PAL1. The event is important because it ushered in the modern era of animal life. To understand the evolution of Earth's habitability, it is therefore key to understand the cause of this 2nd rise. Here, we quantitatively examine possible causes for the 2nd rise of oxygen. We use a biogeochemical box model2 originally developed to calculate the oxygen evolution before and after the 1st rise of oxygen (~2.4 Ga). The Claire et al. (2006) model calculates the evolution of atmospheric oxygen and methane given production and loss fluxes associated with the oxygen, carbon, and iron cycles. Because the model was unable to drive pO2 to end-Proterozoic levels, the authors suggested that another buffer, such as sulfur, is needed to explain the 2nd rise of oxygen. The sulfur and oxygen cycles are tied through various biogeochemical interactions; therefore, once sulfur (as sulfate) began to accumulate in Proterozoic oceans, it likely began to heavily influence the oxygen cycle. We have added a sulfur biogeochemical cycle to this model, enabling exploration of mechanisms that buffer pO2 at intermediate levels in the Proterozoic and fail to do so in the Phanerozoic. Preliminary results show evolution of oxygen and methane that are consistent with geologic proxies. However, the model-generated 2nd rise of oxygen is dependent upon sulfur fluxes that have uncertain magnitudes, so we will present the sensitivity of our results to model assumptions while constraining scenarios for the 2nd rise of atmospheric O2. In the future, we will also integrate isotopic fractionation effects, which will allow comparison with isotopic data from sedimentary sulfides, carbonates, and organic carbon. 1Canfield, C., 2014, Treatise on Geochemistry, 197 2Claire, M.W., et al., 2006, Geobiology

  20. Implications of Rising Sea Level on Everglades Restoration

    NASA Astrophysics Data System (ADS)

    Wanless, H. R.

    2008-05-01

    The strong likelihood of a significant rise in sea level during this century must be incorporated into the design of the Comprehensive Everglades Restoration Plan (CERP) and its execution. With a warming Arctic and increased wind shear in the waters adjacent to Antarctica, accelerated ice melt of both Greenland and Antarctica has begun. With positive feedbacks, this melt appears irreversible on the century scale. Scientists of the Miami-Dade County Climate Change Task Force project that a global rise of sea level of at least 0.9-1.5 meters (3-5 feet) will occur by the end of the century. This anticipated rise will diminish the value of CERP unless (a) the design thoroughly incorporates a realistic sea level rise scenario and (b) there is a refocus of CERP's design to optimize water flow for wetland-community peat growth with the purpose of retarding saline encroachment. The goals of Everglades restoration must become (1) to provide an increase in water flowing at a gradually increasing elevation to permit rapid accumulation of robust organic peat beneath the freshwater wetland and (2) to actively manage the coastal mangrove wetland (e.g., aid hurricane recovery) to help it maintain a robust upwards-building peat margin. If this is done, the central and northern Everglades may survive as a healthy wetland habitat and provide fresh groundwater resources well into the next century. Actively building freshwater and mangrove peat and a dependable supply of freshwater are both critical to retarding saline encroachment up the Everglades depression. Without these, a 1.5 meter rise in sea level could move saline water nearly to Lake Okeechobee. Critical research questions and changes in management need to be addressed for this to succeed. The communities and conditions for optimal freshwater peat buildup must be documented and demonstrated. New management strategies must be designed and maintained to encourage rapid recovery of mangrove forests destroyed by hurricanes