The retrospective binning method improves the consistency of phase binning in respiratory-gated PET/CT

NASA Astrophysics Data System (ADS)

Didierlaurent, D.; Ribes, S.; Batatia, H.; Jaudet, C.; Dierickx, L. O.; Zerdoud, S.; Brillouet, S.; Caselles, O.; Courbon, F.

2012-12-01

This study assesses the accuracy of prospective phase-gated PET/CT data binning and presents a retrospective data binning method that improves image quality and consistency. Respiratory signals from 17 patients who underwent 4D PET/CT were analysed to evaluate the reproducibility of temporal triggers used for the standard phase-based gating method. Breathing signals were reprocessed to implement retrospective PET data binning. The mean and standard deviation of time lags between automatic triggers provided by the Real-time Position Management (RPM, Varian) gating device and inhalation peaks derived from respiratory curves were computed for each patient. The total number of respiratory cycles available for 4D PET/CT according to the binning mode (prospective versus retrospective) was compared. The maximum standardized uptake value (SUVmax), biological tumour volume (BTV) and tumour trajectory measures were determined from the PET/CT images of five patients. Compared to retrospective binning (RB), prospective gating approach led to (i) a significant loss in breathing cycles (15%) and (ii) the inconsistency of data binning due to temporal dispersion of triggers (average 396 ms). Consequently, tumour characterization could be impacted. In retrospective mode, SUVmax was up to 27% higher, where no significant difference appeared in BTV. In addition, prospective mode gave an inconsistent spatial location of the tumour throughout the bins. Improved consistency with breathing patterns and greater motion amplitude of the tumour centroid were observed with retrospective mode. The detection of the tumour motion and trajectory was improved also for small temporal dispersion of triggers. This study shows that the binning mode could have a significant impact on 4D PET images. The consistency of triggers with breathing signals should be checked before clinical use of gated PET/CT images, and our RB method improves 4D PET/CT image quantification.

Role of zonal flow predator-prey oscillations in triggering the transition to H-mode confinement.

PubMed

Schmitz, L; Zeng, L; Rhodes, T L; Hillesheim, J C; Doyle, E J; Groebner, R J; Peebles, W A; Burrell, K H; Wang, G

2012-04-13

Direct evidence of zonal flow (ZF) predator-prey oscillations and the synergistic roles of ZF- and equilibrium E×B flow shear in triggering the low- to high-confinement (L- to H-mode) transition in the DIII-D tokamak is presented. Periodic turbulence suppression is first observed in a narrow layer at and just inside the separatrix when the shearing rate transiently exceeds the turbulence decorrelation rate. The final transition to H mode with sustained turbulence and transport reduction is controlled by equilibrium E×B shear due to the increasing ion pressure gradient.

Observation of the L-H confinement bifurcation triggered by a turbulence-driven shear flow in a tokamak plasma.

PubMed

Yan, Z; McKee, G R; Fonck, R; Gohil, P; Groebner, R J; Osborne, T H

2014-03-28

Comprehensive 2D turbulence and eddy flow velocity measurements on DIII-D demonstrate a rapidly increasing turbulence-driven shear flow that develops ∼100  μs prior to the low-confinement (L mode) to high-confinement (H mode) transition and appears to trigger it. These changes are localized to a narrow layer 1-2 cm inside the magnetic boundary. Increasing heating power increases the Reynolds stress, the energy transfer from turbulence to the poloidal flow, and the edge flow shearing rate that then exceeds the decorrelation rate, suppressing turbulence and triggering the transition.

Burst-mode optical label processor with ultralow power consumption.

PubMed

Ibrahim, Salah; Nakahara, Tatsushi; Ishikawa, Hiroshi; Takahashi, Ryo

2016-04-04

A novel label processor subsystem for 100-Gbps (25-Gbps × 4λs) burst-mode optical packets is developed, in which a highly energy-efficient method is pursued for extracting and interfacing the ultrafast packet-label to a CMOS-based processor where label recognition takes place. The method involves performing serial-to-parallel conversion for the label bits on a bit-by-bit basis by using an optoelectronic converter that is operated with a set of optical triggers generated in a burst-mode manner upon packet arrival. Here we present three key achievements that enabled a significant reduction in the total power consumption and latency of the whole subsystem; 1) based on a novel operation mechanism for providing amplification with bit-level selectivity, an optical trigger pulse generator, that consumes power for a very short duration upon packet arrival, is proposed and experimentally demonstrated, 2) the energy of optical triggers needed by the optoelectronic serial-to-parallel converter is reduced by utilizing a negative-polarity signal while employing an enhanced conversion scheme entitled the discharge-or-hold scheme, 3) the necessary optical trigger energy is further cut down by half by coupling the triggers through the chip's backside, whereas a novel lens-free packaging method is developed to enable a low-cost alignment process that works with simple visual observation.

Trigger mechanism for the abrupt loss of energetic ions in magnetically confined plasmas.

PubMed

Ida, K; Kobayashi, T; Yoshinuma, M; Akiyama, T; Tokuzawa, T; Tsuchiya, H; Itoh, K; Itoh, S-I

2018-02-12

Interaction between a quasi-stable stationary MHD mode and a tongue-shaped deformation is observed in the toroidal plasma with energetic particle driven MHD bursts. The quasi-stable stationary 1/1 MHD mode with interchange parity appears near the resonant rational surface of q = 1 between MHD bursts. The tongue-shaped deformation rapidly appears at the non-resonant non-rational surface as a localized large plasma displacement and then collapses (tongue event). It curbs the stationary 1/1 MHD mode and then triggers the collapse of energetic particle and magnetic field reconnection. The rotating 1/1 MHD mode with tearing parity at the q = 1 resonant surface, namely, the MHD burst, is excited after the tongue event.

Safety of the Wearable Cardioverter Defibrillator (WCD) in Patients with Implanted Pacemakers.

PubMed

Schmitt, Joern; Abaci, Guezine; Johnson, Victoria; Erkapic, Damir; Gemein, Christopher; Chasan, Ritvan; Weipert, Kay; Hamm, Christian W; Klein, Helmut U

2017-03-01

The wearable cardioverter defibrillator (WCD) is an important approach for better risk stratification, applied to patients considered to be at high risk of sudden arrhythmic death. Patients with implanted pacemakers may also become candidates for use of the WCD. However, there is a potential risk that pacemaker signals may mislead the WCD detection algorithm and cause inappropriate WCD shock delivery. The aim of the study was to test the impact of different types of pacing, various right ventricular (RV) lead positions, and pacing modes for potential misleading of the WCD detection algorithm. Sixty patients with implanted pacemakers received the WCD for a short time and each pacing mode (AAI, VVI, and DDD) was tested for at least 30 seconds in unipolar and bipolar pacing configuration. In case of triggering the WCD detection algorithm and starting the sequence of arrhythmia alarms, shock delivery was prevented by pushing of the response buttons. In six of 60 patients (10%), continuous unipolar pacing in DDD mode triggered the WCD detection algorithm. In no patient, triggering occurred with bipolar DDD pacing, unipolar and bipolar AAI, and VVI pacing. Triggering was independent of pacing amplitude, RV pacing lead position, and pulse generator implantation site. Unipolar DDD pacing bears a high risk of false triggering of the WCD detection algorithm. Other types of unipolar pacing and all bipolar pacing modes do not seem to mislead the WCD detection algorithm. Therefore, patients with no reprogrammable unipolar DDD pacing should not become candidates for the WCD. © 2016 Wiley Periodicals, Inc.

Conflict-Triggered Top-Down Control: Default Mode, Last Resort, or No Such Thing?

ERIC Educational Resources Information Center

Bugg, Julie M.

2014-01-01

The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control…

Electronics design of the RPC system for the OPERA muon spectrometer

NASA Astrophysics Data System (ADS)

Acquafredda, R.; Ambrosio, M.; Balsamo, E.; Barichello, G.; Bergnoli, A.; Consiglio, L.; Corradi, G.; dal Corso, F.; Felici, G.; Manea, C.; Masone, V.; Parascandolo, P.; Sorrentino, G.

2004-09-01

The present document describes the front-end electronics of the RPC system that instruments the magnet muon spectrometer of the OPERA experiment. The main task of the OPERA spectrometer is to provide particle tracking information for muon identification and simplify the matching between the Precision Trackers. As no trigger has been foreseen for the experiment, the spectrometer electronics must be self-triggered with single-plane readout capability. Moreover, precision time information must be added within each event frame for off-line reconstruction. The read-out electronics is made of three different stages: the Front-End Boards (FEBs) system, the Controller Boards (CBs) system and the Trigger Boards (TBs) system. The FEB system provides discrimination of the strip incoming signals; a FAST-OR output of the input signals is also available for trigger plane signal generation. FEB signals are acquired by the CB system that provides the zero suppression and manages the communication to the DAQ and Slow Control. A Trigger Board allows to operate in both self-trigger mode (the FEB's FAST-OR signal starts the plane acquisition) or in external-trigger mode (different conditions can be set on the FAST-OR signals generated from different planes).

Simulation of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

NASA Astrophysics Data System (ADS)

Meng, X. T.; Levin, D. S.; Chapman, J. W.; Zhou, B.

2016-09-01

The ATLAS Muon Spectrometer endcap thin-Resistive Plate Chamber trigger project compliments the New Small Wheel endcap Phase-1 upgrade for higher luminosity LHC operation. These new trigger chambers, located in a high rate region of ATLAS, will improve overall trigger acceptance and reduce the fake muon trigger incidence. These chambers must generate a low level muon trigger to be delivered to a remote high level processor within a stringent latency requirement of 43 bunch crossings (1075 ns). To help meet this requirement the High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by CERN Microelectronics group, has been proposed for the digitization of the fast front end detector signals. This paper investigates the HPTDC performance in the context of the overall muon trigger latency, employing detailed behavioral Verilog simulations in which the latency in triggerless mode is measured for a range of configurations and under realistic hit rate conditions. The simulation results show that various HPTDC operational configurations, including leading edge and pair measurement modes can provide high efficiency (>98%) to capture and digitize hits within a time interval satisfying the Phase-1 latency tolerance.

Theory-based model for the pedestal, edge stability and ELMs in tokamaks

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Bateman, G.; Brennan, D. P.; Schnack, D. D.; Snyder, P. B.; Voitsekhovitch, I.; Kritz, A. H.; Janeschitz, G.; Kruger, S.; Onjun, T.; Pacher, G. W.; Pacher, H. D.

2006-04-01

An improved model for triggering edge localized mode (ELM) crashes is developed for use within integrated modelling simulations of the pedestal and ELM cycles at the edge of H-mode tokamak plasmas. The new model is developed by using the BALOO, DCON and ELITE ideal MHD stability codes to derive parametric expressions for the ELM triggering threshold. The whole toroidal mode number spectrum is studied with these codes. The DCON code applies to low mode numbers, while the BALOO code applies to only high mode numbers and the ELITE code applies to intermediate and high mode numbers. The variables used in the parametric stability expressions are the normalized pressure gradient and the parallel current density, which drive ballooning and peeling modes. Two equilibria motivated by DIII-D geometry with different plasma triangularities are studied. It is found that the stable region in the high triangularity discharge covers a much larger region of parameter space than the corresponding stability region in the low triangularity discharge. The new ELM trigger model is used together with a previously developed model for pedestal formation and ELM crashes in the ASTRA integrated modelling code to follow the time evolution of the temperature profiles during ELM cycles. The ELM frequencies obtained in the simulations of low and high triangularity discharges are observed to increase with increasing heating power. There is a transition from second stability to first ballooning mode stability as the heating power is increased in the high triangularity simulations. The results from the ideal MHD stability codes are compared with results from the resistive MHD stability code NIMROD.

Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

NASA Astrophysics Data System (ADS)

Böning, Guido; Todica, Andrei; Vai, Alessandro; Lehner, Sebastian; Xiong, Guoming; Mille, Erik; Ilhan, Harun; la Fougère, Christian; Bartenstein, Peter; Hacker, Marcus

2013-11-01

The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [18F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [18F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group, we randomly deleted various fractions (5% to 60%) of contained trigger events to generate a corrupted group. The filter approach was capable to correct the corrupted group and yield functional parameters with no significant difference to the optimal gated group. We successfully demonstrated the potential of the fully reprocessing approach by applying it to the sub-optimal group, where the functional parameters were significantly improved after reprocessing (mean EF from 41% ± 16% to 60% ± 13%). When applied to the optimal gated group the fully reprocessing approach did not alter the functional parameters significantly (mean EF from 64% ± 8% to 64 ± 7%). This work presents methods to determine and quantify erroneous gating in small animal gated [18F]-FDG PET scans. We demonstrate the importance of a quality check for cardiac triggering contained in PET list-mode data and the benefit of optionally reprocessing the fully recorded physiological information to retrospectively modify or fully replace the cardiac triggering in PET list-mode data. We aim to provide a preliminary guideline of how to proceed in the presence of errors and demonstrate that offline reprocessing by filtering erroneous trigger events and retrospective gating by ECG processing is feasible. Future work will focus on the extension by additional QC methods, which may exploit the amplitude of trigger events and ECG signal by means of pattern recognition. Furthermore, we aim to transfer the proposed QC methods and the fully reprocessing approach to human myocardial PET/CT.

Derivation of a respiration trigger signal in small animal list-mode PET based on respiration-induced variations of the ECG signal.

PubMed

Todica, Andrei; Lehner, Sebastian; Wang, Hao; Zacherl, Mathias J; Nekolla, Katharina; Mille, Erik; Xiong, Guoming; Bartenstein, Peter; la Fougère, Christian; Hacker, Marcus; Böning, Guido

2016-02-01

Raw PET list-mode data contains motion artifacts causing image blurring and decreased spatial resolution. Unless corrected, this leads to underestimation of the tracer uptake and overestimation of the lesion size, as well as inaccuracies with regard to left ventricular volume and ejection fraction (LVEF), especially in small animal imaging. A respiratory trigger signal from respiration-induced variations in the electro-cardiogram (ECG) was detected. Original and revised list-mode PET data were used for calculation of left ventricular function parameters using both respiratory gating techniques. For adequately triggered datasets we saw no difference in mean respiratory cycle period between the reference standard (RRS) and the ECG-based (ERS) methods (1120 ± 159 ms vs 1120 ± 159 ms; P = n.s.). While the ECG-based method showed somewhat higher signal noise (66 ± 22 ms vs 51 ± 29 ms; P < .001), both respiratory triggering techniques yielded similar estimates for EDV, ESV, LVEF (RRS: 387 ± 56 µL, 162 ± 34 µL, 59 ± 5%; ERS: 389 ± 59 µL, 163 ± 35 µL, 59 ± 4%; P = n.s.). This study showed that respiratory gating signals can be accurately derived from cardiac trigger information alone, without the additional requirement for dedicated measurement of the respiratory motion in rats.

Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pushkarev, A. I., E-mail: aipush@mail.ru; Isakova, Y. I.; Khaylov, I. P.

The paper presents the results of studies on shot-to-shot performance of a water Blumlein pulse forming line of 1–1.2 kJ of stored energy. The experiments were carried using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (150 ns, 250–300 kV) and bipolar-pulse mode with the first negative (300–600 ns, 100–150 kV) followed by a second positive (120 ns, 250–300 kV) pulse. The analysis was carried out for two cases when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. It was found that in bipolar pulse mode themore » shot-to-shot variation in breakdown voltage of a preliminary spark gap is small, the standard deviation (1σ) does not exceed 2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar-pulse and unipolar pulse mode is 3–4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we changed the regime of its operation from a self-triggered mode to an externally triggered mode. In the new arrangement the first voltage pulse at the output of Blumlein was used to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a good stability of breakdown voltage and thus allowed to stabilize the duration of the first pulse. The standard deviation of the breakdown voltage and duration of the first pulse did not exceed 2% for a set of 50 pulses. The externally triggered mode of the main gap operation also allowed for a decrease in the charging voltage of the Blumlein to a 0.9–0.95 of self-breakdown voltage of the main spark gap while the energy stored in Marx generator was decreased from 4 kJ to 2.5 kJ. At the same time the energy stored in Blumlein remained the same.« less

Effect of nonlinear energy transport on neoclassical tearing mode stability in tokamak plasmas

NASA Astrophysics Data System (ADS)

Fitzpatrick, Richard

2017-05-01

An investigation is made into the effect of the reduction in anomalous perpendicular electron heat transport inside the separatrix of a magnetic island chain associated with a neoclassical tearing mode in a tokamak plasma, due to the flattening of the electron temperature profile in this region, on the overall stability of the mode. The onset of the neoclassical tearing mode is governed by the ratio of the divergences of the parallel and perpendicular electron heat fluxes in the vicinity of the island chain. By increasing the degree of transport reduction, the onset of the mode, as the divergence ratio is gradually increased, can be made more and more abrupt. Eventually, when the degree of transport reduction passes a certain critical value, the onset of the neoclassical tearing mode becomes discontinuous. In other words, when some critical value of the divergence ratio is reached, there is a sudden bifurcation to a branch of neoclassical tearing mode solutions. Moreover, once this bifurcation has been triggered, the divergence ratio must be reduced by a substantial factor to trigger the inverse bifurcation.

The non-resonant kink modes triggering strong sawtooth-like crashes in the EAST tokamak

NASA Astrophysics Data System (ADS)

Li, Erzhong; Igochine, V.; Dumbrajs, O.; Xu, L.; Chen, K.; Shi, T.; Hu, L.

2014-12-01

Evolution of the safety factor (q) profile during L-H transitions in the Experimental Advanced Superconducting Tokamak (EAST) was accompanied by strong core crashes prior to regular sawtooth behavior. These crashes appeared in the absence of q = 1 (q is the safety factor) rational surface inside the plasma. Analysis indicates that the m/n = 2/1 tearing mode is destabilized and phase-locked with the m/n = 1/1 non-resonant kink mode (the q = 1 rational surface is absent) due to the self-consistent evolution of plasma profiles as the L-H transition occurs (m and n are the poloidal and toroidal mode numbers, respectively). The growing m/n = 1/1 mode destabilizes the m/n = 2/2 kink mode which eventually triggers the strong crash due to an anomalous heat conductivity, as predicted by the transport model of stochastic magnetic fields using experimental parameters. It is also shown that the magnetic topology changes with the amplitude of m/n = 2/2 mode and the value of center safety factor in a reasonable range.

Tearing modes induced by perpendicular electron cyclotron resonance heating in the KSTAR tokamak

NASA Astrophysics Data System (ADS)

Lee, H. H.; Lee, S. G.; Seol, J.; Aydemir, A. Y.; Bae, C.; Yoo, J. W.; Na, Y. S.; Kim, H. S.; Woo, M. H.; Kim, J.; Joung, M.; You, K. I.; Park, B. H.

2014-10-01

This paper reports on experimental evidence that shows perpendicular electron cyclotron resonance heating (ECRH) can trigger classical tearing modes when deposited near a rational flux surface. The complex evolution of an m = 2 island is followed during current ramp-up in KSTAR plasmas, from its initial onset as the rational surface enters the ECRH resonance layer to its eventual lock on the wall after the rational surface leaves the layer. Stability analysis coupled to a transport calculation of the current profile with ECRH shows that the perpendicular ECRH may play a significant role in triggering and destabilizing classical m = 2 tearing modes, in agreement with our experimental observation.

The Acoustic Trigger to Conceptualization: An Hypothesis Concerning the Role of the Spoken Word in the Development of Higher Mental Processes.

ERIC Educational Resources Information Center

Dance, Frank E. X.

One of many aspects of the linguistic centrality of the spoken word is the "acoustic trigger" to conceptualization, the most significant primal trigger in human beings, which when activated results in contrast and comparison leading to symbolic conceptualization. The oral/aural mode, or vocal production and acoustic perception, is developmentally…

Superburst oscillations: ocean and crustal modes excited by carbon-triggered type I X-ray bursts

NASA Astrophysics Data System (ADS)

Chambers, F. R. N.; Watts, A. L.; Cavecchi, Y.; Garcia, F.; Keek, L.

2018-07-01

Accreting neutron stars (NS) can exhibit high frequency modulations in their light curves during thermonuclear X-ray bursts, known as burst oscillations. The frequencies can be offset from the spin frequency of the NS by several Hz, and can drift by 1-3 Hz. One possible explanation is a mode in the bursting ocean, the frequency of which would decrease (in the rotating frame) as the burst cools, hence explaining the drifts. Most burst oscillations have been observed during the H/He-triggered bursts; however there has been one observation of oscillations during a superburst; hours long Type I X-ray bursts caused by unstable carbon burning deeper in the ocean. This paper calculates the frequency evolution of an oceanic r mode during a superburst. The rotating frame frequency varies during the burst from 4-14 Hz and is sensitive to the background parameters, in particular the temperature of the ocean and ignition depth. This calculation is compared to the superburst oscillations observed on 4U-1636-536. The predicted mode frequencies (˜10 Hz) would require a spin frequency of ˜592 Hz to match observations; 6 Hz higher than the spin inferred from an oceanic r-mode model for the H/He-triggered burst oscillations. This model also overpredicts the frequency drift during the superburst by 90 per cent.

Superburst oscillations: ocean and crustal modes excited by Carbon-triggered Type I X-ray bursts

NASA Astrophysics Data System (ADS)

Chambers, F. R. N.; Watts, A. L.; Cavecchi, Y.; Garcia, F.; Keek, L.

2018-04-01

Accreting neutron stars (NS) can exhibit high frequency modulations in their lightcurves during thermonuclear X-ray bursts, known as burst oscillations. The frequencies can be offset from the spin frequency of the NS by several Hz, and can drift by 1-3 Hz. One possible explanation is a mode in the bursting ocean, the frequency of which would decrease (in the rotating frame) as the burst cools, hence explaining the drifts. Most burst oscillations have been observed during H/He triggered bursts, however there has been one observation of oscillations during a superburst; hours' long Type I X-ray bursts caused by unstable carbon burning deeper in the ocean. This paper calculates the frequency evolution of an oceanic r-mode during a superburst. The rotating frame frequency varies during the burst from 4 - 14 Hz, and is sensitive to the background parameters, in particular the temperature of the ocean and ignition depth. This calculation is compared to the superburst oscillations observed on 4U-1636-536. The predicted mode frequencies (˜10 Hz) would require a spin frequency of ˜592 Hz to match observations; 6 Hz higher than the spin inferred from an oceanic r-mode model for the H/He triggered burst oscillations. This model also over-predicts the frequency drift during the superburst by 90%.

Discovery of multiple, ionization-created CS{sub 2} anions and a new mode of operation for drift chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snowden-Ifft, Daniel P.

2014-01-15

This paper focuses on the surprising discovery of multiple species of ionization-created CS{sub 2} anions in gas mixtures containing electronegative CS{sub 2} and O{sub 2}, identified by their slightly different drift velocities. Data are presented to understand the formation mechanism and identity of these new anions. Regardless of the micro-physics, however, this discovery offers a new, trigger-less mode of operation for the drift chambers. A demonstration of trigger-less operation is presented.

Convective Excitation of Inertial Modes in Binary Neutron Star Mergers

NASA Astrophysics Data System (ADS)

De Pietri, Roberto; Feo, Alessandra; Font, José A.; Löffler, Frank; Maione, Francesco; Pasquali, Michele; Stergioulas, Nikolaos

2018-06-01

We present the first very long-term simulations (extending up to ˜140 ms after merger) of binary neutron star mergers with piecewise polytropic equations of state and in full general relativity. Our simulations reveal that, at a time of 30-50 ms after merger, parts of the star become convectively unstable, which triggers the excitation of inertial modes. The excited inertial modes are sustained up to several tens of milliseconds and are potentially observable by the planned third-generation gravitational-wave detectors at frequencies of a few kilohertz. Since inertial modes depend on the rotation rate of the star and they are triggered by a convective instability in the postmerger remnant, their detection in gravitational waves will provide a unique opportunity to probe the rotational and thermal state of the merger remnant. In addition, our findings have implications for the long-term evolution and stability of binary neutron star remnants.

Linear analysis of active-medium two-beam accelerator

NASA Astrophysics Data System (ADS)

Voin, Miron; Schächter, Levi

2015-07-01

We present detailed development of the linear theory of wakefield amplification by active medium and its possible application to a two-beam accelerator (TBA) is discussed. A relativistic train of triggering microbunches traveling along a vacuum channel in an active medium confined by a cylindrical waveguide excites Cherenkov wake in the medium. The wake is a superposition of azimuthally symmetric transverse magnetic modes propagating along a confining waveguide, with a phase velocity equal to the velocity of the triggering bunches. The structure may be designed in such a way that the frequency of one of the modes is close to active-medium resonant frequency, resulting in amplification of the former and domination of a single mode far behind the trigger bunches. Another electron bunch placed in proper phase with the amplified wakefield may be accelerated by the latter. Importantly, the energy for acceleration is provided by the active medium and not the drive bunch as in a traditional TBA. Based on a simplified model, we analyze extensively the impact of various parameters on the wakefield amplification process.

Influences of Duration of Inspiratory Effort, Respiratory Mechanics, and Ventilator Type on Asynchrony With Pressure Support and Proportional Assist Ventilation.

PubMed

Vasconcelos, Renata S; Sales, Raquel P; Melo, Luíz H de P; Marinho, Liégina S; Bastos, Vasco Pd; Nogueira, Andréa da Nc; Ferreira, Juliana C; Holanda, Marcelo A

2017-05-01

Pressure support ventilation (PSV) is often associated with patient-ventilator asynchrony. Proportional assist ventilation (PAV) offers inspiratory assistance proportional to patient effort, minimizing patient-ventilator asynchrony. The objective of this study was to evaluate the influence of respiratory mechanics and patient effort on patient-ventilator asynchrony during PSV and PAV plus (PAV+). We used a mechanical lung simulator and studied 3 respiratory mechanics profiles (normal, obstructive, and restrictive), with variations in the duration of inspiratory effort: 0.5, 1.0, 1.5, and 2.0 s. The Auto-Trak system was studied in ventilators when available. Outcome measures included inspiratory trigger delay, expiratory trigger asynchrony, and tidal volume (V T ). Inspiratory trigger delay was greater in the obstructive respiratory mechanics profile and greatest with a effort of 2.0 s (160 ms); cycling asynchrony, particularly delayed cycling, was common in the obstructive profile, whereas the restrictive profile was associated with premature cycling. In comparison with PSV, PAV+ improved patient-ventilator synchrony, with a shorter triggering delay (28 ms vs 116 ms) and no cycling asynchrony in the restrictive profile. V T was lower with PAV+ than with PSV (630 mL vs 837 mL), as it was with the single-limb circuit ventilator (570 mL vs 837 mL). PAV+ mode was associated with longer cycling delays than were the other ventilation modes, especially for the obstructive profile and higher effort values. Auto-Trak eliminated automatic triggering. Mechanical ventilation asynchrony was influenced by effort, respiratory mechanics, ventilator type, and ventilation mode. In PSV mode, delayed cycling was associated with shorter effort in obstructive respiratory mechanics profiles, whereas premature cycling was more common with longer effort and a restrictive profile. PAV+ prevented premature cycling but not delayed cycling, especially in obstructive respiratory mechanics profiles, and it was associated with a lower V T . Copyright © 2017 by Daedalus Enterprises.

Pulsed laser triggered high speed microfluidic fluorescence activated cell sorter†‡

PubMed Central

Wu, Ting-Hsiang; Chen, Yue; Park, Sung-Yong; Hong, Jason; Teslaa, Tara; Zhong, Jiang F.; Di Carlo, Dino; Teitell, Michael A.

2014-01-01

We report a high speed and high purity pulsed laser triggered fluorescence activated cell sorter (PLACS) with a sorting throughput up to 20 000 mammalian cells s−1 with 37% sorting purity, 90% cell viability in enrichment mode, and >90% purity in high purity mode at 1500 cells s−1 or 3000 beads s−1. Fast switching (30 μs) and a small perturbation volume (~90 pL) is achieved by a unique sorting mechanism in which explosive vapor bubbles are generated using focused laser pulses in a single layer microfluidic PDMS channel. PMID:22361780

Iron Alkynyl Helicenes: Redox-Triggered Chiroptical Tuning in the IR and Near-IR Spectral Regions and Suitable for Telecommunications Applications.

PubMed

Shen, Chengshuo; Loas, Goulc'hen; Srebro-Hooper, Monika; Vanthuyne, Nicolas; Toupet, Loïc; Cador, Olivier; Paul, Frédéric; López Navarrete, Juan T; Ramírez, Francisco J; Nieto-Ortega, Belén; Casado, Juan; Autschbach, Jochen; Vallet, Marc; Crassous, Jeanne

2016-07-04

The combination of a bis-alkynyl-helicene moiety with two iron centers leads to novel electroactive species displaying unprecedented redox-triggered chiroptical switching. Upon oxidation, strong changes of vibrational modes (either local or extended coupled modes) are detected by vibrational circular dichroism and Raman optical activity. Remarkably, the sign of the optical rotation at 1.54 µm (that is, at wavelengths typically used for telecommunications) changes upon oxidation while the topology and stereochemistry of the helicene remain unchanged. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of asymmetric magnetic perturbation on the nonlinear evolution of double tearing modes

NASA Astrophysics Data System (ADS)

Xiong, G. Z.; Wang, L.; Li, X. Q.; Liu, H. F.; Tang, C. J.; Huang, J.; Zhang, X.; Wang, X. Q.

2017-06-01

The effects of asymmetric magnetic perturbation on the triggering and evolution of double tearing modes (DTMs) are investigated using nonlinear magnetohydrodynamics simulations in a slab geometry. We find that for reversed magnetic shear plasmas the resistive reconnection process induced by the initial perturbation at one rational surface can drive a new island at the other rational surface with the same mode number. The four typical states of the mode for the time evolution are found, and include: (i) a linear growth stage; (ii) a linear/nonlinear stable stage; (iii) an interactively driving stage; and (iv) a symmetric DTM stage. These differ from previous simulation results. Moreover, nonlinear DTM growth is found to strongly depend on the asymmetric magnetic perturbation, particularly in the early nonlinear phase. The initial perturbation strength scale of island width suggests that the left island enters into a Sweet-Parker growth process when the right island is sufficiently large to effectively drive the other. These results predict that although externally applied magnetic perturbations can suppress the neoclassical tearing mode they can also trigger new instabilities such as asymmetric DTMs.

Differential T cell response against BK virus regulatory and structural antigens: A viral dynamics modelling approach.

PubMed

Blazquez-Navarro, Arturo; Schachtner, Thomas; Stervbo, Ulrik; Sefrin, Anett; Stein, Maik; Westhoff, Timm H; Reinke, Petra; Klipp, Edda; Babel, Nina; Neumann, Avidan U; Or-Guil, Michal

2018-05-01

BK virus (BKV) associated nephropathy affects 1-10% of kidney transplant recipients, leading to graft failure in about 50% of cases. Immune responses against different BKV antigens have been shown to have a prognostic value for disease development. Data currently suggest that the structural antigens and regulatory antigens of BKV might each trigger a different mode of action of the immune response. To study the influence of different modes of action of the cellular immune response on BKV clearance dynamics, we have analysed the kinetics of BKV plasma load and anti-BKV T cell response (Elispot) in six patients with BKV associated nephropathy using ODE modelling. The results show that only a small number of hypotheses on the mode of action are compatible with the empirical data. The hypothesis with the highest empirical support is that structural antigens trigger blocking of virus production from infected cells, whereas regulatory antigens trigger an acceleration of death of infected cells. These differential modes of action could be important for our understanding of BKV resolution, as according to the hypothesis, only regulatory antigens would trigger a fast and continuous clearance of the viral load. Other hypotheses showed a lower degree of empirical support, but could potentially explain the clearing mechanisms of individual patients. Our results highlight the heterogeneity of the dynamics, including the delay between immune response against structural versus regulatory antigens, and its relevance for BKV clearance. Our modelling approach is the first that studies the process of BKV clearance by bringing together viral and immune kinetics and can provide a framework for personalised hypotheses generation on the interrelations between cellular immunity and viral dynamics.

Lithium granule ablation and penetration during ELM pacing experiments at DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunsford, R.; Bortolon, A.; Roquemore, A. L.

At DIII-D, lithium granules were radially injected into the plasma at the outer midplane to trigger and pace edge localized modes (ELMs). Granules ranging in size from 300 to 1000 microns were horizontally launched into H-mode discharges with velocities near 100 m/s, and granule to granule injection frequencies less than 500 Hz. While the smaller granules were only successful in triggering ELMs approximately 20% of the time, the larger granules regularly demonstrated ELM triggering efficiencies of greater than 80%. A fast visible camera looking along the axis of injection observed the ablation of the lithium granules. We used the durationmore » of ablation as a benchmark for a neutral gas shielding calculation, and approximated the ablation rate and mass deposition location for the various size granules, using measured edge plasma profiles as inputs. In conclusion, this calculation suggests that the low triggering efficiency of the smaller granules is due to the inability of these granules to traverse the steep edge pressure gradient region and reach the top of the pedestal prior to full ablation.« less

Whistler-triggered chorus emissions observed during daytime at low latitude ground station Jammu

NASA Astrophysics Data System (ADS)

Pratap Patel, Ravindra; Singh, K. K.; Singh, A. K.; Singh, R. P.

In this paper, we present whistler-triggered chorus emission recorded during daytime at low latitude ground station Jammu (geomag. Lat. = 22 degree 26 minute N; L = 1.17) during the period from 1996 to 2003. After analysis of the eight years collected data, we found out 29 events, which are definitely identified as chorus emission triggered by whistlers. During the observation period the magnetic activity is high. Analysis shows that the whistlers have propagated along the geomagnetic field line having L-values lying between L = 1.9 and 4.4. These waves could have propagated along the geomagnetic field lines either in ducted mode or pro-longitudinal mode. The measured relative intensity of the triggered emission and whistler wave is approximately the same and also varies from one event to another. It is proposed that these waves are generated through a process of wave-particle interaction and wave-wave interactions. Related parameters of this interaction are computed for different L-value and wave amplitude. With the help of dynamic spectra of these emissions, the proposed mechanisms are explained.

Latency study of the High Performance Time to Digital Converter for the ATLAS Muon Spectrometer trigger upgrade

NASA Astrophysics Data System (ADS)

Meng, X. T.; Levin, D. S.; Chapman, J. W.; Li, D. C.; Yao, Z. E.; Zhou, B.

2017-02-01

The High Performance Time to Digital Converter (HPTDC), a multi-channel ASIC designed by the CERN Microelectronics group, has been proposed for the digitization of the thin-Resistive Plate Chambers (tRPC) in the ATLAS Muon Spectrometer Phase-1 upgrade project. These chambers, to be staged for higher luminosity LHC operation, will increase trigger acceptance and reduce or eliminate the fake muon trigger rates in the barrel-endcap transition region, corresponding to pseudo-rapidity range 1<|η|<1.3. Low level trigger candidates must be flagged within a maximum latency of 1075 ns, thus imposing stringent signal processing time performance requirements on the readout system in general, and on the digitization electronics in particular. This paper investigates the HPTDC signal latency performance based on a specially designed evaluation board coupled with an external FPGA evaluation board, when operated in triggerless mode, and under hit rate conditions expected in Phase-I. This hardware based study confirms previous simulations and demonstrates that the HPTDC in triggerless operation satisfies the digitization timing requirements in both leading edge and pair modes.

Lithium granule ablation and penetration during ELM pacing experiments at DIII-D

DOE PAGES

Lunsford, R.; Bortolon, A.; Roquemore, A. L.; ...

2016-05-25

At DIII-D, lithium granules were radially injected into the plasma at the outer midplane to trigger and pace edge localized modes (ELMs). Granules ranging in size from 300 to 1000 microns were horizontally launched into H-mode discharges with velocities near 100 m/s, and granule to granule injection frequencies less than 500 Hz. While the smaller granules were only successful in triggering ELMs approximately 20% of the time, the larger granules regularly demonstrated ELM triggering efficiencies of greater than 80%. A fast visible camera looking along the axis of injection observed the ablation of the lithium granules. We used the durationmore » of ablation as a benchmark for a neutral gas shielding calculation, and approximated the ablation rate and mass deposition location for the various size granules, using measured edge plasma profiles as inputs. In conclusion, this calculation suggests that the low triggering efficiency of the smaller granules is due to the inability of these granules to traverse the steep edge pressure gradient region and reach the top of the pedestal prior to full ablation.« less

Progress in understanding the enhanced pedestal H-mode in NSTX

DOE PAGES

Gerhardt, S. P.; Canik, J. M.; Maingi, R.; ...

2014-08-01

The paper describes the enhanced pedestal (EP) H-mode observed in the National Spherical Torus Experiment (NSTX). The defining characteristics of EP H-mode are given, namely i)transition after the L- to H-mode transition, ii) region of very steep ion temperature gradient, and iii) associated region of strong rotational shear. A newly observed long-pulse EP H-mode example shows quiescent behavior for as long as the heating and current drive sources are maintained. Cases are shown where the region of steep ion temperature gradient is located at the very edge, and cases where it is shifted up to 10 cm inward from themore » plasma edge; these cases are united by a common dependence of the ion temperature gradient on the toroidal rotation frequency shear. EP H-mode examples have been observed across a wide range of q95 and pedestal collisionality. No strong changes in the fluctuation amplitudes have been observed following the eP H-mode transition, and transport analysis indicates that the ion t hermal transport is comparable to or less than anticipated from a simple neoclassical transport model. Cases are shown where EP H-modes were reliably generated, through these low-q95 examples were difficult to sustain. A case where an externally triggered ELM precipitates the transition to EP H-mode is also shown, though an initial experiment designed to trigger EP-H-modes in this fashion was successful.« less

A field programmable gate array unit for the diagnosis and control of neoclassical tearing modes on MAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Gorman, T.; Gibson, K. J.; Snape, J. A.

2012-10-15

A real-time system has been developed to trigger both the MAST Thomson scattering (TS) system and the plasma control system on the phase and amplitude of neoclassical tearing modes (NTMs), extending the capabilities of the original system. This triggering system determines the phase and amplitude of a given NTM using magnetic coils at different toroidal locations. Real-time processing of the raw magnetic data occurs on a low cost field programmable gate array (FPGA) based unit which permits triggering of the TS lasers on specific amplitudes and phases of NTM evolution. The MAST plasma control system can receive a separate triggermore » from the FPGA unit that initiates a vertical shift of the MAST magnetic axis. Such shifts have fully removed m/n= 2/1 NTMs instabilities on a number of MAST discharges.« less

Space-time evolution of ejected plasma for the triggering of gas switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Shanhong, E-mail: liushanhong108098@163.com; Liu, Xuandong; Shen, Xi

2016-06-15

Ejected plasma has been widely applied to the discharge process of gas spark switches as a trigger technology, and the development process of ejected plasma has a direct and important effect on the discharge characteristics of gas switches. In this paper, both the injection characteristics and space-time evolution of ejected plasma for the triggering of gas spark switch with different stored energies, pulse polarities, and pressures are studied. The discharge characteristics and breakdown process of a gas switch ignited by ejected plasma under different working coefficients are also discussed briefly. The results show that stored energy has significant influence onmore » the characteristics of ejected plasma. With the increase of stored energy, the propulsion mode of ejected plasma in the axial direction transforms from “plasmoid” to “plasma flow,” and the distribution of the ejected plasma goes through “cloud,” “core-cloud,” and “branch” in sequence. The velocity of ejected plasma under negative pulse polarity is obviously higher than that under positive pulse polarity, especially at the very beginning time. The radial dimensions of ejected plasma under two kinds of pulse polarities follow the similar varying pattern over time, which increase first and then decrease, assuming an inverted “U”-shaped curve. With the increase of pressure, the velocity of ejected plasma significantly decreases and the “branch” channels droop earlier. Applying the ejected plasma to the triggering of a gas switch, the switch can be triggered reliably in a much wide working coefficient range of 10%–90%. With the increase of working coefficient, the breakdown process of the switch translates from slow working mode to fast working mode, and the delay time reduces from tens of μs to hundreds of ns.« less

Reduction of ELM Intensity on DIII-D by On-demand Triggering With High Frequency Pellet Injection and Implications for ITER

NASA Astrophysics Data System (ADS)

Baylor, L. R.

2012-10-01

Deuterium pellet injection was used on the DIII-D tokamak to successfully demonstrate for the first time the on-demand triggering of ELMs at a 10x higher rate, and with much smaller intensity, than natural edge localized modes (ELMs). The triggering of small ELMs by high frequency pellet injection has been proposed as a method to prevent large ELMs that can erode the ITER plasma facing components [1]. The demonstration was made by injecting slow (<200 m/s) 1.3 mm diameter deuterium pellets at 60 Hz from the low field side in an ITER similar plasma with 5 Hz natural ELM frequency. The input power was only slightly above the H-mode threshold. Similar non-pellet discharges had ELM energy losses up to 55 kJ (˜8% of total stored energy), while the case with pellets demonstrated ELMs with an average energy loss less than 3 kJ (<1% of the total). Total divertor ELM heat flux was reduced by more than a factor of 10. Central accumulation of Ni was significantly reduced in the pellet triggered ELM case. No significant increase in density or decrease in energy confinement was observed. Stability analysis of these discharges shows that the pedestal parameters are approaching the peeling unstable region just before a natural ELM crash. In the rapid pellet small ELM case, the pedestal conditions are well within the stable region with a narrower pedestal width observed. This narrower width is consistent with a picture in which the pellets are triggering the ELMs before the width expands to the critical ELM width. Nonlinear MHD simulations of the pellet ELM triggering show destabilization of ballooning modes by a local pressure perturbation. The implications of these results for pellet ELM pacing in ITER will be discussed. 6pt [1] P.T. Lang et al., Nucl. Fusion 44, 665 (2004).

Pulse transmission receiver with higher-order time derivative pulse generator

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-08-12

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a front-end amplification/processing circuit; a synchronization circuit coupled to the front-end amplification/processing circuit; a clock coupled to the synchronization circuit; a trigger signal generator coupled to the clock; and at least one higher-order time derivative pulse generator coupled to the trigger signal generator. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Key Physiological Parameters Dictate Triggering of Activity-Dependent Bulk Endocytosis in Hippocampal Synapses

PubMed Central

Wenzel, Eva M.; Morton, Andrew; Ebert, Katrin; Welzel, Oliver; Kornhuber, Johannes; Cousin, Michael A.; Groemer, Teja W.

2012-01-01

To maintain neurotransmission in central neurons, several mechanisms are employed to retrieve synaptically exocytosed membrane. The two major modes of synaptic vesicle (SV) retrieval are clathrin-mediated endocytosis and activity-dependent bulk endocytosis (ADBE). ADBE is the dominant SV retrieval mode during intense stimulation, however the precise physiological conditions that trigger this mode are not resolved. To determine these parameters we manipulated rat hippocampal neurons using a wide spectrum of stimuli by varying both the pattern and duration of stimulation. Using live-cell fluorescence imaging and electron microscopy approaches, we established that stimulation frequency, rather than the stimulation load, was critical in the triggering of ADBE. Thus two hundred action potentials, when delivered at high frequency, were sufficient to induce near maximal bulk formation. Furthermore we observed a strong correlation between SV pool size and ability to perform ADBE. We also identified that inhibitory nerve terminals were more likely to utilize ADBE and had a larger SV recycling pool. Thus ADBE in hippocampal synaptic terminals is tightly coupled to stimulation frequency and is more likely to occur in terminals with large SV pools. These results implicate ADBE as a key modulator of both hippocampal neurotransmission and plasticity. PMID:22675521

On the observations of unique low latitude whistler-triggered VLF/ELF emissions

NASA Astrophysics Data System (ADS)

Altaf, M.; Singh, K. K.; Singh, A. K.; Lalmani

A detailed analysis of the VLF/ELF wave data obtained during a whistler campaign under All India Coordinated Program of Ionosphere Thermosphere Studies (AICPITS) at our low latitude Indian ground station Jammu (geomag. lat. = 22° 26‧ N, L = 1.17) has yielded two types of unusual and unique whistler-triggered VLF/ELF emissions. These include (1) whistler-triggered hook emissions and (2) whistler-triggered long enduring discrete chorus riser emissions in VLF/ELF frequency range during night time. Such types of whistler-triggered emissions have not been reported earlier from any of the ground observations at low latitudes. In the present study, the observed characteristics of these emissions are described and interpreted. Dispersion analysis of these emissions show that the whistlers as well as emissions have propagated along a higher geomagnetic field line path with L-values lying ∼L = 4, suggesting that these triggered emissions are to be regarded as mid-latitude emissions. These waves could have propagated along the geomagnetic field lines either in a ducted mode or in a pro-longitudinal (PL) mode. The measured intensity of the triggered emissions is almost equal to that of the source waves and does not vary throughout the period of observation on that day. It is speculated that these emissions may have been generated through a process of resonant interaction of the whistler waves with energetic electrons. Parameters related to this interaction are computed for different values of L and wave amplitude. The proposed mechanism explains some aspects of the dynamic spectra.

Cardiac Arrhythmia and Injury Induced in Rats by Burst and Pulsed Mode Ultrasound with Gas Body Contrast Agent

PubMed Central

Miller, Douglas L.; Dou, Chunyan; Lucchesi, Benedict R.

2009-01-01

Objective Premature complexes (PCs) in the electrocardiogram (ECG) signal have been reported for myocardial contrast echocardiography and also for burst mode (physical therapy) ultrasound with gas body contrast agent at lower peak rarefactional pressure amplitudes (PRPAs). For contrast echocardiography, irreversibly injured cardiomyocytes have been associated with the arrhythmia. The objective was to determine if cardiomyocyte injury is associated with the PCs induced by the burst mode at lower PRPAs. Methods Anesthetized rats were exposed to focused 1.5 MHz ultrasound in a water bath. Evans blue dye was injected IP to stain injured cardiomyocytes and Definity ultrasound contrast agent was infused IV. Continuous burst mode simulated physical therapy ultrasound. Intermittent 2 ms bursts, or envelopes of pulses simulating diagnostic ultrasound, were triggered 1:4 at end systole. PCs were observed on ECG recordings and stained cardiomyocytes were counted in frozen sections. Results The continuous burst mode produced variable PCs and stained cells above 0.3 MPa PRPA. The triggered bursts above 0.3 MPa and pulse envelopes above 1.2 MPa produced statistically significant (P<0.01) PCs and stained cardiomyocytes. Conclusion Irreversible cardiomyocyte injury was associated with the development of PCs for burst mode and occurred at substantially lower PRPAs than for pulsed ultrasound. PMID:19854967

Transcriptional profile of diurnon-induces toxicity on the urinary bladder of male wistar rats to inform mode of action

EPA Science Inventory

Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea) is a substituted urea herbicide that induces rat urinary bladder urothelial tumors at high dietary levels (2500 ppm). The specific mode of action and molecular alterations triggered by diuron, however, have not been clarified. Th...

Nonlinear dynamics of toroidal Alfvén eigenmodes in presence of tearing modes

NASA Astrophysics Data System (ADS)

Zhu, Jia; Ma, Zhiwei; Wang, Sheng; Zhang, Wei

2016-10-01

A new hybrid kinetic-MHD code CLT-K is developed to study nonlinear dynamics of n =1 toroidal Alfvén eigenmodes (TAEs) with the m/n =2/1 tearing mode. It is found that the n =1 TAE is first excited by isotropic energetic particles in the earlier stage and reaches the steady state due to wave-particle interaction. After the saturation of the n =1 TAE, the tearing mode intervenes and triggers the second growth of the mode. The modes goes into the second steady state due to multiple tearing mode-mode nonlinear coupling. Both wave-particle and wave-wave interactions are observed in our hybrid simulation.

Starting Processes of High Contraction Ratio Scramjet Inlets

DTIC Science & Technology

2012-01-01

shortly before injection, at which point the boxes were switched to relative mode via the “ Taka Taka ” box, shown on Fig. 22. This absolute mode...camera used for the Schlieren visualisation, as well as the trigger for the 32 channel data acquisition system used. Figure 22: Taka ... taka box, used to manipulate the resistance mode during testing Figure 23: Typical raw thin film array signal, showing both absolute and relative

Surface-wave potential for triggering tectonic (nonvolcanic) tremor

USGS Publications Warehouse

Hill, D.P.

2010-01-01

Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

Surface-wave potential for triggering tectonic (nonvolcanic) tremor-corrected

USGS Publications Warehouse

Hill, David P.

2012-01-01

Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle are anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45° incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia megathrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction is μ* ≤ 0:2). Documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, however, are associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (μ ~ 0:6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

Stochastic Threshold Microdose Model for Cell Killing by Insoluble Metallic Nanomaterial Particles

PubMed Central

Scott, Bobby R.

2010-01-01

This paper introduces a novel microdosimetric model for metallic nanomaterial-particles (MENAP)-induced cytotoxicity. The focus is on the engineered insoluble MENAP which represent a significant breakthrough in the design and development of new products for consumers, industry, and medicine. Increased production is rapidly occurring and may cause currently unrecognized health effects (e.g., nervous system dysfunction, heart disease, cancer); thus, dose-response models for MENAP-induced biological effects are needed to facilitate health risk assessment. The stochastic threshold microdose (STM) model presented introduces novel stochastic microdose metrics for use in constructing dose-response relationships for the frequency of specific cellular (e.g., cell killing, mutations, neoplastic transformation) or subcellular (e.g., mitochondria dysfunction) effects. A key metric is the exposure-time-dependent, specific burden (MENAP count) for a given critical target (e.g., mitochondria, nucleus). Exceeding a stochastic threshold specific burden triggers cell death. For critical targets in the cytoplasm, the autophagic mode of death is triggered. For the nuclear target, the apoptotic mode of death is triggered. Overall cell survival is evaluated for the indicated competing modes of death when both apply. The STM model can be applied to cytotoxicity data using Bayesian methods implemented via Markov chain Monte Carlo. PMID:21191483

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: image reconstruction and assessment of image quality.

PubMed

Flohr, Thomas G; Leng, Shuai; Yu, Lifeng; Aiimendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H

2009-12-01

To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. No significant differences in quantitative measures of image quality were found between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6 pitch 3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch = 3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom acquired with the ECG-triggered high-pitch scan mode were visually free from motion artifacts at heart rates of 60 and 70 bpm. However, image quality started to deteriorate for higher heart rates. At equivalent image quality, the ECG-triggered high-pitch scan mode demonstrated lower radiation dose than other cardiac scan techniques on the same DSCT equipment (25% and 60% dose reduction compared to ECG-triggered sequential step-and-shoot and ECG-gated spiral with x-ray pulsing). A high-pitch (up to pitch = 3.2), high-temporal-resolution (up to 75 ms) dual-source CT scan mode produced equivalent image quality relative to single-source scans using a more typical pitch value (pitch = 1.0). The resultant reduction in the overall acquisition time may offer clinical advantage for cardiovascular, trauma, and pediatric CT applications. In addition, ECG-triggered high-pitch scanning may be useful as an alternative to ECG-triggered sequential scanning for patients with low to moderate heart rates up to 70 bpm, with the potential to scan the heart within one heart beat at reduced radiation dose.

Socio-sexuality and episodic memory function in women: further evidence of an adaptive "mating mode".

PubMed

Smith, David S; Jones, Benedict C; Allan, Kevin

2013-08-01

The functionalist memory perspective predicts that information of adaptive value may trigger specific processing modes. It was recently demonstrated that women's memory is sensitive to cues of male sexual dimorphism (i.e., masculinity) that convey information of adaptive value for mate choice because they signal health and genetic quality, as well as personality traits important in relationship contexts. Here, we show that individual differences in women's mating strategies predict the effect of facial masculinity cues upon memory, strengthening the case for functional design within memory. Using the revised socio-sexual orientation inventory, Experiment 1 demonstrates that women pursuing a short-term, uncommitted mating strategy have enhanced source memory for men with exaggerated versus reduced masculine facial features, an effect that reverses in women who favor long-term committed relationships. The reversal in the direction of the effect indicates that it does not reflect the sex typicality of male faces per se. The same pattern occurred within women's source memory for women's faces, implying that the memory bias does not reflect the perceived attractiveness of faces per se. In Experiment 2, we reran the experiment using men's faces to establish the reliability of the core finding and replicated Experiment 1's results. Masculinity cues may therefore trigger a specific mode within women's episodic memory. We discuss why this mode may be triggered by female faces and its possible role in mate choice. In so doing, we draw upon the encoding specificity principle and the idea that episodic memory limits the scope of stereotypical inferences about male behavior.

Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite

PubMed Central

Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

2014-01-01

The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897

QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALOONING MODES

DOE Office of Scientific and Technical Information (OSTI.GOV)

LAO,LL; SNYDER,PB; LEONARD,AW

2003-03-01

A271 QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALOONING MODES. Several testable features of the working model of edge localized modes (ELMs) as intermediate toroidal mode number peeling-ballooning modes are evaluated quantitatively using DIII-D and JT-60U experimental data and the ELITE MHD stability code. These include the hypothesis that ELM sizes are related to the radial widths of the unstable MHD modes, the unstable modes have a strong ballooning character localized in the outboard bad curvature region, and ELM size generally becomes smaller at high edge collisionality. ELMs are triggered when the growth rates of the unstable MHD modes becomemore » significantly large. These testable features are consistent with many ELM observations in DIII-D and JT-60U discharges.« less

A physical mechanism for the onset of radial electric fields in magnetically confined plasmas

NASA Astrophysics Data System (ADS)

Moleti, A.

1996-04-01

A simple physical mechanism is described, which could trigger the Low-mode to High-mode (L-H) transition. The instantaneous ion density profile is significantly modified by a sudden temperature increase, because Larmor radii and banana orbit widths are proportional to thermal velocity. The electric fields that are observed in H-mode plasmas could be produced in the radial region where a large second derivative of the density profile exists, either by strong additional heating or by the heat pulse associated to a sawtooth crash. The L-H transition threshold for the time derivative of the ion temperature is of the order of magnitude of the values that are measured in the outer part of the plasma by electron temperature fast diagnostics at sawtooth crashes. This model agrees with the experimental evidence that L-H transitions are often triggered by a sawtooth crash, and the predicted dependence of the threshold on plasma parameters is fairly consistent with available data.

Cell Death and Cell Death Responses in Liver Disease: Mechanisms and Clinical Relevance

PubMed Central

Luedde, Tom; Kaplowitz, Neil; Schwabe, Robert F.

2015-01-01

Summary Hepatocellular death is present in almost all types of human liver disease and is used as a sensitive parameter for the detection of acute and chronic liver disease of viral, toxic, metabolic, or autoimmune origin. Clinical data and animal models suggest that hepatocyte death is the key trigger of liver disease progression, manifested by the subsequent development of inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Modes of hepatocellular death differ substantially between liver diseases. Different modes of cell death such as apoptosis, necrosis, and necroptosis trigger specific cell death responses and promote progression of liver disease through distinct mechanisms. In this review, we first discuss molecular mechanisms by which different modes of cell death, damage-associated molecular patterns, and specific cell death responses contribute to the development of liver disease. We then review the clinical relevance of cell death, focusing on biomarkers; the contribution of cell death to drug-induced, viral, and fatty liver disease and liver cancer; and evidence for cell death pathways as therapeutic targets. PMID:25046161

Conflict-triggered top-down control: default mode, last resort, or no such thing?

PubMed

Bugg, Julie M

2014-03-01

The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control engagement by testing the Associations as Antagonists to Top-Down Control (AATC) hypothesis. In 4 experiments, list-wide proportion congruence was manipulated, and conflict-triggered top-down control engagement was examined by comparing interference for frequency-matched, 50% congruent items across mostly congruent (low conflict) and mostly incongruent (high conflict) lists. Despite the fact that global levels of conflict were varied identically across experiments, evidence of conflict-triggered top-down control engagement was selective to those experiments in which responses could not be predicted on the majority of trials via simple associative learning, consistent with the AATC hypothesis. In a 5th experiment, older adults showed no evidence of top-down control engagement under conditions in which young adults did, a finding that refined the interpretation of the patterns observed in the prior experiments. Collectively, these findings suggest that top-down control engagement in high conflict contexts is neither the default mode nor an unused (or nonexistent) strategy. Top-down control is best characterized as a last resort that is engaged when reliance on one's environment, and in particular associative responding, is unproductive for achieving task goals.

Conflict-Triggered Top-Down Control: Default Mode, Last Resort, or No Such Thing?

PubMed Central

Bugg, Julie M.

2014-01-01

The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control engagement by testing the Associations as Antagonists to Top-Down Control (AATC) hypothesis. In 4 experiments, list-wide proportion congruence was manipulated, and conflict-triggered top-down control engagement was examined by comparing interference for 50% congruent items across mostly congruent (low conflict) and mostly incongruent (high conflict) lists. Despite the fact that global levels of conflict were varied identically across experiments, evidence of conflict-triggered top-down control engagement was selective to those experiments in which responses could not be predicted on the majority of trials via simple associative learning, consistent with the AATC hypothesis. In a fifth experiment, older adults showed no evidence of top-down control engagement under conditions in which young adults did, a finding that refined the interpretation of the patterns observed in the prior experiments. Collectively, these findings suggest that top-down control engagement in high conflict contexts is neither the default mode nor an unused (or non-existent) strategy. Top-down control is best characterized as a last resort that is engaged when reliance on one’s environment, and in particular associative responding, is unproductive for achieving task goals. PMID:24274385

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, P. W.; Lawrence Livermore National Laboratory, Livermore, California 94550; Xu, X. Q.

We demonstrate that the occurrence of Edge-Localized-Modes (ELM) crashes does not depend only on the linear peeling-ballooning threshold, but also relies on nonlinear processes. Wave-wave interaction constrains the growth time of a mode, thus inducing a shift in the criterion for triggering an ELM crash. An ELM crash requires the P-B growth rate to exceed a critical value γ>γ{sub c}, where γ{sub c} is set by 1/τ{sup ¯}{sub c}, and τ{sup ¯}{sub c} is the averaged mode phase coherence time. For 0

General Relativistic MHD Simulations of Jet Formation

NASA Technical Reports Server (NTRS)

Mizuno, Y.; Nishikawa, K.-I.; Hardee, P.; Koide, S.; Fishman, G. J.

2005-01-01

We have performed 3-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of jet formation from an accretion disk with/without initial perturbation around a rotating black hole. We input a sinusoidal perturbation (m = 5 mode) in the rotation velocity of the accretion disk. The simulation results show the formation of a relativistic jet from the accretion disk. Although the initial perturbation becomes weakened by the coupling among different modes, it survives and triggers lower modes. As a result, complex non-axisymmetric density structure develops in the disk and the jet. Newtonian MHD simulations of jet formation with a non-axisymmetric mode show the growth of the m = 2 mode but GRMHD simulations cannot see the clear growth of the m = 2 mode.

Triggering of longitudinal combustion instabilities in solid rocket motors: Nonlinear combustion response

NASA Technical Reports Server (NTRS)

Wicker, J. M.; Greene, W. D.; Kim, S. I.; Yang, V.

1995-01-01

Pulsed oscillations in solid rocket motors are investigated with emphasis on nonlinear combustion response. The study employs a wave equation governing the unsteady motions in a two-phase flow, and a solution technique based on spatial- and time-averaging. A wide class of combustion response functions is studied to second-order in fluctuation amplitude to determine if, when, and how triggered instabilities arise. Conditions for triggering are derived from analysis of limit cycles, and regions of triggering are found in parametric space. Based on the behavior of model dynamical systems, introduction of linear cross-coupling and quadratic self-coupling among the acoustic modes appears to be the manner in which the nonlinear combustion response produces triggering to a stable limit cycle. Regions of initial conditions corresponding to stable pulses were found, suggesting that stability depends on initial phase angle and harmonic content, as well as the composite amplitude, of the pulse.

Aperiodic Robust Model Predictive Control for Constrained Continuous-Time Nonlinear Systems: An Event-Triggered Approach.

PubMed

Liu, Changxin; Gao, Jian; Li, Huiping; Xu, Demin

2018-05-01

The event-triggered control is a promising solution to cyber-physical systems, such as networked control systems, multiagent systems, and large-scale intelligent systems. In this paper, we propose an event-triggered model predictive control (MPC) scheme for constrained continuous-time nonlinear systems with bounded disturbances. First, a time-varying tightened state constraint is computed to achieve robust constraint satisfaction, and an event-triggered scheduling strategy is designed in the framework of dual-mode MPC. Second, the sufficient conditions for ensuring feasibility and closed-loop robust stability are developed, respectively. We show that robust stability can be ensured and communication load can be reduced with the proposed MPC algorithm. Finally, numerical simulations and comparison studies are performed to verify the theoretical results.

Feedback control of acoustic disturbance transient growth in triggering thermoacoustic instability

NASA Astrophysics Data System (ADS)

Zhao, Dan; Reyhanoglu, Mahmut

2014-08-01

Transient growth of acoustic disturbances could trigger thermoacoustic instability in a combustion system with non-orthogonal eigenmodes, even with stable eigenvalues. In this work, feedback control of transient growth of flow perturbations in a Rijke-type combustion system is considered. For this, a generalized thermoacoustic model with distributed monopole-like actuators is developed. The model is formulated in state-space to gain insights on the interaction between various eigenmodes and the dynamic response of the system to the actuators. Three critical parameters are identified: (1) the mode number, (2) the number of actuators, and (3) the locations of the actuators. It is shown that in general the number of the actuators K is related to the mode number N as K=N2. For simplicity in illustrating the main results of the paper, two different thermoacoustic systems are considered: system (a) with one mode and system (b) that involves two modes. The actuator location effect is studied in system (a) and it is found that the actuator location plays an important role in determining the control effort. In addition, sensitivity analysis of pressure- and velocity-related control parameters is conducted. In system (b), when the actuators are turned off (i.e., open-loop configuration), it is observed that acoustic energy transfers from the high frequency mode to the lower frequency mode. After some time, the energy is transferred back. Moreover, the high frequency oscillation grows into nonlinear limit cycle with the low frequency oscillation amplified. As a linear-quadratic regulator (LQR) is implemented to tune the actuators, both systems become asymptotically stable. However, the LQR controller fails in eliminating the transient growth, which may potentially trigger thermoacoustic instability. In order to achieve strict dissipativity (i.e., unity maximum transient growth), a transient growth controller is systematically designed and tested in both systems. Comparison is then made between the performance of the LQR controller and that of the transient growth controller. It is found in both systems that the transient growth controller achieves both exponential decay of the flow disturbance energy and unity maximum transient growth.

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bortolon, A.; Maingi, R.; Mansfield, D. K.

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

High frequency pacing of edge localized modes by injection of lithium granules in DIII-D H-mode discharges

DOE PAGES

Bortolon, A.; Maingi, R.; Mansfield, D. K.; ...

2016-04-08

A newly installed Lithium Granule Injector (LGI) was used to pace edge localized modes (ELM) in DIII-D. ELM pacing efficiency was studied injecting lithium granules of nominal diameter 0.3–0.9mm, speed of 50–120 m s -1 and average injection rates up to 100 Hz for 0.9mm granules and up to 700 Hz for 0.3mm granules. The efficiency of ELM triggering was found to depend strongly on size of the injected granules, with triggering efficiency close to 100% obtained with 0.9mm diameter granules, lower with smaller sizes, and weakly depending on granule velocity. Robust ELM pacing was demonstrated in ITER-like plasmas formore » the entire shot length, at ELM frequencies 3–5 times larger than the ‘natural’ ELM frequency observed in reference discharges. Within the range of ELM frequencies obtained, the peak ELM heat flux at the outer strike point was reduced with increasing pacing frequency. The peak heat flux reduction at the inner strike point appears to saturate at high pacing frequency. Lithium was found in the plasma core, with a concurrent reduction of metallic impurities and carbon. Altogether, high frequency ELM pacing using the lithium granule injection appears to be compatible with both H-mode energy confinement and attractive H-mode pedestal characteristics, but further assessment is need« less

Mechanism of force mode dip-pen nanolithography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Haijun, E-mail: yanghaijun@sinap.ac.cn, E-mail: swguo@sjtu.edu.cn, E-mail: wanghuabin@cigit.ac.cn; Interfacial Water Division and Key Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, CAS, Shanghai 201800; Xie, Hui

In this work, the underlying mechanism of the force mode dip-pen nanolithography (FMDPN) is investigated in depth by analyzing force curves, tapping mode deflection signals, and “Z-scan” voltage variations during the FMDPN. The operation parameters including the relative “trigger threshold” and “surface delay” parameters are vital to control the loading force and dwell time for ink deposition during FMDPN. A model is also developed to simulate the interactions between the atomic force microscope tip and soft substrate during FMDPN, and verified by its good performance in fitting our experimental data.

Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

DOE PAGES

Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei; ...

2016-12-29

Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. In this paper, on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Finally, following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration withmore » the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.« less

Simultaneous disappearances of plasmaspheric hiss, exohiss, and chorus waves triggered by a sudden decrease in solar wind dynamic pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Nigang; Su, Zhenpeng; Gao, Zhonglei

Magnetospheric whistler mode waves are of great importance in the radiation belt electron dynamics. In this paper, on the basis of the analysis of a rare event with the simultaneous disappearances of whistler mode plasmaspheric hiss, exohiss, and chorus triggered by a sudden decrease in the solar wind dynamic pressure, we provide evidences for the following physical scenarios: (1) nonlinear generation of chorus controlled by the geomagnetic field inhomogeneity, (2) origination of plasmaspheric hiss from chorus, and (3) leakage of plasmaspheric hiss into exohiss. Finally, following the reduction of the solar wind dynamic pressure, the dayside geomagnetic field configuration withmore » the enhanced inhomogeneity became unfavorable for the generation of chorus, and the quenching of chorus directly caused the disappearances of plasmaspheric hiss and then exohiss.« less

[Influence of mediator diffusion on trigger mode of a synapse].

PubMed

Vasilev, A N; Kulish, M V

2014-01-01

The model of postsynaptic membrane activation, is proposed in the paper. This model takes into account inhomogeneity of mediator's space distribution in the region of the synaptic cleft as well as nonlinear nature of interaction between the mediator and receptors on the postsynaptic membrane. Based on equations of this model stationary solutions are calculated for mediator distribution in the synaptic cleft and the number of activated receptors. Kinetics of reactions for activation and deactivation of receptors is analyzed within the concept of a trigger mode of the synapse. It is shown that activation-deactivation processes and redistribution of the mediator in the cleft can be interpreted as successive transitions between two stationary states of the system. Time of transitions between these states is found and its dependence on system parameters (in particular on the width of the synaptic cleft) is analyzed.

Interdecadal Change in the Relationship Between the North Pacific Oscillation and the Pacific Meridional Mode and Its Impact on ENSO

NASA Astrophysics Data System (ADS)

Shin, So-Jung; An, Soon-Il

2018-02-01

Two leading but independent modes of Northern Pacific atmospheric circulation: the North Pacific Oscillation (NPO) and the Pacific Meridional Mode (PMM), are known external triggers of the El Niño-Southern Oscillation (ENSO) by the sequential migration of sea surface temperature (SST) anomalies into the tropics possibly by means of wind-evaporation-SST (WES) feedbacks. Because of the similar roles of NPO and PMM, most previous studies have explored them with no separation. Here, we investigate their independent and combined effects in triggering ENSO, and find that when the NPO and PMM occur simultaneously during spring, ENSO or ENSO-like SST anomalies are generated during the following winter; whereas when either the NPO or PMM occur alone, ENSO events rarely occur. Furthermore, the relationship between NPO and PMM shows noticeable interdecadal variability, which is related to decadal changes in the mean upper-level jet stream over the North Pacific. Changes in the upper-level jet stream modify the location of the center of the Aleutian Low, which plays a role in bridging the NPO and PMM processes, especially when it migrates to the southwest. The period when NPO and PMM are well correlated coincides somewhat with the active ENSO period, and vice versa, indicating that a more efficient trigger due to combined NPO-PMM processes results in a higher variation of ENSO. Finally, analysis of the coupled model control simulations strongly supports our observational analysis results.

Proton and non-proton activation of ASIC channels

PubMed Central

Gautschi, Ivan; van Bemmelen, Miguel Xavier; Schild, Laurent

2017-01-01

The Acid-Sensing Ion Channels (ASIC) exhibit a fast desensitizing current when activated by pH values below 7.0. By contrast, non-proton ligands are able to trigger sustained ASIC currents at physiological pHs. To analyze the functional basis of the ASIC desensitizing and sustained currents, we have used ASIC1a and ASIC2a mutants with a cysteine in the pore vestibule for covalent binding of different sulfhydryl reagents. We found that ASIC1a and ASIC2a exhibit two distinct currents, a proton-induced desensitizing current and a sustained current triggered by sulfhydryl reagents. These currents differ in their pH dependency, their sensitivity to the sulfhydryl reagents, their ionic selectivity and their relative magnitude. We propose a model for ASIC1 and ASIC2 activity where the channels can function in two distinct modes, a desensitizing mode and a sustained mode depending on the activating ligands. The pore vestibule of the channel represents a functional site for binding non-proton ligands to activate ASIC1 and ASIC2 at neutral pH and to prevent channel desensitization. PMID:28384246

APNEA list mode data acquisition and real-time event processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogle, R.A.; Miller, P.; Bramblett, R.L.

1997-11-01

The LMSC Active Passive Neutron Examinations and Assay (APNEA) Data Logger is a VME-based data acquisition system using commercial-off-the-shelf hardware with the application-specific software. It receives TTL inputs from eighty-eight {sup 3}He detector tubes and eight timing signals. Two data sets are generated concurrently for each acquisition session: (1) List Mode recording of all detector and timing signals, timestamped to 3 microsecond resolution; (2) Event Accumulations generated in real-time by counting events into short (tens of microseconds) and long (seconds) time bins following repetitive triggers. List Mode data sets can be post-processed to: (1) determine the optimum time bins formore » TRU assay of waste drums, (2) analyze a given data set in several ways to match different assay requirements and conditions and (3) confirm assay results by examining details of the raw data. Data Logger events are processed and timestamped by an array of 15 TMS320C40 DSPs and delivered to an embedded controller (PowerPC604) for interim disk storage. Three acquisition modes, corresponding to different trigger sources are provided. A standard network interface to a remote host system (Windows NT or SunOS) provides for system control, status, and transfer of previously acquired data. 6 figs.« less

Rational design of a dual-mode optical and chemical prodrug.

PubMed

McCoy, Colin P; Rooney, Clare; Jones, David S; Gorman, Sean P; Nieuwenhuyzen, Mark

2007-01-01

The purpose of this study is to demonstrate the rational design and behaviour of the first dual-mode optical and chemical prodrug, exemplified by an acetyl salicylic acid-based system. A cyclic 1,4-benzodioxinone prodrug was synthesised by reaction of 3,5-dimethoxybenzoin and acetyl salicoyl chloride with pyridine. After purification by column chromatography and recrystallization, characterization was achieved using infrared and NMR spectroscopies, mass spectrometry, elemental analysis and single crystal X-ray diffraction. Light-triggered drug liberation was characterised via UV-visible spectroscopy following low-power 365 nm irradiation for controlled times. Chemical drug liberation was characterised via UV-visible spectroscopy in pH 5.5 solution. The synthetic method yielded pure prodrug, with full supporting characterisation. Light-triggered drug liberation proceeded at a rate of 8.30x10(-2) s-1, while chemical, hydrolytic liberation proceeded independently at 1.89x10(-3) s-1. The photochemical and hydrolytic reactions were both quantitative. This study demonstrates the first rational dual-mode optical and chemical prodrug, using acetyl salicylic acid as a model, acting as a paradigm for future dual-mode systems. Photochemical drug liberation proceeds 44 times faster than chemical liberation, suggesting potential use in drug-eluting medical devices where an additional burst of drug is required at the onset of infection.

Fast ion stabilization of the ion temperature gradient driven modes in the Joint European Torus hybrid-scenario plasmas: a trigger mechanism for internal transport barrier formation

NASA Astrophysics Data System (ADS)

Romanelli, M.; Zocco, A.; Crisanti, F.; Contributors, JET-EFDA

2010-04-01

Understanding and modelling turbulent transport in thermonuclear fusion plasmas are crucial for designing and optimizing the operational scenarios of future fusion reactors. In this context, plasmas exhibiting state transitions, such as the formation of an internal transport barrier (ITB), are particularly interesting since they can shed light on transport physics and offer the opportunity to test different turbulence suppression models. In this paper, we focus on the modelling of ITB formation in the Joint European Torus (JET) [1] hybrid-scenario plasmas, where, due to the monotonic safety factor profile, magnetic shear stabilization cannot be invoked to explain the transition. The turbulence suppression mechanism investigated here relies on the increase in the plasma pressure gradient in the presence of a minority of energetic ions. Microstability analysis of the ion temperature gradient driven modes (ITG) in the presence of a fast-hydrogen minority shows that energetic ions accelerated by the ion cyclotron resonance heating (ICRH) system (hydrogen, nH,fast/nD,thermal up to 10%, TH,fast/TD,thermal up to 30) can increase the pressure gradient enough to stabilize the ITG modes driven by the gradient of the thermal ions (deuterium). Numerical analysis shows that, by increasing the temperature of the energetic ions, electrostatic ITG modes are gradually replaced by nearly electrostatic modes with tearing parity at progressively longer wavelengths. The growth rate of the microtearing modes is found to be lower than that of the ITG modes and comparable to the local E × B-velocity shearing rate. The above mechanism is proposed as a possible trigger for the formation of ITBs in this type of discharges.

Streptomyces exploration is triggered by fungal interactions and volatile signals.

PubMed

Jones, Stephanie E; Ho, Louis; Rees, Christiaan A; Hill, Jane E; Nodwell, Justin R; Elliot, Marie A

2017-01-03

It has long been thought that the life cycle of Streptomyces bacteria encompasses three developmental stages: vegetative hyphae, aerial hyphae and spores. Here, we show interactions between Streptomyces and fungi trigger a previously unobserved mode of Streptomyces development. We term these Streptomyces cells 'explorers', for their ability to adopt a non-branching vegetative hyphal conformation and rapidly transverse solid surfaces. Fungi trigger Streptomyces exploratory growth in part by altering the composition of the growth medium, and Streptomyces explorer cells can communicate this exploratory behaviour to other physically separated streptomycetes using an airborne volatile organic compound (VOC). These results reveal that interkingdom interactions can trigger novel developmental behaviours in bacteria, here, causing Streptomyces to deviate from its classically-defined life cycle. Furthermore, this work provides evidence that VOCs can act as long-range communication signals capable of propagating microbial morphological switches.

Fipronil is a powerful uncoupler of oxidative phosphorylation that triggers apoptosis in human neuronal cell line SHSY5Y.

PubMed

Vidau, Cyril; González-Polo, Rosa A; Niso-Santano, Mireia; Gómez-Sánchez, Rubén; Bravo-San Pedro, José M; Pizarro-Estrella, Elisa; Blasco, Rafael; Brunet, Jean-Luc; Belzunces, Luc P; Fuentes, José M

2011-12-01

Fipronil is a phenylpyrazole insecticide known to elicit neurotoxicity via an interaction with ionotropic receptors, namely GABA and glutamate receptors. Recently, we showed that fipronil and other phenylpyrazole compounds trigger cell death in Caco-2 cells. In this study, we investigated the mode of action and the type of cell death induced by fipronil in SH-SY5Y human neuroblastoma cells. Flow cytometric and western blot analyses demonstrated that fipronil induces cellular events belonging to the apoptosis process, such as mitochondrial potential collapse, cytochrome c release, caspase-3 activation, nuclear condensation and phosphatidylserine externalization. In addition, fipronil induces a rapid ATP depletion with concomitant activation of anaerobic glycolysis. This cellular response is characteristic of mitochondrial injury associated with a defect of the respiration process. Therefore, we also investigated the effect of fipronil on the oxygen consumption in isolated mitochondria. Interestingly, we show for the first time that fipronil is a strong uncoupler of oxidative phosphorylation at relative low concentrations. Thus in this study, we report a new mode of action by which the insecticide fipronil could triggers apoptosis. Copyright © 2011 Elsevier Inc. All rights reserved.

Accreting white dwarf models for type 1 supernovae. 1: Presupernova evolution and triggering mechanisms

NASA Technical Reports Server (NTRS)

Nomoto, K.

1981-01-01

As a plausible explosion model for a Type I supernova, the evolution of carbon-oxygen white dwarfs accreting helium in binary systems was investigated from the onset of accretion up to the point at which a thermonuclear explosion occurs. The relationship between the conditions in the binary system and the triggering mechanism for the supernova explosion is discussed, especially for the cases with relatively slow accretion rate. It is found that the growth of a helium zone on the carbon-oxygen core leads to a supernova explosion which is triggered either by the off-center helium detonation for slow and intermediate accretion rates or by the carbon deflagration for slow and rapid accretion rates. Both helium detonation and carbon deflagration are possible for the case of slow accretion, since in this case the initial mass of the white dwarf is an important parameter for determining the mode of ignition. Finally, various modes of building up the helium zone on the white dwarf, namely, direct transfer of helium from the companion star and the various types and strength of the hydrogen shell flashes are discussed in some detail.

The OPERA muon spectrometer tracking electronics

NASA Astrophysics Data System (ADS)

Ambrosio, M.; Barichello, G.; Brugnera, R.; Carrara, E.; Consiglio, L.; Corradi, A.; Dal Corso, F.; Dusini, S.; Felici, G.; Garfagnini, A.; Manea, C.; Masone, V.; Paoloni, A.; Paoluzzi, G.; Papalino, G.; Parascandolo, P.; Sorrentino, G.; Spinetti, M.; Stanco, L.; Terranova, F.; Votano, L.

2004-11-01

The document describes the front-end electronics that instrument the spectrometer of the OPERA experiment. The spectrometer is made of two separate modules. Each module consists of 22 RPC planes equipped with horizontal and vertical strips readout for a total amount of about 25,000 digital channels. The front end electronics is self-triggered and has single plane readout capability. It is made of three different stages: the Front End Boards (FEBs) system, the Controller Boards (CBs) system and the Timing Boards (TBs) system. The FEB system provides discrimination of the strip incoming signals; a FAST OR output of the input signals is also available for trigger plane signal generation. FEBs discriminated signals are acquired by the CBs system that manages also the communication to the experiment DAQ and Slow Control interface. A Trigger Board allows to operate in both self-trigger (the FEB FAST OR signal starts the plane acquisition) or external-trigger (different conditions can be set on the OR signals generated from different planes) modes.

Spike Triggered Covariance in Strongly Correlated Gaussian Stimuli

PubMed Central

Aljadeff, Johnatan; Segev, Ronen; Berry, Michael J.; Sharpee, Tatyana O.

2013-01-01

Many biological systems perform computations on inputs that have very large dimensionality. Determining the relevant input combinations for a particular computation is often key to understanding its function. A common way to find the relevant input dimensions is to examine the difference in variance between the input distribution and the distribution of inputs associated with certain outputs. In systems neuroscience, the corresponding method is known as spike-triggered covariance (STC). This method has been highly successful in characterizing relevant input dimensions for neurons in a variety of sensory systems. So far, most studies used the STC method with weakly correlated Gaussian inputs. However, it is also important to use this method with inputs that have long range correlations typical of the natural sensory environment. In such cases, the stimulus covariance matrix has one (or more) outstanding eigenvalues that cannot be easily equalized because of sampling variability. Such outstanding modes interfere with analyses of statistical significance of candidate input dimensions that modulate neuronal outputs. In many cases, these modes obscure the significant dimensions. We show that the sensitivity of the STC method in the regime of strongly correlated inputs can be improved by an order of magnitude or more. This can be done by evaluating the significance of dimensions in the subspace orthogonal to the outstanding mode(s). Analyzing the responses of retinal ganglion cells probed with Gaussian noise, we find that taking into account outstanding modes is crucial for recovering relevant input dimensions for these neurons. PMID:24039563

3D pulsed laser-triggered high-speed microfluidic fluorescence-activated cell sorter

PubMed Central

Chen, Yue; Wu, Ting-Hsiang; Kung, Yu-Chun; Teitell, Michael A.; Chiou, Pei-Yu

2014-01-01

We report a 3D microfluidic pulsed laser-triggered fluorescence-activated cell sorter capable of sorting at a throughput of 23,000 cells sec−1 with 90% purity in high-purity mode and at a throughput of 45,000 cells sec−1 with 45% purity in enrichment mode in one stage and in a single channel. This performance is realized by exciting laser-induced cavitation bubbles in a 3D PDMS microfluidic channel to generate high-speed liquid jets that deflect detected fluorescent cells and particles focused by 3D sheath flows. The ultrafast switching mechanism (20 μsec complete on-off cycle), small liquid jet perturbation volume, and three-dimensional sheath flow focusing for accurate timing control of fast (1.5 m sec−1) passing cells and particles are three critical factors enabling high-purity sorting at high-throughput in this sorter. PMID:23844418

Identity physics experiment on internal transport barriers in JT-60U and JET

NASA Astrophysics Data System (ADS)

de Vries, P. C.; Sakamoto, Y.; Litaudon, X.; Beurskens, M. N. A.; Brix, M.; Crombé, K.; Fujita, T.; Giroud, C.; Hawkes, N. C.; Hayashi, N.; Joffrin, E.; Mantica, P.; Matsunaga, G.; Oyama, N.; Parail, V.; Salmi, A.; Shinohara, K.; Strintzi, D.; Suzuki, T.; Takechi, M.; Takenaga, H.; Tala, T.; Tsalas, M.; Urano, H.; Voitsekhovitch, I.; Yoshida, M.; EFDA contributors, JET; JT-60 Team

2009-12-01

A series of experiments have been carried out in 2008 at JT-60U and JET to find common characteristics and explain differences between internal transport barriers (ITBs). The identity experiments succeeded in matching the profiles of most dimensionless parameters at the time ITBs were triggered. Thereafter the q-profile development deviated due to differences in non-inductive current density profile, affecting the ITB. Furthermore, the ITBs in JET were more strongly influenced by the H-mode pedestal or edge localized modes. It was found to be difficult to match the plasma rotation characteristics in both devices. However, the wide range of Mach numbers obtained in these experiments shows that the rotation has little effect on the triggering of ITBs in plasmas with reversed magnetic shear. On the other hand the toroidal rotation and more specifically the rotational shear had an impact on the subsequent growth and allowed the formation of strong ITBs.

Tailorable drug capacity of dexamethasone-loaded conducting polymer matrix

NASA Astrophysics Data System (ADS)

Krukiewicz, K.

2018-05-01

The unique properties of conducting polymers, which are in the same time biocompatible and electrically responsive materials, make them perfect candidates for controlled drug release systems. In this study, the electrically-triggered controlled release system based on dexamethasone-loaded poly (3, 4-ethylenedioxypyrrole) (PEDOP) matrix is described. It is shown that the electropolymerization conditions can facilitate or suppress the formation of PEDOP/Dex matrix, as well as they can have the effect on its electrochemical performance. The release experiments performed in three different modes show that the drug capacity of PEDOP matrix increases with the increase in Dex concentration in the step of matrix synthesis, and higher Dex concentrations make it easier to control the amount of Dex released in an electrically-triggered mode. These results confirm the importance of the careful optimization of immobilization conditions to maximize drug capacity of matrix and maintain its electrochemical properties.

Multi-mode clustering model for hierarchical wireless sensor networks

NASA Astrophysics Data System (ADS)

Hu, Xiangdong; Li, Yongfu; Xu, Huifen

2017-03-01

The topology management, i.e., clusters maintenance, of wireless sensor networks (WSNs) is still a challenge due to its numerous nodes, diverse application scenarios and limited resources as well as complex dynamics. To address this issue, a multi-mode clustering model (M2 CM) is proposed to maintain the clusters for hierarchical WSNs in this study. In particular, unlike the traditional time-trigger model based on the whole-network and periodic style, the M2 CM is proposed based on the local and event-trigger operations. In addition, an adaptive local maintenance algorithm is designed for the broken clusters in the WSNs using the spatial-temporal demand changes accordingly. Numerical experiments are performed using the NS2 network simulation platform. Results validate the effectiveness of the proposed model with respect to the network maintenance costs, node energy consumption and transmitted data as well as the network lifetime.

Fundamental Processes of Atomization in Fluid-Fluid Flows

NASA Technical Reports Server (NTRS)

McCready, M. J.; Chang, H.-C.; Leighton, D. T.

2001-01-01

This report outlines the major results of the grant "Fundamental Processes of Atomization in Fluid-Fluid Flows." These include: 1) the demonstration that atomization in liquid/liquid shear flow is driven by a viscous shear instability that triggers the formation of a long thin sheet; 2) discovery of a new mode of interfacial instability for oscillatory two-layer systems whereby a mode that originates within the less viscous liquid phase causes interfacial deformation as the oscillation proceeds; 3) the demonstration that rivulet formation from gravity front occurs because the local front shape specified by gravity and surface tension changes from a nose to a wedge geometry, thus triggering a large increase in viscous resistance; and 4) extension of the studies on nonlinear wave evolution on falling films and in stratified flow, particularly the evolution towards large-amplitude solitary waves that tend to generate drops.

Simulation of rockfalls triggered by earthquakes

USGS Publications Warehouse

Kobayashi, Y.; Harp, E.L.; Kagawa, T.

1990-01-01

A computer program to simulate the downslope movement of boulders in rolling or bouncing modes has been developed and applied to actual rockfalls triggered by the Mammoth Lakes, California, earthquake sequence in 1980 and the Central Idaho earthquake in 1983. In order to reproduce a movement mode where bouncing predominated, we introduced an artificial unevenness to the slope surface by adding a small random number to the interpolated value of the mid-points between the adjacent surveyed points. Three hundred simulations were computed for each site by changing the random number series, which determined distances and bouncing intervals. The movement of the boulders was, in general, rather erratic depending on the random numbers employed, and the results could not be seen as deterministic but stochastic. The closest agreement between calculated and actual movements was obtained at the site with the most detailed and accurate topographic measurements. ?? 1990 Springer-Verlag.

A comparison of oncogene-induced senescence and replicative senescence: implications for tumor suppression and aging.

PubMed

Nelson, David M; McBryan, Tony; Jeyapalan, Jessie C; Sedivy, John M; Adams, Peter D

2014-06-01

Cellular senescence is a stable proliferation arrest associated with an altered secretory pathway, the senescence-associated secretory phenotype. However, cellular senescence is initiated by diverse molecular triggers, such as activated oncogenes and shortened telomeres, and is associated with varied and complex physiological endpoints, such as tumor suppression and tissue aging. The extent to which distinct triggers activate divergent modes of senescence that might be associated with different physiological endpoints is largely unknown. To begin to address this, we performed gene expression profiling to compare the senescence programs associated with two different modes of senescence, oncogene-induced senescence (OIS) and replicative senescence (RS [in part caused by shortened telomeres]). While both OIS and RS are associated with many common changes in gene expression compared to control proliferating cells, they also exhibit substantial differences. These results are discussed in light of potential physiological consequences, tumor suppression and aging.

Diagnostic accuracy of sub-mSv prospective ECG-triggering cardiac CT in young infant with complex congenital heart disease.

PubMed

Gao, Wei; Zhong, Yu Min; Sun, Ai Min; Wang, Qian; Ouyang, Rong Zhen; Hu, Li Wei; Qiu, Han Sheng; Wang, Shi Yu; Li, Jian Ying

2016-06-01

To explore the clinical value and evaluate the diagnostic accuracy of sub-mSv low-dose prospective ECG-triggering cardiac CT (CCT) in young infants with complex congenital heart disease (CHD). A total of 102 consecutive infant patients (53 boys and 49 girls with mean age of 2.9 ± 2.4 m and weight less than 5 kg) with complex CHD were prospectively enrolled. Scans were performed on a 64-slice high definition CT scanner with low dose prospective ECG-triggering mode and reconstructed with 80 % adaptive statistical iterative reconstruction algorithm. All studies were performed during free breathing with sedation. The subjective image quality was evaluated by 5-point grading scale and interobserver variability was calculated. The objective image noise (standard deviation, SD) and contrast to noise ratio (CNR) was calculated. The effective radiation dose from the prospective ECG-triggering mode was recorded and compared with the virtual conventional retrospective ECG-gating mode. The detection rate for the origin of coronary artery was calculated. All patients also underwent echocardiography before CCT examination. 81 patients had surgery and their preoperative CCT and echocardiography findings were compared with the surgical results and sensitivity, specificity, positive and negative predictive values and accuracy were calculated for separate cardiovascular anomalies. Heart rates were 70-161 beats per minute (bpm) with mean value of 129.19 ± 14.52 bpm. The effective dose of 0.53 ± 0.15 mSv in the prospective ECG-triggering cardiac CT was lower than the calculated value in a conventional retrospective ECG-gating mode (2.00 ± 0.35 mSv) (p < 0.001). The mean CNR and SD were 28.19 ± 13.00 and 15.75 ± 3.61HU, respectively. The image quality scores were 4.31 ± 0.36 and 4.29 ± 0.41 from reviewer 1 and 2 respectively with an excellent agreement between them (Kappa = 0.85). The detection rate for the origins of the left and right coronary arteries was 96 and 90 %, respectively. The detection rates of the origins of left coronary artery and right coronary artery in all cases were 96 % (78/81) and 90 % (73/81), respectively. Twenty cases of conotruncal anomalies and ALCAPA were validated surgically and the accuracy of cardiac CT diagnosis was 95 % (19/20). The overall deformity based sensitivity, specificity, positive predictive value and negative predictive value were 94.0.1, 99.9, 98.6, 99.5 % respectively, by CCT, and 88.2, 99.9, 97.8, 99.0 %, respectively, by echocardiography. Prospective ECG-triggering CCT with sub-mSv effective dose provides excellent imaging quality and high diagnostic accuracy for young infants with complex CHD.

Experimental observation of multi-scale interactions among kink /tearing modes and high-frequency fluctuations in the HL-2A core NBI plasmas

NASA Astrophysics Data System (ADS)

Chen, W.; Jiang, M.; Xu, Y.; Shi, P. W.; Yu, L. M.; Ding, X. T.; Shi, Z. B.; Ji, X. Q.; Yu, D. L.; Li, Y. G.; Yang, Z. C.; Zhong, W. L.; Qiu, Z. Y.; Li, J. Q.; Dong, J. Q.; Yang, Q. W.; Liu, Yi.; Yan, L. W.; Xu, M.; Duan, X. R.

2017-11-01

Multi-scale interactions have been observed recently in the HL-2A core NBI plasmas, including the synchronous coupling between m/n=1/1 kink mode and m/n=2/1 tearing mode, nonlinear couplings of TAE/BAE and m/n=2/1 TM near q=2 surface, AITG/KBM/BAE and m/n=1/1 kink mode near q=1 surface, and between m/n=1/1 kink mode and high-frequency turbulence. Experimental results suggest that several couplings can exist simultaneously, Alfvenic fluctuations have an important contribution to the high-frequency turbulence spectra, and the couplings reveal the electromagnetic character. Multi-scale interactions via the nonlinear modulation process maybe enhance plasma transport and trigger sawtooth-crash onset.

Streptomyces exploration is triggered by fungal interactions and volatile signals

PubMed Central

Jones, Stephanie E; Ho, Louis; Rees, Christiaan A; Hill, Jane E; Nodwell, Justin R; Elliot, Marie A

2017-01-01

It has long been thought that the life cycle of Streptomyces bacteria encompasses three developmental stages: vegetative hyphae, aerial hyphae and spores. Here, we show interactions between Streptomyces and fungi trigger a previously unobserved mode of Streptomyces development. We term these Streptomyces cells ‘explorers’, for their ability to adopt a non-branching vegetative hyphal conformation and rapidly transverse solid surfaces. Fungi trigger Streptomyces exploratory growth in part by altering the composition of the growth medium, and Streptomyces explorer cells can communicate this exploratory behaviour to other physically separated streptomycetes using an airborne volatile organic compound (VOC). These results reveal that interkingdom interactions can trigger novel developmental behaviours in bacteria, here, causing Streptomyces to deviate from its classically-defined life cycle. Furthermore, this work provides evidence that VOCs can act as long-range communication signals capable of propagating microbial morphological switches. DOI: http://dx.doi.org/10.7554/eLife.21738.001 PMID:28044982

Development of a beam test telescope based on the Alibava readout system

NASA Astrophysics Data System (ADS)

Marco-Hernández, R.

2011-01-01

A telescope for a beam test have been developed as a result of a collaboration among the University of Liverpool, Centro Nacional de Microelectrónica (CNM) of Barcelona and Instituto de Física Corpuscular (IFIC) of Valencia. This system is intended to carry out both analogue charge collection and spatial resolution measurements with different types of microstrip or pixel silicon detectors in a beam test environment. The telescope has four XY measurement as well as trigger planes (XYT board) and it can accommodate up to twelve devices under test (DUT board). The DUT board uses two Beetle ASICs for the readout of chilled silicon detectors. The board could operate in a self-triggering mode. The board features a temperature sensor and it can be mounted on a rotary stage. A peltier element is used for cooling the DUT. Each XYT board measures the track space points using two silicon strip detectors connected to two Beetle ASICs. It can also trigger on the particle tracks in the beam test. The board includes a CPLD which allows for the synchronization of the trigger signal to a common clock frequency, delaying and implementing coincidence with other XYT boards. An Alibava mother board is used to read out and to control each XYT/DUT board from a common trigger signal and a common clock signal. The Alibava board has a TDC on board to have a time stamp of each trigger. The data collected by each Alibava board is sent to a master card by means of a local data/address bus following a custom digital protocol. The master board distributes the trigger, clock and reset signals. It also merges the data streams from up to sixteen Alibava boards. The board has also a test channel for testing in a standard mode a XYT or DUT board. This board is implemented with a Xilinx development board and a custom patch board. The master board is connected with the DAQ software via 100M Ethernet. Track based alignment software has also been developed for the data obtained with the DAQ software.

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.; Park, G. Y.; Snyder, P. B.; Chang, C. S.

2017-06-01

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. The neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] is used in carrying out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. Simulations with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. However, the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

DOE PAGES

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.; ...

2017-06-08

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. We use the neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] to carry out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. In simulationsmore » with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. But the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.« less

Investigation of the plasma shaping effects on the H-mode pedestal structure using coupled kinetic neoclassical/MHD stability simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pankin, A. Y.; Rafiq, T.; Kritz, A. H.

The effects of plasma shaping on the H-mode pedestal structure are investigated. High fidelity kinetic simulations of the neoclassical pedestal dynamics are combined with the magnetohydrodynamic (MHD) stability conditions for triggering edge localized mode (ELM) instabilities that limit the pedestal width and height in H-mode plasmas. We use the neoclassical kinetic XGC0 code [Chang et al., Phys. Plasmas 11, 2649 (2004)] to carry out a scan over plasma elongation and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD ELITE code [Snyder et al., Phys. Plasmas 9, 2037 (2002)]. In simulationsmore » with the XGC0 code, which includes coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. The differences in the predicted H-mode pedestal width and height for the DIII-D discharges with different elongation and triangularities are discussed. For the discharges with higher elongation, it is found that the gradients of the plasma profiles in the H-mode pedestal reach semi-steady states. In these simulations, the pedestal slowly continues to evolve to higher pedestal pressures and bootstrap currents until the peeling-ballooning stability conditions are satisfied. The discharges with lower elongation do not reach the semi-steady state, and ELM crashes are triggered at earlier times. The plasma elongation is found to have a stronger stabilizing effect than the plasma triangularity. For the discharges with lower elongation and lower triangularity, the ELM frequency is large, and the H-mode pedestal evolves rapidly. It is found that the temperature of neutrals in the scrape-off-layer (SOL) region can affect the dynamics of the H-mode pedestal buildup. But the final pedestal profiles are nearly independent of the neutral temperature. The elongation and triangularity affect the pedestal widths of plasma density and electron temperature profiles differently. This provides a new mechanism of controlling the pedestal bootstrap current and the pedestal stability.« less

Evaluation of ventilators used during transport of critically ill patients: a bench study.

PubMed

Boussen, Salah; Gainnier, Marc; Michelet, Pierre

2013-11-01

To evaluate the most recent transport ventilators' operational performance regarding volume delivery in controlled mode, trigger function, and the quality of pressurization in pressure support mode. Eight recent transport ventilators were included in a bench study in order to evaluate their accuracy to deliver a set tidal volume under normal resistance and compliance conditions, ARDS conditions, and obstructive conditions. The performance of the triggering system was assessed by the measure of the decrease in pressure and the time delay required to open the inspiratory valve. The quality of pressurization was obtained by computing the integral of the pressure-time curve for the first 300 ms and 500 ms after the onset of inspiration. For the targeted tidal volumes of 300, 500, and 800 mL the errors ranged from -3% to 48%, -7% to 18%, and -5% to 25% in the normal conditions, -4% to 27%, -2% to 35%, and -3% to 35% in the ARDS conditions, and -4% to 53%, -6% to 30%, and -30% to 28% in the obstructive conditions. In pressure support mode the pressure drop range was 0.4-1.7 cm H2O, the trigger delay range was 68-198 ms, and the pressurization performance (percent of ideal pressurization, as measured by pressure-time product at 300 ms and 500 ms) ranges were -9% to 44% at 300 ms and 6%-66% at 500 ms (P < .01). There were important differences in the performance of the tested ventilators. The most recent turbine ventilators outperformed the pneumatic ventilators. The best performers among the turbine ventilators proved comparable to modern ICU ventilators.

Proteomics analysis suggests broad functional changes in potato leaves triggered by phosphites and a complex indirect mode of action against Phytophthora infestans.

PubMed

Lim, Sanghyun; Borza, Tudor; Peters, Rick D; Coffin, Robert H; Al-Mughrabi, Khalil I; Pinto, Devanand M; Wang-Pruski, Gefu

2013-11-20

Phosphite (salts of phosphorous acid; Phi)-based fungicides are increasingly used in controlling oomycete pathogens, such as the late blight agent Phytophthora infestans. In plants, low amounts of Phi induce pathogen resistance through an indirect mode of action. We used iTRAQ-based quantitative proteomics to investigate the effects of phosphite on potato plants before and after infection with P. infestans. Ninety-three (62 up-regulated and 31 down-regulated) differentially regulated proteins, from a total of 1172 reproducibly identified proteins, were identified in the leaf proteome of Phi-treated potato plants. Four days post-inoculation with P. infestans, 16 of the 31 down-regulated proteins remained down-regulated and 42 of the 62 up-regulated proteins remained up-regulated, including 90% of the defense proteins. This group includes pathogenesis-related, stress-responsive, and detoxification-related proteins. Callose deposition and ultrastructural analyses of leaf tissues after infection were used to complement the proteomics approach. This study represents the first comprehensive proteomics analysis of the indirect mode of action of Phi, demonstrating broad effects on plant defense and plant metabolism. The proteomics data and the microscopy study suggest that Phi triggers a hypersensitive response that is responsible for induced resistance of potato leaves against P. infestans. Phosphie triggers complex functional changes in potato leaves that are responsible for the induced resistance against Phytophthora infestans. This article is part of a Special Issue entitled: Translational Plant Proteomics. Copyright © 2013 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, W. M.; Snyder, P. B.; Bortolon, A.

In a new high pedestal regime ("Super H-mode") we predicted and accessed DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. And while elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. In similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Targeting myofascial taut bands by ultrasound.

PubMed

Thomas, Kisha; Shankar, Hariharan

2013-07-01

Myofascial pain syndrome (MPS) is a frequent diagnosis in chronic pain and is characterized by tender, taut bands known as trigger points. The trigger points are painful areas in skeletal muscle that are associated with a palpable nodule within a taut band of muscle fibers. Despite the prevalence of myofascial pain syndrome, diagnosis is based on clinical criteria alone. A growing body of evidence that suggests that taut bands are readily visualized under ultrasound-guided exam, especially when results are correlated with elastography, multidimensional imaging, and physical exam findings such as local twitch response. The actual image characteristic in B mode appears to be controversial. Ultrasonography provides an objective modality to assist with diagnosis and treatment of trigger points in the future.

Structural phase transition in deuterated benzil C14D10O2 : Neutron inelastic scattering

NASA Astrophysics Data System (ADS)

Goossens, D. J.; Welberry, T. R.; Hagen, M. E.; Fernandez-Baca, J. A.

2006-04-01

Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C14D10O2 . The transition in benzil, in which the unit cell goes from a trigonal P3121 unit cell above TC to a cell doubled P21 unit cell below TC , leads to the emergence of a Bragg peak at the M -point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the Γ -point leads to the triggering of an instability at the M -point causing the transition to occur. This suggestion has been investigated by measuring the phonon spectrum at the M -point for a range of temperatures above TC and the phonon dispersion relation along the Γ-M direction just above TC . It is found that the transverse acoustic phonon at the M -point is of lower energy than the Γ -point optic mode and has a softening with temperature as T approaches TC from above that is much faster than that of the Γ -point optic mode. This behavior is inconsistent with the view that the Γ -point mode is responsible for triggering the phase transition. Rather the structural phase transition in benzil appears to be driven by a conventional soft TA mode at the M -point.

ICRF Mode Conversion Flow Drive Experiments on Alcator C-Mod

NASA Astrophysics Data System (ADS)

Lin, Y.; Reinke, M. L.; Rice, J. E.; Wukitch, S. J.; Granetz, R.; Greenwald, M.; Hubbard, A. E.; Marmar, E. S.; Podpaly, Y. A.; Porkolab, M.; Tsujii, N.; Wolfe, S.

2011-12-01

We have carried out a detailed study of the dependence of ICRF mode conversion flow drive (MCFD) on plasma and RF parameters. The flow drive efficiency is found to depend strongly on the 3He concentration in D(3He) plasmas, a key parameter separating the ICRF minority heating regime and mode conversion regime. At +90 ° antenna phasing (waves in the co-Ip direction) and dipole phasing, the driven flow is in the co-Ip direction, and the change of the rotation velocity increases with both PRF and Ip, and scales unfavorably vs. plasma density and antenna frequency. When MCFD is applied to I-mode plasmas, the plasma rotation increases until the onset of MHD modes triggered by large sawtooth crashes. Very high performance I-mode plasmas with HITER98,y2˜1.4 and Te0˜8 keV have been obtained in these experiments.

Brain activity during bilateral rapid alternate finger tapping measured with magnetoencephalography

NASA Astrophysics Data System (ADS)

Fukuda, Hiroshi; Odagaki, Masato; Hiwaki, Osamu; Kodabashi, Atsushi; Fujimoto, Toshiro

2009-04-01

Using magnetoencephalography (MEG), brain regions involved in an alternate bimanual tapping task by index fingers triggered with spontaneous timing were investigated. The tapping mode in which both index fingers moved simultaneously was interlaced during the task. The groups of the alternate tapping (AL mode) and the simultaneous tapping (SI mode) were extracted from the successive alternating taps with a histogram of intervals between the right and left index fingers. MEG signals in each mode were averaged separately before and after the tapping initiation of the dominant index finger. The activities of the contralateral sensorimotor cortex before and after the tapping initiation in the AL mode were larger than that in the SI mode. The result indicates that the activity of the contralateral sensorimotor cortex depends on the degree of achievement in the difficult motor task such as the voluntary alternate tapping movements.

Dual-mode disturbance-accommodating pointing controller for Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Addington, Stewart I.; Johnson, C. D.

1995-03-01

Cyclic thermal expansions and mechanical stiction effects in the solar arrays on the Hubble Space Telescope (HST) are triggering repeated occurrences of damped, relaxation-type flex-body vibrations of the solar arrays. Those solar array vibrations are, in turn, causing unwanted deviations of the telescope from its specified pointing direction. In this paper we propose two strategies one can adopt in designing a telescope-pointing controller to cope with the aforementioned disturbances: 1) a total isolation (TI) control strategy whereby the HST controller torques are designed to adaptively counteract and cancel out the persistent disturbing torques that are causing the unwanted telescope motions and 2) an array damping (AD) control strategy whereby the HST controller torques are used to actively augment the natural dampening of the solar array vibrations and the attendant telescope motions, between triggerings of the stiction-related flex-body relaxation oscillations. Using the principles of disturbance accommodation control theory, a dual-mode controller for a generic, planar-motion (single-axis) model of the HST is proposed. This controller incorporates both the TI and AD modes of disturbance accommodation. Simulation studies of the closed-loop system using generic parameter values clearly indicate, qualitatively, the enhanced pointing performance such a controller can achieve.

Atom detection and photon production in a scalable, open, optical microcavity.

PubMed

Trupke, M; Goldwin, J; Darquié, B; Dutier, G; Eriksson, S; Ashmore, J; Hinds, E A

2007-08-10

A microfabricated Fabry-Perot optical resonator has been used for atom detection and photon production with less than 1 atom on average in the cavity mode. Our cavity design combines the intrinsic scalability of microfabrication processes with direct coupling of the cavity field to single-mode optical waveguides or fibers. The presence of the atom is seen through changes in both the intensity and the noise characteristics of probe light reflected from the cavity input mirror. An excitation laser passing transversely through the cavity triggers photon emission into the cavity mode and hence into the single-mode fiber. These are first steps toward building an optical microcavity network on an atom chip for applications in quantum information processing.

Triggering of frequent turbidity currents in Monterey Canyon and the role of antecedent conditioning

NASA Astrophysics Data System (ADS)

Clare, M. A.; Rosenberger, K. J.; Talling, P.; Barry, J.; Maier, K. L.; Parsons, D. R.; Simmons, S.; Gales, J. A.; Gwiazda, R.; McGann, M.; Paull, C. K.

2017-12-01

Turbidity currents pose a hazard to seafloor infrastructure, deliver organic carbon and nutrients to deep-sea communities, and form economically important deposits. Thus, determining the tempo of turbidity current activity and whether different triggers result in different flow modes is important. Identification of specific triggers is challenging, however, because most studies of turbidity currents are based on their deposits. New direct monitoring of flows and environmental conditions provides the necessary temporal constraints to identify triggering mechanisms. The Coordinated Canyon Experiment (CCE) in Monterey Canyon, offshore California is the most ambitious attempt yet to measure turbidity flows and their triggers. The CCE provides precise constraint on flow timing, initiation, and potential triggers based on measurements at 7 different instrumented moorings and 2 metocean buoys. Fifteen turbidity flows were measured in 18 months; with recorded velocities >8 m/s and run-outs of up to 50 km. Presence of live estuarine foraminifera within moored sediment traps suggests that that flows originated in water depths of <10 m, but it is unclear specifically how these flows were triggered. Turbidity currents are thought to be triggered by processes including earthquakes, river floods and storm waves. Here we analyse seismicity, local river discharge, internal tides, wave height, direction and period data. We identify no clear control of any of these individual variables on flow timing. None of the recorded earthquakes (

Time-resolved imaging of the plasma development in a triggered vacuum switch

NASA Astrophysics Data System (ADS)

Park, Wung-Hoa; Kim, Moo-Sang; Son, Yoon-Kyoo; Frank, Klaus; Lee, Byung-Joon; Ackerman, Thilo; Iberler, Marcus

2017-12-01

Triggered vacuum switches (TVS) are particularly used in pulsed power technology as closing switches for high voltages and high charge transfer. A non-sealed-off prototype was designed with a side-on quartz window to investigate the evolution of the trigger discharge into the main discharge. The image acquisition was done with a fast CCD camera PI-MAX2 from Princeton Instruments. The CCD camera has a maximum exposure time of 2 ns. The electrode configuration of the prototype is a conventional six-rod gap type, a capacitor bank with C = 16.63 μF, which corresponds at 20 kV charging voltage to a total stored charge of 0.3 C or a total energy of 3.3 kJ. The peak current is 88 kA. According to the tremendously highly different light intensities during the trigger and main discharge, the complete discharge is split into three phases: a trigger breakdown phase, an intermediate phase and a main discharge phase. The CCD camera images of the first phase show instabilities of the trigger breakdown, in phase 2 three different discharge modes are observed. After the first current maximum the discharge behavior is reproducible.

Nonlinear behavior of solar gravity modes driven by He-3 in the core. I - Bifurcation analysis

NASA Technical Reports Server (NTRS)

Merryfield, William J.; Gough, Douglas; Toomre, Juri

1990-01-01

The nonlinear development of solar gravity modes driven by He-3 burning in the solar core is investigated by means of an idealized dynamical model. Possible outcomes that have been suggested in the literature include the triggering of subcritical direct convection, leading to core mixing, and the saturation of the excitation processes, leading to sustained finite-amplitude oscillations. The present simple model suggests that the latter is the more likely. The limiting amplitude of the oscillations is estimated, ignoring possible resonances with other gravity modes, to be of order 10 km/s at the solar surface. Such oscillations would be easily observable. That large-amplitude gravity modes have not been observed suggests either that these modes are not unstable in the present era or that they are limited to much smaller amplitudes by resonant coupling.

Effect-based trigger values for in vitro bioassays: Reading across from existing water quality guideline values.

PubMed

Escher, Beate I; Neale, Peta A; Leusch, Frederic D L

2015-09-15

Cell-based bioassays are becoming increasingly popular in water quality assessment. The new generations of reporter-gene assays are very sensitive and effects are often detected in very clean water types such as drinking water and recycled water. For monitoring applications it is therefore imperative to derive trigger values that differentiate between acceptable and unacceptable effect levels. In this proof-of-concept paper, we propose a statistical method to read directly across from chemical guideline values to trigger values without the need to perform in vitro to in vivo extrapolations. The derivation is based on matching effect concentrations with existing chemical guideline values and filtering out appropriate chemicals that are responsive in the given bioassays at concentrations in the range of the guideline values. To account for the mixture effects of many chemicals acting together in a complex water sample, we propose bioanalytical equivalents that integrate the effects of groups of chemicals with the same mode of action that act in a concentration-additive manner. Statistical distribution methods are proposed to derive a specific effect-based trigger bioanalytical equivalent concentration (EBT-BEQ) for each bioassay of environmental interest that targets receptor-mediated toxicity. Even bioassays that are indicative of the same mode of action have slightly different numeric trigger values due to differences in their inherent sensitivity. The algorithm was applied to 18 cell-based bioassays and 11 provisional effect-based trigger bioanalytical equivalents were derived as an illustrative example using the 349 chemical guideline values protective for human health of the Australian Guidelines for Water Recycling. We illustrate the applicability using the example of a diverse set of water samples including recycled water. Most recycled water samples were compliant with the proposed triggers while wastewater effluent would not have been compliant with a few. The approach is readily adaptable to any water type and guideline or regulatory framework and can be expanded from the protection goal of human health to environmental protection targets. While this work constitutes a proof of principle, the applicability remains limited at present due to insufficient experimental bioassay data on individual regulated chemicals and the derived effect-based trigger values are of course only provisional. Once the experimental database is expanded and made more robust, the proposed effect-based trigger values may provide guidance in a regulatory context. Copyright © 2015 Elsevier Ltd. All rights reserved.

Overview of Emic Triggered Chorus Emissions in Cluster Data

NASA Astrophysics Data System (ADS)

Grison, B.; Pickett, J. S.; Omura, Y.; Santolik, O.; Engebretson, M. J.; Dandouras, I. S.; Masson, A.; Decreau, P. M.; Adrian, M. L.; Cornilleau Wehrlin, N.

2010-12-01

Electromagnetic ion cyclotron (EMIC) triggered emissions have been recently observed onboard the Cluster spacecraft close to the plasmapause in the equatorial region of the magnetosphere (Pickett et al., 2010). The nonlinear mechanism of the wave amplification is the same as for the well known whistler-mode chorus emissions (Omura et al., 2010). The EMIC triggered emissions appear as risers: electromagnetic structures that have a positive frequency drift with time. They can thus be considered as the EMIC analogue of rising frequency whistler-mode chorus emissions. In addition, they propagate away from the magnetic equator. These EMIC risers are not common in Cluster data. We present an overview of the properties of all the identified cases. Risers can be sorted out in two groups: in the first one the starting frequency of EMIC emissions is close to one half of the local proton gyrofrequency and the risers have a clear left-hand polarization. In the second group the risers have an opposite polarization with a starting frequency close to one half of the He+ gyrofrequency. Most of the cases have been detected close to 22 MLT (magnetic local time). This dependence will be investigated to determine if it is linked to the orbit effects or if there is a physical cause.

A plant effector-triggered immunity signaling sector is inhibited by pattern-triggered immunity.

PubMed

Hatsugai, Noriyuki; Igarashi, Daisuke; Mase, Keisuke; Lu, You; Tsuda, Yayoi; Chakravarthy, Suma; Wei, Hai-Lei; Foley, Joseph W; Collmer, Alan; Glazebrook, Jane; Katagiri, Fumiaki

2017-09-15

Since signaling machineries for two modes of plant-induced immunity, pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), extensively overlap, PTI and ETI signaling likely interact. In an Arabidopsis quadruple mutant, in which four major sectors of the signaling network, jasmonate, ethylene, PAD4, and salicylate, are disabled, the hypersensitive response (HR) typical of ETI is abolished when the Pseudomonas syringae effector AvrRpt2 is bacterially delivered but is intact when AvrRpt2 is directly expressed in planta These observations led us to discovery of a network-buffered signaling mechanism that mediates HR signaling and is strongly inhibited by PTI signaling. We named this mechanism the ETI-Mediating and PTI-Inhibited Sector (EMPIS). The signaling kinetics of EMPIS explain apparently different plant genetic requirements for ETI triggered by different effectors without postulating different signaling machineries. The properties of EMPIS suggest that information about efficacy of the early immune response is fed back to the immune signaling network, modulating its activity and limiting the fitness cost of unnecessary immune responses. © 2017 The Authors.

Implement trigger for a NI data acquisition card PCI 5105 in the measurement studio development environment for a high speed demodulator based on fiber Fabry-Pérot tunable filter (FFP-TF)

NASA Astrophysics Data System (ADS)

Zhang, Hongtao; Yang, Shangming; Fan, Lingling; Wang, Pengfei; Zhao, Xilin; Wang, Zhenhua; Cui, Hong-Liang

2010-04-01

In this paper we report a scheme of low-cost, small-size differential electrical converter to change analog trigger signals into digital trigger signals. This converter successfully resolves the incompatibility between the digital trigger mode of NI (National Instruments) data acquisition card PCI 5105 in Measurement Studio development environment for a demodulator and the requirement from instability of spectra of fiber Bragg grating (FBG) sensors. The instability is caused by intrinsic drifts of FFP-TF inside this high speed demodulator. The obtained results of frequency response about the converter have clearly demonstrated that this method is effective when the frequency of trigger signal is less than 3,000 Hz. This converter can satisfy the current requirements of demodulator based on FFP-TF, since mostly actual working scanning frequency of FFP-TF is less than 1,000 Hz. This method may be recommended to resolve similar problems for other NI customers who have developed their data acquisition system based on Measurement Studio.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solomon, W. M., E-mail: solomon@fusion.gat.com; Bortolon, A.; Grierson, B. A.

A new high pedestal regime (“Super H-mode”) has been predicted and accessed on DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. While elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. Similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Exploration of the Super H-mode regime on DIII-D and potential advantages for burning plasma devices

DOE PAGES

Solomon, W. M.; Snyder, P. B.; Bortolon, A.; ...

2016-03-25

In a new high pedestal regime ("Super H-mode") we predicted and accessed DIII-D. Super H-mode was first achieved on DIII-D using a quiescent H-mode edge, enabling a smooth trajectory through pedestal parameter space. By exploiting Super H-mode, it has been possible to access high pedestal pressures at high normalized densities. And while elimination of Edge localized modes (ELMs) is beneficial for Super H-mode, it may not be a requirement, as recent experiments have maintained high pedestals with ELMs triggered by lithium granule injection. Simulations using TGLF for core transport and the EPED model for the pedestal find that ITER canmore » benefit from the improved performance associated with Super H-mode, with increased values of fusion power and gain possible. In similar studies demonstrate that the Super H-mode pedestal can be advantageous for a steady-state power plant, by providing a path to increasing the bootstrap current while simultaneously reducing the demands on the core physics performance.« less

Functional Interrupts and Destructive Failures from Single Event Effect Testing of Point-Of-Load Devices

NASA Technical Reports Server (NTRS)

Chen, Dakai; Phan, Anthony; Kim, Hak; Swonger, James; Musil, Paul; LaBel, Kenneth

2013-01-01

We show examples of single event functional interrupt and destructive failure in modern POL devices. The increasing complexity and diversity of the design and process introduce hard SEE modes that are triggered by various mechanisms.

The Elephant Trunk Nebula and the Trumpler 37 cluster: contribution of triggered star formation to the total population of an H II region

NASA Astrophysics Data System (ADS)

Getman, Konstantin V.; Feigelson, Eric D.; Sicilia-Aguilar, Aurora; Broos, Patrick S.; Kuhn, Michael A.; Garmire, Gordon P.

2012-11-01

Rich young stellar clusters produce H ii regions whose expansion into the nearby molecular cloud is thought to trigger the formation of new stars. However, the importance of this mode of star formation is uncertain. This investigation seeks to quantify triggered star formation (TSF) in IC 1396A (aka the Elephant Trunk Nebula), a bright-rimmed cloud (BRC) on the periphery of the nearby giant H ii region IC 1396 produced by the Trumpler 37 cluster. X-ray selection of young stars from Chandra X-ray Observatory data is combined with existing optical and infrared surveys to give a more complete census of the TSF population. Over 250 young stars in and around IC 1396A are identified; this doubles the previously known population. A spatio-temporal gradient of stars from the IC 1396A cloud towards the primary ionizing star HD 206267 is found. We argue that the TSF mechanism in IC 1396A is a radiation-driven implosion process persisting over several million years. Analysis of the X-ray luminosity and initial mass functions indicates that >140 stars down to 0.1 M⊙ were formed by TSF. Considering other BRCs in the IC 1396 H ii region, we estimate the TSF contribution for the entire H ii region exceeds 14-25 per cent today, and may be higher over the lifetime of the H ii region. Such triggering on the periphery of H ii regions may be a significant mode of star formation in the Galaxy.

A Dynamic Scheduling Method of Earth-Observing Satellites by Employing Rolling Horizon Strategy

PubMed Central

Dishan, Qiu; Chuan, He; Jin, Liu; Manhao, Ma

2013-01-01

Focused on the dynamic scheduling problem for earth-observing satellites (EOS), an integer programming model is constructed after analyzing the main constraints. The rolling horizon (RH) strategy is proposed according to the independent arriving time and deadline of the imaging tasks. This strategy is designed with a mixed triggering mode composed of periodical triggering and event triggering, and the scheduling horizon is decomposed into a series of static scheduling intervals. By optimizing the scheduling schemes in each interval, the dynamic scheduling of EOS is realized. We also propose three dynamic scheduling algorithms by the combination of the RH strategy and various heuristic algorithms. Finally, the scheduling results of different algorithms are compared and the presented methods in this paper are demonstrated to be efficient by extensive experiments. PMID:23690742

On the conditions for nonlinear growth in magnetospheric chorus and triggered emissions

NASA Astrophysics Data System (ADS)

Gołkowski, Mark; Gibby, Andrew R.

2017-09-01

The nonlinear whistler mode instability associated with magnetospheric chorus and VLF triggered emissions continues to be poorly understood. Following up on formulations of other authors, an analytical exploration of the stability of the phenomenon from a new vantage point is given. This exploration derives an additional requirement on the anisotropy of the energetic electron distribution relative to the linear treatment of the instability, and shows that the nonlinear instability is most favorable to increasing growth rate when electrons become initially trapped in the wave potential of a constant frequency wave. These results imply that the initiation of the nonlinear instability at the equator requires a positive frequency sweep rate, while the initiation of the instability by a constant frequency triggering wave must occur at a location downstream of the geomagnetic equator.

A dynamic scheduling method of Earth-observing satellites by employing rolling horizon strategy.

PubMed

Dishan, Qiu; Chuan, He; Jin, Liu; Manhao, Ma

2013-01-01

Focused on the dynamic scheduling problem for earth-observing satellites (EOS), an integer programming model is constructed after analyzing the main constraints. The rolling horizon (RH) strategy is proposed according to the independent arriving time and deadline of the imaging tasks. This strategy is designed with a mixed triggering mode composed of periodical triggering and event triggering, and the scheduling horizon is decomposed into a series of static scheduling intervals. By optimizing the scheduling schemes in each interval, the dynamic scheduling of EOS is realized. We also propose three dynamic scheduling algorithms by the combination of the RH strategy and various heuristic algorithms. Finally, the scheduling results of different algorithms are compared and the presented methods in this paper are demonstrated to be efficient by extensive experiments.

Laser Mode Behavior of the Cassini CIRS Fourier Transform Spectrometer at Saturn

NASA Technical Reports Server (NTRS)

Brasunas, John C.

2012-01-01

The CIRS Fourier transform spectrometer aboard the NASA/ESA/ASI Cassini orbiter has been acquiring spectra of the Saturnian system since 2004. The CIRS reference interferometer employs a laser diode to trigger the interferogram sampling. Although the control of laser diode drive current and operating temperature are stringent enough to restrict laser wavelength variation to a small fraction of CIRS finest resolution element, the CIRS instrument does need to be restarted every year or two, at which time it may start in a new laser mode. By monitoring the Mylar absorption features in uncalibrated spectra due to the beam splitter Mylar substrate, it can be shown that these jumps are to adjacent modes and that most of the eight-year operation so far is restricted to three adjacent modes. For a given mode, the wavelength stability appears consistent with the stability of the laser diode drive curren.t and operating temperature.

An examination of the default mode network in individuals with autonomous sensory meridian response (ASMR).

PubMed

Smith, Stephen D; Katherine Fredborg, Beverley; Kornelsen, Jennifer

2017-08-01

Autonomous Sensory Meridian Response (ASMR) is a perceptual condition in which specific visual and auditory stimuli consistently trigger tingling sensations on the scalp and neck, sometimes spreading to the back and limbs. These triggering stimuli are often social, almost intimate, in nature (e.g., hearing whispering, or watching someone brush her hair), and often elicit a calm and positive emotional state. Surprisingly, despite its prevalence in the general population, no published study has examined the neural underpinnings of ASMR. In the current study, the default mode network (DMN) of 11 individuals with ASMR was contrasted to that of 11 matched controls. The results indicated that the DMN of individuals with ASMR showed significantly less functional connectivity than that of controls. The DMN of individuals with ASMR also demonstrated increased connectivity between regions in the occipital, frontal, and temporal cortices, suggesting that ASMR was associated with a blending of multiple resting-state networks. This atypical functional connectivity likely influences the unique sensory-emotional experiences associated with ASMR.

Engineering a pH-Regulated Switch in the Major Light-Harvesting Complex of Plants (LHCII): Proof of Principle.

PubMed

Liguori, Nicoletta; Natali, Alberto; Croce, Roberta

2016-12-15

Under excess light, photosynthetic organisms employ feedback mechanisms to avoid photodamage. Photoprotection is triggered by acidification of the lumen of the photosynthetic membrane following saturation of the metabolic activity. A low pH triggers thermal dissipation of excess absorbed energy by the light-harvesting complexes (LHCs). LHCs are not able to sense pH variations, and their switch to a dissipative mode depends on stress-related proteins and allosteric cofactors. In green algae the trigger is the pigment-protein complex LHCSR3. Its C-terminus is responsible for a pH-driven conformational change from a light-harvesting to a quenched state. Here, we show that by replacing the C-terminus of the main LHC of plants with that of LHCSR3, it is possible to regulate its excited-state lifetime solely via protonation, demonstrating that the protein template of LHCs can be modified to activate reversible quenching mechanisms independent of external cofactors and triggers.

LIGO-VIRGO Triggered Follow-Up with NASA High Energy Photon Survey Missions

NASA Technical Reports Server (NTRS)

Camp, Jordan

2010-01-01

We discuss the proposed use of LIGO-VIRGO S6 triggers from comparatively loud events to search for both prompt and afterglow EM counterparts with RXTE, SWIFT and FERMI. Using a 2 or 3-fold coincident trigger from the two LIGO and one VIRGO detectors to provide sky position information, we can search the data from these missions within a limited time window and a constrained portion of their respective FOVs, allowing us to look at a level below the threshold normally used to publicly indicate an event. Since we propose to use these missions in their survey mode, no re-pointing of the missions is envisioned. The search for a coincidence between the data from LIGO-VIRGO and the EM survey missions can then be analyzed off-line; if a coincident EM signal is found it would have a significant effect in establishing the validity of the GW trigger. We discuss some relevant aspects of the NASA missions and give some preliminary estimates of thresholds and coincident background rates.

Conversion of the dominantly ideal perturbations into a tearing mode after a sawtooth crash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Igochine, V., E-mail: valentin.igochine@ipp.mpg.de; Gude, A.; Günter, S.

2014-11-15

Forced magnetic reconnection is a topic of common interest in astrophysics, space science, and magnetic fusion research. The tearing mode formation process after sawtooth crashes implies the existence of this type of magnetic reconnection and is investigated in great detail in the ASDEX Upgrade tokamak. The sawtooth crash provides a fast relaxation of the core plasma temperature and can trigger a tearing mode at a neighbouring resonant surface. It is demonstrated for the first time that the sawtooth crash leads to a dominantly ideal kink mode formation at the resonant surface immediately after the sawtooth crash. Local measurements show thatmore » this kink mode transforms into a tearing mode on a much longer timescale (10{sup −3}s−10{sup −2}s) than the sawtooth crash itself (10{sup −4}s). The ideal kink mode formed after the sawtooth crash provides the driving force for magnetic reconnection and its amplitude is one of the critical parameters for the length of the transition phase from a ideal into an resistive mode. Nonlinear two fluid MHD simulations confirm these observations.« less

Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

NASA Astrophysics Data System (ADS)

Kleiner, A.; Graves, J. P.; Brunetti, D.; Cooper, W. A.; Halpern, F. D.; Luciani, J.-F.; Lütjens, H.

2016-09-01

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that infernal modes drive fast growing islands on neighbouring rational surfaces. Numerical simulations of such instabilities in a MAST-like configuration are performed with the initial value stability code XTOR-2F in the resistive frame. The evolution of magnetic islands are computed from XTOR-2F simulations and an analytical model is developed based on Rutherford’s theory in combination with a model of resistive infernal modes. The parameter {{Δ }\\prime} is extended from the linear phase to the non-linear phase. Additionally, the destabilising contribution due to a helically perturbed bootstrap current is considered. Comparing the numerical XTOR-2F simulations to the model, we find that coupling has a strong destabilising effect on (neoclassical) tearing modes and is able to seed 2/1 magnetic islands in situations when the standard NTM theory predicts stability.

The role of turbulence-flow interactions in L- to H-mode transition dynamics: recent progress

NASA Astrophysics Data System (ADS)

Schmitz, L.

2017-02-01

Recent experimental and simulation work has substantially advanced the understanding of L-mode plasma edge turbulence and plasma flows and their mutual interaction across the L-H transition. Flow acceleration and E   ×   B shear flow amplification via the turbulent Reynolds stress have been directly observed in multiple devices, using multi-tip probe arrays, Doppler backscattering, beam emission spectroscopy, and gas puff imaging diagnostics. L-H transitions characterized by limit-cycle oscillations (LCO) allow probing of the trigger dynamics and the synergy of turbulence-driven and pressure-gradient-driven flows with high spatio-temporal resolution. L-mode turbulent structures exhibit characteristic changes in topology (tilting) and temporal and radial correlation preceding the L-H transition. Long-range toroidal flow correlations increase preceding edge-transport-barrier formation. The energy transfer from the turbulence spectrum to large-scale axisymmetric flows has been quantified in L-LCO and fast L-H transitions in several devices. After formation of a transient barrier, the increasing ion pressure gradient (via the E   ×   B flow shear associated with diamagnetic flow) sustains fluctuation suppression and secures the transition to H-mode. Heuristic models of the L-H trigger dynamics have progressed from 0D predator-prey models to 1D extended models, including neoclassical ion flow-damping and pressure-gradient evolution. Initial results from 2D and 3D reduced fluid models have been obtained for high-collisionality regimes.

The Structural Phase Transition in Deuterated Benzil, C 14D 10O 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goosens, D. J.; Welberry, T. R.; Hagen, Mark E

2006-01-01

Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}. The transition in benzil, in which the unit cell goes from a trigonal P3{sub 1}21 unit cell above T{sub c} to a cell doubled P2{sub 1} unit cell below T{sub c}, leads to the emergence of a Bragg peak at the M-point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the {lambda}-point leads to the triggering of an instability at the M-point causing the transition to occur. This suggestionmore » has been investigated by measuring the phonon spectrum at the M-point for a range of temperatures above T{sub c} and the phonon dispersion relation along the {lambda}-M direction just above T{sub c}. It is found that the transverse acoustic phonon at the M-point is of lower energy than the {lambda}-point optic mode and has a softening with temperature as T approaches T{sub c} from above that is much faster than that of the {lambda}-point optic mode. This behavior is inconsistent with the view that the {lambda}-point mode is responsible for triggering the phase transition. Rather the structural phase transition in benzil appears to be driven by a conventional soft TA mode at the M-point.« less

Structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}: Neutron inelastic scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goossens, D. J.; Welberry, T. R.; Hagen, M. E.

2006-04-01

Neutron inelastic scattering has been used to examine the structural phase transition in deuterated benzil C{sub 14}D{sub 10}O{sub 2}. The transition in benzil, in which the unit cell goes from a trigonal P3{sub 1}21 unit cell above T{sub C} to a cell doubled P2{sub 1} unit cell below T{sub C}, leads to the emergence of a Bragg peak at the M-point of the high temperature Brillouin zone. It has previously been suggested that the softening of a transverse optic phonon at the {gamma}-point leads to the triggering of an instability at the M-point causing the transition to occur. This suggestionmore » has been investigated by measuring the phonon spectrum at the M-point for a range of temperatures above T{sub C} and the phonon dispersion relation along the {gamma}-M direction just above T{sub C}. It is found that the transverse acoustic phonon at the M-point is of lower energy than the {gamma}-point optic mode and has a softening with temperature as T approaches T{sub C} from above that is much faster than that of the {gamma}-point optic mode. This behavior is inconsistent with the view that the {gamma}-point mode is responsible for triggering the phase transition. Rather the structural phase transition in benzil appears to be driven by a conventional soft TA mode at the M-point.« less

Results from the Autonomous Triggering of in situ Sensors on Kilauea Volcano, HI, from Eruption Detection by Spacecraft

NASA Astrophysics Data System (ADS)

Doubleday, J.; Behar, A.; Davies, A.; Mora-Vargas, A.; Tran, D.; Abtahi, A.; Pieri, D. C.; Boudreau, K.; Cecava, J.

2008-12-01

Response time in acquiring sensor data in volcanic emergencies can be greatly improved through use of autonomous systems. For instance, ground-based observations and data processing applications of the JPL Volcano Sensor Web have promptly triggered spacecraft observations [e.g., 1]. The reverse command and information flow path can also be useful, using autonomous analysis of spacecraft data to trigger in situ sensors. In this demonstration project, SO2 sensors were incorporated into expendable "Volcano Monitor" capsules and placed downwind of the Pu'u 'O'o vent of Kilauea volcano, Hawai'i. In nominal (low) power conservation mode, data from these sensors were collected and transmitted every hour to the Volcano Sensor Web through the Iridium Satellite Network. When SO2 readings exceeded a predetermined threshold, the modem within the Volcano Monitor sent an alert to the Sensor Web, and triggered a request for prompt Earth Observing-1 (EO-1) spacecraft data acquisition. The Volcano Monitors were also triggered by the Sensor Web in response to an eruption detection by the MODIS instrument on Terra. During these pre- defined "critical events" the Sensor Web ordered the SO2 sensors within the Volcano Monitor to increase their sampling frequency to every 5 minutes (high power "burst mode"). Autonomous control of the sensors' sampling frequency enabled the Sensor Web to monitor and respond to rapidly evolving conditions, and allowed rapid compilation and dissemination of these data to the scientific community. Reference: [1] Davies et al., (2006) Eos, 87, (1), 1 and 5. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA. Support was provided by the NASA AIST program, the Idaho Space Grant Consortium, and the New Mexico Space Grant Program. We also especially thank the personnel of the USGS Hawaiian Volcano Observatory for their invaluable scientific guidance and logistical assistance.

Determination of Delta m(d) and absolute calibration of flavor taggers for the Delta m(s) analysis, in fully reconstructed decays at the CDF experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gomez, Jonatan Piedra

2005-04-21

The new trigger processor, the Silicon Vertex Tracking (SVT), has dramatically improved the B physics capabilities of the upgraded CDF II Detector; for the first time in a hadron collider, the SVT has enabled the access to non-lepton-triggered B meson decays. Within the new available range of decay modes, the Bmore » $$0\\atop{s}$$ → D$$-\\atop{s}$$π + signature is of paramount importance in the measurement of the Δm s mixing frequency. The analysis reported here is a step towards the measurement of this frequency; two where our goals: carrying out the absolute calibration of the opposite side flavor taggers, used in the Δm s measurement; and measuring the B$$0\\atop{d}$$ mixing frequency in a B → Dπ sample, establishing the feasibility of the mixing measurement in this sample whose decay-length is strongly biased by the selective SVT trigger. We analyze a total integrated luminosity of 355 pb -1 collected with the CDF II Detector. By triggering on muons, using the conventional di-muon trigger; or displaced tracks, using the SVT trigger, we gather a sample rich in bottom and charm mesons.« less

Triggering of the Ms = 5.4 Little Skull Mountain, Nevada, earthquake with dynamic strains

USGS Publications Warehouse

Gomberg, Joan; Bodin, Paul

1994-01-01

We have developed an approach to test the viability of dynamic strains as a triggering mechanism by quantifying the dynamic strain tensor at seismogenic depths. We focus on the dynamic strains at the hypocenter of the Ms = 5.4 Little Skull Mountain (LSM), Nevada, earthquake. This event is noteworthy because it is the largest earthquake demonstrably triggered at remote distances (∼280 km) by the Ms = 7.4 Landers, California, earthquake and because of its ambiguous association with magmatic activity. Our analysis shows that, if dynamic strains initiate remote triggering, the orientation and modes of faulting most favorable for being triggered by a given strain transient change with depth. The geometry of the most probable LSM fault plane was favorably oriented with respect to the geometry of the dynamic strain tensor. We estimate that the magnitude of the peak dynamic strains at the hypocentral depth of the LSM earthquake were ∼4 μstrain (∼.2 MPa) which are ∼50% smaller than those estimated from velocity seismograms recorded at the surface. We suggest that these strains are too small to cause Mohr-Coulomb style failure unless the fault was prestrained to near failure levels, the fault was exceptionally weak, and/or the dynamic strains trigger other processes that lead to failure.

Dynamic stresses, coulomb failure, and remote triggering: corrected

USGS Publications Warehouse

Hill, David P.

2012-01-01

Dynamic stresses associated with crustal surface waves with 15–30 s periods and peak amplitudes <1  MPa are capable of triggering seismicity at sites remote from the generating mainshock under appropriate conditions. Coulomb failure models based on a frictional strength threshold offer one explanation for instances of rapid‐onset triggered seismicity that develop during the surface‐wave peak dynamic stressing. Evaluation of the triggering potential of surface‐wave dynamic stresses acting on critically stressed faults using a Mohr’s circle representation together with the Coulomb failure criteria indicates that Love waves should have a higher triggering potential than Rayleigh waves for most fault orientations and wave incidence angles. That (1) the onset of triggered seismicity often appears to begin during the Rayleigh wave rather than the earlier arriving Love wave, and (2) Love‐wave amplitudes typically exceed those for Rayleigh waves suggests that the explanation for rapid‐onset dynamic triggering may not reside solely with a simple static‐threshold friction mode. The results also indicate that normal faults should be more susceptible to dynamic triggering by 20‐s Rayleigh‐wave stresses than thrust faults in the shallow seismogenic crust (<10  km) while the advantage tips in favor of reverse faults greater depths. This transition depth scales with wavelength and coincides roughly with the transition from retrograde‐to‐prograde particle motion. Locally elevated pore pressures may have a role in the observed prevalence of dynamic triggering in extensional regimes and geothermal/volcanic systems. The result is consistent with the apparent elevated susceptibility of extensional or transtensional tectonic regimes to remote triggering by Rayleigh‐wave dynamic stresses than compressional or transpressional regimes.

A dual-mode disturbance-accommodating controller for the Hubble Space Telescope

NASA Astrophysics Data System (ADS)

Addington, Stewart; Johnson, C. D.

Cyclic thermal expansions and mechanical stiction effects in the Solar Arrays on the Hubble Space Telescope (HST) are triggering repeated occurrences of damped, relaxation-type flex-body vibrations of the solar arrays. Those solar array vibrations are, in turn, causing unwanted, oscillating disturbance torques on the HST main body, which cause unwanted deviations of the telescope from its specified pointing direction. In this paper we propose two strategies one can adopt in designing a telescope-pointing controller to cope with the aforementioned disturbances: (1) a `total isolation' (TI) control strategy whereby the HST controller torques are designed to adaptively counteract and cancel-out the persistent disturbing torques that are causing the unwanted telescope motions, and (2) an `array damping' (AD) control strategy whereby the HST controller torques are used to actively augment the natural dampening of the solar array vibrations and the attendant telescope motions, between triggerings of the stiction-related flex-body relaxation oscillations. Using the principles of Disturbance-Accommodating Control (DAC) Theory a dual-mode controller for a generic, planar-motion (single-axis) model of the HST is proposed. This controller incorporates both the TI and AD modes of disturbance-accommodation. Simulation studies of the closed-loop system using generic parameter values clearly indicate, qualitatively, the enhanced pointing-performance such a controller can achieve.

Tributyltin-induced apoptosis requires glycolytic adenosine trisphosphate production.

PubMed

Stridh, H; Fava, E; Single, B; Nicotera, P; Orrenius, S; Leist, M

1999-10-01

The toxicity of tributyltin chloride (TBT) involves Ca(2+) overload, cytoskeletal damage, and mitochondrial failure leading to cell death by apoptosis or necrosis. Here, we examined whether the intracellular ATP level modulates the mode of cell death after exposure to TBT. When Jurkat cells were energized by the mitochondrial substrate, pyruvate, low concentrations of TBT (1-2 microM) triggered an immediate depletion of intracellular ATP followed by necrotic death. When ATP levels were maintained by the addition of glucose, the mode of cell death was typically apoptotic. Glycolytic ATP production was required for apoptosis at two distinct steps. First, maintenance of adequate ATP levels accelerated the decrease of mitochondrial membrane potential, and the release of the intermembrane proteins adenylate kinase and cytochrome c from mitochondria. A possible role of the adenine nucleotide exchanger in this first ATP-dependent step is suggested by experiments performed with the specific inhibitor, bongkrekic acid. This substance delayed cytochrome c release in a manner similar to that caused by ATP depletion. Second, caspase activation following cytochrome c release was only observed in ATP-containing cells. Bcl-2 had only a minor effect on TBT-triggered caspase activation or cell death. We conclude that intracellular ATP concentrations control the mode of cell death in TBT-treated Jurkat cells at both the mitochondrial and caspase activation levels.

Utility of dual source CT with ECG-triggered high-pitch spiral acquisition (Flash Spiral Cardio mode) to evaluate morphological features of ventricles in children with complex congenital heart defects.

PubMed

Nakagawa, Motoo; Ozawa, Yoshiyuki; Nomura, Norikazu; Inukai, Sachiko; Tsubokura, Satoshi; Sakurai, Keita; Shimohira, Masashi; Ogawa, Masaki; Shibamoto, Yuta

2016-04-01

We evaluated the ability of dual source CT (DSCT) with ECG-triggered high-pitch spiral acquisition (Flash Spiral Cardio mode) to depict the morphological features of ventricles in pediatric patients with congenital heart defects (CHD). Between July 2013 and April 2015, 78 pediatric patients with CHD (median age 4 months) were examined using DSCT with the Flash Spiral Cardio mode. The types of ventricular abnormalities were ventricular septal defect (VSD) in 42 (the malaligned type in 11, perimembranous type in 23, supracristal type in 2, atrioventricular type in 2, and muscular type in 4), single ventricle (SV) in 11, and congenital corrected transposition of the great arteries (ccTGA) in 4. We evaluated the accuracy of the diagnosis of the VSD type. In cases of SV and ccTGA, we assessed the detectability of the anatomical features of both ventricles for a diagnosis of ventricular situs. DSCT confirmed the diagnoses for all VSDs. The type of defect was precisely diagnosed for all patients. The anatomical features of both ventricles were also depicted and ventricular situs of SV and ccTGA was correctly diagnosed. The results suggest that DSCT has the ability to clearly depict the configuration of ventricles.

Elves, Forbush Decreases and Solar Activity Studies at the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Colalillo, Roberta

The Pierre Auger Observatory, designed to observe cosmic rays at the highest energies, can also be a valid ground based instrument for the observation of transient luminous events and for studying the modulation of galactic cosmic rays due to solar activity. The Fluorescence Detector can observe elves, transient luminous emissions from altitudes between 80 and 95 km above sea level, with timescales of tens of microseconds, which are triggered by lightning activity. A dedicated trigger and an extended readout scheme were introduced to enhance detection efficiency of these events and to improve the knowledge of some peculiar characteristics. The low energy mode of the Surface Detector, on the other hand, records variations in the flux of low energy secondary particles with extreme detail. With the Scaler mode, it is possible to register the rate of signals for deposited energies between 15-100 MeV; the Histogram mode, using the calibration peak and charge histograms of the individual pulses detected by each water-Cherenkov station, covers different deposited energy ranges up to 1 GeV. The variations in the flux of galactic cosmic rays have been studied on short and intermediate time scales (Forbush decreases), but also a long-term analysis, which shows the sensitivity of the Observatory to the solar cycle variation, is in progress.

Electro-optical resonance modulation of vertical-cavity surface-emitting lasers.

PubMed

Germann, Tim David; Hofmann, Werner; Nadtochiy, Alexey M; Schulze, Jan-Hindrik; Mutig, Alex; Strittmatter, André; Bimberg, Dieter

2012-02-27

Optical and electrical investigations of vertical-cavity surface-emitting lasers (VCSEL) with a monolithically integrated electro-optical modulator (EOM) allow for a detailed physical understanding of this complex compound cavity laser system. The EOM VCSEL light output is investigated to identify optimal working points. An electro-optic resonance feature triggered by the quantum confined Stark effect is used to modulate individual VCSEL modes by more than 20 dB with an extremely small EOM voltage change of less than 100 mV. Spectral mode analysis reveals modulation of higher order modes and very low wavelength chirp of < 0.5 nm. Dynamic experiments and simulation predict an intrinsic bandwidth of the EOM VCSEL exceeding 50 GHz.

Developmental changes in Ca2+ channel subtypes regulating endocytosis at the calyx of Held

PubMed Central

Midorikawa, Mitsuharu; Okamoto, Yuji; Sakaba, Takeshi

2014-01-01

At the mammalian central synapse, Ca2+ influx through Ca2+ channels triggers neurotransmitter release by exocytosis of synaptic vesicles, which fuse with the presynaptic membrane and are subsequently retrieved by endocytosis. At the calyx of Held terminal, P/Q-type Ca2+ channels mainly mediate exocytosis, while N- and R-type channels have a minor role in young terminals (postnatal days 8–11). The role of each Ca2+ channel subtype in endocytosis remains to be elucidated; therefore, we examined the role of each type of Ca2+ channel in endocytosis, by using whole-cell patch-clamp recordings in conjunction with capacitance measurement techniques. We found that at the young calyx terminal, when R-type Ca2+ channels were blocked, the slow mode of endocytosis was further slowed, while blocking of either P/Q- or N-type Ca2+ channels had no major effect. In more mature terminals (postnatal days 14–17), the slow mode of endocytosis was mainly triggered by P/Q-type Ca2+ channels, suggesting developmental changes in the regulation of the slow mode of endocytosis by different Ca2+ channel subtypes. In contrast, a fast mode of endocytosis was observed after strong stimulation in young terminals that was mediated mainly by P/Q-type, but not R- or N-type Ca2+ channels. These results suggest that different types of Ca2+ channels regulate the two different modes of endocytosis. The results may also suggest that exo- and endocytosis are regulated independently at different sites in young animals but are more tightly coupled in older animals, allowing more efficient synaptic vesicle cycling adapted for fast signalling. PMID:24907302

Equatorial Kelvin waves generated in the western tropical Pacific Ocean trigger mass and heat transport within the Middle America Trench off Costa Rica

NASA Astrophysics Data System (ADS)

Thomson, Richard E.; Davis, Earl E.

2017-07-01

Sequences of correlated seafloor temperature, current velocity, and acoustic backscatter events recorded at Ocean Drilling Program (ODP) sites at 4300 m depth in the Middle America Trench have been inferred to result from tidally induced turbidity currents generated in the vicinity of the 3300 m deep sill at the southern end of the trench. New data from the borehole observatories extend the temperature records to 11 years (November 2002 to December 2013) and confirm the highly episodic nature of the events. We present satellite altimetry data and ocean circulation model results to show that event timing is correlated with intraseasonal Kelvin wave motions in the equatorial Pacific. The observed temperature events had a mean (±1 standard deviation) occurrence interval of 61 (±24) days, which spans the periods of the first two baroclinic modes. Lag times between peak bottom water temperatures at the ODP sites and the passage of eastward-propagating Kelvin wave crests at locations in the eastern equatorial Pacific are consistent with the time for mode-1 waves to propagate to the southern end of the trench at a mean phase speed of 2.0 m s-1. Findings indicate that Kelvin wave currents augment tidal motions in the vicinity of the sill, triggering turbidity currents that travel northwestward along the trench axis at mean speeds of ˜0.1 m s-1. We conclude that mode-1 (or, possibly, mixed mode-1 and mode-2) baroclinic Kelvin waves generated by large-scale atmospheric processes in the western tropical Pacific lead to heat and mass transport deep within Middle America Trench in the eastern tropical Pacific.

Tsunami normal modes with solid earth and atmospheric coupling and inversion of the TEC data to estimate tsunami water height in the case of the Queen Charlotte tsunami.

NASA Astrophysics Data System (ADS)

Rakoto, V.; Lognonne, P. H.; Rolland, L.

2016-12-01

Large underwater earthquakes (Mw > 7) can transmit part of their energy to the surrounding ocean through large sea-floor motions, generating tsunamis that propagate over long distances. The forcing effect of long period ocean surface vibrations due to tsunami waves on the atmosphere trigger atmospheric internal gravity waves (IGWs) that induce ionospheric disturbances when they reach the upper atmosphere. In this poster, we study the IGWs associated to tsunamis using a normal modes 1D modeling approach. Our model is first applied to the case of the October 2012 Haida Gwaii tsunami observed offshore Hawaii. We found three resonances between tsunami modes and the atmospheric gravity modes occurring around 1.5 mHz, 2 mHz and 2.5 mHz, with a large fraction of the energy of the tsunami modes transferred from the ocean to the atmosphere. At theses frequencies, the gravity branches are interacting with the tsunami one and have large amplitude in the ocean. As opposed to the tsunami, a fraction of their energy is therefore transferred from the atmosphere to the ocean. We also show that the fundamental of the gravity waves should arrive before the tsunami due to higher group velocity below 1.6 mHz. We demonstrate that only the 1.5 mHz resonance of the tsunami mode can trigger observable ionospheric perturbations, most often monitored using GPS dual-frequency measurements. Indeed, we show that the modes at 2 mHz and 2.5 mHz are already evanescent at the height of the F2 peak and have little energy in the ionosphere. This normal modes modeling offers a novel and comprehensive study of the transfer function from a propagating tsunami to the upper atmosphere. In particular, we can invert the perturbed TEC data induced by a tsunami in order to estimate the amplitude of the tsunami waveform using a least square method. This method has been performed in the case of the Haida Gwaii tsunami. The results showed a good agreement with the measurement of the dart buoy.

Design, fabrication, and testing of an ultrasonic de-icing system for helicopter rotor blades

NASA Astrophysics Data System (ADS)

Palacios, Jose Luis

A low-power, non-thermal ultrasonic de-icing system is introduced as a possible substitute for current electro-thermal systems. The system generates delaminating ultrasonic transverse shear stresses at the interface of accreted ice. A PZT-4 disk driven at 28.5 KHz (radial resonance of the disk) instantaneously de-bonds 2 mm thick freezer ice layers. The ice layers are accreted to a 0.7 mm thick, 30.4 cm x 30.4 cm steel plate at an environment temperature of -20°C. A power input of 50 Watts is applied to the actuator (50 V, 19.6 KV/m), which translates to a de-icing power of 0.07 W/cm2. A finite element model of the actuator bonded to the isotropic plate is used to guide the design of the system, and predicts the transverse shear stresses at the ice interface. Wind tunnel icing tests were conducted to demonstrate the potential use of the proposed system under impact icing conditions. Both glaze ice and rime ice were generated on steel and composite plates by changing the cloud conditions of the wind tunnel. Continuous ultrasonic vibration prevented impact ice formation around the actuator location at an input power not exceeding 0.18 W/cm 2 (1.2 W/in2). As ice thickness reached a critical thickness of approximately 1.2 mm, shedding occurred on those locations where ultrasonic transverse shear stresses exceeded the shear adhesion strength of the ice. Finite element transverse shear stress predictions correlate with observed experimental impact ice de-bonding behavior. To increase the traveling distance of propagating ultrasonic waves, ultrasonic shear horizontal wave modes are studied. Wave modes providing large modal interface transverse shear stress concentration coefficients (ISCC) between the host structure (0.7 mm thick steel plate) and accreted ice (2.5 mm thick ice layer) are identified and investigated for a potential increase in the wave propagation distance. Ultrasonic actuators able to trigger these optimum wave modes are designed and fabricated. Despite exciting wave modes with high ISCC values, instantaneous ice de-bonding is not observed at input powers under 100 Watts. The two triggered ultrasonic wave modes of the structure occur at high excitation frequencies, 202 KHz and 500 KHz respectively. At these frequencies, the ultrasonic actuators do not provide large enough transverse shear stresses to exceed the shear adhesion strength of the ice layer. Neither the actuator exciting the SH1 mode (202 KHz), nor the actuator triggering the SH2 mode (500 KHz) instantaneously de-bonds ice layers with an input power under 100 Watts.

A keyboard control method for loop measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Z.W.

1994-12-31

This paper describes a keyboard control mode based on the DEC VAX computer. The VAX Keyboard code can be found under running of a program was developed. During the loop measurement or multitask operation, it ables to be distinguished from a keyboard code to stop current operation or transfer to another operation while previous information can be held. The combining of this mode, the author successfully used one key control loop measurement for test Dual Input Memory module which is used in a rearrange Energy Trigger system for LEP 8 Bunch operation.

Kisspeptin as a promising oocyte maturation trigger for in vitro fertilisation in humans.

PubMed

Kasum, Miro; Franulić, Daniela; Čehić, Ermin; Orešković, Slavko; Lila, Albert; Ejubović, Emina

2017-08-01

The aim of this review is to analyse the effectiveness of exogenous kisspeptin administration as a novel alternative of triggering oocyte maturation, instead of currently used triggers such as human chorionic gonadotropin (hCG) or gonadotropin releasing hormone (GnRH) agonist, in women undergoing in vitro fertilisation (IVF) treatment. Kisspeptin has been considered a master regulator of two modes of GnRH and hence gonadotropin secretion, pulses and surges. Administration of kisspeptin-10 and kisspeptin-54 induces the luteinising hormone (LH) surge required for egg maturation and ovulation in animal investigations and LH release during the preovulatory phase of the menstrual cycle and hypothalamic amenorrhoea in humans. Exogenous kisspeptin-54 has been successfully administered as a promising method of triggering oocyte maturation, following ovarian stimulation with gonadotropins and GnRH antagonists in women undergoing IVF, due to its efficacy considering achieved pregnancy rates compared to hCG and GnRH agonists. Also, its safety in patients at high risk of developing ovarian hyperstimulation syndrome is noteworthy. Nevertheless, further studies would be desirable to establish the optimal trigger of egg maturation and to improve the reproductive outcome for women undergoing IVF treatment.

The mechanism of growth of the low-frequency East Asia-Pacific teleconnection and the triggering role of tropical intraseasonal oscillation

NASA Astrophysics Data System (ADS)

Wang, Jiabao; Wen, Zhiping; Wu, Renguang; Guo, Yuanyuan; Chen, Zesheng

2016-06-01

The East Asia-Pacific (EAP) pattern is a well-known meridional teleconnection over East Asia during boreal summer. In this study, the mechanism for growth of the EAP on intraseasonal timescale is investigated through a vorticity budget. It is found that the beta-effect and high-frequency transient eddies have primary contributions to the growth of the low-frequency EAP. The former leads to a westward shift of disturbances associated with the low-frequency EAP and the latter favors an amplification of disturbances, respectively. The interaction between low-frequency disturbances and zonal flow has a damping effect by dragging disturbances eastward. The impact of boreal summer intraseasonal oscillation (BSISO) on the triggering of the low-frequency EAP is also examined in this study based on observational analysis and a linear model experiment. It is shown that an elongated anomalous convection band located in the vicinity of Philippines associated with the dominant mode of BSISO has a significant impact on the initiation of low-frequency EAP via Rossby wave propagation, whereas anomalous convection located over the North Indian Ocean has a limited impact. Based on the results of present study, the low-frequency EAP could be a self-sustained mode, and the BSISO plays a substantial role in triggering the low-frequency EAP.

Evaluation of an adaptive detector collimation for prospectively ECG-triggered coronary CT angiography with third-generation dual-source CT.

PubMed

Messerli, Michael; Dewes, Patricia; Scholtz, Jan-Erik; Arendt, Christophe; Wildermuth, Simon; Vogl, Thomas J; Bauer, Ralf W

2018-05-01

To investigate the impact of an adaptive detector collimation on the dose parameters and accurateness of scan length adaption at prospectively ECG-triggered sequential cardiac CT with a wide-detector third-generation dual-source CT. Ideal scan lengths for human hearts were retrospectively derived from 103 triple-rule-out examinations. These measures were entered into the new scanner operated in prospectively ECG-triggered sequential cardiac scan mode with three different detector settings: (1) adaptive collimation, (2) fixed 64 × 0.6-mm collimation, and (3) fixed 96 × 0.6-mm collimation. Differences in effective scan length and deviation from the ideal scan length and dose parameters (CTDIvol, DLP) were documented. The ideal cardiac scan length could be matched by the adaptive collimation in every case while the mean scanned length was longer by 15.4% with the 64 × 0.6 mm and by 27.2% with the fixed 96 × 0.6-mm collimation. While the DLP was almost identical between the adaptive and the 64 × 0.6-mm collimation (83 vs. 89 mGycm at 120 kV), it was 62.7% higher with the 96 × 0.6-mm collimation (135 mGycm), p < 0.001. The adaptive detector collimation for prospectively ECG-triggered sequential acquisition allows for adjusting the scan length as accurate as this can only be achieved with a spiral acquisition. This technique allows keeping patient exposure low where patient dose would significantly increase with the traditional step-and-shoot mode. • Adaptive detector collimation allows keeping patient exposure low in cardiac CT. • With novel detectors the desired scan length can be accurately matched. • Differences in detector settings may cause 62.7% of excessive dose.

Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tie, W., E-mail: twh.110.666@163.com, E-mail: 84470220@qq.com; Xi'an Jiaotong University, Xi'an 710049; Liu, S.

The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 10{sup 6 }cm/s. The electron temperature decreased from 2.0 eVmore » to 1.3 eV, and the electron density increased from 3.1 × 10{sup 15}/cm{sup 3} to 6.3 × 10{sup 15}/cm{sup 3} at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.« less

Scaling of the MHD perturbation amplitude required to trigger a disruption and predictions for ITER

NASA Astrophysics Data System (ADS)

de Vries, P. C.; Pautasso, G.; Nardon, E.; Cahyna, P.; Gerasimov, S.; Havlicek, J.; Hender, T. C.; Huijsmans, G. T. A.; Lehnen, M.; Maraschek, M.; Markovič, T.; Snipes, J. A.; the COMPASS Team; the ASDEX Upgrade Team; Contributors, JET

2016-02-01

The amplitude of locked instabilities, likely magnetic islands, seen as precursors to disruptions has been studied using data from the JET, ASDEX Upgrade and COMPASS tokamaks. It was found that the thermal quench, that often initiates the disruption, is triggered when the amplitude has reached a distinct level. This information can be used to determine thresholds for simple disruption prediction schemes. The measured amplitude in part depends on the distance of the perturbation to the measurement coils. Hence the threshold for the measured amplitude depends on the mode location (i.e. the rational q-surface) and thus indirectly on parameters such as the edge safety factor, q 95, and the internal inductance, li(3), that determine the shape of the q-profile. These dependencies can be used to set the disruption thresholds more precisely. For the ITER baseline scenario, with typically q 95  =  3.2, li(3)  =  0.9 and taking into account the position of the measurement coils on ITER, the maximum allowable measured locked mode amplitude normalized to engineering parameters was estimated to be a·B ML(r c)/I p  =  0.92 m mT/MA, or directly as a fraction edge poloidal magnetic field: B ML(r c)/B θ (a)  =  5 · 10-3. But these values decrease for operation at higher q 95 or lower li(3). The analysis found furthermore that the above empirical criterion to trigger a thermal quench is more consistent with a criterion derived with the concept of a critical island size, i.e. the thermal quench seemed to be triggered at a distinct island width.

New measurements from fully reconstructed hadronic final states of the $$B^0_2$$ meson at CDF II experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Da Ronco, Saverio

2006-01-01

This thesis reports the reconstruction and lifetime measurement of B +, Bmore » $$0/atop{d}$$ and B$$0/atop{s}$$ mesons, performed using fully reconstructed hadronic decays collected by a dedicated trigger at CDF II experiment. This dedicated trigger selects significantly displaced tracks from primary vertex of p$$\\bar{p}$$ collisions generated at Tevatron collider, obtaining, in this way, huge data samples enriched of long-lived particles, and is therefore suitable for reconstruction of B meson in hadronic decay modes. Due to the trigger track impact parameter selections, the proper decay time distributions of the B mesons no longer follow a simply exponential decay law. This complicates the lifetime measurement and requires a correct understanding and treatment of all the involved effects to keep systematic uncertainties under control. This thesis presents a method to extract the lifetime of B mesons in “ct- biased” samples, based on a Monte Carlo approach, to correct for the effects of the trigger and analysis selections. We present the results of this method when applied on fully re- constructed decays of B collected by CDF II in the data taking runs up to August 2004, corresponding to an integrated luminosity of about 360 pb -1. The lifetimes are extracted using the decay modes B + → $$\\bar{D}$$ 0π +,B$$0\\atop{d}$$ → D -π +, B$$0\\atop{d}$$ → D -π +π -π +, B$$0\\atop{s}$$ → D$$-\\atop{s}$$π + and B$$0\\atop{s}$$ → D$$-\\atop{s}$$ π +π -π +(and c.c.) and performing combined mass-lifetime unbinned maximum likelihood fits.« less

Edge-localized-modes in tokamaks

DOE PAGES

Leonard, Anthony W.

2014-09-11

Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients in the H-mode transport barrier grow to exceed the MHD stability limit the ELM instability grows explosively rapidly transporting energy and particles onto open field lines and material surfaces. Though ELMs provide additional particle and impurity transport through the H-mode transport barrier, enabling steady operation, the resulting heat flux transients to plasma facing surfaces project to large amplitude in future low collisionality burning plasma tokamaks. Measurements of the ELM heat flux deposition onto material surfaces in the divertor and main chamber indicate significant broadening compared to inter-ELM heatmore » flux, with a timescale for energy deposition that is consistent with sonic ion flow and numerical simulation. Comprehensive ELM simulation is highlighting the important physics processes of ELM transport including parallel transport due to magnetic reconnection and turbulence resulting from collapse of the H-mode transport barrier. As a result, encouraging prospects for ELM control and/or suppression in future tokamaks include intrinsic modes of ELM free operation, ELM triggering with frequent small pellet injection and the application of 3D magnetic fields.« less

Edge-localized-modes in tokamaksa)

NASA Astrophysics Data System (ADS)

Leonard, A. W.

2014-09-01

Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients in the H-mode transport barrier grow to exceed the MHD stability limit the ELM instability grows explosively, rapidly transporting energy and particles onto open field lines and material surfaces. Though ELMs provide additional particle and impurity transport through the H-mode transport barrier, enabling steady operation, the resulting heat flux transients to plasma facing surfaces project to large amplitude in future low collisionality burning plasma tokamaks. Measurements of the ELM heat flux deposition onto material surfaces in the divertor and main chamber indicate significant broadening compared to inter-ELM heat flux, with a timescale for energy deposition that is consistent with sonic ion flow and numerical simulation. Comprehensive ELM simulation is highlighting the important physics processes of ELM transport including parallel transport due to magnetic reconnection and turbulence resulting from collapse of the H-mode transport barrier. Encouraging prospects for ELM control and/or suppression in future tokamaks include intrinsic modes of ELM free operation, ELM triggering with frequent small pellet injection and the application of 3D magnetic fields.

A transportable 50 kA dual mode lightning simulator

NASA Technical Reports Server (NTRS)

Salisbury, K.; Lloyd, S.; Chen, Y. G.

1991-01-01

A transportable lightning simulator was designed, built and tested, which is capable of delivering more than 50 kA to an 8 micro-H test object. The simulator was designed to be a versatile device in the lightning laboratory while meeting the requirements of MIL-STD-1757A for component E current waveforms. The system is capable of operating in either a ringing mode with a Q greater than 5 and a nominal frequency of 160 kHz, or a unipolar mode with no hardware configuration changes. The ringing mode is obtained by the LCR series circuit formed by the pulse generator and test object. The unipolar mode is obtained by closing an electrically triggered crowbar switch at peak current. The simulator exceeds the peak current requirement and rate of rise requirements for MIL-STD-1757A in both the ringing and unipolar modes. The pulse half width in the unipolar mode is in excess of 50 microsec and the action is in excess of 10(exp 5) A(exp 2)s. The design, component values, and test results are presented.

Superradiance in the BTZ black hole with Robin boundary conditions

NASA Astrophysics Data System (ADS)

Dappiaggi, Claudio; Ferreira, Hugo R. C.; Herdeiro, Carlos A. R.

2018-03-01

We show the existence of superradiant modes of massive scalar fields propagating in BTZ black holes when certain Robin boundary conditions, which never include the commonly considered Dirichlet boundary conditions, are imposed at spatial infinity. These superradiant modes are defined as those solutions whose energy flux across the horizon is towards the exterior region. Differently from rotating, asymptotically flat black holes, we obtain that not all modes which grow up exponentially in time are superradiant; for some of these, the growth is sourced by a bulk instability of AdS3, triggered by the scalar field with Robin boundary conditions, rather than by energy extraction from the BTZ black hole. Thus, this setup provides an example wherein Bosonic modes with low frequency are pumping energy into, rather than extracting energy from, a rotating black hole.

Development of Micro and Nanostructured Materials for Interfacial Self-Healing

ERIC Educational Resources Information Center

Blaiszik, Benjamin James

2009-01-01

Damage in polymeric coatings, adhesives, microelectronic components, and composites spans many length scales. For small scale damage, autonomic self-healing can repair multiple damage modes without manual intervention. In autonomic self-healing materials, a healing response is triggered by damage to the material. Size scale considerations, such as…

New Frontiers in Networking with Emphasis on Defense Applications

DTIC Science & Technology

2016-06-01

through its own experiences. d. The presence of “ elephants ” in the network is triggered partly by big data and partly by high resolution videos...transporting elephants and found even for this very limited mode of operation, good architectures with orders of magnitude rate and cost improvements are

The Foot Engine: A Learning Styles Approach to Teaching History through Technology.

ERIC Educational Resources Information Center

Benson, Bernard W.; Eaves, Judith Y.

1985-01-01

This minicourse can be used in secondary U.S. history courses to teach about the social, economic, industrial, and technological changes that can be triggered by a single technological innovation. The lesson contains sequenced activities that alternatively stress right and left brain modes of learning. (RM)

Amplitude Frequency Response Measurement: A Simple Technique

ERIC Educational Resources Information Center

Satish, L.; Vora, S. C.

2010-01-01

A simple method is described to combine a modern function generator and a digital oscilloscope to configure a setup that can directly measure the amplitude frequency response of a system. This is achieved by synchronously triggering both instruments, with the function generator operated in the "Linear-Sweep" frequency mode, while the oscilloscope…

Developing and applying the adverse outcome pathway concept for understanding and predicting neurotoxicity

EPA Science Inventory

To support a paradigm shift in regulatory toxicology testing and risk assessment, the Adverse Outcome Pathway (AOP) concept has recently been proposed. This concept is similar to that for Mode of Action (MOA), describing a sequence of measurable key events triggered by a molecula...

The Catalog of Event Data of the Operational Deep-ocean Assessment and Reporting of Tsunamis (DART) Stations at the National Data Buoy Center

NASA Astrophysics Data System (ADS)

Bouchard, R.; Locke, L.; Hansen, W.; Collins, S.; McArthur, S.

2007-12-01

DART systems are a critical component of the tsunami warning system as they provide the only real-time, in situ, tsunami detection before landfall. DART systems consist of a surface buoy that serves as a position locater and communications transceiver and a Bottom Pressure Recorder (BPR) on the seafloor. The BPR records temperature and pressure at 15-second intervals to a memory card for later retrieval for analysis and use by tsunami researchers, but the BPRs are normally recovered only once every two years. The DART systems also transmit subsets of the data, converted to an estimation of the sea surface height, in near real-time for use by the tsunami warning community. These data are available on NDBC's webpages, http://www.ndbc.noaa.gov/dart.shtml. Although not of the resolution of the data recorded to the BPR memory card, the near real-time data have proven to be of value in research applications [1]. Of particular interest are the DART data associated with geophysical events. The DART BPR continuously compares the measured sea height with a predicted sea-height and when the difference exceeds a threshold value, the BPR goes into Event Mode. Event Mode provides an extended, more frequent near real-time reporting of the sea surface heights for tsunami detection. The BPR can go into Event Mode because of geophysical triggers, such as tsunamis or seismic activity, which may or may not be tsunamigenic. The BPR can also go into Event Mode during recovery of the BPR as it leaves the seafloor, or when manually triggered by the Tsunami Warning Centers in advance of an expected tsunami. On occasion, the BPR will go into Event Mode without any associated tsunami or seismic activity or human intervention and these are considered "False'' Events. Approximately one- third of all Events can be classified as "False". NDBC is responsible for the operations, maintenance, and data management of the DART stations. Each DART station has a webpage with a drop-down list of all Events. NDBC maintains the non-geophysical Events in order to maintain the continuity of the time series records. In 2007, NDBC compiled all DART Events that occurred while under NDBC's operational control and made an assessment on their validity. The NDBC analysts performed the assessment using the characteristics of the data time series, triggering criteria, and associated seismic events. The compilation and assessments are catalogued in a NDBC technical document. The Catalog also includes a listing of the one-hour, high-resolution data, retrieved remotely from the BPRs that are not available on the web pages. The Events are classified by their triggering mechanism and listed by station location and, for those Events associated with geophysical triggers, they are listed by their associated seismic events. The Catalog provides researchers with a valuable tool in locating, assessing, and applying near real-time DART data to tsunami research and will be updated following DART Events. A link to the published Catalog can be found on the NDBC DART website, http://www.ndbc.noaa.gov/dart.shtml. Reference: [1] Gower, J. and F. González (2006), U.S. Warning System Detected the Sumatra Tsunami, Eos Trans. AGU, 87(10), 105-112.

EMIC triggered chorus emissions in Cluster data

NASA Astrophysics Data System (ADS)

Grison, B.; SantolíK, O.; Cornilleau-Wehrlin, N.; Masson, A.; Engebretson, M. J.; Pickett, J. S.; Omura, Y.; Robert, P.; Nomura, R.

2013-03-01

Electromagnetic ion cyclotron (EMIC) triggered chorus emissions have recently been a subject of several experimental, theoretical and simulation case studies, noting their similarities with whistler-mode chorus. We perform a survey of 8 years of Cluster data in order to increase the database of EMIC triggered emissions. The results of this is that EMIC triggered emissions have been unambiguously observed for only three different days. These three events are studied in detail. All cases have been observed at the plasmapause between 22 and 24 magnetic local time (MLT) and between - 15° and 15° magnetic latitude (λm). Triggered emissions are also observed for the first time below the local He+ gyrofrequency (fHe+). The number of events is too low to produce statistical results, nevertheless we point out a variety of common properties of those waves. The rising tones have a high level of coherence and the waves propagate away from the equatorial region. The propagation angle and degree of polarization are related to the distance from the equator, whereas the slope and the frequency extent vary from one event to the other. From the various spacecraft separations, we determine that the triggering process is a localized phenomenon in space and time. However, we are unable to determine the occurrence rates of these waves. Small frequency extent rising tones are more common than large ones. The newly reported EMIC triggered events are generally observed during periods of large AE index values and in time periods close to solar maximum.

Testing of the coalescence mechanism in high energy heavy ion collisions using two-particle correlations with identified particle trigger

NASA Astrophysics Data System (ADS)

Choudhury, Subikash; Sarkar, Debojit; Chattopadhyay, Subhasis

2016-05-01

In central Au-Au collisions at top RHIC energy, two-particle correlation measurements with identified hadron trigger have shown attenuation of near-side proton triggered jetlike yield at intermediate transverse momentum (p T ),2

CALET Data Processing and On-Orbit Detector Calibration

NASA Astrophysics Data System (ADS)

Asaoka, Yoichi

2016-07-01

The CALET (CALorimetric Electron Telescope), launched to the International Space Station (ISS) in August 2015 and accumulating scientific data since October 2015, aims at long duration observations of high-energy cosmic rays onboard the ISS. The CALET detector features the very thick calorimeter of 30 radiation-length which consists of imaging and total absorption calorimeters (IMC and TASC respectively). It will directly measure the cosmic-ray electron spectrum in the energy range of 1 GeV-20 TeV with 2% energy resolution. In addition, the instrument has capabilities to measure the spectra of gamma-rays, protons and nuclei well into the TeV range. Precise pointing direction is determined with an attached Advanced Stellar Camera (ASC). To operate the CALET onboard ISS, the CALET Ground Support Equipment (CALET-GSE) and Waseda CALET Operations Center (WCOC) have been established at JAXA and Waseda Univ., respectively. Scientific operations of CALET are planned in the WCOC taking into account the orbital variations of geomagnetic rigidity cutoff. Scheduled command sequence is utilized to control CALET observation mode on orbit. A calibration data trigger mode, such as recording pedestal and penetrating particle events, a low-energy electron trigger mode operating at high geomagnetic latitude, and other dedicated trigger modes are scheduled around the ISS orbit while maintaining the maximum exposure to high-energy electrons. Scientific raw data called CALET Level 0 data are generated from raw telemetry packets in the CALET-GSE on an hourly basis by correcting time-order and by completing the data set using stored data taken during loss of real-time telemetry downlink. Level 0 data are processed to CALET Level 1 data in the WCOC by interpreting all the raw packets and building cosmic-ray event data as well as house keeping data. Level 1 data are then distributed to the collaboration for scientific data analysis. Level 1 data analysis is focused on the detector calibration which consists of timing, arrival direction, and energy of incoming cosmic-ray events. Timing calibration is performed using time-pair data generated from the timing of the pulse-per-second (PPS) signal obtained in the GPS receiver. Arrival direction is calculated from the reconstructed track using the ASC data. Alignment of fibers in the IMC and of the TASC with respect to the IMC need to be calibrated. Energy calibration is the most important calibration to measure the cosmic-ray spectra and is based on the energy deposit of minimum ionizing particles (MIP). By using a special trigger mode for penetrating particles, it is possible to calibrate the response of each detector element. Position and temperature dependence of the MIP signal are also measured and corrected in the calibration. By applying all the necessary calibrations, CALET Level 2 data for physics analysis are produced from the Level 1 data. In this contribution, we will review offline data processing and calibration of CALET flight data.

A split recognition mode combined with cascade signal amplification strategy for highly specific, sensitive detection of microRNA.

PubMed

Wang, Rui; Wang, Lei; Zhao, Haiyan; Jiang, Wei

2016-12-15

MicroRNAs (miRNAs) are vital for many biological processes and have been regarded as cancer biomarkers. Specific and sensitive detection of miRNAs is essential for cancer diagnosis and therapy. Herein, a split recognition mode combined with cascade signal amplification strategy is developed for highly specific and sensitive detection of miRNA. The split recognition mode possesses two specific recognition processes, which are based on toehold-mediated strand displacement reaction (TSDR) and direct hybridization reaction. Two recognition probes, hairpin probe (HP) with overhanging toehold domain and assistant probe (AP), are specially designed. Firstly, the toehold domain of HP and AP recognize part of miRNA simultaneously, accompanied with TSDR to unfold the HP and form the stable DNA Y-shaped junction structure (YJS). Then, the AP in YJS can further act as primer to initiate strand displacement amplification, releasing numerous trigger sequences. Finally, the trigger sequences hybridize with padlock DNA to initiate circular rolling circle amplification and generate enhanced fluorescence responses. In this strategy, the dual recognition effect of split recognition mode guarantees the excellent selectivity to discriminate let-7b from high-homology sequences. Furthermore, the high amplification efficiency of cascade signal amplification guarantees a high sensitivity with the detection limit of 3.2 pM and the concentration of let-7b in total RNA sample extracted from Hela cells is determined. These results indicate our strategy will be a promising miRNA detection strategy in clinical diagnosis and disease treatment. Copyright © 2016 Elsevier B.V. All rights reserved.

Limit cycle oscillations at the L-I-H transition in TJ-II plasmas: triggering, temporal ordering and radial propagation

NASA Astrophysics Data System (ADS)

Estrada, T.; Ascasíbar, E.; Blanco, E.; Cappa, A.; Castejón, F.; Hidalgo, C.; van Milligen, B. Ph.; Sánchez, E.

2015-06-01

The spatiotemporal evolution of the interaction between turbulence and flows has been studied close to the L-H transition threshold conditions in the edge of TJ-II plasmas. As in other devices the temporal dynamics of the interaction displays limit cycle oscillations (LCO) with a characteristic predator-prey relationship between flows and turbulence. At TJ-II, the turbulence-flow front is found to propagate radially outwards at the onset of the LCO and in some particular cases, after a short time interval without oscillations, a reversal in the front propagation velocity is observed. Associated to this velocity reversal, a change in the temporal ordering of the LCO is measured. However, the change in the temporal ordering is not related to an intrinsic change in the nature of the LCO. In all cases the turbulence increase leads the process and produces an increase in the E × B flow shear. Dedicated experiments have been carried out to investigate the physical mechanisms triggering the onset of the LCO. At TJ-II the LCO are preferentially observed close to the transition threshold conditions at specific magnetic configurations having a low order rational surface located at the inner side of the E × B flow shear location. The behaviour of different frequency modes has been analysed and interpreted in terms of a geodesic acoustic mode generated by the non-linear mode coupling of Alfvén eigenmodes that evolves towards a low frequency flow, plus a MHD mode linked to the low order rational surface, as precursors of the LCO.

Design of an amplifier model accounting for thermal effect in fully aperiodic large pitch fibers

NASA Astrophysics Data System (ADS)

Tragni, K.; Molardi, C.; Poli, F.; Dauliat, R.; Leconte, B.; Darwich, D.; du Jeu, R.; Malleville, M. A.; Jamier, R.; Selleri, S.; Roy, P.; Cucinotta, A.

2018-02-01

Yb-doped Photonic Crystal Fibers (PCFs) have triggered a significant power scaling into fiber-based lasers. However thermally-induced effects, like mode instability, can compromise the output beam quality. PCF design with improved Higher Order Mode (HOM) delocalization and effective thermal resilience can contain the problem. In particular, Fully- Aperiodic Large-Pitch Fibers (FA-LPFs) have shown interesting properties in terms of resilience to thermal effects. In this paper the performances of a Yb-doped FA-LPF amplifier are experimentally and numerically investigated. Modal properties and gain competition between Fundamental Mode (FM) and first HOM have been calculated, in presence of thermal effects. The main doped fiber characteristics have been derived by comparison between experimental and numerical results.

Plasma crystal dynamics measured with a three-dimensional plenoptic camera

NASA Astrophysics Data System (ADS)

Jambor, M.; Nosenko, V.; Zhdanov, S. K.; Thomas, H. M.

2016-03-01

Three-dimensional (3D) imaging of a single-layer plasma crystal was performed using a commercial plenoptic camera. To enhance the out-of-plane oscillations of particles in the crystal, the mode-coupling instability (MCI) was triggered in it by lowering the discharge power below a threshold. 3D coordinates of all particles in the crystal were extracted from the recorded videos. All three fundamental wave modes of the plasma crystal were calculated from these data. In the out-of-plane spectrum, only the MCI-induced hot spots (corresponding to the unstable hybrid mode) were resolved. The results are in agreement with theory and show that plenoptic cameras can be used to measure the 3D dynamics of plasma crystals.

Plasma crystal dynamics measured with a three-dimensional plenoptic camera.

PubMed

Jambor, M; Nosenko, V; Zhdanov, S K; Thomas, H M

2016-03-01

Three-dimensional (3D) imaging of a single-layer plasma crystal was performed using a commercial plenoptic camera. To enhance the out-of-plane oscillations of particles in the crystal, the mode-coupling instability (MCI) was triggered in it by lowering the discharge power below a threshold. 3D coordinates of all particles in the crystal were extracted from the recorded videos. All three fundamental wave modes of the plasma crystal were calculated from these data. In the out-of-plane spectrum, only the MCI-induced hot spots (corresponding to the unstable hybrid mode) were resolved. The results are in agreement with theory and show that plenoptic cameras can be used to measure the 3D dynamics of plasma crystals.

On the interplay between neoclassical tearing modes and nonlocal transport in toroidal plasmas

NASA Astrophysics Data System (ADS)

Ji, X. Q.; Xu, Y.; Hidalgo, C.; Diamond, P. H.; Liu, Yi; Pan, O.; Shi, Z. B.; Yu, D. L.

2016-09-01

This Letter presents the first observation on the interplay between nonlocal transport and neoclassical tearing modes (NTMs) during transient nonlocal heat transport events in the HL-2A tokamak. The nonlocality is triggered by edge cooling and large-scale, inward propagating avalanches. These lead to a locally enhanced pressure gradient at the q = 3/2 (or 2/1) rational surface and hence the onset of the NTM in relatively low β plasmas (βN < 1). The NTM, in return, regulates the nonlocal transport by truncation of avalanches by local sheared toroidal flows which develop near the magnetic island. These findings have direct implications for understanding the dynamic interaction between turbulence and large-scale mode structures in fusion plasmas.

Rate of Change in Lake Level and its Impact on Reservoir-triggered Seismicity

NASA Astrophysics Data System (ADS)

Simpson, D. W.

2017-12-01

With recent interest in increased seismicity related to fluid injection, it is useful to review cases of reservoir-triggered earthquakes to explore common characteristics and seek ways to mitigate the influence of anthropogenic impacts. Three reservoirs - Koyna, India; Nurek, Tajikistan; and Aswan, Egypt - are well-documented cases of triggered earthquakes with recorded time series of seismicity and water levels that extend for more than 30 years. The geological setting, regional tectonics and modes of reservoir utilization, along with the characteristics of the reservoir-seismicity interaction, are distinctly different in each of these three cases. Similarities and differences between these three cases point to regional and local geological and hydrological structures and the rate of changes in reservoir water level as important factors controlling the presence and timing of triggered seismicity. In a manner similar to the way in which the rate of fluid injection influences injection-related seismicity, the rate of change in reservoir water level is a significant factor in determining whether or not reservoir-triggered seismicity occurs. The high rate of annual water level rise may be important in sustaining the exceptionally long sequence of earthquakes at Koyna. In addition to the rate of filling being a determining factor in whether or not earthquakes are triggered, changes in the rate of filling may influence the time of occurrence of individual earthquakes.

Probabilistic liquefaction triggering based on the cone penetration test

USGS Publications Warehouse

Moss, R.E.S.; Seed, R.B.; Kayen, R.E.; Stewart, J.P.; Tokimatsu, K.

2005-01-01

Performance-based earthquake engineering requires a probabilistic treatment of potential failure modes in order to accurately quantify the overall stability of the system. This paper is a summary of the application portions of the probabilistic liquefaction triggering correlations proposed recently proposed by Moss and co-workers. To enable probabilistic treatment of liquefaction triggering, the variables comprising the seismic load and the liquefaction resistance were treated as inherently uncertain. Supporting data from an extensive Cone Penetration Test (CPT)-based liquefaction case history database were used to develop a probabilistic correlation. The methods used to measure the uncertainty of the load and resistance variables, how the interactions of these variables were treated using Bayesian updating, and how reliability analysis was applied to produce curves of equal probability of liquefaction are presented. The normalization for effective overburden stress, the magnitude correlated duration weighting factor, and the non-linear shear mass participation factor used are also discussed.

Rational-q Triggered Transport Changes With Varying Toroidal Rotation in DIII-D

NASA Astrophysics Data System (ADS)

Austin, M. E.; Burrell, K. H.; Waltz, R. E.; van Zeeland, M. A.; McKee, G. R.; Shafer, M. W.; Rhodes, T. L.

2007-11-01

Comparison of rational-q triggered ITBs in discharges with varying toroidal torque injection was carried out. Experiments were conducted in negative central shear discharges with different mixes of co/counter neutral beam injection (NBI) that altered the equilibrium ExB shear in conditions where transient improvements in transport occur near integer qmin values. The transport changes were seen in high and low rotation cases; however, the latter discharges did not transition to improved core confinement. Observations support the model that sufficient background ExB shear is required for barrier formation and zonal flow effects at integer qmin act as trigger in this case. The lack of TAE modes in the balanced injection cases indicates they are not linked to the transient confinement improvement. Fluctuation data obtained in co and balanced NBI show similar reductions in turbulence near integer qmin as well as poloidal velocity excursions that may be further evidence of zonal flow.

Nonlinear simulations of peeling-ballooning modes with anomalous electron viscosity and their role in edge localized mode crashes

DOE PAGES

Xu, X. Q.; Dudson, B.; Snyder, P. B.; ...

2010-10-22

A minimum set of equations based on the peeling-ballooning (P-B) model with nonideal physics effects (diamagnetic drift, E×B drift, resistivity, and anomalous electron viscosity) is found to simulate pedestal collapse when using the new BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Nonlinear simulations of P-B modes demonstrate that the P-B modes trigger magnetic reconnection, which leads to the pedestal collapse. With the addition of a model of the anomalous electron viscosity under the assumption that the electron viscosity is comparable to the anomalous electron thermal diffusivity, it is found from simulations using a realisticmore » high-Lundquist number that the pedestal collapse is limited to the edge region and the edge localized mode (ELM) size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs.« less

Mode-locking evolution in ring fiber lasers with tunable repetition rate.

PubMed

Korobko, D A; Fotiadi, A A; Zolotovskii, I O

2017-09-04

We have applied a simple approach to analyze behavior of the harmonically mode-locked fiber laser incorporating an adjustable Mach-Zehnder interferometer (MZI). Our model is able to describe key features of the laser outputs and explore limitations of physical mechanisms responsible for laser operation at different pulse repetition rates tuned over a whole GHz range. At low repetition rates the laser operates as a harmonically mode-locked soliton laser triggered by a fast saturable absorber. At high repetition rates the laser mode-locking occurs due to dissipative four-wave mixing seeded by MZI and gain spectrum filtering. However, the laser stability in this regime is rather low due to poor mode selectivity provided by MZI that is able to support the desired laser operation just near the lasing threshold. The use of a double MZI instead of a single MZI could improve the laser stability and extends the range of the laser tunability. The model predicts a gap between two repetitive rate ranges where pulse train generation is not supported.

Potential Modes of Intercellular α-Synuclein Transmission

PubMed Central

Valdinocci, Dario; Radford, Rowan A. W.; Siow, Sue Maye; Chung, Roger S.; Pountney, Dean L.

2017-01-01

Intracellular aggregates of the α-synuclein protein result in cell loss and dysfunction in Parkinson’s disease and atypical Parkinsonism, such as multiple system atrophy and dementia with Lewy bodies. Each of these neurodegenerative conditions, known collectively as α-synucleinopathies, may be characterized by a different suite of molecular triggers that initiate pathogenesis. The mechanisms whereby α-synuclein aggregates mediate cytotoxicity also remain to be fully elucidated. However, recent studies have implicated the cell-to-cell spread of α-synuclein as the major mode of disease propagation between brain regions during disease progression. Here, we review the current evidence for different modes of α-synuclein cellular release, movement and uptake, including exocytosis, exosomes, tunneling nanotubes, glymphatic flow and endocytosis. A more detailed understanding of the major modes by which α-synuclein pathology spreads throughout the brain may provide new targets for therapies that halt the progression of disease. PMID:28241427

Potential Modes of Intercellular α-Synuclein Transmission.

PubMed

Valdinocci, Dario; Radford, Rowan A W; Siow, Sue Maye; Chung, Roger S; Pountney, Dean L

2017-02-22

Intracellular aggregates of the α-synuclein protein result in cell loss and dysfunction in Parkinson's disease and atypical Parkinsonism, such as multiple system atrophy and dementia with Lewy bodies. Each of these neurodegenerative conditions, known collectively as α-synucleinopathies, may be characterized by a different suite of molecular triggers that initiate pathogenesis. The mechanisms whereby α-synuclein aggregates mediate cytotoxicity also remain to be fully elucidated. However, recent studies have implicated the cell-to-cell spread of α-synuclein as the major mode of disease propagation between brain regions during disease progression. Here, we review the current evidence for different modes of α-synuclein cellular release, movement and uptake, including exocytosis, exosomes, tunneling nanotubes, glymphatic flow and endocytosis. A more detailed understanding of the major modes by which α-synuclein pathology spreads throughout the brain may provide new targets for therapies that halt the progression of disease.

Dynamics of energetic particle driven modes and MHD modes in wall-stabilized high-β plasmas on JT-60U and DIII-D

NASA Astrophysics Data System (ADS)

Matsunaga, G.; Okabayashi, M.; Aiba, N.; Boedo, J. A.; Ferron, J. R.; Hanson, J. M.; Hao, G. Z.; Heidbrink, W. W.; Holcomb, C. T.; In, Y.; Jackson, G. L.; Liu, Y. Q.; Luce, T. C.; McKee, G. R.; Osborne, T. H.; Pace, D. C.; Shinohara, K.; Snyder, P. B.; Solomon, W. M.; Strait, E. J.; Turnbull, A. D.; Van Zeeland, M. A.; Watkins, J. G.; Zeng, L.; the DIII-D Team; the JT-60 Team

2013-12-01

In the wall-stabilized high-β plasmas in JT-60U and DIII-D, interactions between energetic particle (EP) driven modes (EPdMs) and edge localized modes (ELMs) have been observed. The interaction between the EPdM and ELM are reproducibly observed. Many EP diagnostics indicate a strong correlation between the distorted waveform of the EPdM and the EP transport to the edge. The waveform distortion is composed of higher harmonics (n ⩾ 2) and looks like a density snake near the plasma edge. According to statistical analyses, ELM triggering by the EPdMs requires a finite level of waveform distortion and pedestal recovery. ELM pacing by the EPdMs occurs when the repetition frequency of the EPdMs is higher than the natural ELM frequency. EPs transported by EPdMs are thought to contribute to change the edge stability.

Respirator triggering of electron-beam computed tomography (EBCT): differences in dynamic changes between augmented ventilation and controlled mechanical ventilation

NASA Astrophysics Data System (ADS)

Recheis, Wolfgang A.; Kleinsasser, Axel; Schuster, Antonius H.; Loeckinger, Alexander; Frede, Thomas; Springer, Peter; Hoermann, Christoph; zur Nedden, Dieter

2000-04-01

The purpose was to evaluate differences in dynamic changes of the lung aeration (air-tissue ratio) between augmented modes of ventilation (AMV) and controlled mechanical ventilation (CMV) in normal subjects. 4 volunteers, ventilated with the different respirator protocols via face mask, were scanned using the EBCT in the 50 ms mode. A software analyzed the respirator's digitized pressure and volume signals of two subsequent ventilation phases. Using these values it was possible to calculate the onset of inspiration or expiration of the next respiratory phase. The calculated starting point was then used to trigger the EBCT. The dynamic changes of air- tissue ratios were evaluated in three separate regions: a ventral, an intermediate and a dorsal area. AMV results in increase of air-tissue ratio in the dorsal lung area due to the active contraction of the diaphragm, whereas CMV results in a more pronounced increase in air-tissue ratio of the ventral lung area. This study gives further insight into the dynamic changes of the lung's biomechanics by comparing augmented ventilation and controlled mechanical ventilation in the healthy proband.

Ultrafast Photoinduced Multimode Antiferromagnetic Spin Dynamics in Exchange-Coupled Fe/RFeO3 (R = Er or Dy) Heterostructures.

PubMed

Tang, Jin; Ke, Yajiao; He, Wei; Zhang, Xiangqun; Zhang, Wei; Li, Na; Zhang, Yongsheng; Li, Yan; Cheng, Zhaohua

2018-05-25

Antiferromagnetic spin dynamics is important for both fundamental and applied antiferromagnetic spintronic devices; however, it is rarely explored by external fields because of the strong exchange interaction in antiferromagnetic materials. Here, the photoinduced excitation of ultrafast antiferromagnetic spin dynamics is achieved by capping antiferromagnetic RFeO 3 (R = Er or Dy) with an exchange-coupled ferromagnetic Fe film. Compared with antiferromagnetic spin dynamics of bare RFeO 3 orthoferrite single crystals, which can be triggered effectively by ultrafast laser heating just below the phase transition temperature, the ultrafast photoinduced multimode antiferromagnetic spin dynamic modes, for exchange-coupled Fe/RFeO 3 heterostructures, including quasiferromagnetic resonance, impurity, coherent phonon, and quasiantiferromagnetic modes, are observed in a temperature range of 10-300 K. These experimental results not only offer an effective means to trigger ultrafast antiferromagnetic spin dynamics of rare-earth orthoferrites, but also shed light on the ultrafast manipulation of antiferromagnetic magnetization in Fe/RFeO 3 heterostructures. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fishbone activity in experimental advanced superconducting tokamak neutral beam injection plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Liqing; Zhang, Jizong; Chen, Kaiyun, E-mail: Kychen@ipp.cas.cn, E-mail: lqhu@ipp.cas.cn

2015-12-15

Repetitive fishbones near the trapped ion procession frequency were observed for the first time in the neutral beam injection high confinement plasmas in Experimental Advanced Superconducting Tokamak (EAST) tokamak, and diagnosed using a solid-state neutral particle analyzer based on a compact silicon photodiode together with an upgraded high spatial-temporal-resolution multi-arrays soft X-ray (SX) system. This 1/1 typical internal kink mode propagates in the ion-diamagnetism direction with a rotation speed faster than the bulk plasma in the plasma frame. From the SX measurements, this mode frequency is typical of chirping down and the energetic particle effect related to the twisting modemore » structure. This ion fishbone was found able to trigger a multiple core sawtooth crashes with edge-2/1 sideband modes, as well as to lead to a transition from fishbone to long lived saturated kink mode to fishbone. Furthermore, using SX tomography, a correlation between mode amplitude and mode frequency was found. Finally, a phenomenological prey–predator model was found to reproduce the fishbone nonlinear process well.« less

Relationships between the extratropical ENSO precursor and leading modes of atmospheric variability in the Southern Hemisphere

NASA Astrophysics Data System (ADS)

Qin, Jianhuang; Ding, Ruiqiang; Wu, Zhiwei; Li, Jianping; Zhao, Sen

2017-03-01

Previous studies suggest that the atmospheric precursor of El Niño-Southern Oscillation (ENSO) in the extratropical Southern Hemisphere (SH) might trigger a quadrapole sea surface temperature anomaly (SSTA) in the South Pacific and subsequently influence the following ENSO. Such a quadrapole SSTA is referred to as the South Pacific quadrapole (SPQ). The present study investigated the relationships between the atmospheric precursor signal of ENSO and leading modes of atmospheric variability in the extratropical SH [including the SH annular mode (SAM), the first Pacific-South America (PSA1) mode, and the second Pacific-South America (PSA2) mode]. The results showed that the atmospheric precursor signal in the extratropical SH basically exhibits a barotropic wavenumber-3 structure over the South Pacific and is significantly correlated with the SAM and the PSA2 mode during austral summer. Nevertheless, only the PSA2 mode was found to be a precursor for the following ENSO. It leads the SPQ-like SSTA by around one month, while the SAM and the PSA1 mode do not show any obvious linkage with either ENSO or the SPQ. This suggests that the PSA2 mode may provide a bridge between the preceding circulation anomalies over the extratropical SH and the following ENSO through the SPQ-like SSTA.

Sub-nanosecond ranging possibilities of optical radar at various signal levels and transmitted pulse widths

NASA Technical Reports Server (NTRS)

Poultney, S. K.

1971-01-01

The behavior of the photomultiplier is considered, as well as the method of derivation of the photomultiplier output pulse and its relation to the reflected light pulse width and amplitude, and the calibration of range precision and accuracy. Pulsed laser radars with light pulse widths of 30, 3, and 0.1 nanosec a considered, with the 0.1 nanosec system capable of highest precision in several modes of operation, including a high repetition rate, single photoelectron reception mode. An alternate calibration scheme using a fast, triggerable light pulser is described in detail.

Sawtooth pacing by real-time auxiliary power control in a tokamak plasma.

PubMed

Goodman, T P; Felici, F; Sauter, O; Graves, J P

2011-06-17

In the standard scenario of tokamak plasma operation, sawtooth crashes are the main perturbations that can trigger performance-degrading, and potentially disruption-generating, neoclassical tearing modes. This Letter demonstrates sawtooth pacing by real-time control of the auxiliary power. It is shown that the sawtooth crash takes place in a reproducible manner shortly after the removal of that power, and this can be used to precisely prescribe, i.e., pace, the individual sawteeth. In combination with preemptive stabilization of the neoclassical tearing modes, sawtooth pacing provides a new sawtooth control paradigm for improved performance in burning plasmas.

Brittle Fracture Mechanics of Snow : In Situ Testing and Distinct Element Modeling

NASA Astrophysics Data System (ADS)

Faillettaz, J.; Daudon, D.; Louchet, F.

A snow slab avalanche release usually results from the rupture of the snow cover at the interface between an upper layer (slab) and an underlying substrate. Amazingly, the models proposed so far to predict this kind of rupture were only based on continuum mechanics, as they did not take into account the existing cracks or cohesion defects at the interface between the two layers, and their possible unstable propagation that eventually triggers the avalanche. This is why the present work, essentially devoted to human triggered avalanches, is based instead on Griffith's fracture approach, widely used in modelling brittle fracture of materials. The possible rupture scenario involves a propagation in a shear mode of a "basal crack" nucleated and gradually grown at the interface by the skier's weight, followed by a mode I opening and propagation of a "crown crack" at the top of the sheared zone. Different avalanche sizes are predicted according whether the basal crack propagation reaches or not the Griffith's instabil- ity size before crown crack opening (Louchet 2000). Accurate predictions therefore require a precise knowledge of snow toughness values in both modes. A theoretical estimation of toughness considering snow as an ice foam was proposed by Kirchner and Michot (2000), but the question of whether these results may be extended to an assembly of sintered grains is still open. A mode I toughness measurement of snow was also published for the first time by Kirchner and Michot on samples gathered in the Vosges range. In the present work, we developed an experimental set similar to Michot's, in order to measure mode I toughness: a vertical crack of increasing size is gradually machined from the top surface in an horizontal snow beam until failure takes place under its own weight. The toughness value is computed from the snow weight and the crack length at the onset of rapid crack propagation. A similar device was designed for mode II testing, but is still under development. The experimental cam- paign carried out in the Alps during the 2000-2001 winter on homogeneous sintered snow with a density of 200 kg/m3 (typical of a snow slab) gave results of the same or- der of magnitude as Michot's. A numerical modeling of these toughness experiments was performed using a distinct element code, considering snow as a cohesive granu- lar material. Both crack propagation and rupture patterns are in close agreement with experiments. References: Kirchner, Michot, Suzuki 2000 Fracture thoughness of snow in tension 1 Philisophical Magazine A, vol 80,N5, p1265-1272. Louchet 2001,A transition in dry snow slab avalanche triggering modes, Annales de glaciologie, vol 32,Symphosium on Snow, Avalanches and Impact of the Frest Cover, Innsbruck,Austria,22-26 may 2000, p2285-289 2

Physics of GAM-initiated L-H transition in a tokamak

NASA Astrophysics Data System (ADS)

Askinazi, L. G.; Belokurov, A. A.; Bulanin, V. V.; Gurchenko, A. D.; Gusakov, E. Z.; Kiviniemi, T. P.; Lebedev, S. V.; Kornev, V. A.; Korpilo, T.; Krikunov, S. V.; Leerink, S.; Machielsen, M.; Niskala, P.; Petrov, A. V.; Tukachinsky, A. S.; Yashin, A. Yu; Zhubr, N. A.

2017-01-01

Based on experimental observations using the TUMAN-3M and FT-2 tokamaks, and the results of gyrokinetic modeling of the interplay between turbulence and the geodesic acoustic mode (GAM) in these installations, a simple model is proposed for the analysis of the conditions required for L-H transition triggering by a burst of radial electric field oscillations in a tokamak. In the framework of this model, one-dimensional density evolution is considered to be governed by an anomalous diffusion coefficient dependent on radial electric field shear. The radial electric field is taken as the sum of the oscillating term and the quasi-stationary one determined by density and ion temperature gradients through a neoclassical formula. If the oscillating field parameters (amplitude, frequency, etc) are properly adjusted, a transport barrier forms at the plasma periphery and sustains after the oscillations are switched off, manifesting a transition into the high confinement mode with a strong inhomogeneous radial electric field and suppressed transport at the plasma edge. The electric field oscillation parameters required for L-H transition triggering are compared with the GAM parameters observed at the TUMAN-3M (in the discharges with ohmic L-H transition) and FT-2 tokamaks (where no clear L-H transition was observed). It is concluded based on this comparison that the GAM may act as a trigger for the L-H transition, provided that certain conditions for GAM oscillation and tokamak discharge are met.

Podosomes, But Not the Maturation Status, Determine the Protease-Dependent 3D Migration in Human Dendritic Cells.

PubMed

Cougoule, Céline; Lastrucci, Claire; Guiet, Romain; Mascarau, Rémi; Meunier, Etienne; Lugo-Villarino, Geanncarlo; Neyrolles, Olivier; Poincloux, Renaud; Maridonneau-Parini, Isabelle

2018-01-01

Dendritic cells (DC) are professional Antigen-Presenting Cells scattered throughout antigen-exposed tissues and draining lymph nodes, and survey the body for pathogens. Their ability to migrate through tissues, a 3D environment, is essential for an effective immune response. Upon infection, recognition of Pathogen-Associated Molecular Patterns (PAMP) by Toll-like receptors (TLR) triggers DC maturation. Mature DC (mDC) essentially use the protease-independent, ROCK-dependent amoeboid mode in vivo , or in collagen matrices in vitro . However, the mechanisms of 3D migration used by human immature DC (iDC) are still poorly characterized. Here, we reveal that human monocyte-derived DC are able to use two migration modes in 3D. In porous matrices of fibrillar collagen I, iDC adopted the amoeboid migration mode. In dense matrices of gelled collagen I or Matrigel, iDC used the protease-dependent, ROCK-independent mesenchymal migration mode. Upon TLR4 activation by LPS, mDC-LPS lose the capacity to form podosomes and degrade the matrix along with impaired mesenchymal migration. TLR2 activation by Pam 3 CSK 4 resulted in DC maturation, podosome maintenance, and efficient mesenchymal migration. Under all these conditions, when DC used the mesenchymal mode in dense matrices, they formed 3D podosomes at the tip of cell protrusions. Using PGE 2 , known to disrupt podosomes in DC, we observed that the cells remained in an immature status and the mesenchymal migration mode was abolished. We also observed that, while CCL5 (attractant of iDC) enhanced both amoeboid and mesenchymal migration of iDC, CCL19 and CCL21 (attractants of mDC) only enhanced mDC-LPS amoeboid migration without triggering mesenchymal migration. Finally, we examined the migration of iDC in tumor cell spheroids, a tissue-like 3D environment. We observed that iDC infiltrated spheroids of tumor cells using both migration modes. Altogether, these results demonstrate that human DC adopt the mesenchymal mode to migrate in 3D dense environments, which relies on their capacity to form podosomes independent of their maturation status, paving the way of further investigations on in vivo DC migration in dense tissues and its regulation during infections.

Electron Alfvén waves in collisionless magnetic reconnection with a guide field

NASA Astrophysics Data System (ADS)

Zhao, S.; Wang, X.; Xiao, C.; Pu, Z.

2017-12-01

It is well known that many wave modes may be related to some important reconnection issues, such as particle acceleration, the reconnection trigger, reconnection rate, etc. Here a new wave mode, the electron Alfvén wave, is introduced for the first time, with both theoretical derivations and observational data analysis. Firstly, we present a theoretical derivation of the dispersion relations of the electron Alfvén mode in a rescaled `Electron Fluid' model. Secondly, based on in situ measurements of the Magnetospheric Multiscale Mission (MMS) spacecraft, an electron Alfvén wave is identified in the electron dissipation region of a reconnection event at the magnetopause. In the last part, the excitation of the electron Alfven waves and some related reconnection issues are discussed.

Impact of laser phase and amplitude noises on streak camera temporal resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wlotzko, V., E-mail: wlotzko@optronis.com; Optronis GmbH, Ludwigstrasse 2, 77694 Kehl; Uhring, W.

2015-09-15

Streak cameras are now reaching sub-picosecond temporal resolution. In cumulative acquisition mode, this resolution does not entirely rely on the electronic or the vacuum tube performances but also on the light source characteristics. The light source, usually an actively mode-locked laser, is affected by phase and amplitude noises. In this paper, the theoretical effects of such noises on the synchronization of the streak system are studied in synchroscan and triggered modes. More precisely, the contribution of band-pass filters, delays, and time walk is ascertained. Methods to compute the resulting synchronization jitter are depicted. The results are verified by measurement withmore » a streak camera combined with a Ti:Al{sub 2}O{sub 3} solid state laser oscillator and also a fiber oscillator.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, K.; Chen, H.; Wu, W.

We present that in the upgrade of ATLAS experiment, the front-end electronics components are subjected to a large radiation background. Meanwhile high speed optical links are required for the data transmission between the on-detector and off-detector electronics. The GBT architecture and the Versatile Link (VL) project are designed by CERN to support the 4.8 Gbps line rate bidirectional high-speed data transmission which is called GBT link. In the ATLAS upgrade, besides the link with on-detector, the GBT link is also used between different off-detector systems. The GBTX ASIC is designed for the on-detector front-end, correspondingly for the off-detector electronics, themore » GBT architecture is implemented in Field Programmable Gate Arrays (FPGA). CERN launches the GBT-FPGA project to provide examples in different types of FPGA. In the ATLAS upgrade framework, the Front-End LInk eXchange (FELIX) system is used to interface the front end electronics of several ATLAS subsystems. The GBT link is used between them, to transfer the detector data and the timing, trigger, control and monitoring information. The trigger signal distributed in the down-link from FELIX to the front-end requires a fixed and low latency. In this paper, several optimizations on the GBT-FPGA IP core are introduced, to achieve a lower fixed latency. For FELIX, a common firmware will be used to interface different front-ends with support of both GBT modes: the forward error correction mode and the wide mode. The modified GBT-FPGA core has the ability to switch between the GBT modes without FPGA reprogramming. Finally, the system clock distribution of the multi-channel FELIX firmware is also discussed in this paper.« less

Optimization on fixed low latency implementation of the GBT core in FPGA

DOE PAGES

Chen, K.; Chen, H.; Wu, W.; ...

2017-07-11

We present that in the upgrade of ATLAS experiment, the front-end electronics components are subjected to a large radiation background. Meanwhile high speed optical links are required for the data transmission between the on-detector and off-detector electronics. The GBT architecture and the Versatile Link (VL) project are designed by CERN to support the 4.8 Gbps line rate bidirectional high-speed data transmission which is called GBT link. In the ATLAS upgrade, besides the link with on-detector, the GBT link is also used between different off-detector systems. The GBTX ASIC is designed for the on-detector front-end, correspondingly for the off-detector electronics, themore » GBT architecture is implemented in Field Programmable Gate Arrays (FPGA). CERN launches the GBT-FPGA project to provide examples in different types of FPGA. In the ATLAS upgrade framework, the Front-End LInk eXchange (FELIX) system is used to interface the front end electronics of several ATLAS subsystems. The GBT link is used between them, to transfer the detector data and the timing, trigger, control and monitoring information. The trigger signal distributed in the down-link from FELIX to the front-end requires a fixed and low latency. In this paper, several optimizations on the GBT-FPGA IP core are introduced, to achieve a lower fixed latency. For FELIX, a common firmware will be used to interface different front-ends with support of both GBT modes: the forward error correction mode and the wide mode. The modified GBT-FPGA core has the ability to switch between the GBT modes without FPGA reprogramming. Finally, the system clock distribution of the multi-channel FELIX firmware is also discussed in this paper.« less

Optimization on fixed low latency implementation of the GBT core in FPGA

NASA Astrophysics Data System (ADS)

Chen, K.; Chen, H.; Wu, W.; Xu, H.; Yao, L.

2017-07-01

In the upgrade of ATLAS experiment [1], the front-end electronics components are subjected to a large radiation background. Meanwhile high speed optical links are required for the data transmission between the on-detector and off-detector electronics. The GBT architecture and the Versatile Link (VL) project are designed by CERN to support the 4.8 Gbps line rate bidirectional high-speed data transmission which is called GBT link [2]. In the ATLAS upgrade, besides the link with on-detector, the GBT link is also used between different off-detector systems. The GBTX ASIC is designed for the on-detector front-end, correspondingly for the off-detector electronics, the GBT architecture is implemented in Field Programmable Gate Arrays (FPGA). CERN launches the GBT-FPGA project to provide examples in different types of FPGA [3]. In the ATLAS upgrade framework, the Front-End LInk eXchange (FELIX) system [4, 5] is used to interface the front-end electronics of several ATLAS subsystems. The GBT link is used between them, to transfer the detector data and the timing, trigger, control and monitoring information. The trigger signal distributed in the down-link from FELIX to the front-end requires a fixed and low latency. In this paper, several optimizations on the GBT-FPGA IP core are introduced, to achieve a lower fixed latency. For FELIX, a common firmware will be used to interface different front-ends with support of both GBT modes: the forward error correction mode and the wide mode. The modified GBT-FPGA core has the ability to switch between the GBT modes without FPGA reprogramming. The system clock distribution of the multi-channel FELIX firmware is also discussed in this paper.

Multi-hop Whistler-Mode ELF/VLF Signals and Triggered Emissions Excited by the HAARP HF Heater

DTIC Science & Technology

2004-12-28

distribution along the field line [ Angerami and Thomas, 1964] to infer the equatorial electron density Neq. This analysis revealed values of L ’ 4.9 and...the ELF/VLF receiver used on RV Tangaroa. References Angerami , J. J., and J. O. Thomas (1964), Studies of planetary atmospheres: 1. The distribution of

Thinking through the Photographic Encounter: Engaging with the Camera as Nomadic Weapon

ERIC Educational Resources Information Center

Coats, Cala

2014-01-01

This paper considers the photographic act as an affective and affirmative encounter--a reflexive, embodied, and relational community engagement that may produce a rupture in our habitual modes of thinking. The author uses the Deleuzo-Guattarian concept of the nomadic weapon to consider how the camera may become an affective trigger for…

Eye Gaze versus Arrows as Spatial Cues: Two Qualitatively Different Modes of Attentional Selection

ERIC Educational Resources Information Center

Marotta, Andrea; Lupianez, Juan; Martella, Diana; Casagrande, Maria

2012-01-01

This study aimed to evaluate the type of attentional selection (location- and/or object-based) triggered by two different types of central noninformative cues: eye gaze and arrows. Two rectangular objects were presented in the visual field, and subjects' attention was directed to the end of a rectangle via the observation of noninformative…

Avalanche mode of motion - Implications from lunar examples.

NASA Technical Reports Server (NTRS)

Howard, K. A.

1973-01-01

A large avalanche (21 square kilometers) at the Apollo 17 landing site moved out several kilometers over flat ground beyond its source slope. If not triggered by impacts, then it was as 'efficient' as terrestrial avalanches attributed to air-cushion sliding. Evidently lunar avalanches are able to flow despite the lack of lubricating or cushioning fluid.

77 FR 37573 - Effective Date of Requirement for Premarket Approval for an Implantable Pacemaker Pulse Generator

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-22

... triggered, inhibited, and asynchronous modes and is implanted in the human body. * * * * * (c) Date PMA or... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 870 [Docket No..., established a comprehensive system for the regulation of medical devices intended for human use. Section 513...

Torque control for electric motors

NASA Technical Reports Server (NTRS)

Bernard, C. A.

1980-01-01

Method for adjusting electric-motor torque output to accomodate various loads utilizes phase-lock loop to control relay connected to starting circuit. As load is imposed, motor slows down, and phase lock is lost. Phase-lock signal triggers relay to power starting coil and generate additional torque. Once phase lock is recoverd, relay restores starting circuit to its normal operating mode.

Avalanche mode of motion: Implications from lunar examples

USGS Publications Warehouse

Howard, K.A.

1973-01-01

A large avalanche (21 square kilometers) at the Apollo 17 landing site moved out several kilometers over flat ground beyond its source slope. If not triggered by impacts, then it was as "efficient" as terrestrial avalanches attributed to air-cushion sliding. Evidently lunar avalanches are able to flow despite the lack of lubricating or cushioning fluid.

Triggering of explosive reconnection in a thick current sheet via current sheet compression: Less current sheet thinning, more temperature anisotropy

NASA Astrophysics Data System (ADS)

Shimizu, K.; Shinohara, I.; Fujimoto, M.

2016-12-01

Two-dimensional kinetic simulations of compression of thick current sheets are performed to see how it can lead to triggering of explosive magnetic reconnection. The current sheet under study is simply in a Harris-like anti-paralell and symmetric geometry. A one-dimensional pre-study shows that the compression is more effective to make the plasma anisotropy than to thin the current sheet width. When the lobe magnetic field is amplified by a factor of 2, the plasma temperature anisotropy inside the current sheet reaches 2 but the current sheet thickness is reduced only by 1/sqrt(2). If a current sheet thickness needs to be comparable to the ion inertial scale for reconnection triggering take place, as is widely and frequently mentioned in the research community, the initial thickness cannot be more than a few ion scale for reconnection to set-in. On the other hand, the temperature anisotropy of 2 can be significant for the triggering problem. Two-dimensional simulations show explosive magnetic reconnection to take place even when the initial current sheet thickness more than an order of magnitude thicker than the ion scale, indicating the resilient triggering drive supplied by the temperature anisotropy. We also discuss how the reconnection triggering capability of the temperature anisotropy boosted tearing mode for thick current sheets compares with the instabilities in the plane orthogonal to the reconnecting field.

Development of a new scintillation-trigger detector for the MTV experiment using aluminum-metallized film tape

NASA Astrophysics Data System (ADS)

Sakamoto, Yuko; Ozaki, Sachi; Tanaka, Saki; Tanuma, Ryosuke; Yoshida, Tatsuru; Murata, Jiro

2014-09-01

A new type of trigger-scintillation counter array designed for the MTV experiment at TRIUMF-ISAC has been developed, using aluminum-metallized film tape for wrapping. The MTV experiment aims to perform the finest precision test of time reversal symmetry in nuclear beta decay. In that purpose, we search non-zero T-Violating transverse polarization of electrons emitted from polarized Li-8 nuclei. It uses a cylindrical drift chamber (CDC) as the main electron-tracking detector. The trigger-scintillation counter consists of 12-segmented 1 mm thick 300 mm long thin plastic scintillation counters. This counter is placed inside the CDC to generate a trigger signal. The required assembling precision of +-0.5 mm was a tricky point when we tried to use conventional total reflection mode. Indeed, produce an air-layer surrounding the scintillating bar to keep good light transmission was the main issue. For this reason, we tried to use a new wrapping material made of metallized-aluminum tape, which has a good mirror-like reflecting surface on both sides of the tape. Through this report, we will compare detection efficiency and light attenuation between conventional and new wrapping materials.

A Simulation of the Front End Signal Digitization for the ATLAS Muon Spectrometer thin RPC trigger upgrade project

NASA Astrophysics Data System (ADS)

Meng, Xiangting; Chapman, John; Levin, Daniel; Dai, Tiesheng; Zhu, Junjie; Zhou, Bing; Um Atlas Group Team

2016-03-01

The ATLAS Muon Spectrometer Phase-I (and Phase-II) upgrade includes the BIS78 muon trigger detector project: two sets of eight very thin Resistive Place Chambers (tRPCs) combined with small Monitored Drift Tube (MDT) chambers in the pseudorapidity region 1<| η|<1.3. The tRPCs will be comprised of triplet readout layer in each of the eta and azimuthal phi coordinates, with about 400 readout strips per layer. The anticipated hit rate is 100-200 kHz per strip. Digitization of the strip signals will be done by 32-channel CERN HPTDC chips. The HPTDC is a highly configurable ASIC designed by the CERN Microelectronics group. It can work in both trigger and trigger-less modes, be readout in parallel or serially. For Phase-I operation, a stringent latency requirement of 43 bunch crossings (1075 ns) is imposed. The latency budget for the front end digitization must be kept to a minimal value, ideally less than 350 ns. We conducted detailed HPTDC latency simulations using the Behavioral Verilog code from the CERN group. We will report the results of these simulations run for the anticipated detector operating environment and for various HPTDC configurations.

Potential sea-level rise from Antarctic ice-sheet instability constrained by observations.

PubMed

Ritz, Catherine; Edwards, Tamsin L; Durand, Gaël; Payne, Antony J; Peyaud, Vincent; Hindmarsh, Richard C A

2015-12-03

Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

Potential sea-level rise from Antarctic ice-sheet instability constrained by observations

NASA Astrophysics Data System (ADS)

Ritz, Catherine; Edwards, Tamsin L.; Durand, Gaël; Payne, Antony J.; Peyaud, Vincent; Hindmarsh, Richard C. A.

2015-12-01

Large parts of the Antarctic ice sheet lying on bedrock below sea level may be vulnerable to marine-ice-sheet instability (MISI), a self-sustaining retreat of the grounding line triggered by oceanic or atmospheric changes. There is growing evidence that MISI may be underway throughout the Amundsen Sea embayment (ASE), which contains ice equivalent to more than a metre of global sea-level rise. If triggered in other regions, the centennial to millennial contribution could be several metres. Physically plausible projections are challenging: numerical models with sufficient spatial resolution to simulate grounding-line processes have been too computationally expensive to generate large ensembles for uncertainty assessment, and lower-resolution model projections rely on parameterizations that are only loosely constrained by present day changes. Here we project that the Antarctic ice sheet will contribute up to 30 cm sea-level equivalent by 2100 and 72 cm by 2200 (95% quantiles) where the ASE dominates. Our process-based, statistical approach gives skewed and complex probability distributions (single mode, 10 cm, at 2100; two modes, 49 cm and 6 cm, at 2200). The dependence of sliding on basal friction is a key unknown: nonlinear relationships favour higher contributions. Results are conditional on assessments of MISI risk on the basis of projected triggers under the climate scenario A1B (ref. 9), although sensitivity to these is limited by theoretical and topographical constraints on the rate and extent of ice loss. We find that contributions are restricted by a combination of these constraints, calibration with success in simulating observed ASE losses, and low assessed risk in some basins. Our assessment suggests that upper-bound estimates from low-resolution models and physical arguments (up to a metre by 2100 and around one and a half by 2200) are implausible under current understanding of physical mechanisms and potential triggers.

Autonomous Triggering of in situ Sensors on Kilauea Volcano, HI, from Eruption Detection by the EO-1 Spacecraft: Design and Operational Scenario.

NASA Astrophysics Data System (ADS)

Boudreau, K.; Cecava, J. R.; Behar, A.; Davies, A. G.; Tran, D. Q.; Abtahi, A. A.; Pieri, D. C.; Jpl Volcano Sensor Web Team, A

2007-12-01

Response time in acquiring sensor data in volcanic emergencies can be greatly improved through use of autonomous systems. For instance, ground-based observations and data processing applications of the JPL Volcano Sensor Web have promptly triggered spacecraft observations [e.g., 1]. The reverse command and information flow path can also be useful, using autonomous analysis of spacecraft data to trigger in situ sensors. In this demonstration project, SO2 sensors have been incorporated into expendable "Volcano Monitor" capsules to be placed downwind of the Pu'U 'O'o vent of Kilauea volcano, Hawai'i. In nominal (low) power conservation mode, data from these sensors are collected and transmitted every hour to the Volcano Sensor Web through the Iridium Satellite Network. If SO2 readings exceed a predetermined threshold, the modem within the Volcano Monitor sends an alert to the Sensor Web, triggering a request for prompt Earth Observing-1 ( EO-1) spacecraft data acquisition. During pre-defined "critical events" as perceived by multiple sensors (which could include both in situ and spaceborne devices), however, the Sensor Web can order the SO2 sensors within the Volcano Monitor to increase their sampling frequency to once per minute (high power "burst mode"). Autonomous control of the sensors' sampling frequency enables the Sensor Web to monitor and respond to rapidly evolving conditions before and during an eruption, and allows near real-time compilation and dissemination of these data to the scientific community. Reference: [1] Davies et al., (2006) Eos, 87, (1), 1&5. This work was performed at the Jet Propulsion Laboratory-California Institute of Technology, under contract to NASA. Support was provided by the NASA AIST program, the Idaho Space Grant Consortium, and the New Mexico Space Grant Program. We thank the personnel of the USGS Hawaiian Volcano Observatory for their invaluable assistance.

Effects of unconventional breakup modes on incomplete fusion of weakly bound nuclei

NASA Astrophysics Data System (ADS)

Diaz-Torres, Alexis; Quraishi, Daanish

2018-02-01

The incomplete fusion dynamics of 6Li+209Bi collisions at energies above the Coulomb barrier is investigated. The classical dynamical model implemented in the platypus code is used to understand and quantify the impact of both 6Li resonance states and transfer-triggered breakup modes (involving short-lived projectile-like nuclei such as 8Be and 5Li) on the formation of incomplete fusion products. Model calculations explain the experimental incomplete-fusion excitation function fairly well, indicating that (i) delayed direct breakup of 6Li reduces the incomplete fusion cross sections and (ii) the neutron-stripping channel practically determines those cross sections.

Arousal and gambling mode preference: a review of the literature.

PubMed

Baudinet, Julian; Blaszczynski, Alexander

2013-06-01

The purpose of this paper is to review the literature examining subjective and physiological arousal associated with an individual's preferred modes of gambling. Arousal is hypothesised to play a central role in the onset and maintenance of problem gambling. Most studies have failed to differentiate relevant patterns of arousal elicited by stimuli associated with preferred versus non-preferred modes of gambling on the assumption that similar processes motivate all gamblers. At the conceptual level, sub-typing theories of problem gambling propose differences in the motivation to gamble, and the associated role arousal plays in maintaining behaviours. A review of the existing literature reveals preliminary findings that indicate that gamblers respond differentially to preferred compared to non-preferred gambling stimuli, and that gamblers may display greater reactivity in arousal to gambling cues compared to non-gamblers. Understanding differences in such patterns of arousal can be used to inform clinical interventions by effectively targeting the nature and role of arousal associated with preferred modes of gambling, and determining the extent to which non-preferred modes act as secondary reinforces triggering by gambling urges.

Drug-sensing hydrogels for the inducible release of biopharmaceuticals

NASA Astrophysics Data System (ADS)

Ehrbar, Martin; Schoenmakers, Ronald; Christen, Erik H.; Fussenegger, Martin; Weber, Wilfried

2008-10-01

Drug-dependent dissociation or association of cellular receptors represents a potent pharmacologic mode of action for regulating cell fate and function. Transferring the knowledge of pharmacologically triggered protein-protein interactions to materials science will enable novel design concepts for stimuli-sensing smart hydrogels. Here, we show the design and validation of an antibiotic-sensing hydrogel for the trigger-inducible release of human vascular endothelial growth factor. Genetically engineered bacterial gyrase subunit B (GyrB) (ref. 4) coupled to polyacrylamide was dimerized by the addition of the aminocoumarin antibiotic coumermycin, resulting in hydrogel formation. Addition of increasing concentrations of clinically validated novobiocin (Albamycin) dissociated the GyrB subunits, thereby resulting in dissociation of the hydrogel and dose- and time-dependent liberation of the entrapped protein pharmaceutical VEGF121 for triggering proliferation of human umbilical vein endothelial cells. Pharmacologically controlled hydrogels have the potential to fulfil the promises of stimuli-sensing materials as smart devices for spatiotemporally controlled delivery of drugs within the patient.

On the ligand binding profile and desensitization of plant ionotropic glutamate receptor (iGluR)-like channels functioning in MAMP-triggered Ca²⁺ influx.

PubMed

Kwaaitaal, Mark; Maintz, Jens; Cavdar, Meltem; Panstruga, Ralph

2012-11-01

The generation of intracellular microbe-associated molecular pattern (MAMP)-triggered Ca²⁺ transients was recently demonstrated to involve ionotropic Glutamate Receptor (iGluR)-like channels in Arabidopsis and tobacco. Here we elaborate on our previous findings and refine our insights in the putative agonist binding profile and potential mode of desensitization of MAMP-activated plant iGluRs. Based on results from pharmacological inhibition and desensitization experiments, we propose that plant iGluR complexes responsible for the MAMP-triggered Ca²⁺ signature have a binding profile that combines the specificities of mammalian NMDA-and non-NMDA types of iGluRs, possibly reflecting the evolutionary history of plant and animal iGluRs. We further hypothesize that, analogous to the mammalian NMDA-NR1 receptor, desensitization of plant iGluR-like channels might involve binding of the ubiquitous Ca²⁺ sensor calmodulin to a cytoplasmic C-terminal domain.

Sensitive SERS detection of DNA methyltransferase by target triggering primer generation-based multiple signal amplification strategy.

PubMed

Li, Ying; Yu, Chuanfeng; Han, Huixia; Zhao, Caisheng; Zhang, Xiaoru

2016-07-15

A novel and sensitive surface-enhanced Raman scattering (SERS) method is proposed for the assay of DNA methyltransferase (MTase) activity and evaluation of inhibitors by developing a target triggering primer generation-based multiple signal amplification strategy. By using of a duplex substrate for Dam MTase, two hairpin templates and a Raman probe, multiple signal amplification mode is achieved. Once recognized by Dam MTase, the duplex substrate can be cleaved by Dpn I endonuclease and two primers are released for triggering the multiple signal amplification reaction. Consequently, a wide dynamic range and remarkably high sensitivity are obtained under isothermal conditions. The detection limit is 2.57×10(-4)UmL(-1). This assay exhibits an excellent selectivity and is successfully applied in the screening of inhibitors for Dam MTase. In addition, this novel sensing system is potentially universal as the recognition element can be conveniently designed for other target analytes by changing the substrate of DNA MTase. Copyright © 2016 Elsevier B.V. All rights reserved.

Activation of the NLRP3 inflammasome by proteins that signal for necroptosis.

PubMed

Kang, Tae-Bong; Yang, Seung-Hoon; Toth, Beata; Kovalenko, Andrew; Wallach, David

2014-01-01

Necroptosis-a form of programmed necrotic cell death-and its resulting release of damage-associated molecular patterns (DAMPs) are believed to participate in the triggering of inflammatory processes. To assess the relative contribution of this cell death mode to inflammation, we need to know what other cellular effects can be exerted by molecules shown to trigger necrotic death, and the extent to which those effects might themselves contribute to inflammation. Here, we describe the technical approaches that have been applied to assess the impact of the main signaling molecules known to mediate activation of necroptosis upon generation of inflammatory cytokines in LPS-treated mouse bone marrow-derived dendritic cells. The findings obtained by this assessment indicated that signaling molecules known to initiate necroptosis can also initiate activation of the NLRP3 inflammasome, thereby inducing inflammation independently of cell death by triggering the generation of proinflammatory cytokines such as IL-1β. © 2014 Elsevier Inc. All rights reserved.

Development of longitudinally excited CO2 laser

NASA Astrophysics Data System (ADS)

Masroon, N. S.; Tanaka, M.; Tei, M.; Uno, K.; Tsuyama, M.; Nakano, H.

2018-05-01

Simple, compact, and affordable discharged-pumped CO2 laser controlled by a fast high voltage solid state switch has been developed. In this study, longitudinal excitation scheme has been adapted for simple configuration. In the longitudinal excitation scheme, the discharge is produced along the direction of the laser axis, and the electrodes are well separated with a small discharge cross-section. Triggered spark gap switch is usually used to switch out the high voltage because of simple and low cost. However, the triggered spark gap operates in the arc mode and suffer from recovery problem causing a short life time and low efficiency for high repetition rate operation. As a result, there is now considerable interest in replacing triggered spark gap switch with solid state switches. Solid state switches have significant advantages compared to triggered spark gap switch which include longer service lifetime, low cost and stable high trigger pulse. We have developed simple and low cost fast high voltage solid state switch that consists of series connected-MOSFETs. It has been installed to the longitudinally excited CO2 laser to realize the gap switch less operation. Characteristics of laser oscillation by varying the discharge length, charging voltage, capacitance and gas pressure have been evaluated. Longer discharge length produce high power of laser oscillation. Optimum charging voltage and gas pressure were existed for longitudinally excited CO2 laser.

Moisture-triggered physically transient electronics

PubMed Central

Gao, Yang; Zhang, Ying; Wang, Xu; Sim, Kyoseung; Liu, Jingshen; Chen, Ji; Feng, Xue; Xu, Hangxun; Yu, Cunjiang

2017-01-01

Physically transient electronics, a form of electronics that can physically disappear in a controllable manner, is very promising for emerging applications. Most of the transient processes reported so far only occur in aqueous solutions or biofluids, offering limited control over the triggering and degradation processes. We report novel moisture-triggered physically transient electronics, which exempt the needs of resorption solutions and can completely disappear within well-controlled time frames. The triggered transient process starts with the hydrolysis of the polyanhydride substrate in the presence of trace amounts of moisture in the air, a process that can generate products of corrosive organic acids to digest various inorganic electronic materials and components. Polyanhydride is the only example of polymer that undergoes surface erosion, a distinct feature that enables stable operation of the functional devices over a predefined time frame. Clear advantages of this novel triggered transience mode include that the lifetime of the devices can be precisely controlled by varying the moisture levels and changing the composition of the polymer substrate. The transience time scale can be tuned from days to weeks. Various transient devices, ranging from passive electronics (such as antenna, resistor, and capacitor) to active electronics (such as transistor, diodes, optoelectronics, and memories), and an integrated system as a platform demonstration have been developed to illustrate the concept and verify the feasibility of this design strategy. PMID:28879237

Transition-metal prion protein attachment: Competition with copper

NASA Astrophysics Data System (ADS)

Hodak, Miroslav; Bernholc, Jerry

2012-02-01

Prion protein, PrP, is a protein capable of binding copper ions in multiple modes depending on their concentration. Misfolded PrP is implicated in a group of neurodegenerative diseases, which include ``mad cow disease'' and its human form, variant Creutzfeld-Jacob disease. An increasing amount of evidence suggests that attachment of non-copper metal ions to PrP triggers transformations to abnormal forms similar to those observed in prion diseases. In this work, we use hybrid Kohn-Sham/orbital-free density functional theory simulations to investigate copper replacement by other transition metals that bind to PrP, including zinc, iron and manganese. We consider all known copper binding modes in the N-terminal domain of PrP. Our calculations identify modes most susceptible to copper replacement and reveal metals that can successfully compete with copper for attachment to PrP.

A front end readout electronics ASIC chip for position sensitive solid state detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kravis, S.D.; Tuemer, T.O.; Visser, G.J.

1998-12-31

A mixed signal Application Specific Integrated Circuit (ASIC) chip for front end readout electronics of position sensitive solid state detectors has been manufactured. It is called RENA (Readout Electronics for Nuclear Applications). This chip can be used for both medical and industrial imaging of X-rays and gamma rays. The RENA chip is a monolithic integrated circuit and has 32 channels with low noise high input impedance charge sensitive amplifiers. It works in pulse counting mode with good energy resolution. It also has a self triggering output which is essential for nuclear applications when the incident radiation arrives at random. Different,more » externally selectable, operational modes that includes a sparse readout mode is available to increase data throughput. It also has externally selectable shaping (peaking) times.« less

Stationary multifaceted asymmetric radiation from the edge and improved confinement mode in a superconducting tokamak.

PubMed

Gao, X; Xie, J K; Wan, Y X; Ushigusa, K; Wan, B N; Zhang, S Y; Li, J; Kuang, G L

2002-01-01

Stationary multifaceted asymmetric radiation from the edge (MARFE) is studied by gas-puffing feedback control according to an empirical MARFE critical density ( approximately 1.8 x 10(13) cm(-3)) in the HT-7 Ohmic discharges (where the plasma current I(p) is about 170 kA, loop voltage V(loop)=2-3 V, toroidal field B(T)=1.9 T, and Z(eff)=3-4). It is observed that an improved confinement mode characterized by D(alpha) line emissions drops and the line-averaged density increase is triggered in the stationary MARFE discharges. The mode is not a symmetric "detachment" state, because the quasi-steady-state poloidally asymmetric radiation (e.g., C III line emissions) still exists. This phenomenon has not been predicted by the current MARFE theory.

A hot-spot-active magnetic graphene oxide substrate for microRNA detection based on cascaded chemiluminescence resonance energy transfer

NASA Astrophysics Data System (ADS)

Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying

2015-02-01

Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal ``off'' state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an ``open'' configuration of the hairpin probe and a CRET signal ``on'' state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing.Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal ``off'' state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an ``open'' configuration of the hairpin probe and a CRET signal ``on'' state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing. Electronic supplementary information (ESI) available: Sequences of RNA and DNA used in this study, relationship of the proposed three modes, CRET mechanism of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein system, calculation of the surface coverage of hairpin probe I-1 on MGO, control experiment, comparison between different modes for microRNA detection, and advantages of the proposed strategy. See DOI: 10.1039/c4nr06603k

PULSATION-TRIGGERED MASS LOSS FROM AGB STARS: THE 60 DAY CRITICAL PERIOD

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDonald, I.; Zijlstra, A. A., E-mail: iain.mcdonald-2@jb.man.ac.uk, E-mail: albert.zijlstra@manchester.ac.uk

2016-06-01

Low- and intermediate-mass stars eject much of their mass during the late, red giant branch (RGB) phase of evolution. The physics of their strong stellar winds is still poorly understood. In the standard model, stellar pulsations extend the atmosphere, allowing a wind to be driven through radiation pressure on condensing dust particles. Here, we investigate the onset of the wind, using nearby RGB stars drawn from the Hipparcos catalog. We find a sharp onset of dust production when the star first reaches a pulsation period of 60 days. This approximately coincides with the point where the star transitions to themore » first overtone pulsation mode. Models of the spectral energy distributions show stellar mass-loss rate suddenly increasing at this point, by a factor of ∼10 over the existing (chromospherically driven) wind. The dust emission is strongly correlated with both pulsation period and amplitude, indicating stellar pulsation is the main trigger for the strong mass loss, and determines the mass-loss rate. Dust emission does not strongly correlate with stellar luminosity, indicating radiation pressure on dust has little effect on the mass-loss rate. RGB stars do not normally appear to produce dust, whereas dust production by asymptotic giant branch stars appears commonplace, and is probably ubiquitous above the RGB-tip luminosity. We conclude that the strong wind begins with a step change in mass-loss rate and is triggered by stellar pulsations. A second rapid mass-loss-rate enhancement is suggested when the star transitions to the fundamental pulsation mode at a period of ∼300 days.« less

Aerodynamic and Acoustic Effects of Abrupt Frequency Changes in Excised Larynges

ERIC Educational Resources Information Center

Alipour, Fariborz; Finnegan, Eileen M.; Scherer, Ronald C.

2009-01-01

Purpose: To determine the aerodynamic and acoustic effects due to a sudden change from chest to falsetto register or vice versa. It was hypothesized that the continuous change in subglottal pressure and flow rate alone (pressure-flow sweep [PFS]) can trigger a mode change in the canine larynx. Method: Ten canine larynges were each mounted over a…

Sinuous flow in metals.

PubMed

Yeung, Ho; Viswanathan, Koushik; Compton, Walter Dale; Chandrasekar, Srinivasan

2015-08-11

Annealed metals are surprisingly difficult to cut, involving high forces and an unusually thick "chip." This anomaly has long been explained, based on ex situ observations, using a model of smooth plastic flow with uniform shear to describe material removal by chip formation. Here we show that this phenomenon is actually the result of a fundamentally different collective deformation mode--sinuous flow. Using in situ imaging, we find that chip formation occurs via large-amplitude folding, triggered by surface undulations of a characteristic size. The resulting fold patterns resemble those observed in geophysics and complex fluids. Our observations establish sinuous flow as another mesoscopic deformation mode, alongside mechanisms such as kinking and shear banding. Additionally, by suppressing the triggering surface undulations, sinuous flow can be eliminated, resulting in a drastic reduction of cutting forces. We demonstrate this suppression quite simply by the application of common marking ink on the free surface of the workpiece material before the cutting. Alternatively, prehardening a thin surface layer of the workpiece material shows similar results. Besides obvious implications to industrial machining and surface generation processes, our results also help unify a number of disparate observations in the cutting of metals, including the so-called Rehbinder effect.

Disruption mitigation and avoidance at ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Maraschek, M.; Pautasso, G.; Esposito, B.; Granucci, G.; Stober, J.; Treutterer, W.

2009-11-01

Disruptions are a major concern for tokamaks and in particular for ITER. They cause high heat loads during the thermal quench and high mechanical forces during the subsequent current quench. The generation and loss of runaway electrons (highly accelerated electrons carrying large fractions of the plasma current) can produce damage to the vessel structures. Therefore, schemes are implemented in present tokamaks to mitigate or to even avoid them. Mitigation has been proven to be effective through the injection of noble gases causing a reduction of the thermal heat load by radiation and a reduction of the mechanical forces. In addition 25% of the required density for the collisional suppression of runaways in ITER has been reached. For the trigger of the noble gas injection a locked mode detector is routinely used at ASDEX Upgrade. An extension to more complex precursors is planed. A different approach has been used for disruption avoidance by injecting ECRH triggered by the loop voltage increase before the disruption. The avoidance of an ongoing density limit disruption has been achieved when the ECRH is deposited at resonant surfaces where MHD modes, such as the m=2/n=1, occur. Present schemes for the mitigation and eventually avoidance of disruptions will be discussed.

c-Src activity is differentially required by cancer cell motility modes.

PubMed

Logue, Jeremy S; Cartagena-Rivera, Alexander X; Chadwick, Richard S

2018-04-01

Cancer cell migration requires that cells respond and adapt to their surroundings. In the absence of extracellular matrix cues, cancer cells will undergo a mesenchymal to ameboid transition, whereas a highly confining space will trigger a switch to "leader bleb-based" migration. To identify oncogenic signaling pathways mediating these transitions, we undertook a targeted screen using clinically useful inhibitors. Elevated Src activity was found to change actin and focal adhesion dynamics, whereas inhibiting Src triggered focal adhesion disassembly and blebbing. On non-adherent substrates and in collagen matrices, amoeboid-like, blebbing cells having high Src activity formed protrusions of the plasma membrane. To evaluate the role of Src in confined cells, we use a novel approach that places cells under a slab of polydimethylsiloxane (PDMS), which is held at a defined height. Using this method, we find that leader bleb-based migration is resistant to Src inhibition. High Src activity was found to markedly change the architecture of cortical actomyosin, reduce cell mechanical properties, and the percentage of cells that undergo leader bleb-based migration. Thus, Src is a signal transducer that can potently influence transitions between migration modes with implications for the rational development of metastasis inhibitors.

Low-pressure pulsed focused ultrasound with microbubbles promotes an anticancer immunological response.

PubMed

Liu, Hao-Li; Hsieh, Han-Yi; Lu, Li-An; Kang, Chiao-Wen; Wu, Ming-Fang; Lin, Chun-Yen

2012-11-11

High-intensity focused-ultrasound (HIFU) has been successfully employed for thermal ablation of tumors in clinical settings. Continuous- or pulsed-mode HIFU may also induce a host antitumor immune response, mainly through expansion of antigen-presenting cells in response to increased cellular debris and through increased macrophage activation/infiltration. Here we demonstrated that another form of focused ultrasound delivery, using low-pressure, pulsed-mode exposure in the presence of microbubbles (MBs), may also trigger an antitumor immunological response and inhibit tumor growth. A total of 280 tumor-bearing animals were subjected to sonographically-guided FUS. Implanted tumors were exposed to low-pressure FUS (0.6 to 1.4 MPa) with MBs to increase the permeability of tumor microvasculature. Tumor progression was suppressed by both 0.6 and 1.4-MPa MB-enhanced FUS exposures. We observed a transient increase in infiltration of non-T regulatory (non-Treg) tumor infiltrating lymphocytes (TILs) and continual infiltration of CD8+ cytotoxic T-lymphocytes (CTL). The ratio of CD8+/Treg increased significantly and tumor growth was inhibited. Our findings suggest that low-pressure FUS exposure with MBs may constitute a useful tool for triggering an anticancer immune response, for potential cancer immunotherapy.

Aeroelastic Stability of Idling Wind Turbines

NASA Astrophysics Data System (ADS)

Wang, Kai; Riziotis, Vasilis A.; Voutsinas, Spyros G.

2016-09-01

Wind turbine rotors in idling operation mode can experience high angles of attack, within the post stall region that are capable of triggering stall-induced vibrations. In the present paper rotor stability in slow idling operation is assessed on the basis of non-linear time domain and linear eigenvalue analysis. Analysis is performed for a 10 MW conceptual wind turbine designed by DTU. First the flow conditions that are likely to favour stall induced instabilities are identified through non-linear time domain aeroelastic analysis. Next, for the above specified conditions, eigenvalue stability simulations are performed aiming at identifying the low damped modes of the turbine. Finally the results of the eigenvalue analysis are evaluated through computations of the work of the aerodynamic forces by imposing harmonic vibrations following the shape and frequency of the various modes. Eigenvalue analysis indicates that the asymmetric and symmetric out-of-plane modes have the lowest damping. The results of the eigenvalue analysis agree well with those of the time domain analysis.

Effects of Spatial Variability of Soil Properties on the Triggering of Rainfall-Induced Shallow Landslides

NASA Astrophysics Data System (ADS)

Fan, Linfeng; Lehmann, Peter; Or, Dani

2015-04-01

Naturally-occurring spatial variations in soil properties (e.g., soil depth, moisture, and texture) affect key hydrological processes and potentially the mechanical response of soil to hydromechanical loading (relative to the commonly-assumed uniform soil mantle). We quantified the effects of soil spatial variability on the triggering of rainfall-induced shallow landslides at the hillslope- and catchment-scales, using a physically-based landslide triggering model that considers interacting soil columns with mechanical strength thresholds (represented by the Fiber Bundle Model). The spatial variations in soil properties are represented as Gaussian random distributions and the level of variation is characterized by the coefficient of variation and correlation lengths of soil properties (i.e., soil depth, soil texture and initial water content in this study). The impacts of these spatial variations on landslide triggering characteristics were measured by comparing the times to triggering and landslide volumes for heterogeneous soil properties and homogeneous cases. Results at hillslope scale indicate that for spatial variations of an individual property (without cross correlation), the increasing of coefficient of variation introduces weak spots where mechanical damage is accelerated and leads to earlier onset of landslide triggering and smaller volumes. Increasing spatial correlation length of soil texture and initial water content also induces early landslide triggering and small released volumes due to the transition of failure mode from brittle to ductile failure. In contrast, increasing spatial correlation length of soil depth "reduces" local steepness and postpones landslide triggering. Cross-correlated soil properties generally promote landslide initiation, but depending on the internal structure of spatial distribution of each soil property, landslide triggering may be reduced. The effects of cross-correlation between initial water content and soil texture were investigated in detail at the catchment scale by incorporating correlations of both variables with topography. Results indicate that the internal structure of the spatial distribution of each soil property together with their interplays determine the overall performance of the coupled spatial variability. This study emphasizes the importance of both the randomness and spatial structure of soil properties on landslide triggering and characteristics.

Manipulation and control of instabilities for surfactant-laden liquid film flowing down an inclined plane using a deformable solid layer

NASA Astrophysics Data System (ADS)

Tomar, Dharmendra S.; Sharma, Gaurav

2018-01-01

We analyzed the linear stability of surfactant-laden liquid film with a free surface flowing down an inclined plane under the action of gravity when the inclined plane is coated with a deformable solid layer. For a flow past a rigid incline and in the presence of inertia, the gas-liquid (GL) interface is prone to the free surface instability and the presence of surfactant is known to stabilize the free surface mode when the Marangoni number increases above a critical value. The rigid surface configuration also admits a surfactant induced Marangoni mode which remains stable for film flows with a free surface. This Marangoni mode was observed to become unstable for a surfactant covered film flow past a flexible inclined plane in a creeping flow limit when the wall is made sufficiently deformable. In view of these observations, we investigate the following two aspects. First, what is the effect of inertia on Marangoni mode instability induced by wall deformability? Second, and more importantly, whether it is possible to use a deformable solid coating to obtain stable flow for the surfactant covered film for cases when the Marangoni number is below the critical value required for stabilization of free surface instability. In order to explore the first question, we continued the growth rates for the Marangoni mode from the creeping flow limit to finite Reynolds numbers (Re) and observed that while the increase in Reynolds number has a small stabilizing effect on growth rates, the Marangoni mode still remains unstable for finite Reynolds numbers as long as the wall is sufficiently deformable. The Marangoni mode remains the dominant mode for zero and small Reynolds numbers until the GL mode also becomes unstable with the increase in Re. Thus, for a given set of parameters and beyond a critical Re, there is an exchange of dominant mode of instability from the Marangoni to free surface GL mode. With respect to the second important aspect, our results clearly demonstrate that for cases when the stabilizing contribution of surfactant is not sufficient for suppressing GL mode instability, a deformable solid coating could be employed to suppress free surface instability without triggering Marangoni or liquid-solid interfacial modes. Specifically, we have shown that for a given solid thickness, as the shear modulus of the solid layer decreases (i.e., the solid becomes more deformable) the GL mode instability is suppressed. With further decrease in shear modulus, the Marangoni and liquid-solid interfacial modes become unstable. Thus, there exists a stability window in terms of shear modulus where the surfactant-laden film flow remains stable even when the Marangoni number is below the critical value required for free surface instability suppression. Further, when the Marangoni number is greater than the critical value so that the GL mode remains stable in the rigid limit or with the deformable wall, the increase in wall deformability or solid thickness triggers Marangoni mode instability and, thus, renders a stable flow configuration into an unstable one. Thus, we show that the soft solid layer can be used to manipulate and control the stability of surfactant-laden film flows.

Study of Opto-electronic Properties of a Single Microtubule in the Microwave Regime

DTIC Science & Technology

2013-01-09

apparently microtubule grows continuously from tubulins, in that growth randomly triggered rapid growth and long silence modes are superimposed by...synchrony and de-synchrony glues. When such synchrony is introduced in an artificial cell like environment, microtubule does not grow freely, similar to...NOTES 14. ABSTRACT The research establishes the supremacy of synchrony by proving that though apparently microtubule grows continuously from

Single photons from a gain medium below threshold

NASA Astrophysics Data System (ADS)

Ghosh, Sanjib; Liew, Timothy C. H.

2018-06-01

The emission from a nonlinear photonic mode coupled weakly to a gain medium operating below threshold is predicted to exhibit antibunching. In the steady state regime, analytical solutions for the relevant observable quantities are found in accurate agreement with exact numerical results. Under pulsed excitation, the unequal time second-order correlation function demonstrates the triggered probabilistic generation of single photons well separated in time.

Treatment of pediculosis capitis: a critical appraisal of the current literature.

PubMed

Feldmeier, Hermann

2014-10-01

Pediculosis capitis is the most common ectoparasitic disease in children in industrialized countries and extremely common in resource-poor communities of the developing world. The extensive use of pediculicides with a neurotoxic mode of action has led to the development and spread of resistant head lice populations all over the world. This triggered the development of compounds with other modes of action. The current literature on treatment approaches of head lice infestation was searched, and published randomized controlled trials were critically analyzed. The following compounds/family of compounds were identified: spinosad, a novel compound with a new neurotoxic mode of action, isopropyl myristate, 1,2-octanediol, ivermectin, plant-based products, and dimeticones. The efficacy and safety of these compounds are reviewed and recommendations for the treatment of pediculosis capitis in individuals as well as the interruption of ongoing epidemics are provided.

Dynamical current-induced ferromagnetic and antiferromagnetic resonances

NASA Astrophysics Data System (ADS)

Guimarães, F. S. M.; Lounis, S.; Costa, A. T.; Muniz, R. B.

2015-12-01

We demonstrate that ferromagnetic and antiferromagnetic excitations can be triggered by the dynamical spin accumulations induced by the bulk and surface contributions of the spin Hall effect. Due to the spin-orbit interaction, a time-dependent spin density is generated by an oscillatory electric field applied parallel to the atomic planes of Fe/W(110) multilayers. For symmetric trilayers of Fe/W/Fe in which the Fe layers are ferromagnetically coupled, we demonstrate that only the collective out-of-phase precession mode is excited, while the uniform (in-phase) mode remains silent. When they are antiferromagnetically coupled, the oscillatory electric field sets the Fe magnetizations into elliptical precession motions with opposite angular velocities. The manipulation of different collective spin-wave dynamical modes through the engineering of the multilayers and their thicknesses may be used to develop ultrafast spintronics devices. Our work provides a general framework that probes the realistic responses of materials in the time or frequency domain.

Dynamics of nonspherical microbubble oscillations above instability threshold

NASA Astrophysics Data System (ADS)

Guédra, Matthieu; Cleve, Sarah; Mauger, Cyril; Blanc-Benon, Philippe; Inserra, Claude

2017-12-01

Time-resolved dynamics of nonspherical oscillations of micrometer-sized bubbles are captured and analyzed using high-speed imaging. The axisymmetry of the bubble shape is ensured with certainty for the first time from the recordings of two synchronous high-speed cameras located at 90∘. The temporal dynamics of finite-amplitude nonspherical oscillations are then analyzed for various acoustic pressures above the instability threshold. The experimental results are compared with recent theories accounting for nonlinearities and mode coupling, highlighting particular effects inherent to these mechanisms (saturation of the instability, triggering of nonparametric shape modes). Finally, the amplitude of the nonspherical oscillations is given as function of the driving pressure both for quadrupolar and octupolar bubbles.

Apparatus for coating a surface with a metal utilizing a plasma source

DOEpatents

Brown, I.G.; MacGill, R.A.; Galvin, J.E.

1991-05-07

An apparatus and method are disclosed for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time. 10 figures.

Apparatus for coating a surface with a metal utilizing a plasma source

DOEpatents

Brown, Ian G.; MacGill, Robert A.; Galvin, James E.

1991-01-01

An apparatus and method for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time.

ELM Suppression and Pedestal Structure in I-Mode Plasmas

NASA Astrophysics Data System (ADS)

Walk, John

2013-10-01

The I-mode regime is characterized by the formation of a temperature pedestal and enhanced energy confinement (H98 up to 1.2), without an accompanying density pedestal or drop in particle transport. Unlike ELMy H-modes, I-mode operation appears to have naturally-occurring suppression of large ELMs in addition to its highly favorable scalings of pedestal structure (and therefore overall performance). Instead, continuous Weakly Coherent Modes help to regulate density. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Peeling-ballooning MHD calculations are completed using the ELITE code, showing I-mode pedestals to be generally MHD-stable. Under certain conditions, intermittent ELMs are observed in I-mode at reduced field, typically triggered by sawtooth crashes; modification of the temperature pedestal (and therefore the pressure profile stability) by sawtooth heat pulses is being examined in ELITE. Modeled stability to KBM turbulence in I-mode and ELMy H-mode suggests that typical I-modes are stable against KBM turbulence. Measured I-mode pedestals are significantly wider (more stable) than the width scaling with the square root of poloidal beta characteristic of the KBM-limited pedestals in ELMy H-mode. Finally, we explore scalings of pedestal structure with engineering parameters compared to ELMy H-modes on C-Mod. In particular, we focus on scalings of the pressure pedestal with heating power (and its relation to the favorable scaling of confinement with power in I-mode) and on relationships between heat flux and pedestal temperature gradients. This work is supported by DOE agreement DE-FC02-99ER54512. Theory work at General Atomics is supported by DOE agreement DE-FG02-99ER54309.

The role of zonal flows and predator–prey oscillations in triggering the formation of edge and core transport barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmitz, Lothar; Zeng, Lei; Rhodes, Terry L.

2014-04-24

Here, we present direct evidence of low frequency, radially sheared, turbulence-driven flows (zonal flows (ZFs)) triggering edge transport barrier formation preceding the L- to H-mode transition via periodic turbulence suppression in limit-cycle oscillations (LCOs), consistent with predator–prey dynamics. The final transition to edge-localized mode-free H-mode occurs after the equilibrium E × B flow shear increases due to ion pressure profile evolution. ZFs are also observed to initiate formation of an electron internal transport barrier (ITB) at the q = 2 rational surface via local suppression of electron-scale turbulence. Multi-channel Doppler backscattering (DBS) has revealed the radial structure of the ZF-induced shear layer and the E × B shearing rate, ω E×B, in both barrier types. During edge barrier formation, the shearing rate lags the turbulence envelope during the LCO by 90°, transitioning to anti-correlation (180°) when the equilibrium shear dominates the turbulence-driven flow shear due to the increasing edge pressure gradient. The time-dependent flow shear and the turbulence envelope are anti-correlated (180° out of phase) in the electron ITB. LCOs with time-reversed evolution dynamics (transitioning from an equilibrium-flow dominated to a ZF-dominated state) have also been observed during the H–L back-transition and are potentially of interest for controlled ramp-down of the plasma stored energy and pressure (normalized to the poloidal magnetic field)more » $$\\beta_{\\theta} =2\\mu_{0} n{( {T_{{\\rm e}} +T_{{\\rm i}}})}/{B_{\\theta}^{2}}$$ in ITER.« less

The role of zonal flows and predator-prey oscillations in triggering the formation of edge and core transport barriers

NASA Astrophysics Data System (ADS)

Schmitz, L.; Zeng, L.; Rhodes, T. L.; Hillesheim, J. C.; Peebles, W. A.; Groebner, R. J.; Burrell, K. H.; McKee, G. R.; Yan, Z.; Tynan, G. R.; Diamond, P. H.; Boedo, J. A.; Doyle, E. J.; Grierson, B. A.; Chrystal, C.; Austin, M. E.; Solomon, W. M.; Wang, G.

2014-07-01

We present direct evidence of low frequency, radially sheared, turbulence-driven flows (zonal flows (ZFs)) triggering edge transport barrier formation preceding the L- to H-mode transition via periodic turbulence suppression in limit-cycle oscillations (LCOs), consistent with predator-prey dynamics. The final transition to edge-localized mode-free H-mode occurs after the equilibrium E × B flow shear increases due to ion pressure profile evolution. ZFs are also observed to initiate formation of an electron internal transport barrier (ITB) at the q = 2 rational surface via local suppression of electron-scale turbulence. Multi-channel Doppler backscattering (DBS) has revealed the radial structure of the ZF-induced shear layer and the E × B shearing rate, ωE×B, in both barrier types. During edge barrier formation, the shearing rate lags the turbulence envelope during the LCO by 90°, transitioning to anti-correlation (180°) when the equilibrium shear dominates the turbulence-driven flow shear due to the increasing edge pressure gradient. The time-dependent flow shear and the turbulence envelope are anti-correlated (180° out of phase) in the electron ITB. LCOs with time-reversed evolution dynamics (transitioning from an equilibrium-flow dominated to a ZF-dominated state) have also been observed during the H-L back-transition and are potentially of interest for controlled ramp-down of the plasma stored energy and pressure (normalized to the poloidal magnetic field) \\beta_{\\theta} =2\\mu_{0} n{( {T_{e} +T_{i}})}/{B_{\\theta}^{2}} in ITER.

Bacillus thuringiensis Crystal Protein Cry6Aa Triggers Caenorhabditis elegans Necrosis Pathway Mediated by Aspartic Protease (ASP-1)

PubMed Central

Zhang, Fengjuan; Peng, Donghai; Cheng, Chunsheng; Zhou, Wei; Ju, Shouyong; Wan, Danfeng; Yu, Ziquan; Shi, Jianwei; Deng, Yaoyao; Wang, Fenshan; Ye, Xiaobo; Hu, Zhenfei; Lin, Jian; Ruan, Lifang; Sun, Ming

2016-01-01

Cell death plays an important role in host-pathogen interactions. Crystal proteins (toxins) are essential components of Bacillus thuringiensis (Bt) biological pesticides because of their specific toxicity against insects and nematodes. However, the mode of action by which crystal toxins to induce cell death is not completely understood. Here we show that crystal toxin triggers cell death by necrosis signaling pathway using crystal toxin Cry6Aa-Caenorhabditis elegans toxin-host interaction system, which involves an increase in concentrations of cytoplasmic calcium, lysosomal lyses, uptake of propidium iodide, and burst of death fluorescence. We find that a deficiency in the necrosis pathway confers tolerance to Cry6Aa toxin. Intriguingly, the necrosis pathway is specifically triggered by Cry6Aa, not by Cry5Ba, whose amino acid sequence is different from that of Cry6Aa. Furthermore, Cry6Aa-induced necrosis pathway requires aspartic protease (ASP-1). In addition, ASP-1 protects Cry6Aa from over-degradation in C. elegans. This is the first demonstration that deficiency in necrosis pathway confers tolerance to Bt crystal protein, and that Cry6A triggers necrosis represents a newly added necrosis paradigm in the C. elegans. Understanding this model could lead to new strategies for nematode control. PMID:26795495

Calcium and Egg Activation in Drosophila

PubMed Central

Sartain, Caroline V.; Wolfner, Mariana F.

2012-01-01

Summary In many animals, a rise in intracellular calcium levels is the trigger for egg activation, the process by which an arrested mature oocyte transitions to prepare for embryogenesis. In nearly all animals studied to date, this calcium rise, and thus egg activation, is triggered by the fertilizing sperm. However in the insects that have been examined, fertilization is not necessary to activate their oocytes. Rather, these insects’ eggs activate as they transit through the female’s reproductive tract, regardless of male contribution. Recent studies in Drosophila have shown that egg activation nevertheless requires calcium and that the downstream events and molecules of egg activation are also conserved, despite the difference in initial trigger. Genetic studies have uncovered essential roles for the calcium-dependent enzyme calcineurin and its regulator calcipressin, and have hinted at roles for calmodulin, in Drosophila egg activation. Physiological and in vitro studies have led to a model in which mechanical forces that impact the Drosophila oocyte as it moves through the reproductive tract triggers the influx of calcium from the external environment, thereby initiating egg activation. Future research will aim to test this model, as well as to determine the spatiotemporal dynamics of cytoplasmic calcium flux and mode of signal propagation in this unique system. PMID:23218670

Seeking a paleontological signature for mass extinctions caused by flood basalt eruptions

NASA Astrophysics Data System (ADS)

Payne, J.; Bush, A. M.; Chang, E. T.; Heim, N. A.; Knope, M. L.; Pruss, S. B.

2016-12-01

Flood basalt eruptions coincide with numerous extinction events in the fossil record. Increasingly precise absolute age determinations for both the timing of eruption and of species extinctions have strengthened the case for flood basalt eruptions as the single most important trigger for major mass extinction events in the fossil record. However, the extent to which flood basalt eruptions cause a pattern of biotic loss distinctive from extinctions triggered by other geological or biological processes remains an open question. In the absence of diagnostic mapping between geological triggers and biological losses, establishing the identities of causal agents for mass extinctions will continue to depend primarily on evidence for temporal coincidence. Here we use a synoptic database of marine animal genera spanning the Phanerozoic, including times of first and last occurrence, body size, motility, life position, feeding mode, and respiratory physiology to assess whether extinction events temporally associated with flood basalt eruptions exhibit a diagnostic pattern of extinction selectivity. We further ask whether any events not associated with known large igneous provinces nevertheless display extinction patterns suggestive of such a cause. Finally, we ask whether extinction events associated with other primary causes, such as glaciation or bolide impact, are distinguishable from events apparently triggered by flood basalt eruptions on the basis of extinction selectivity patterns

Nuclear accumulation of the Arabidopsis immune receptor RPS4 is necessary for triggering EDS1-dependent defense.

PubMed

Wirthmueller, Lennart; Zhang, Yan; Jones, Jonathan D G; Parker, Jane E

2007-12-04

Recognition of specific pathogen molecules inside the cell by nucleotide-binding domain and leucine-rich repeat (NB-LRR) receptors constitutes an important layer of innate immunity in plants. Receptor activation triggers host cellular reprogramming involving transcriptional potentiation of basal defenses and localized programmed cell death. The sites and modes of action of NB-LRR receptors are, however, poorly understood. Arabidopsis Toll/Interleukin-1 (TIR) type NB-LRR receptor RPS4 recognizes the bacterial type III effector AvrRps4. We show that epitope-tagged RPS4 expressed under its native regulatory sequences distributes between endomembranes and nuclei in healthy and AvrRps4-triggered tissues. RPS4 accumulation in the nucleus, mediated by a bipartite nuclear localization sequence (NLS) at its C terminus, is necessary for triggering immunity through authentic activation by AvrRps4 in Arabidopsis or as an effector-independent "deregulated" receptor in tobacco. A strikingly conserved feature of TIR-NB-LRR receptors is their recruitment of the nucleocytoplasmic basal-defense regulator EDS1 in resistance to diverse pathogens. We find that EDS1 is an indispensable component of RPS4 signaling and that it functions downstream of RPS4 activation but upstream of RPS4-mediated transcriptional reprogramming in the nucleus.

Performance of a 512 x 512 Gated CMOS Imager with a 250 ps Exposure Time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teruya, A T; Moody, J D; Hsing, W W

2012-10-01

We describe the performance of a 512x512 gated CMOS read out integrated circuit (ROIC) with a 250 ps exposure time. A low-skew, H-tree trigger distribution system is used to locally generate individual pixel gates in each 8x8 neighborhood of the ROIC. The temporal width of the gate is voltage controlled and user selectable via a precision potentiometer. The gating implementation was first validated in optical tests of a 64x64 pixel prototype ROIC developed as a proof-of-concept during the early phases of the development program. The layout of the H-Tree addresses each quadrant of the ROIC independently and admits operation ofmore » the ROIC in two modes. If “common mode” triggering is used, the camera provides a single 512x512 image. If independent triggers are used, the camera can provide up to four 256x256 images with a frame separation set by the trigger intervals. The ROIC design includes small (sub-pixel) optical photodiode structures to allow test and characterization of the ROIC using optical sources prior to bump bonding. Reported test results were obtained using short pulse, second harmonic Ti:Sapphire laser systems operating at λ~ 400 nm at sub-ps pulse widths.« less

Measurement of the $B^-$ lifetime using a simulation free approach for trigger bias correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaltonen, T.; /Helsinki Inst. of Phys.; Adelman, J.

2010-04-01

The collection of a large number of B hadron decays to hadronic final states at the CDF II detector is possible due to the presence of a trigger that selects events based on track impact parameters. However, the nature of the selection requirements of the trigger introduces a large bias in the observed proper decay time distribution. A lifetime measurement must correct for this bias and the conventional approach has been to use a Monte Carlo simulation. The leading sources of systematic uncertainty in the conventional approach are due to differences between the data and the Monte Carlo simulation. Inmore » this paper they present an analytic method for bias correction without using simulation, thereby removing any uncertainty between data and simulation. This method is presented in the form of a measurement of the lifetime of the B{sup -} using the mode B{sup -} {yields} D{sup 0}{pi}{sup -}. The B{sup -} lifetime is measured as {tau}{sub B{sup -}} = 1.663 {+-} 0.023 {+-} 0.015 ps, where the first uncertainty is statistical and the second systematic. This new method results in a smaller systematic uncertainty in comparison to methods that use simulation to correct for the trigger bias.« less

Natural Frequencies Evaluation on Partially Damaged Building using Ambient Vibration Technique

NASA Astrophysics Data System (ADS)

Kamarudin, A. F.; Zainal Abidin, M. H.; Daud, M. E.; Noh, M. S. Md; Madun, A.; Ibrahim, A.; Matarul, J.; Mokhatar, S. N.

2018-04-01

Severe damages observed on the school blocks, roads, retaining walls and drainage within the compound of SMK Kundasang Sabah possibly due to the ground movements triggered by the Ranau earthquake in 1991. Ambient vibration measurements were carried on the remaining demolished 3-storey building which partially damaged in order to measure the predominant building frequencies using tri-axial 1 Hz seismometer sensors. Popular methods of Horizontal-to-vertical spectral ratios (HVSR) and Fourier amplitude spectra (FAS) were used to compute the ambient vibration wave fields of each building axes (Transverse or North-South (NS), Longitudinal or East-West (EW) and vertical) into Fourier spectra. Two main modes of translation and torsion were observed from the peaks frequencies obtained at 2.99 to 3.10 Hz (1st mode), 4.85 Hz (2nd mode) and 5.63 to 5.85 Hz (3rd mode). The building experiencing translation modes of bending and shear in the NS and EW directions. It could be seen when the amplitudes tends to increase when the floor are increased. Meanwhile, the torsional bending mode is expected to occur when the deformation amplitudes are found to be increasing horizontally, when moving into partially structural damaged section located on the East wing of building.

Transportation Energy Futures Series: Freight Transportation Modal Shares: Scenarios for a Low-Carbon Future

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brogan, J. J.; Aeppli, A. E.; Beagan, D. F.

2013-03-01

Truck, rail, water, air, and pipeline modes each serve a distinct share of the freight transportation market. The current allocation of freight by mode is the product of technologic, economic, and regulatory frameworks, and a variety of factors -- price, speed, reliability, accessibility, visibility, security, and safety -- influence mode. Based on a comprehensive literature review, this report considers how analytical methods can be used to project future modal shares and offers insights on federal policy decisions with the potential to prompt shifts to energy-efficient, low-emission modes. There are substantial opportunities to reduce the energy used for freight transportation, butmore » it will be difficult to shift large volumes from one mode to another without imposing considerable additional costs on businesses and consumers. This report explores federal government actions that could help trigger the shifts in modal shares needed to reduce energy consumption and emissions. This is one in a series of reports produced as a result of the Transportation Energy Futures project, a Department of Energy-sponsored multi-agency effort to pinpoint underexplored strategies for reducing GHGs and petroleum dependence related to transportation.« less

Automated Characterization of Rotating MHD Modes and Subsequent Locking in a Tokamak

NASA Astrophysics Data System (ADS)

Riquezes, Juan; Sabbagh, Steven; Berkery, Jack

2016-10-01

Disruption avoidance in tokamaks is highly desired to maintain steady plasma operation, and is critical for future reactor-scale devices, such as ITER, to avoid potential damage to device components. This high priority research is being conducted at PPPL by analyzing data from NSTX and its upgrade, NSTX-U. A key cause of disruptions is the physical event chain that comprises the appearance of rotating MHD modes, their slowing by resonant field drag mechanisms, and their subsequent locking. The present research aims to define algorithms to automatically find and characterize such physical event chains in the machine database. Characteristics such as identification of a mode locking time based on a loss of torque balance and bifurcation of the mode rotation frequency are examined to determine the reliability of such events in predicting disruptions. A goal is to detect such behavior as early as possible during a plasma discharge, and to further examine potential ways to forecast it. This capability could be used to provide a warning to use active mode control as a disruption avoidance mechanism, or to trigger a controlled plasma shutdown if desired. Supported by US DOE Contracts DE-FG02-99ER54524 and DE-AC02-09CH11466.

The Operational Role of the Belgian User Support and Operations Centre for the Atmosphere-Space Interactions Monitor (ASIM) on-board the International Space Station.

NASA Astrophysics Data System (ADS)

Muller, C.; Moreau, D., Sr.; Pandey, P. K.; Crosby, N. B.

2014-12-01

The Belgian User Support and Operations Centre (B.USOC) is an operational centre managing technological and scientific payloads on the International Space Station (ISS). B.USOC is the Facility Responsible Centre (FRC) for the European Space Agency's (ESA) Atmosphere-Space Interactions Monitor (ASIM) payload and also manages the Scientific Mission Centre of the Centre National d'Etudes Spatiales (CNES) PICARD satellite that monitors solar activity, among various other space missions. In this respect, B.USOC is ideally positioned to manage possible synergies between ASIM, the satellite TARANIS (Tool for the Analysis of RAdiation from lightNIng and Sprites), other space missions and ground-based networks. The ASIM mission (Neubert, 2009) consists of a package of two nadir instruments: one for the visible spectrum and another for X-ray and gamma-ray frequencies. In the normal operating mode "trigger mode" both instruments continuously measure, but, do not record data below certain thresholds. Another mode is a "timed mode", where, during a certain time the observations are recorded even in the absence of triggers. The "timed mode" demands a lot of flexibility from both scientific teams and B.USOC, as, ASIM's main targets of investigation (sprites and elves) are related to intense thunderstorms and thus, require reliable meteorological forecasts in the entire range of ISS latitudes. Moreover, ASIM is sensitive to a large number of phenomena of which most have a direct relationship with solar activity and therefore would probably need support from the ESA SSA (Space Situational Awareness) Space Weather Coordination Centre (SSCC) that shares the same campus with B.USOC. Local cooperation between the two centres, together with other space payloads such as TARANIS and ground-based networks will greatly optimize ASIM payload operations as well as scientific return. Neubert, T., and the ASIM Team, ASIM - an Instrument Suite for the International Space Station, Corte Workshop 2008, Coupling of Thunderstorms and Lightning Discharges to Near-Earth, Corsica, 2008, edited by N. B. Crosby et al, American Institute of Physics, 978-0-7354-0657-5/09/, 2009.

Overview of recent and current research on the TCV tokamak

NASA Astrophysics Data System (ADS)

S. Codathe TCV Team

2013-10-01

Through a diverse research programme, the Tokamak à Configuration Variable (TCV) addresses physics issues and develops tools for ITER and for the longer term goals of nuclear fusion, relying especially on its extreme plasma shaping and electron cyclotron resonance heating (ECRH) launching flexibility and preparing for an ECRH and NBI power upgrade. Localized edge heating was unexpectedly found to decrease the period and relative energy loss of edge localized modes (ELMs). Successful ELM pacing has been demonstrated by following individual ELM detection with an ECRH power cut before turning the power back up to trigger the next ELM, the duration of the cut determining the ELM period. Negative triangularity was also seen to reduce the ELM energy release. H-mode studies have focused on the L-H threshold dependence on the main ion species and on the divertor leg length. Both L- and H-modes have been explored in the snowflake configuration with emphasis on edge measurements, revealing that the heat flux to the strike points on the secondary separatrix increases as the X-points approach each other, well before they coalesce. In L-mode, a systematic scan of the auxiliary power deposition profile, with no effect on confinement, has ruled it out as the cause of confinement degradation. An ECRH power absorption observer based on transmitted stray radiation was validated for eventual polarization control. A new profile control methodology was introduced, relying on real-time modelling to supplement diagnostic information; the RAPTOR current transport code in particular has been employed for joint control of the internal inductance and central temperature. An internal inductance controller using the ohmic transformer has also been demonstrated. Fundamental investigations of neoclassical tearing mode (NTM) seed island formation by sawtooth crashes and of NTM destabilization in the absence of a sawtooth trigger were carried out. Both stabilizing and destabilizing agents (electron cyclotron current drive on or inside the q = 1 surface, respectively) were used to pace sawtooth oscillations, permitting precise control of their period. Locking of the sawtooth period to a pre-defined ECRH modulation period was also demonstrated. Sawtooth control has permitted nearly failsafe NTM prevention when combined with backup NTM stabilization by ECRH.

Modification of Silicone Elastomer Surfaces with Zwitterionic Polymers: Short-Term Fouling Resistance and Triggered Biofouling Release.

PubMed

Shivapooja, Phanindhar; Yu, Qian; Orihuela, Beatriz; Mays, Robin; Rittschof, Daniel; Genzer, Jan; López, Gabriel P

2015-11-25

We present a method for dual-mode-management of biofouling by modifying surface of silicone elastomers with zwitterionic polymeric grafts. Poly(sulfobetaine methacrylate) was grafted from poly(vinylmethylsiloxane) elastomer substrates using thiol-ene click chemistry and surface-initiated, controlled radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionality. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. Such dual-functional surfaces may be useful in developing environmentally and biologically friendly coatings for biofouling management on marine, industrial, and biomedical equipment because they can obviate the use of toxic compounds.

SU-F-T-263: Dosimetric Characteristics of the Cine Acquisition Mode of An A-Si EPID

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bawazeer, O; Deb, P; Sarasanandarajah, S

2016-06-15

Purpose: To investigate the dosimetric characteristics of Varian a-Si-500 electronic portal imaging device (EPID) operated in cine mode particularly considering linearity with delivered dose, dose rate, field size, phantom thickness, MLC speed and common IMRT fields. Methods: The EPID that attached to a Varian Clinac 21iX linear accelerator, was irradiated with 6 and 18 MV using 600 MU/min. Image acquisition is controlled by the IAS3 software, Trigger delay was 6 ms, BeamOnDelay and FrameStartDelay were zero. Different frame rates were utilized. Cine mode response was calculated using MATLAB as summation of mean pixel values in a region of interest ofmore » the acquired images. The performance of cine mode was compared to integrated mode and dose measurements in water using CC13 ionization chamber. Results: Figure1 illustrates that cine mode has nonlinear response for small MU, when delivering 10 MU was about 0.5 and 0.64 for 6 and 18 MV respectively. This is because the missing acquired images that were calculated around four images missing in each delivery. With the increase MU the response became linear and comparable with integrated mode and ionization chamber within 2%. Figure 2 shows that cine mode has comparable response with integrated mode and ionization chamber within 2% with changing dose rate for 10 MU delivered. This indicates that the dose rate change has no effect on nonlinearity of cine mode response. Except nonlinearity, cine mode is well matched to integrated mode response within 2% for field size, phantom thickness, MLC speed dependences. Conclusion: Cine mode has similar dosimetric characteristics to integrated mode with open and IMRT fields, and the main limitation with cine mode is missing images. Therefore, the calibration of EPID images with this mode should be run with large MU, and when IMRT verification field has low MU, the correction for missing images are required.« less

Avalanche weak layer shear fracture parameters from the cohesive crack model

NASA Astrophysics Data System (ADS)

McClung, David

2014-05-01

Dry slab avalanches release by mode II shear fracture within thin weak layers under cohesive snow slabs. The important fracture parameters include: nominal shear strength, mode II fracture toughness and mode II fracture energy. Alpine snow is not an elastic material unless the rate of deformation is very high. For natural avalanche release, it would not be possible that the fracture parameters can be considered as from classical fracture mechanics from an elastic framework. The strong rate dependence of alpine snow implies that it is a quasi-brittle material (Bažant et al., 2003) with an important size effect on nominal shear strength. Further, the rate of deformation for release of an avalanche is unknown, so it is not possible to calculate the fracture parameters for avalanche release from any model which requires the effective elastic modulus. The cohesive crack model does not require the modulus to be known to estimate the fracture energy. In this paper, the cohesive crack model was used to calculate the mode II fracture energy as a function of a brittleness number and nominal shear strength values calculated from slab avalanche fracture line data (60 with natural triggers; 191 with a mix of triggers). The brittleness number models the ratio of the approximate peak value of shear strength to nominal shear strength. A high brittleness number (> 10) represents large size relative to fracture process zone (FPZ) size and the implications of LEFM (Linear Elastic Fracture Mechanics). A low brittleness number (e.g. 0.1) represents small sample size and primarily plastic response. An intermediate value (e.g. 5) implies non-linear fracture mechanics with intermediate relative size. The calculations also implied effective values for the modulus and the critical shear fracture toughness as functions of the brittleness number. The results showed that the effective mode II fracture energy may vary by two orders of magnitude for alpine snow with median values ranging from 0.08 N/m (non-linear) to 0.18 N/m (LEFM) for median slab density around 200 kg/m3. Schulson and Duval (2009) estimated the fracture energy of solid ice (mode I) to be about 0.22-1 N/m which yields rough theoretical limits of about 0.05- 0.2 N/m for density 200 kg/m3 when the ice volume fraction is accounted for. Mode I results from lab tests (Sigrist, 2006) gave 0.1 N/m (200 kg/m3). The median effective mode II shear fracture toughness was calculated between 0.31 to 0.35 kPa(m)1/2 for the avalanche data. All the fracture energy results are much lower than previously calculated from propagation saw tests (PST) results for a weak layer collapse model (1.3 N/m) (Schweizer et al., 2011). The differences are related to model assumptions and estimates of the effective slab modulus. The calculations in this paper apply to quasi-static deformation and mode II weak layer fracture whereas the weak layer collapse model is more appropriate for dynamic conditions which follow fracture initiation (McClung and Borstad, 2012). References: Bažant, Z.P. et al. (2003) Size effect law and fracture mechanics of the triggering of dry snow slab avalanches, J. Geophys. Res. 108(B2): 2119, doi:10.1029/2002JB))1884.2003. McClung, D.M. and C.P. Borstad (2012) Deformation and energy of dry snow slabs prior to fracture propagation, J. Glaciol. 58(209), 2012 doi:10.3189/2012JoG11J009. Schulson, E.M and P. Duval (2009) Creep and fracture of ice, Cambridge University Press, 401 pp. Schweizer, J. et al. (2011) Measurements of weak layer fracture energy, Cold Reg. Sci. and Tech. 69: 139-144. Sigrist, C. (2006) Measurement of fracture mechanical properties of snow and application to dry snow slab avalanche release, Ph.D thesis: 16736, ETH, Zuerich: 139 pp.

Unique concurrent observations of whistler mode hiss, chorus, and triggered emissions

NASA Astrophysics Data System (ADS)

Hosseini, Poorya; Gołkowski, Mark; Turner, Drew L.

2017-06-01

We present a unique 2 h ground-based observation of concurrent magnetospheric hiss, chorus, VLF triggered emissions as well as ELF/VLF signals generated locally by the High Frequency Active Auroral Research Program (HAARP) facility. Eccentricity of observed wave polarization is used as a criteria to identify magnetospheric emissions and estimate their ionospheric exit points. The observations of hiss and chorus in the unique background of coherent HAARP ELF/VLF waves and triggered emissions allow for more accurate characterization of hiss and chorus properties than in typical ground-based observations. Eccentricity and azimuth results suggest a moving ionospheric exit point associated with a single ducted path at L 5. The emissions exhibit dynamics in time suggesting an evolution of a magnetospheric source from hiss generation to chorus generation or a moving plasmapause location. We introduce a frequency band-limited autocorrelation method to quantify the relative coherency of the emissions. A range of coherency was observed from high order of coherency in local HAARP transmissions and their echoes to lower coherency in natural chorus and hiss emissions.

The DNA Inflammasome in Human Myeloid Cells Is Initiated by a STING-Cell Death Program Upstream of NLRP3

PubMed Central

Gaidt, Moritz M.; Ebert, Thomas S.; Chauhan, Dhruv; Ramshorn, Katharina; Pinci, Francesca; Zuber, Sarah; O’Duill, Fionan; Schmid-Burgk, Jonathan L.; Hoss, Florian; Buhmann, Raymund; Wittmann, Georg; Latz, Eicke; Subklewe, Marion; Hornung, Veit

2018-01-01

Summary Detection of cytosolic DNA constitutes a central event in the context of numerous infectious and sterile inflammatory conditions. Recent studies have uncovered a bipartite mode of cytosolic DNA recognition, in which the cGAS-STING axis triggers antiviral immunity, whereas AIM2 triggers inflammasome activation. Here, we show that AIM2 is dispensable for DNA-mediated inflammasome activation in human myeloid cells. Instead, detection of cytosolic DNA by the cGAS-STING axis induces a cell death program initiating potassium efflux upstream of NLRP3. Forward genetics identified regulators of lysosomal trafficking to modulate this cell death program, and subsequent studies revealed that activated STING traffics to the lysosome, where it triggers membrane permeabilization and thus lysosomal cell death (LCD). Importantly, the cGAS-STING-NLRP3 pathway constitutes the default inflammasome response during viral and bacterial infections in human myeloid cells. We conclude that targeting the cGAS-STING-LCD-NLRP3 pathway will ameliorate pathology in inflammatory conditions that are associated with cytosolic DNA sensing. PMID:29033128

Distinct neuronal coding schemes in memory revealed by selective erasure of fast synchronous synaptic transmission.

PubMed

Xu, Wei; Morishita, Wade; Buckmaster, Paul S; Pang, Zhiping P; Malenka, Robert C; Südhof, Thomas C

2012-03-08

Neurons encode information by firing spikes in isolation or bursts and propagate information by spike-triggered neurotransmitter release that initiates synaptic transmission. Isolated spikes trigger neurotransmitter release unreliably but with high temporal precision. In contrast, bursts of spikes trigger neurotransmission reliably (i.e., boost transmission fidelity), but the resulting synaptic responses are temporally imprecise. However, the relative physiological importance of different spike-firing modes remains unclear. Here, we show that knockdown of synaptotagmin-1, the major Ca(2+) sensor for neurotransmitter release, abrogated neurotransmission evoked by isolated spikes but only delayed, without abolishing, neurotransmission evoked by bursts of spikes. Nevertheless, knockdown of synaptotagmin-1 in the hippocampal CA1 region did not impede acquisition of recent contextual fear memories, although it did impair the precision of such memories. In contrast, knockdown of synaptotagmin-1 in the prefrontal cortex impaired all remote fear memories. These results indicate that different brain circuits and types of memory employ distinct spike-coding schemes to encode and transmit information. Copyright © 2012 Elsevier Inc. All rights reserved.

Investigation of Self Triggered Cosmic Ray Detectors using Silicon Photomultiplier

NASA Astrophysics Data System (ADS)

Knox, Adrian; Niduaza, Rommel; Hernandez, Victor; Ruiz, Daniel; Ramos, Daniel; Fan, Sewan; Fatuzzo, Laura; Ritt, Stefan

2015-04-01

The silicon photomultiplier (SiPM) is a highly sensitive light detector capable of measuring single photons. It costs a fraction of the photomultiplier tube and operates slightly above the breakdown voltage. At this conference we describe our investigation of SiPM, the multipixel photon counters (MPPC) from Hamamatsu as readout detectors for plastic scintillators working for detecting cosmic ray particles. Our setup consists of scintillator sheets embedded with blue to green wavelength shifting fibers optically coupled to MPPCs to detect scintillating light. Four detector assemblies would be constructed and arranged to work in self triggered mode. Using custom matching tee boxes, the amplified MPPC signals are fed to discriminators with threshold set to give a reasonable coincidence count rate. Moreover, the detector waveforms are digitized using a 5 Giga Samples per second waveform digitizer, the DRS4, and triggered with the coincidence logic to capture the MPPC waveforms. Offline analysis of the digitized waveforms is accomplished using the CERN package PAW and results of our experiments and the data analysis would also be discussed. US Department of Education Title V Grant Number PO31S090007.

A hot-spot-active magnetic graphene oxide substrate for microRNA detection based on cascaded chemiluminescence resonance energy transfer.

PubMed

Bi, Sai; Chen, Min; Jia, Xiaoqiang; Dong, Ying

2015-02-28

Herein, a cascaded chemiluminescence resonance energy transfer (C-CRET) process was demonstrated from horseradish peroxidase (HRP)-mimicking DNAzyme-catalyzed luminol-H2O2 to fluorescein and further to graphene oxide (GO) when HRP-mimicking DNAzyme/fluorescein was in close proximity to the GO surface. The proposed C-CRET system was successfully implemented to construct three modes of C-CRET hot-spot-active substrates (modes I, II and III) by covalently immobilizing HRP-mimicking DNAzyme/fluorescein-labeled hairpin DNAs (hot-spot-generation probes) on magnetic GO (MGO), resulting in a signal "off" state due to the quenching of the luminol/H2O2/HRP-mimicking DNAzyme/fluorescein CRET system by GO. Upon the introduction of microRNA-122 (miRNA-122), the targets (mode I) or the new triggers that were generated through a strand displacement reaction (SDR) initiated by miRNA-122 (modes II and III) hybridized with the loop domains of hairpin probes on MGO to form double-stranded (modes I and II) or triplex-stem structures (mode III), causing an "open" configuration of the hairpin probe and a CRET signal "on" state, thus achieving sensitive and selective detection of miRNA-122. More importantly, the substrate exhibited excellent controllability, reversibility and reproducibility through SDR and magnetic separation (modes II and III), especially sequence-independence for hairpin probes in mode III, holding great potential for the development of a versatile platform for optical biosensing.

Distinct Modes of Macrophage Recognition for Apoptotic and Necrotic Cells Are Not Specified Exclusively by Phosphatidylserine Exposure

PubMed Central

Cocco, Regina E.; Ucker, David S.

2001-01-01

The distinction between physiological (apoptotic) and pathological (necrotic) cell deaths reflects mechanistic differences in cellular disintegration and is of functional significance with respect to the outcomes that are triggered by the cell corpses. Mechanistically, apoptotic cells die via an active and ordered pathway; necrotic deaths, conversely, are chaotic and passive. Macrophages and other phagocytic cells recognize and engulf these dead cells. This clearance is believed to reveal an innate immunity, associated with inflammation in cases of pathological but not physiological cell deaths. Using objective and quantitative measures to assess these processes, we find that macrophages bind and engulf native apoptotic and necrotic cells to similar extents and with similar kinetics. However, recognition of these two classes of dying cells occurs via distinct and noncompeting mechanisms. Phosphatidylserine, which is externalized on both apoptotic and necrotic cells, is not a specific ligand for the recognition of either one. The distinct modes of recognition for these different corpses are linked to opposing responses from engulfing macrophages. Necrotic cells, when recognized, enhance proinflammatory responses of activated macrophages, although they are not sufficient to trigger macrophage activation. In marked contrast, apoptotic cells profoundly inhibit phlogistic macrophage responses; this represents a cell-associated, dominant-acting anti-inflammatory signaling activity acquired posttranslationally during the process of physiological cell death. PMID:11294896

Stability of Elevated-qmin Steady-State Scenarios on DIII-D

NASA Astrophysics Data System (ADS)

Holcomb, C. T.; Victor, B.; Ferron, J. R.; Luce, T. C.; Schuster, E.

2016-10-01

Limits to high performance steady-state operation with qmin >1.4 and βN <= 3.5 are identified and explained. Various βN and q-profile histories were produced while testing feedback control of these profiles. Ten pulses had no core MHD at βN=3.4-3.5, with qmin=1.4-1.8, and q95=5-5.8. These have predicted ideal-wall kink βN limits between 4 and 5. One pulse had an n=1 tearing mode (TM) at βN=3.5 with no clear trigger. Five pulses developed n=1 TMs when βN=2, qmin=2, and q95=4.7. Stability calculations for these latter cases will be shown. In seven other shots, additional NBI power from sources with more normal injection was used, and these had off-axis fishbone (OAFB) modes at βN=3.5. These sources produce more large-radius trapped ions whose precession can drive OAFB. Preliminary analysis suggests a threshold power or voltage exists. In some cases OAFB appear to trigger n=1 TMs. These studies seek to clarify the operational limits of a steady-state scenario for next step devices. Supported by US DOE under DE-AC52-07NA27344, DE-FC02-04ER54698, DE-FG02-09ER55064.

Multichannel FPGA-Based Data-Acquisition-System for Time-Resolved Synchrotron Radiation Experiments

NASA Astrophysics Data System (ADS)

Choe, Hyeokmin; Gorfman, Semen; Heidbrink, Stefan; Pietsch, Ullrich; Vogt, Marco; Winter, Jens; Ziolkowski, Michael

2017-06-01

The aim of this contribution is to describe our recent development of a novel compact field-programmable gatearray (FPGA)-based data acquisition (DAQ) system for use with multichannel X-ray detectors at synchrotron radiation facilities. The system is designed for time resolved counting of single photons arriving from several-currently 12-independent detector channels simultaneously. Detector signals of at least 2.8 ns duration are latched by asynchronous logic and then synchronized with the system clock of 100 MHz. The incoming signals are subsequently sorted out into 10 000 time-bins where they are counted. This occurs according to the arrival time of photons with respect to the trigger signal. Repeatable mode of triggered operation is used to achieve high statistic of accumulated counts. The time-bin width is adjustable from 10 ns to 1 ms. In addition, a special mode of operation with 2 ns time resolution is provided for two detector channels. The system is implemented in a pocketsize FPGA-based hardware of 10 cm × 10 cm × 3 cm and thus can easily be transported between synchrotron radiation facilities. For setup of operation and data read-out, the hardware is connected via USB interface to a portable control computer. DAQ applications are provided in both LabVIEW and MATLAB environments.

Mechanical confinement triggers glioma linear migration dependent on formin FHOD3

PubMed Central

Monzo, Pascale; Chong, Yuk Kien; Guetta-Terrier, Charlotte; Krishnasamy, Anitha; Sathe, Sharvari R.; Yim, Evelyn K. F.; Ng, Wai Hoe; Ang, Beng Ti; Tang, Carol; Ladoux, Benoit; Gauthier, Nils C.; Sheetz, Michael P.

2016-01-01

Glioblastomas are extremely aggressive brain tumors with highly invasive properties. Brain linear tracks such as blood vessel walls constitute their main invasive routes. Here we analyze rat C6 and patient-derived glioma cell motility in vitro using micropatterned linear tracks to mimic blood vessels. On laminin-coated tracks (3–10 μm), these cells used an efficient saltatory mode of migration similar to their in vivo migration. This saltatory migration was also observed on larger tracks (50–400 μm in width) at high cell densities. In these cases, the mechanical constraints imposed by neighboring cells triggered this efficient mode of migration, resulting in the formation of remarkable antiparallel streams of cells along the tracks. This motility involved microtubule-dependent polarization, contractile actin bundles and dynamic paxillin-containing adhesions in the leading process and in the tail. Glioma linear migration was dramatically reduced by inhibiting formins but, surprisingly, accelerated by inhibiting Arp2/3. Protein expression and phenotypic analysis indicated that the formin FHOD3 played a role in this motility but not mDia1 or mDia2. We propose that glioma migration under confinement on laminin relies on formins, including FHOD3, but not Arp2/3 and that the low level of adhesion allows rapid antiparallel migration. PMID:26912794

Recent progress towards a quantitative description of filamentary SOL transport

NASA Astrophysics Data System (ADS)

Carralero, D.; Siccinio, M.; Komm, M.; Artene, S. A.; D'Isa, F. A.; Adamek, J.; Aho-Mantila, L.; Birkenmeier, G.; Brix, M.; Fuchert, G.; Groth, M.; Lunt, T.; Manz, P.; Madsen, J.; Marsen, S.; Müller, H. W.; Stroth, U.; Sun, H. J.; Vianello, N.; Wischmeier, M.; Wolfrum, E.; ASDEX Upgrade Team; COMPASS Team; Contributors, JET; The EUROfusion MST Team

2017-05-01

A summary of recent results on filamentary transport, mostly obtained with the ASDEX-Upgrade tokamak (AUG), is presented and discussed in an attempt to produce a coherent picture of scrape-off layer (SOL) filamentary transport. A clear correlation is found between L-mode density shoulder formation in the outer midplane and a transition between the sheath-limited and the inertial filamentary regimes. Divertor collisionality is found to be the parameter triggering the transition. A clear reduction of the ion temperature takes place in the far SOL after the transition, both for the background and the filaments. This coincides with a strong variation of the ion temperature distribution, which deviates from Gaussianity and becomes dominated by a strong peak below 5 eV. The filament transition mechanism triggered by a critical value of collisionality seems to be generally applicable to inter-ELM H-mode plasmas, although a secondary threshold related to deuterium fueling is observed. EMC3-EIRENE simulations of neutral dynamics show that an ionization front near the main chamber wall is formed after the shoulder formation. Finally, a clear increase of SOL opacity to neutrals is observed, associated with the shoulder formation. A common SOL transport framework is proposed to account for all these results, and their potential implications for future generation devices are discussed.

Off-axis fishbone-like instability and excitation of resistive wall modes in JT-60U and DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okabayashi, M.; Solomon, W. M.; Budny, R. V.

2011-05-15

An energetic-particle (EP)-driven ''off-axis-fishbone-like mode (OFM)'' often triggers a resistive wall mode (RWM) in JT-60U and DIII-D devices, preventing long-duration high-{beta}{sub N} discharges. In these experiments, the EPs are energetic ions (70-85 keV) injected by neutral beams to produce high-pressure plasmas. EP-driven bursting events reduce the EP density and the plasma rotation simultaneously. These changes are significant in high-{beta}{sub N} low-rotation plasmas, where the RWM stability is predicted to be strongly influenced by the EP precession drift resonance and by the plasma rotation near the q=2 surface (kinetic effects). Analysis of these effects on stability with a self-consistent perturbation tomore » the mode structure using the MARS-K code showed that the impact of EP losses and rotation drop is sufficient to destabilize the RWM in low-rotation plasmas, when the plasma rotation normalized by Alfven frequency is only a few tenths of a percent near the q=2 surface. The OFM characteristics are very similar in JT-60U and DIII-D, including nonlinear mode evolution. The modes grow initially like a classical fishbone, and then the mode structure becomes strongly distorted. The dynamic response of the OFM to an applied n=1 external field indicates that the mode retains its external kink character. These comparative studies suggest that an energetic particle-driven 'off-axis-fishbone-like mode' is a new EP-driven branch of the external kink mode in wall-stabilized plasmas, analogous to the relationship of the classical fishbone branch to the internal kink mode.« less

Integration of Synaptic Vesicle Cargo Retrieval with Endocytosis at Central Nerve Terminals

PubMed Central

Cousin, Michael A.

2017-01-01

Central nerve terminals contain a limited number of synaptic vesicles (SVs) which mediate the essential process of neurotransmitter release during their activity-dependent fusion. The rapid and accurate formation of new SVs with the appropriate cargo is essential to maintain neurotransmission in mammalian brain. Generating SVs containing the correct SV cargo with the appropriate stoichiometry is a significant challenge, especially when multiple modes of endocytosis exist in central nerve terminals, which occur at different locations within the nerve terminals. These endocytosis modes include ultrafast endocytosis, clathrin-mediated endocytosis (CME) and activity-dependent bulk endocytosis (ADBE) which are triggered by specific patterns of neuronal activity. This review article will assess the evidence for the role of classical adaptor protein complexes in SV retrieval, discuss the role of monomeric adaptors and how interactions between specific SV cargoes can facilitate retrieval. In addition it will consider the evidence for preassembled plasma membrane cargo complexes and their role in facilitating these endocytosis modes. Finally it will present a unifying model for cargo retrieval at the presynapse, which integrates endocytosis modes in time and space. PMID:28824381

Carbon microgranule injection into NSTX-U discharges for edge diagnostic research

NASA Astrophysics Data System (ADS)

Lunsford, Robert; Roquemore, A. Lane; Scotti, Filippo; Mansfield, Dennis; Bortolon, Alessandro; Kaita, Robert; Maingi, Rajesh

2016-10-01

Microgranule injection is a versatile means for investigating edge plasmas in fusion devices. Employing a dual bladed rotary turbine, carbon microgranules ranging in diameter from 300 - 700 microns are radially injected into NSTX-U discharges at approximately 50 m/sec. Utilizing multiple high speed camera views, a 3D reconstruction of the injection geometry is created which characterizes the ablation rate and granule trajectory. By coupling this with a neutral gas shielding (NGS) ablation model, the granule mass deposition profile can be determined. Simulation projects a depositional barycenter near the pedestal shoulder for H-mode discharges, and 20 cm inboard of the LCFS for L-mode discharges. Spectroscopic measurements of this localized particle source can be used to characterize impurity transport within the discharge, and potentially allows for direct measurement of the safety factor profile (q). In addition, the transient pressure peaking resultant from injection into H-mode plasmas can also result in the prompt triggering of an edge localized mode (ELM). Work supported by DOE Contract No. DE-AC02-09CH11466.

Edge-localized mode avoidance and pedestal structure in I-mode plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to themore » structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs, consistent with the observed suppression of large ELMs in I-mode.« less

Edge-localized mode avoidance and pedestal structure in I-mode plasmasa)

NASA Astrophysics Data System (ADS)

Walk, J. R.; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E.; Snyder, P. B.; Osborne, T.; Dominguez, A.; Cziegler, I.

2014-05-01

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle Pnet/n ¯e, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of Pnet/n ¯e. This is consistent with targets for increased performance in I-mode, elevating pedestal βp and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs, consistent with the observed suppression of large ELMs in I-mode.

Online track detection in triggerless mode for INO

NASA Astrophysics Data System (ADS)

Jain, A.; Padmini, S.; Joseph, A. N.; Mahesh, P.; Preetha, N.; Behere, A.; Sikder, S. S.; Majumder, G.; Behera, S. P.

2018-03-01

The India based Neutrino Observatory (INO) is a proposed particle physics research project to study the atmospheric neutrinos. INO-Iron Calorimeter (ICAL) will consist of 28,800 detectors having 3.6 million electronic channels expected to activate with 100 Hz single rate, producing data at a rate of 3 GBps. Data collected contains a few real hits generated by muon tracks and the remaining noise-induced spurious hits. Estimated reduction factor after filtering out data of interest from generated data is of the order of 103. This makes trigger generation critical for efficient data collection and storage. Trigger is generated by detecting coincidence across multiple channels satisfying trigger criteria, within a small window of 200 ns in the trigger region. As the probability of neutrino interaction is very low, track detection algorithm has to be efficient and fast enough to process 5 × 106 events-candidates/s without introducing significant dead time, so that not even a single neutrino event is missed out. A hardware based trigger system is presently proposed for on-line track detection considering stringent timing requirements. Though the trigger system can be designed with scalability, a lot of hardware devices and interconnections make it a complex and expensive solution with limited flexibility. A software based track detection approach working on the hit information offers an elegant solution with possibility of varying trigger criteria for selecting various potentially interesting physics events. An event selection approach for an alternative triggerless readout scheme has been developed. The algorithm is mathematically simple, robust and parallelizable. It has been validated by detecting simulated muon events for energies of the range of 1 GeV-10 GeV with 100% efficiency at a processing rate of 60 μs/event on a 16 core machine. The algorithm and result of a proof-of-concept for its faster implementation over multiple cores is presented. The paper also discusses about harnessing the computing capabilities of multi-core computing farm, thereby optimizing number of nodes required for the proposed system.

Synchronous oscillation prior to disruption caused by kink modes in HL-2A tokamak plasmas

NASA Astrophysics Data System (ADS)

Jiang, M.; Hu, D.; Wang, X. G.; Shi, Z. B.; Xu, Y.; Chen, W.; Ding, X. T.; Zhong, W. L.; Dong, Y. B.; Ji, X. Q.; Zhang, Y. P.; Gao, J. M.; Li, J. X.; Yang, Z. C.; Li, Y. G.; Liu, Y.

2015-08-01

A class of evident MHD activities prior to major disruption has been observed during recent radiation induced disruptions of the HL-2A tokamak discharges. It can be named SOD, synchronous oscillations prior to disruption, characterized by synchronous oscillation of electron cyclotron emission (ECE), core soft x-ray, Mirnov coil, and {{D}α} radiation signals at the divertor plate. The SOD activity is mostly observed in a parametric regime where the poloidal beta is low enough before disruption, typically corresponding to those radiation-induced disruptions. It has been found that the m/n = 2/1 mode is dominant during the SODs, and consequently it is the drop of the mode frequency and the final mode locking that lead to thermal quench. The mode frequency before the mode locking corresponds to the toroidal rotation frequency of the edge plasma. It is also found that during SODs, the location of the q = 2 surface is moving outward, and most of the plasma current is enclosed within the surface. This demonstrates that the current channel lies inside the rational surface during SOD, and thus the resistive kink mode is unstable. Further analysis of the electron temperature perturbation structure shows that the plasma is indeed dominated by the resistive kink mode, with kink-like perturbation in the core plasma region. It suggests that it is the nonlinear growth of the m/n = 2/1 resistive kink mode and its higher order harmonics, rather than the spontaneous overlapping of multiple neighboring islands, that ultimately triggered the disruption.

Anticipatory UPR Activation: A Protective Pathway and Target in Cancer

PubMed Central

Shapiro, David J.; Livezey, Mara; Yu, Liqun; Zheng, Xiaobin; Andruska, Neal

2016-01-01

The endoplasmic reticulum (EnR) stress sensor, the unfolded protein response (UPR), plays a key role in regulating intracellular protein homeostasis. The extensively studied reactive mode of UPR activation is characterized by unfolded protein, or other EnR stress, triggering UPR activation. Here we focus on the emerging anticipatory mode of UPR activation in which mitogenic steroid and peptide hormones and other effectors pre-activate the UPR and anticipate a future need for increased protein folding capacity. Mild UPR activation in breast cancer can be protective and contributes to antiestrogen resistance. Hyperactivation of the anticipatory UPR pathway in cancer cells with a small molecule converts it from cytoprotective to cytotoxic, highlighting its potential as a therapeutic target in estrogen receptor positive breast cancer. PMID:27354311

XBox Input -Version 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-10-03

Contains class for connecting to the Xbox 360 controller, displaying the user inputs {buttons, triggers, analog sticks), and controlling the rumble motors. Also contains classes for converting the raw Xbox 360 controller inputs into meaningful commands for the following objects: • Robot arms - Provides joint control and several tool control schemes • UGV's - Provides translational and rotational commands for "skid-steer" vehicles • Pan-tilt units - Provides several modes of control including velocity, position, and point-tracking • Head-mounted displays (HMO)- Controls the viewpoint of a HMO • Umbra frames - Controls the position andorientation of an Umbra posrot objectmore » • Umbra graphics window - Provides several modes of control for the Umbra OSG window viewpoint including free-fly, cursor-focused, and object following.« less

The interaction between fishbone modes and shear Alfvén waves in tokamak plasmas

NASA Astrophysics Data System (ADS)

He, Hongda; Liu, Yueqiang; Dong, J. Q.; Hao, G. Z.; Wu, Tingting; He, Zhixiong; Zhao, K.

2016-05-01

The resonant interaction between the energetic particle triggered fishbone mode and the shear Alfvén waves is computationally investigated and firmly demonstrated based on a tokamak plasma equilibrium, using the self-consistent MHD-kinetic hybrid code MARS-K (Liu et al 2008 Phys. Plasmas 15 112503). This type of continuum resonance, occurring critically due to the mode’s toroidal rotation in the plasma frame, significantly modifies the eigenmode structure of the fishbone instability, by introducing two large peaks of the perturbed parallel current density near but offside the q  =  1 rational surface (q is the safety factor). The self-consistently computed radial plasma displacement substantially differs from that being assumed in the conventional fishbone theory.

Self-Replicating Cracks: A Collaborative Fracture Mode in Thin Films

NASA Astrophysics Data System (ADS)

Marthelot, Joël; Roman, Benoît; Bico, José; Teisseire, Jérémie; Dalmas, Davy; Melo, Francisco

2014-08-01

Straight cracks are observed in thin coatings under residual tensile stress, resulting into the classical network pattern observed in china crockery, old paintings, or dry mud. Here, we present a novel fracture mechanism where delamination and propagation occur simultaneously, leading to the spontaneous self-replication of an initial template. Surprisingly, this mechanism is active below the standard critical tensile load for channel cracks and selects a robust interaction length scale on the order of 30 times the film thickness. Depending on triggering mechanisms, crescent alleys, spirals, or long bands are generated over a wide range of experimental parameters. We describe with a simple physical model, the selection of the fracture path and provide a configuration diagram displaying the different failure modes.

Thomson Scattering Diagnostic Data Acquisition Systems for Modern Fusion Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ivanenko, S.V.; Khilchenko, A.D.; Ovchar, V.K.

2015-07-01

Uniquely designed complex data acquisition system for Thomson scattering diagnostic was developed. It allows recording short duration (3-5 ns) scattered pulses with 2 GHz sampling rate and 10-bit total resolution in oscilloscope mode. The system consists up to 48 photo detector modules with 0- 200 MHz bandwidth, 1-48 simultaneously sampling ADC modules and synchronization subsystem. The photo detector modules are based on avalanche photodiodes (APD) and ultra-low noise trans-impedance amplifiers. ADC modules include fast analog to digital converters and digital units based on the FPGA (Field- Programmable Gate Array) for data processing and storage. The synchronization subsystem is used tomore » form triggering pulses and to organize the simultaneously mode of ADC modules operation. (authors)« less

Dynamo Enhancement and Mode Selection Triggered by High Magnetic Permeability.

PubMed

Kreuzahler, S; Ponty, Y; Plihon, N; Homann, H; Grauer, R

2017-12-08

We present results from consistent dynamo simulations, where the electrically conducting and incompressible flow inside a cylinder vessel is forced by moving impellers numerically implemented by a penalization method. The numerical scheme models jumps of magnetic permeability for the solid impellers, resembling various configurations tested experimentally in the von Kármán sodium experiment. The most striking experimental observations are reproduced in our set of simulations. In particular, we report on the existence of a time-averaged axisymmetric dynamo mode, self-consistently generated when the magnetic permeability of the impellers exceeds a threshold. We describe a possible scenario involving both the turbulent flow in the vicinity of the impellers and the high magnetic permeability of the impellers.

Constraining AGN triggering mechanisms through the clustering analysis of active black holes

NASA Astrophysics Data System (ADS)

Gatti, M.; Shankar, F.; Bouillot, V.; Menci, N.; Lamastra, A.; Hirschmann, M.; Fiore, F.

2016-02-01

The triggering mechanisms for active galactic nuclei (AGN) are still debated. Some of the most popular ones include galaxy interactions (IT) and disc instabilities (DIs). Using an advanced semi-analytic model (SAM) of galaxy formation, coupled to accurate halo occupation distribution modelling, we investigate the imprint left by each separate triggering process on the clustering strength of AGN at small and large scales. Our main results are as follows: (I) DIs, irrespective of their exact implementation in the SAM, tend to fall short in triggering AGN activity in galaxies at the centre of haloes with Mh > 1013.5 h-1 M⊙. On the contrary, the IT scenario predicts abundance of active central galaxies that generally agrees well with observations at every halo mass. (II) The relative number of satellite AGN in DIs at intermediate-to-low luminosities is always significantly higher than in IT models, especially in groups and clusters. The low AGN satellite fraction predicted for the IT scenario might suggest that different feeding modes could simultaneously contribute to the triggering of satellite AGN. (III) Both scenarios are quite degenerate in matching large-scale clustering measurements, suggesting that the sole average bias might not be an effective observational constraint. (IV) Our analysis suggests the presence of both a mild luminosity and a more consistent redshift dependence in the AGN clustering, with AGN inhabiting progressively less massive dark matter haloes as the redshift increases. We also discuss the impact of different observational selection cuts in measuring AGN clustering, including possible discrepancies between optical and X-ray surveys.

Search for Scalar Top Quark Pair-Production in Scenario with Violated R-parity in pp¯ Collisions at √s = 1.96 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Takashi

A search for the pair production of supersymmetric partner of the top quark in scenario with R-parity violation is presented. The quantum number called R-parity distinguishes particles in standard model from supersymmetric particles. A scalar top quark (stop) is assumed to decay only via R p-violating supersymmetric coupling into tau lepton and b-quark. To collect events with multiple taus, a new special tau trigger (the lepton plus track trigger) is installed in Run II experiment of the Collider Detector at Fermilab (CDF). The goal of the lepton plus track trigger is to collect generic dilepton (ll, lτ, ττ) events withmore » lower p T threshold (8 GeV/c) and without prescale even at high luminosity. The Z → ττ event, where one τ-lepton decays leptonically and the other hadronically, is a good benchmark to calibrate the lepton plus track trigger and τ identification. The data sample of 72 pb -1, collected using the electron plus track trigger, contains clear a τ signal from Z → ττ events. The data used in stop search correspond to 200 pb -1. The lower stop mass bound of 134 GeV/c 2 at a 95% confidence level is obtained. This limit is also directly applicable to the case of the third generation scalar leptoquark (LQ 3) assuming a 100% branching for the LQ 3 → τb decay mode.« less

Electron acceleration via magnetic island coalescence

NASA Astrophysics Data System (ADS)

Shinohara, I.; Yumura, T.; Tanaka, K. G.; Fujimoto, M.

2009-06-01

Electron acceleration via fast magnetic island coalescence that happens as quick magnetic reconnection triggering (QMRT) proceeds has been studied. We have carried out a three-dimensional full kinetic simulation of the Harris current sheet with a large enough simulation run for two magnetic islands coalescence. Due to the strong inductive electric field associated with the non-linear evolution of the lower-hybrid-drift instability and the magnetic island coalescence process observed in the non-linear stage of the collisionless tearing mode, electrons are significantly accelerated at around the neutral sheet and the subsequent X-line. The accelerated meandering electrons generated by the non-linear evolution of the lower-hybrid-drift instability are resulted in QMRT, and QMRT leads to fast magnetic island coalescence. As a whole, the reconnection triggering and its transition to large-scale structure work as an effective electron accelerator.

The third level trigger and output event unit of the UA1 data-acquisition system

NASA Astrophysics Data System (ADS)

Cittolin, S.; Demoulin, M.; Fucci, A.; Haynes, W.; Martin, B.; Porte, J. P.; Sphicas, P.

1989-12-01

The upgraded UA1 experiment utilizes twelve 3081/E emulators for its third-level trigger system. The system is interfaced to VME, and is controlled by 68000 microprocessor VME boards on the input and output. The output controller communicates with an IBM 9375 mainframe via the CERN-IBM developed VICI interface. The events selected by the emulators are output on IBM-3480 cassettes. The user interface to this system is based on a series of Macintosh personal computer connected to the VME bus. These Macs are also used for developing software for the emulators and for monitoring the entire system. The same configuration has also been used for offline event reconstruction. A description of the system, together with details of both the online and offline modes of operation and an eveluation of its performance are presented.

An optical fiber-based flexible readout system for micro-pattern gas detectors

NASA Astrophysics Data System (ADS)

Li, C.; Feng, C. Q.; Zhu, D. Y.; Liu, S. B.; An, Q.

2018-04-01

This paper presents an optical fiber-based readout system that is intended to provide a general purpose multi-channel readout solution for various Micro-Pattern Gas Detectors (MPGDs). The proposed readout system is composed of several front-end cards (FECs) and a data collection module (DCM). The FEC exploits the capability of an existing 64-channel generic TPC readout ASIC chip, named AGET, to implement 256 channels readout. AGET offers FEC a large flexibility in gain range (4 options from 120 fC to 10 pC), peaking time (16 options from 50 ns to 1 us) and sampling freqency (100 MHz max.). The DCM contains multiple 1 Gbps optical fiber serial link interfaces that allow the system scaling up to 1536 channels with 6 FECs and 1 DCM. Further scaling up is possible through cascading of multiple DCMs, by configuring one DCM as a master while other DCMs in slave mode. This design offers a rapid readout solution for different application senario. Tests indicate that the nonlinearity of each channel is less than 1%, and the equivalent input noise charge is typically around 0.7 fC in RMS (root mean square), with a noise slope of about 0.01 fC/pF. The system level trigger rate limit is about 700 Hz in all channel readout mode. When in hit channel readout mode, supposing that typically 10 percent of channels are fired, trigger rate can go up to about 7 kHz. This system has been tested with Micromegas detector and GEM detector, confirming its capability in MPGD readout. Details of hardware and FPGA firmware design, as well as system performances, are described in the paper.

Experimental Development of Low-emittance Field-emission Electron Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lueangaranwong, A.; Buzzard, C.; Divan, R.

2016-10-10

Field emission electron sources are capable of extreme brightness when excited by static or time-dependent electro- magnetic fields. We are currently developing a cathode test stand operating in DC mode with possibility to trigger the emission using ultra-short (~ 100-fs) laser pulses. This contribution describes the status of an experiment to investigate field-emission using cathodes under development at NIU in collaboration with the Argonne’s Center for Nanoscale Materials.

What Can Geolocated Sferics Tell Us About Terrestrial Gamma-Ray Flashes?

NASA Technical Reports Server (NTRS)

Connaughton, V.; Briggs, M. S.; Holzworth, R. H.; Hutchins, M. L.; Fishman, G. J.; Smith, D. M.

2010-01-01

The Fermi Gamma-ray Burst Monitor (GBM) has been detecting TGFs with increasing sensitivity over the past two years, owing to changes in flight software that have lowered its threshold for triggering and, recently, allowed a search for TGFs weaker than those which would cause an onboard trigger. Associations between TGFs detected in the first 18 months of operation and sferics detected using the World Wide Lightning Location Network (WWLLN) show that TGF peaks and lightning discharges are simultaneous to within tens of microseconds, and that GBM triggered on TGFs that occurred up to a distance of 300 km from the sub-spacecraft position. In the work presented here, we look for associations between TGFs detected by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and WWLLN sferics over the same 18 months, and we compare the match rate and detection horizon of the two instruments. We also look for associations between WWLLN sferics and more recent GBM TGFs, both triggered events and weaker TGFs uncovered in our untriggered search. We discuss whether in this new mode, GBM is detecting TGFs that are more distant from the sub-spacecraft point than 300 km, or whether the weaker TGFs are instead indicative of a luminosity distribution, either because the weaker ones originate deeper in the atmosphere or because they are intrinsically dimmer.

Redox-Triggered Bonding-Induced Emission of Thiol-Functionalized Gold Nanoclusters for Luminescence Turn-On Detection of Molecular Oxygen.

PubMed

Ao, Hang; Feng, Hui; Zhao, Mengting; Zhao, Meizhi; Chen, Jianrong; Qian, Zhaosheng

2017-11-22

Most optical sensors for molecular oxygen were developed based on the quenching effect of the luminescence of oxygen-sensitive probes; however, the signal turn-off mode of these probes is undesirable to quantify and visualize molecular oxygen. Herein, we report a novel luminescence turn-on detection strategy for molecular oxygen via the specific oxygen-triggered bonding-induced emission of thiol-functionalized gold nanoclusters. Thiol-functionalized gold nanoclusters were prepared by a facile one-step synthesis, and as-prepared gold nanoclusters possess significant aggregation-induced emission (AIE) property. It is the first time to discover the oxygen-triggered bonding-induced emission (BIE) behavior of gold nanoclusters, which results in disulfide-linked covalent bonding assemblies with intensely red luminescence. This specific redox-triggered BIE is capable of quantitatively detecting dissolved oxygen in aqueous solution in a light-up manner, and trace amount of dissolved oxygen at ppb level is achieved based on this detection method. A facile and convenient test strip for oxygen detection was also developed to monitor molecular oxygen in a gas matrix. Covalent bonding-induced emission is proven to be a more efficient way to attain high brightness of AIEgens than a physical aggregation-induced emission process, and provides a more convenient and desirable detection method for molecular oxygen than the previous sensors.

QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALLOONING MODES

DOE Office of Scientific and Technical Information (OSTI.GOV)

LAO, LL; SNYDER, PB; LEONARD, AW

2002-07-01

OAK A271 QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALLOONING MODES. Two of the major issues crucial for the design of the next generation tokamak burning plasma devices are the predictability of the edge pedestal height and control of the divertor heat load in H-mode configurations. Both of these are strongly impacted by edge localized modes (ELMs) and their size. A working model for ELMs is that they are intermediate toroidal mode number, n {approx} 5-30, peeling-ballooning modes driven by the large edge pedestal pressure gradient P{prime} and the associated large edge bootstrap current density J{sub BS}. the interplay betweenmore » P{prime} and J{sub BS} as a discharge evolves can excite peeling-ballooning modes over a wide spectrum of n. The pedestal current density plays a dual role by stabilizing the high n ballooning modes via opening access to second stability but providing free energy to drive the intermediate n peeling modes. This makes a systematic evaluation of this model particularly challenging. This paper describes recent quantitative tests of this model using experimental data from the DIII-D and the JT-60U tokamaks. These tests are made possible by recent improvements to the ELITE MHD stability code, which allow an efficient evaluation of the unstable peeling-ballooning modes, as well as by improvements to other diagnostic and analysis techniques. Some of the key testable features of this model are: (1) ELMs are triggered when the growth rates of intermediate n MHD modes become significantly large; (2) ELM sizes are related to the radial widths of the unstable modes; (3) the unstable modes have a strong ballooning character localized in the outboard bad curvature region; (4) at high collisionality, ELM size generally becomes smaller because J{sub BS} is reduced.« less

Investigation of peeling-ballooning stability prior to transient outbursts accompanying transitions out of H-mode in DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldon, David; Boivin, Rejean L.; Groebner, Richard J.

Here, the H-mode transport barrier allows confinement of roughly twice as much energy as in an L-mode plasma. Termination of H-mode necessarily requires release of this energy, and the timescale of that release is of critical importance for the lifetimes of plasma facing components in next step tokamaks such as ITER. H-L transition sequences in modern tokamaks often begin with a transient outburst which appears to be superficially similar to and has sometimes been referred to as a type-I edge localized mode (ELM). Type-I ELMs have been shown to be consistent with ideal peeling ballooning instability and are characterized bymore » significant (up to ~50%) reduction of pedestal height on short (~1 ms) timescales. Knowing whether or not this type of instability is present during H-L back transitions will be important for planning for plasma ramp-down in ITER. This paper presents tests of pre-transition experimental data against ideal peeling-ballooning stability calculations with the ELITE code and supports 2 those results with secondary experiments that together show that the transient associated with the H-L transition is not triggered by the same physics as are type-I ELMs.« less

Investigation of peeling-ballooning stability prior to transient outbursts accompanying transitions out of H-mode in DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldon, D., E-mail: deldon@princeton.edu; Princeton University, Princeton, New Jersey 08543; Boivin, R. L.

The H-mode transport barrier allows confinement of roughly twice as much energy as in an L-mode plasma. Termination of H-mode necessarily requires release of this energy, and the timescale of that release is of critical importance for the lifetimes of plasma facing components in next step tokamaks such as ITER. H-L transition sequences in modern tokamaks often begin with a transient outburst which appears to be superficially similar to and has sometimes been referred to as a type-I edge localized mode (ELM). Type-I ELMs have been shown to be consistent with ideal peeling ballooning instability and are characterized by significantmore » (up to ∼50%) reduction of pedestal height on short (∼1 ms) timescales. Knowing whether or not this type of instability is present during H-L back transitions will be important of planning for plasma ramp-down in ITER. This paper presents tests of pre-transition experimental data against ideal peeling-ballooning stability calculations with the ELITE code and supports those results with secondary experiments that together show that the transient associated with the H-L transition is not triggered by the same physics as are type-I ELMs.« less

Investigation of peeling-ballooning stability prior to transient outbursts accompanying transitions out of H-mode in DIII-D

DOE PAGES

Eldon, David; Boivin, Rejean L.; Groebner, Richard J.; ...

2015-05-14

Here, the H-mode transport barrier allows confinement of roughly twice as much energy as in an L-mode plasma. Termination of H-mode necessarily requires release of this energy, and the timescale of that release is of critical importance for the lifetimes of plasma facing components in next step tokamaks such as ITER. H-L transition sequences in modern tokamaks often begin with a transient outburst which appears to be superficially similar to and has sometimes been referred to as a type-I edge localized mode (ELM). Type-I ELMs have been shown to be consistent with ideal peeling ballooning instability and are characterized bymore » significant (up to ~50%) reduction of pedestal height on short (~1 ms) timescales. Knowing whether or not this type of instability is present during H-L back transitions will be important for planning for plasma ramp-down in ITER. This paper presents tests of pre-transition experimental data against ideal peeling-ballooning stability calculations with the ELITE code and supports 2 those results with secondary experiments that together show that the transient associated with the H-L transition is not triggered by the same physics as are type-I ELMs.« less

Water exchange between Algeciras Bay and the Strait of Gibraltar: A study based on HF coastal radar

NASA Astrophysics Data System (ADS)

Chioua, J.; Dastis, C.; González, C. J.; Reyes, E.; Mañanes, R.; Ruiz, M. I.; Álvarez, E.; Yanguas, F.; Romero, J.; Álvarez, O.; Bruno, M.

2017-09-01

This study analyses the water mass exchanges at subinertial scale between Algeciras Bay and the adjacent Strait of Gibraltar. The mechanisms triggering this exchange process is investigated with the aid of recently-acquired data on surface currents obtained using a system of HF coastal radars deployed on the eastern side of the Strait, and remotely-sensed images of sea surface temperature (SST) and chlorophyll from the MODIS sensor of the Aqua satellite. HF radar data on surface currents are analyzed by the application of real empirical orthogonal function (EOF) decomposition, which produces three EOF modes explaining more than 70% of the variance of the surface currents at the mouth of the Bay (modes 2, 3, and 6). Mode 2 is related to the fluctuations of the Atlantic Jet in the central zone of the Strait, mainly due to a combined effect of the atmospheric pressure fluctuations in the Western Mediterranean Sea and local wind in the eastern side of the Strait; mode 3 is related to the coastal currents induced by zonal wind forcing on the north-western coast of the Strait and Alboran Sea; and mode 6 seems to be related to water transport induced by winds blowing with a significant north component into and out of the Bay.

Overview of recent HL-2A experiments

NASA Astrophysics Data System (ADS)

Duan, X. R.; Liu, Yi; Xu, M.; Yan, L. W.; Xu, Y.; Song, X. M.; Dong, J. Q.; Ding, X. T.; Chen, L. Y.; Lu, B.; Liu, D. Q.; Rao, J.; Xuan, W. M.; Yang, Q. W.; Zheng, G. Y.; Zou, X. L.; Liu, Y. Q.; Zhong, W. L.; Zhao, K. J.; Ji, X. Q.; Mao, W. C.; Wang, Q. M.; Li, Q.; Cao, J. Y.; Cao, Z.; Lei, G. J.; Zhang, J. H.; Li, X. D.; Bai, X. Y.; Cheng, J.; Chen, W.; Cui, Z. Y.; Delpech, L.; Diamond, P. H.; Dong, Y. B.; Ekedahl, A.; Hoang, T.; Huang, Y.; Ida, K.; Itoh, K.; Itoh, S.-I.; Isobe, M.; Inagaki, S.; Mazon, D.; Morita, S.; Peysson, Y.; Shi, Z. B.; Wang, X. G.; Xiao, G. L.; Yu, D. L.; Yu, L. M.; Zhang, Y. P.; Zhou, Y.; Cui, C. H.; Feng, B. B.; Huang, M.; Li, Y. G.; Li, B.; Li, G. S.; Li, H. J.; Li, Qing; Peng, J. F.; Wang, Y. Q.; Yuan, B. S.; Liu, Yong; HL-2A Team

2017-10-01

Since the last Fusion Energy Conference, significant progress has been made in the following areas. The first high coupling efficiency low-hybrid current drive (LHCD) with a passive-active multi-junction (PAM) antenna was successfully demonstrated in the H-mode on the HL-2A tokamak. Double critical impurity gradients of electromagnetic turbulence were observed in H-mode plasmas. Various ELM mitigation techniques have been investigated, including supersonic molecular beam injection (SMBI), impurity seeding, resonant magnetic perturbation (RMP) and low-hybrid wave (LHW). The ion internal transport barrier was observed in neutral beam injection (NBI) heated plasmas. Neoclassical tearing modes (NTMs) driven by the transient perturbation of local electron temperature during non-local thermal transport events have been observed, and a new type of non-local transport triggered by the ion fishbone was found. A long-lasting runaway electron plateau was achieved after argon injection and the runaway current was successfully suppressed by SMBI. It was found that low-n Alfvénic ion temperature gradient (AITG) modes can be destabilized in ohmic plasmas, even with weak magnetic shear and low-pressure gradients. For the first time, the synchronization of geodesic acoustic mode (GAM) and magnetic fluctuations was observed in edge plasmas, revealing frequency entrainment and phase lock. The spatiotemporal features of zonal flows were also studied using multi-channel correlation Doppler reflectometers.

Analysis of electron temperature, impurity transport and MHD activity with multi-energy soft x-ray diagnostic in EAST tokamak

NASA Astrophysics Data System (ADS)

Heng, LAN; Guosheng, XU; Kevin, TRITZ; Ning, YAN; Tonghui, SHI; Yongliang, LI; Tengfei, WANG; Liang, WANG; Jingbo, CHEN; Yanmin, DUAN; Yi, YUAN; Youwen, SUN; Shuai, GU; Qing, ZANG; Ran, CHEN; Liang, CHEN; Xingwei, ZHENG; Shuliang, CHEN; Huan, LIU; Yang, YE; Huiqian, WANG; Baonian, WAN; the EAST Team

2017-12-01

A new edge tangential multi-energy soft x-ray (ME-SXR) diagnostic with high temporal (≤ 0.1 ms) and spatial (∼1 cm) resolution has been developed for a variety of physics topics studies in the EAST tokamak plasma. The fast edge electron temperature profile (approximately from r/a∼ 0.6 to the scrape-off layer) is investigated using ME-SXR diagnostic system. The data process was performed by the ideal ‘multi-foil’ technique, with no priori assumptions of plasma profiles. Reconstructed ME-SXR emissivity profiles for a variety of EAST experimental scenarios are presented here for the first time. The applications of the ME-SXR for study of the effects of resonant magnetic perturbation on edge localized modes and the first time neon radiating divertor experiment in EAST are also presented in this work. It has been found that neon impurity can suppress the 2/1 tearing mode and trigger a 3/1 MHD mode.

Effect of Isotope Mass in Simulations of JET H-mode Discharges

NASA Astrophysics Data System (ADS)

Snyder, S. E.; Onjun, T.; Kritz, A. H.; Bateman, G.; Parail, V.

2004-11-01

In JET type-I ELMy H-mode discharges, it is found that the height of the pressure pedestal increases and the frequency of the ELMs decreases with increasing isotope mass. These experimentally observed trends are obtained in these simulations only if the pedestal width increases with isotope mass. Simulations are carried out using the JETTO integrated modeling code with a dynamic model for the H-mode pedestal and the ELMs.(T. Onjun et al, Phys. Plasmas 11 (2004) 1469 and 3006.) The HELENA and MISHKA stability codes are applied to calibrate the stability criteria used to trigger ELM crashes in the JETTO code and to explore possible access to second stability in the pedestal. In the simulations, transport in the pedestal is given by the ion thermal neoclassical diffusivity, which increases with isotope mass. Consequently, as the isotope mass is increased, the pressure gradient and the bootstrap current in the pedestal rebuild more slowly after each ELM crash. Several models are explored in which the pedestal width increases with isotope mass.

Study of neoclassical effects on the pedestal structure in ELMy H-mode plasmas

NASA Astrophysics Data System (ADS)

Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Rafiq, T.; Park, G. Y.; Ku, S.; Chang, C. S.; Snyder, P. B.

2009-11-01

The neoclassical effects on the H-mode pedestal structure are investigated in this study. First principles' kinetic simulations of the neoclassical pedestal dynamics are combined with the MHD stability conditions for triggering ELM crashes that limit the pedestal width and height in H-mode plasmas. The neoclassical kinetic XGC0 code [1] is used to produce systematic scans over plasma parameters including plasma current, elongation, and triangularity. As plasma profiles evolve, the MHD stability limits of these profiles are analyzed with the ideal MHD stability ELITE code [2]. The scalings of the pedestal width and height are presented as a function of the scanned plasma parameters. Simulations with the XGC0 code, which include coupled ion-electron dynamics, yield predictions for both ion and electron pedestal profiles. Differences in the electron and ion pedestal scalings are investigated. [1] C.S. Chang et al, Phys. Plasmas 11 (2004) 2649. [2] P.B. Snyder et al, Phys. Plasmas, 9 (2002) 2037.

Extremely Low-Frequency Waves Inside the Diamagnetic Cavity of Comet 67P/Churyumov-Gerasimenko

NASA Astrophysics Data System (ADS)

Madsen, B.; Wedlund, C. Simon; Eriksson, A.; Goetz, C.; Karlsson, T.; Gunell, H.; Spicher, A.; Henri, P.; Vallières, X.; Miloch, W. J.

2018-05-01

The European Space Agency/Rosetta mission to comet 67P/Churyumov-Gerasimenko has provided several hundred observations of the cometary diamagnetic cavity induced by the interaction between outgassed cometary particles, cometary ions, and the solar wind magnetic field. Here we present the first electric field measurements of four preperihelion and postperihelion cavity crossings on 28 May 2015 and 17 February 2016, using the dual-probe electric field mode of the Langmuir probe (LAP) instrument of the Rosetta Plasma Consortium. We find that on large scales, variations in the electric field fluctuations capture the cavity and boundary regions observed in the already well-studied magnetic field, suggesting the electric field mode of the LAP instrument as a reliable tool to image cavity crossings. In addition, the LAP electric field mode unravels for the first time extremely low-frequency waves within two cavities. These low-frequency electrostatic waves are likely triggered by lower-hybrid waves observed in the surrounding magnetized plasma.

Proposal of a micromagnetic standard problem for ferromagnetic resonance simulations

NASA Astrophysics Data System (ADS)

Baker, Alexander; Beg, Marijan; Ashton, Gregory; Albert, Maximilian; Chernyshenko, Dmitri; Wang, Weiwei; Zhang, Shilei; Bisotti, Marc-Antonio; Franchin, Matteo; Hu, Chun Lian; Stamps, Robert; Hesjedal, Thorsten; Fangohr, Hans

2017-01-01

Nowadays, micromagnetic simulations are a common tool for studying a wide range of different magnetic phenomena, including the ferromagnetic resonance. A technique for evaluating reliability and validity of different micromagnetic simulation tools is the simulation of proposed standard problems. We propose a new standard problem by providing a detailed specification and analysis of a sufficiently simple problem. By analyzing the magnetization dynamics in a thin permalloy square sample, triggered by a well defined excitation, we obtain the ferromagnetic resonance spectrum and identify the resonance modes via Fourier transform. Simulations are performed using both finite difference and finite element numerical methods, with OOMMF and Nmag simulators, respectively. We report the effects of initial conditions and simulation parameters on the character of the observed resonance modes for this standard problem. We provide detailed instructions and code to assist in using the results for evaluation of new simulator tools, and to help with numerical calculation of ferromagnetic resonance spectra and modes in general.

Frequency domain analysis of knock images

NASA Astrophysics Data System (ADS)

Qi, Yunliang; He, Xin; Wang, Zhi; Wang, Jianxin

2014-12-01

High speed imaging-based knock analysis has mainly focused on time domain information, e.g. the spark triggered flame speed, the time when end gas auto-ignition occurs and the end gas flame speed after auto-ignition. This study presents a frequency domain analysis on the knock images recorded using a high speed camera with direct photography in a rapid compression machine (RCM). To clearly visualize the pressure wave oscillation in the combustion chamber, the images were high-pass-filtered to extract the luminosity oscillation. The luminosity spectrum was then obtained by applying fast Fourier transform (FFT) to three basic colour components (red, green and blue) of the high-pass-filtered images. Compared to the pressure spectrum, the luminosity spectra better identify the resonant modes of pressure wave oscillation. More importantly, the resonant mode shapes can be clearly visualized by reconstructing the images based on the amplitudes of luminosity spectra at the corresponding resonant frequencies, which agree well with the analytical solutions for mode shapes of gas vibration in a cylindrical cavity.

Remotely Triggered Solar Blind Signaling Using Deep Ultraviolet (UV) LEDs

DTIC Science & Technology

2011-06-01

Setup used to measure intensity as a function of current. Due to the large difference in intensity between the LEDs of different lens types, the...duty cycle has the smaller rate of intensity drop. Even though the duration of the pulse is double that of the other current, the extra time...neutral troops. If activated, the prototype responds by emitting ten 300 ms flashes followed by a return to passive mode. The dimensions of the

System Detects Vibrational Instabilities

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr.

1990-01-01

Sustained vibrations at two critical frequencies trigger diagnostic response or shutdown. Vibration-analyzing electronic system detects instabilities of combustion in rocket engine. Controls pulse-mode firing of engine and identifies vibrations above threshold amplitude at 5.9 and/or 12kHz. Adapted to other detection and/or control schemes involving simultaneous real-time detection of signals above or below preset amplitudes at two or more specified frequencies. Potential applications include rotating machinery and encoders and decoders in security systems.

11th Annual CMMI Technology Conference and User Group

DTIC Science & Technology

2011-11-17

Examples of triggers may include: – Cost performance – Schedule performance – Results of management reviews – Occurrence of the risk • as a...Analysis (PHA) – Method 3 – Through bottom- up analysis of design data (e.g., flow diagrams, Failure Mode Effects and Criticality Analysis (FMECA...of formal reviews and the setting up of delta or follow- up reviews can be used to give the organization more places to look at the products as they

Spatial-mode storage in a gradient-echo memory

NASA Astrophysics Data System (ADS)

Higginbottom, D. B.; Sparkes, B. M.; Rancic, M.; Pinel, O.; Hosseini, M.; Lam, P. K.; Buchler, B. C.

2012-08-01

Three-level atomic gradient echo memory (Λ-GEM) is a proposed candidate for efficient quantum storage and for linear optical quantum computation with time-bin multiplexing [Hosseini , Nature (London)NATUAS0028-083610.1038/nature08325 461, 241 (2009)]. In this paper we investigate the spatial multimode properties of a Λ-GEM system. Using a high-speed triggered CCD, we demonstrate the storage of complex spatial modes and images. We also present an in-principle demonstration of spatial multiplexing by showing selective recall of spatial elements of a stored spin wave. Using our measurements, we consider the effect of diffusion within the atomic vapor and investigate its role in spatial decoherence. Our measurements allow us to quantify the spatial distortion due to both diffusion and inhomogeneous control field scattering and compare these to theoretical models.

Fragments of the Bacterial Toxin Microcin B17 as Gyrase Poisons

PubMed Central

Collin, Frédéric; Thompson, Robert E.; Jolliffe, Katrina A.; Payne, Richard J.; Maxwell, Anthony

2013-01-01

Fluoroquinolones are very important drugs in the clinical antibacterial arsenal; their success is principally due to their mode of action: the stabilisation of a gyrase-DNA intermediate (the cleavage complex), which triggers a chain of events leading to cell death. Microcin B17 (MccB17) is a modified peptide bacterial toxin that acts by a similar mode of action, but is unfortunately unsuitable as a therapeutic drug. However, its structure and mechanism could inspire the design of new antibacterial compounds that are needed to circumvent the rise in bacterial resistance to current antibiotics. Here we describe the investigation of the structural features responsible for MccB17 activity and the identification of fragments of the toxin that retain the ability to stabilise the cleavage complex. PMID:23593482

Fragments of the bacterial toxin microcin B17 as gyrase poisons.

PubMed

Collin, Frédéric; Thompson, Robert E; Jolliffe, Katrina A; Payne, Richard J; Maxwell, Anthony

2013-01-01

Fluoroquinolones are very important drugs in the clinical antibacterial arsenal; their success is principally due to their mode of action: the stabilisation of a gyrase-DNA intermediate (the cleavage complex), which triggers a chain of events leading to cell death. Microcin B17 (MccB17) is a modified peptide bacterial toxin that acts by a similar mode of action, but is unfortunately unsuitable as a therapeutic drug. However, its structure and mechanism could inspire the design of new antibacterial compounds that are needed to circumvent the rise in bacterial resistance to current antibiotics. Here we describe the investigation of the structural features responsible for MccB17 activity and the identification of fragments of the toxin that retain the ability to stabilise the cleavage complex.

Interface instabilities during displacements of two miscible fluids in a vertical pipe

NASA Astrophysics Data System (ADS)

Scoffoni, J.; Lajeunesse, E.; Homsy, G. M.

2001-03-01

We study experimentally the downward vertical displacement of one miscible fluid by another in a vertical pipe at sufficiently high velocities for diffusive effects to be negligible. For certain viscosity ratios and flow rates, the interface between the two fluids can destabilize. We determine the dimensionless flow rate Uc above which the instability is triggered and its dependence on the viscous ratio M, resulting in a stability map Uc=Uc(M). Two different instability modes have been observed: an asymmetric "corkscrew" mode and an axisymmetric one. We remark that the latter is always eventually disturbed by "corkscrew" type instabilities. We speculate that these instabilities are driven by the viscosity stratification and are analogous to those already observed in core annular flows of immiscible fluids.

Rotation and kinetic modifications of the tokamak ideal-wall pressure limit.

PubMed

Menard, J E; Wang, Z; Liu, Y; Bell, R E; Kaye, S M; Park, J-K; Tritz, K

2014-12-19

The impact of toroidal rotation, energetic ions, and drift-kinetic effects on the tokamak ideal wall mode stability limit is considered theoretically and compared to experiment for the first time. It is shown that high toroidal rotation can be an important destabilizing mechanism primarily through the angular velocity shear; non-Maxwellian fast ions can also be destabilizing, and drift-kinetic damping can potentially offset these destabilization mechanisms. These results are obtained using the unique parameter regime accessible in the spherical torus NSTX of high toroidal rotation speed relative to the thermal and Alfvén speeds and high kinetic pressure relative to the magnetic pressure. Inclusion of rotation and kinetic effects significantly improves agreement between measured and predicted ideal stability characteristics and may provide new insight into tearing mode triggering.

Electronics for a prototype variable field of view PET camera using the PMT-quadrant-sharing detector array

NASA Astrophysics Data System (ADS)

Li, H.; Wong, Wai-Hoi; Zhang, N.; Wang, J.; Uribe, J.; Baghaei, H.; Yokoyama, S.

1999-06-01

Electronics for a prototype high-resolution PET camera with eight position-sensitive detector modules has been developed. Each module has 16 BGO (Bi/sub 4/Ge/sub 3/O/sub 12/) blocks (each block is composed of 49 crystals). The design goals are component and space reduction. The electronics is composed of five parts: front-end analog processing, digital position decoding, fast timing, coincidence processing and master data acquisition. The front-end analog circuit is a zone-based structure (each zone has 3/spl times/3 PMTs). Nine ADCs digitize integration signals of an active zone identified by eight trigger clusters; each cluster is composed of six photomultiplier tubes (PMTs). A trigger corresponding to a gamma ray is sent to a fast timing board to obtain a time-mark, and the nine digitized signals are passed to the position decoding board, where a real block (four PMTs) can be picked out from the zone for position decoding. Lookup tables are used for energy discrimination and to identify the gamma-hit crystal location. The coincidence board opens a 70-ns initial timing window, followed by two 20-ns true/accidental time-mark lookup table windows. The data output from the coincidence board can be acquired either in sinogram mode or in list mode with a Motorola/IRONICS VME-based system.

Search of GRB with AGILE Minicalorimeter

NASA Astrophysics Data System (ADS)

Fuschino, F.; Labanti, C.; Galli, M.; Marisaldi, M.; Bulgarelli, A.; Gianotti, F.; Trifoglio, M.; Argan, A.; Del Monte, E.; Donnarumma, I.; Feroci, M.; Lazzarotto, F.; Pacciani, L.; Tavani, M.; Trois, A.

2008-04-01

AGILE, the small scientific mission of the Italian Space Agency devoted to Hard-X and Gamma-ray astrophysics, was successfully launched on April 23, 2007. The AGILE payload is composed of a tungsten-silicon tracker (ST), operating in the gamma-ray energy range 30 MeV 50 GeV; Super-AGILE, an X-ray imager operating in the energy range 15 45 keV; the Minicalorimeter (MCAL) and an Anticoincidence shield. MCAL is a detector of about 1400 cm2 sensitive in the range 0.3 200 MeV, that can be used both as a slave of the ST to contribute to the AGILE Gamma Ray imaging Detector (GRID operative mode) and autonomously for detection of transient events (BURST operative mode). MCAL is made of 30 CsI(Tl) bar-shaped scintillation detectors with photodiode readout at both ends, arranged in two orthogonal layers. Energy and position of interaction can be derived from a proper composition of the signals readout at the bar's ends, absolute time tagging can be achieved with a μs resolution. The Burst logic deals with various rate-meters on different time scales, energy bands, and MCAL spatial zones. Different algorithms can be chosen for Burst triggering considering also the contribution of other detectors like Super AGILE. In this paper the various trigger logic will be reviewed as well as their on-ground test performed with a dedicated experimental setup.

Cryogenic pellet production developments for long-pulse plasma operation

NASA Astrophysics Data System (ADS)

Meitner, S. J.; Baylor, L. R.; Combs, S. K.; Fehling, D. T.; McGill, J. M.; Duckworth, R. C.; McGinnis, W. D.; Rasmussen, D. A.

2014-01-01

Long pulse plasma operation on large magnetic fusion devices require multiple forms of cryogenically formed pellets for plasma fueling, on-demand edge localized mode (ELM) triggering, radiative cooling of the divertor, and impurity transport studies. The solid deuterium fueling and ELM triggering pellets can be formed by extrusions created by helium cooled, twin-screw extruder based injection system that freezes deuterium in the screw section. A solenoid actuated cutter mechanism is activated to cut the pellets from the extrusion, inserting them into the barrel, and then fired by the pneumatic valve pulse of high pressure gas. Fuel pellets are injected at a rate up to 10 Hz, and ELM triggering pellets are injected at rates up to 20 Hz. The radiative cooling and impurity transport study pellets are produced by introducing impurity gas into a helium cooled section of a pipe gun where it deposits in-situ. A pneumatic valve is opened and propellant gas is released downstream where it encounters a passive punch which initially accelerates the pellet before the gas flow around the finishes the pellet acceleration. This paper discusses the various cryogenic pellet production techniques based on the twin-screw extruder, pipe gun, and pellet punch designs.

Uncertainty Quantification of Non-linear Oscillation Triggering in a Multi-injector Liquid-propellant Rocket Combustion Chamber

NASA Astrophysics Data System (ADS)

Popov, Pavel; Sideris, Athanasios; Sirignano, William

2014-11-01

We examine the non-linear dynamics of the transverse modes of combustion-driven acoustic instability in a liquid-propellant rocket engine. Triggering can occur, whereby small perturbations from mean conditions decay, while larger disturbances grow to a limit-cycle of amplitude that may compare to the mean pressure. For a deterministic perturbation, the system is also deterministic, computed by coupled finite-volume solvers at low computational cost for a single realization. The randomness of the triggering disturbance is captured by treating the injector flow rates, local pressure disturbances, and sudden acceleration of the entire combustion chamber as random variables. The combustor chamber with its many sub-fields resulting from many injector ports may be viewed as a multi-scale complex system wherein the developing acoustic oscillation is the emergent structure. Numerical simulation of the resulting stochastic PDE system is performed using the polynomial chaos expansion method. The overall probability of unstable growth is assessed in different regions of the parameter space. We address, in particular, the seven-injector, rectangular Purdue University experimental combustion chamber. In addition to the novel geometry, new features include disturbances caused by engine acceleration and unsteady thruster nozzle flow.

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems

PubMed Central

Albattat, Ali; Gruenwald, Benjamin C.; Yucelen, Tansel

2016-01-01

The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches. PMID:27537894

Evidence for the role of turbulence-induced poloidal flow shear in triggering the L-H transition

NASA Astrophysics Data System (ADS)

Yu, C. X.; Xu, Y. H.; Jiang, Y.; Luo, J. R.; Mao, J. S.; Liu, B. H.; Li, J. G.

1999-11-01

We have studied the role of turbulence-driven Reynolds stress induced poloidal flow shear in triggering the L-H transition induced by turbulent heating (TH) on HT-6M tokamak. This improved confinement regime has a set of features similar to that of H-mode are commonly observed in large tokamaks. The time evolution indicates that V_θ begins to evolve 0.1ms prior to the change in Er which precedes any measurable change in local confinement characteristics. The measurements of the turbulence-driven Reynolds stress S shows that S and its gradient in the edge region evolve sharply after the start of the TH pulse. Moreover, the time evolution and the temporal structure of the poloidal velocity computed from the measured Reynolds stress profile and the directly measured V_θ look remarkably similar. The time behavior and magnitude of the Reynolds stress-induced-V_θ B_φ term are also found to be in good correlation with that of the measured E_r. These results suggest that the turbulence-driven Reynolds stress might be the dominant mechanism to generate the poloidal flow shear which causes the rapid changes in Er and its shear to trigger the transition.

Transient switching control strategy from regenerative braking to anti-lock braking with a semi-brake-by-wire system

NASA Astrophysics Data System (ADS)

Li, Liang; Li, Xujian; Wang, Xiangyu; Liu, Yahui; Song, Jian; Ran, Xu

2016-02-01

Regenerative braking is an important technology in improving fuel economy of an electric vehicle (EV). However, additional motor braking will change the dynamic characteristics of the vehicle, leading to braking instability, especially when the anti-lock braking system (ABS) is triggered. In this paper, a novel semi-brake-by-wire system, without the use of a pedal simulator and fail-safe device, is proposed. In order to compensate for the hysteretic characteristics of the designed brake system while ensure braking reliability and fuel economy when the ABS is triggered, a novel switching compensation control strategy using sliding mode control is brought forward. The proposed strategy converts the complex coupling braking process into independent control of hydraulic braking and regenerative braking, through which a balance between braking performance, braking reliability, braking safety and fuel economy is achieved. Simulation results show that the proposed strategy is effective and adaptable in different road conditions while the large wheel slip rate is triggered during a regenerative braking course. The research provides a new possibility of low-cost equipment and better control performance for the regenerative braking in the EV and the hybrid EV.

Cryogenic pellet production developments for long-pulse plasma operation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meitner, S. J.; Baylor, L. R.; Combs, S. K.

Long pulse plasma operation on large magnetic fusion devices require multiple forms of cryogenically formed pellets for plasma fueling, on-demand edge localized mode (ELM) triggering, radiative cooling of the divertor, and impurity transport studies. The solid deuterium fueling and ELM triggering pellets can be formed by extrusions created by helium cooled, twin-screw extruder based injection system that freezes deuterium in the screw section. A solenoid actuated cutter mechanism is activated to cut the pellets from the extrusion, inserting them into the barrel, and then fired by the pneumatic valve pulse of high pressure gas. Fuel pellets are injected at amore » rate up to 10 Hz, and ELM triggering pellets are injected at rates up to 20 Hz. The radiative cooling and impurity transport study pellets are produced by introducing impurity gas into a helium cooled section of a pipe gun where it deposits in-situ. A pneumatic valve is opened and propellant gas is released downstream where it encounters a passive punch which initially accelerates the pellet before the gas flow around the finishes the pellet acceleration. This paper discusses the various cryogenic pellet production techniques based on the twin-screw extruder, pipe gun, and pellet punch designs.« less

On Event-Triggered Adaptive Architectures for Decentralized and Distributed Control of Large-Scale Modular Systems.

PubMed

Albattat, Ali; Gruenwald, Benjamin C; Yucelen, Tansel

2016-08-16

The last decade has witnessed an increased interest in physical systems controlled over wireless networks (networked control systems). These systems allow the computation of control signals via processors that are not attached to the physical systems, and the feedback loops are closed over wireless networks. The contribution of this paper is to design and analyze event-triggered decentralized and distributed adaptive control architectures for uncertain networked large-scale modular systems; that is, systems consist of physically-interconnected modules controlled over wireless networks. Specifically, the proposed adaptive architectures guarantee overall system stability while reducing wireless network utilization and achieving a given system performance in the presence of system uncertainties that can result from modeling and degraded modes of operation of the modules and their interconnections between each other. In addition to the theoretical findings including rigorous system stability and the boundedness analysis of the closed-loop dynamical system, as well as the characterization of the effect of user-defined event-triggering thresholds and the design parameters of the proposed adaptive architectures on the overall system performance, an illustrative numerical example is further provided to demonstrate the efficacy of the proposed decentralized and distributed control approaches.

Launch Vehicle Failure Dynamics and Abort Triggering Analysis

NASA Technical Reports Server (NTRS)

Hanson, John M.; Hill, Ashely D.; Beard, Bernard B.

2011-01-01

Launch vehicle ascent is a time of high risk for an on-board crew. There are many types of failures that can kill the crew if the crew is still on-board when the failure becomes catastrophic. For some failure scenarios, there is plenty of time for the crew to be warned and to depart, whereas in some there is insufficient time for the crew to escape. There is a large fraction of possible failures for which time is of the essence and a successful abort is possible if the detection and action happens quickly enough. This paper focuses on abort determination based primarily on data already available from the GN&C system. This work is the result of failure analysis efforts performed during the Ares I launch vehicle development program. Derivation of attitude and attitude rate abort triggers to ensure that abort occurs as quickly as possible when needed, but that false positives are avoided, forms a major portion of the paper. Some of the potential failure modes requiring use of these triggers are described, along with analysis used to determine the success rate of getting the crew off prior to vehicle demise.

Nonlinear ballooning modes in tokamaks: stability and saturation

NASA Astrophysics Data System (ADS)

Ham, C. J.; Cowley, S. C.; Brochard, G.; Wilson, H. R.

2018-07-01

The nonlinear dynamics of magneto-hydrodynamic ballooning mode perturbations is conjectured to be characterised by the motion of isolated elliptical flux tubes. The theory of stability, dynamics and saturation of such tubes in tokamaks is developed using a generalised Archimedes’ principle. The equation of motion for a tube moving against a drag force in a general axisymmetric equilibrium is derived and then applied to a simplified ‘s–α’ equilibrium. The perturbed nonlinear tube equilibrium (saturated) states are investigated in an ‘s–α’ equilibrium with specific pressure and magnetic shear profiles. The energy of these nonlinear (ballooning) saturated states is calculated. In some cases, particularly at low magnetic shear, these finitely displaced states can have a lower energy than the equilibrium state even if the profile is linearly stable to ballooning modes (infinitesimal tube displacements) at all radii. Thus nonlinear ballooning modes can be metastable. The amplitude of the saturated tube displacement in such cases can be as large as the pressure gradient scale length. We conjecture that triggering a transition into these filamentary states can lead to hard instability limits. A short survey of different pressure profiles is presented to illustrate the variety of behaviour of perturbed elliptical flux tubes.

Exploring SMBH assembly with semi-analytic modelling

NASA Astrophysics Data System (ADS)

Ricarte, Angelo; Natarajan, Priyamvada

2018-02-01

We develop a semi-analytic model to explore different prescriptions of supermassive black hole (SMBH) fuelling. This model utilizes a merger-triggered burst mode in concert with two possible implementations of a long-lived steady mode for assembling the mass of the black hole in a galactic nucleus. We improve modelling of the galaxy-halo connection in order to more realistically determine the evolution of a halo's velocity dispersion. We use four model variants to explore a suite of observables: the M•-σ relation, mass functions of both the overall and broad-line quasar population, and luminosity functions as a function of redshift. We find that `downsizing' is a natural consequence of our improved velocity dispersion mappings, and that high-mass SMBHs assemble earlier than low-mass SMBHs. The burst mode of fuelling is sufficient to explain the assembly of SMBHs to z = 2, but an additional steady mode is required to both assemble low-mass SMBHs and reproduce the low-redshift luminosity function. We discuss in detail the trade-offs in matching various observables and the interconnected modelling components that govern them. As a result, we demonstrate the utility as well as the limitations of these semi-analytic techniques.

Exocytosis and Endocytosis: Modes, Functions, and Coupling Mechanisms*

PubMed Central

Wu, Ling-Gang; Hamid, Edaeni; Shin, Wonchul; Chiang, Hsueh-Cheng

2016-01-01

Vesicle exocytosis releases content to mediate many biological events, including synaptic transmission essential for brain functions. Following exocytosis, endocytosis is initiated to retrieve exocytosed vesicles within seconds to minutes. Decades of studies in secretory cells reveal three exocytosis modes coupled to three endocytosis modes: (a) full-collapse fusion, in which vesicles collapse into the plasma membrane, followed by classical endocytosis involving membrane invagination and vesicle reformation; (b) kiss-and-run, in which the fusion pore opens and closes; and (c) compound exocytosis, which involves exocytosis of giant vesicles formed via vesicle-vesicle fusion, followed by bulk endocytosis that retrieves giant vesicles. Here we review these exo- and endocytosis modes and their roles in regulating quantal size and synaptic strength, generating synaptic plasticity, maintaining exocytosis, and clearing release sites for vesicle replenishment. Furthermore, we highlight recent progress in understanding how vesicle endocytosis is initiated and is thus coupled to exocytosis. The emerging model is that calcium influx via voltage-dependent calcium channels at the calcium microdomain triggers endocytosis and controls endocytosis rate; calmodulin and synaptotagmin are the calcium sensors; and the exocytosis machinery, including SNARE proteins (synaptobrevin, SNAP25, and syntaxin), is needed to coinitiate endocytosis, likely to control the amount of endocytosis. PMID:24274740

Balloon-borne measurements of aerosol, condensation nuclei, and cloud particles in the stratosphere at McMurdo Station, Antarctica, during the spring of 1987

NASA Technical Reports Server (NTRS)

Hofmann, D. J.; Rosen, J. M.; Harder, J. W.; Hereford, J. V.

1989-01-01

Measurements of the vertical profile of particles with condensation nuclei counters and eight channel aerosol detectors at McMurdo Station, Antarctica, in 1987 verified observations made in 1986 concerning the absence of upwelling in the polar vortex and the presence of a condensation nuclei layer in conjunction with the ozone hole region. New observations of a bimodal aerosol size distribution, consisting of a large-particle mode mixed in with the small-particle sulfate mode, at temperatures below -79 C are consistent with the presence of nitric acid-water particles at low concentrations. Higher concentrations of large particles were observed in association with nacreous clouds. An unusual particle layer which contained enhanced concentrations of both the small-particle (sulfate) mode and the large-particle (nitric acid) mode was detected at temperatures below -85 C, suggesting simultaneous nucleation and growth phenomena. The vortex condensation nuclei layer was observed to form at the same time as the ozone hole, indicating that formation of the layer is triggered by photochemical processes and may be important in controlling ozone depletion above 22 km.

ECCD-induced tearing mode stabilization via active control in coupled NIMROD/GENRAY HPC simulations

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Kruger, S. E.; Held, E. D.; Harvey, R. W.

2012-10-01

Actively controlled electron cyclotron current drive (ECCD) applied within magnetic islands formed by neoclassical tearing modes (NTMs) has been shown to control or suppress these modes. In conjunction with ongoing experimental efforts, the development and verification of integrated numerical models of this mode stabilization process is of paramount importance in determining optimal NTM stabilization strategies for ITER. In the advanced model developed by the SWIM Project, the equations/closures of extended (not reduced) MHD contain new terms arising from 3D (not toroidal or bounce-averaged) RF-induced quasilinear diffusion. The quasilinear operator formulation models the equilibration of driven current within the island using the same extended MHD dynamics which govern the physics of island formation, yielding a more accurate and self-consistent picture of 3D island response to RF drive. Results of computations which model ECRF deposition using ray tracing, assemble the 3D quasilinear operator from ray/profile data, and calculate the resultant forces within the extended MHD code will be presented. We also discuss the efficacy of various numerical active feedback control systems, which gather data from synthetic diagnostics to dynamically trigger and spatially align RF fields.

Aerodynamic and acoustic effects of abrupt frequency changes in excised larynges.

PubMed

Alipour, Fariborz; Finnegan, Eileen M; Scherer, Ronald C

2009-04-01

To determine the aerodynamic and acoustic effects due to a sudden change from chest to falsetto register or vice versa. It was hypothesized that the continuous change in subglottal pressure and flow rate alone (pressure-flow sweep [PFS]) can trigger a mode change in the canine larynx. Ten canine larynges were each mounted over a tapered tube that supplied pressurized, heated, and humidified air. Glottographic signals were recorded during each PFS experiment, during which airflow was increased in a gradual manner for a period of 20-30 s. Abrupt changes in fundamental frequency (F(0)) and mode of vibration occurred during the PFS in the passive larynx without any change in adduction or elongation. The lower frequency mode of oscillation of the vocal folds, perceptually identified as the chest register, had relatively large amplitude oscillation, significant vocal fold contact, a rich spectral content, and a relatively loud audio signal. The higher frequency mode of oscillation, perceptually identified as falsetto, had little or no vocal fold contact and a dominant first partial. Relatively abrupt F(0) changes also occurred for gradual adduction changes, with the chest register corresponding to greater adduction, falsetto to less adduction.

Descent and Landing Triggers for the Orion Multi-Purpose Crew Vehicle Exploration Flight Test-1

NASA Technical Reports Server (NTRS)

Bihari, Brian D.; Semrau, Jeffrey D.; Duke, Charity J.

2013-01-01

The Orion Multi-Purpose Crew Vehicle (MPCV) will perform a flight test known as Exploration Flight Test-1 (EFT-1) currently scheduled for 2014. One of the primary functions of this test is to exercise all of the important Guidance, Navigation, Control (GN&C), and Propulsion systems, along with the flight software for future flights. The Descent and Landing segment of the flight is governed by the requirements levied on the GN&C system by the Landing and Recovery System (LRS). The LRS is a complex system of parachutes and flight control modes that ensure that the Orion MPCV safely lands at its designated target in the Pacific Ocean. The Descent and Landing segment begins with the jettisoning of the Forward Bay Cover and concludes with sensing touchdown. This paper discusses the requirements, design, testing, analysis and performance of the current EFT-1 Descent and Landing Triggers flight software.

Performance Evaluation of CMUT-Based Ultrasonic Transformers for Galvanic Isolation.

PubMed

Heller, Jacques; Boulme, Audren; Alquier, Daniel; Ngo, Sophie; Certon, Dominique

2018-04-01

This paper presents the development of a novel acoustic transformer with high galvanic isolation dedicated to power switch triggering. The transformer is based on two capacitive micromachined ultrasonic transducers layered on each side of a silicon substrate; one is the primary circuit, and the other is the secondary circuit. The thickness mode resonance of the substrate is leveraged to transmit the triggering signal. The fabrication and characterization of an initial prototype is presented in this paper. All experimental results are discussed, from the electrical impedance measurements to the power efficiency measurements, for different electrical load conditions. A comparison with a specifically developed finite-element method model is done. Simulations are finally used to identify the optimization rules of this initial prototype. It is shown that the power efficiency can be increased from 35% to 60%, and the transmitted power can be increased from 1.6 to 45 mW/Volt.

Taus and the Trigger for Discovery at ATLAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demers, Sarah

This five year grant allowed Yale Professor Sarah Demers and her students and postdocs to contribute to the ATLAS Experiment at CERN's Large Hadron Collider. We worked on a particular mode of the Higgs Boson decay, contributing to the discovery of this particle as well as measuring the particle's properties. We also performed a "first of its kind" measurement at a hadron collider in the measurement of tau polarization, which increased the sensitivity of ATLAS in a number of exciting ways, both for making measurements of known particles and for hunting for new ones. We also contributed to the taumore » trigger - the real-time selection that chooses data that includes the signature of the tau lepton. Four PhD students in the Yale Physics Department received their PhDs during the term of this grant, with at least partial support from the grant.« less

Phonon triggered rhombohedral lattice distortion in vanadium at high pressure

DOE PAGES

Antonangeli, Daniele; Farber, Daniel L.; Bosak, Alexei; ...

2016-08-19

In spite of the simple body-centered-cubic crystal structure, the elements of group V, vanadium, niobium and tantalum, show strong interactions between the electronic properties and lattice dynamics. Further, these interactions can be tuned by external parameters, such as pressure and temperature. We used inelastic x-ray scattering to probe the phonon dispersion of single-crystalline vanadium as a function of pressure to 45 GPa. Our measurements show an anomalous high-pressure behavior of the transverse acoustic mode along the (100) direction and a softening of the elastic modulus C44 that triggers a rhombohedral lattice distortion occurring between 34 and 39 GPa. Lastly, ourmore » results provide the missing experimental confirmation of the theoretically predicted shear instability arising from the progressive intra-band nesting of the Fermi surface with increasing pressure, a scenario common to all transition metals of group V.« less

VLF wave injections from the ground

NASA Technical Reports Server (NTRS)

Helliwell, R. A.

1983-01-01

Experiments on wave-particle interactions using VLF whistler-mode waves injected into the magnetosphere from Antartica are described. The injected signals are single-frequency coherent waves whose amplitudes and frequencies may be changed slowly with time, or else two or more coherent wave trains transmitted simultaneously to determine the nature of the response to multifrequency excitation. The waves may be amplified 30 dB or more and may trigger intense emissions having bandwidths that vary from a few to several hundred Hertz. In most cases significant growth and triggering occur only when the driving signal is essentially monochromatic (bandwidth 10 Hz). If two frequencies are transmitted simultaneously the signal at the lower frequency tends to be suppressed by 20 dB or more. These results are interpreted in terms of a feedback interaction between the waves and counter-streaming cyclotron resonant electrons in a region several hundred wavelengths long, centered on the magnetic equator.

The Triggering of Large-Scale Waves by CME Initiation

NASA Astrophysics Data System (ADS)

Forbes, Terry

Studies of the large-scale waves generated at the onset of a coronal mass ejection (CME) can provide important information about the processes in the corona that trigger and drive CMEs. The size of the region where the waves originate can indicate the location of the magnetic forces that drive the CME outward, and the rate at which compressive waves steepen into shocks can provide a measure of how the driving forces develop in time. However, in practice it is difficult to separate the effects of wave formation from wave propagation. The problem is particularly acute for the corona because of the multiplicity of wave modes (e.g. slow versus fast MHD waves) and the highly nonuniform structure of the solar atmosphere. At the present time large-scale numerical simulations provide the best hope for deconvolving wave propagation and formation effects from one another.

Humic Substances: Determining Potential Molecular Regulatory Processes in Plants

PubMed Central

Shah, Zahid Hussain; Rehman, Hafiz M.; Akhtar, Tasneem; Alsamadany, Hameed; Hamooh, Bahget T.; Mujtaba, Tahir; Daur, Ihsanullah; Al Zahrani, Yahya; Alzahrani, Hind A. S.; Ali, Shawkat; Yang, Seung H.; Chung, Gyuhwa

2018-01-01

Humic substances (HSs) have considerable effects on soil fertility and crop productivity owing to their unique physiochemical and biochemical properties, and play a vital role in establishing biotic and abiotic interactions within the plant rhizosphere. A comprehensive understanding of the mode of action and tissue distribution of HS is, however, required, as this knowledge could be useful for devising advanced rhizospheric management practices. These substances trigger various molecular processes in plant cells, and can strengthen the plant’s tolerance to various kinds of abiotic stresses. HS manifest their effects in cells through genetic, post-transcriptional, and post-translational modifications of signaling entities that trigger different molecular, biochemical, and physiological processes. Understanding of such fundamental mechanisms will provide a better perspective for defining the cues and signaling crosstalk of HS that mediate various metabolic and hormonal networks operating in plant systems. Various regulatory activities and distribution strategies of HS have been discussed in this review. PMID:29593751

Muscarinic receptor regulates extracellular signal regulated kinase by two modes of arrestin binding.

PubMed

Jung, Seung-Ryoung; Kushmerick, Christopher; Seo, Jong Bae; Koh, Duk-Su; Hille, Bertil

2017-07-11

Binding of agonists to G-protein-coupled receptors (GPCRs) activates heterotrimeric G proteins and downstream signaling. Agonist-bound GPCRs are then phosphorylated by protein kinases and bound by arrestin to trigger desensitization and endocytosis. Arrestin plays another important signaling function. It recruits and regulates activity of an extracellular signal-regulated kinase (ERK) cascade. However, molecular details and timing of ERK activation remain fundamental unanswered questions that limit understanding of how arrestin-dependent GPCR signaling controls cell functions. Here we validate and model a system that tracks the dynamics of interactions of arrestin with receptors and of ERK activation using optical reporters. Our intermolecular FRET measurements in living cells are consistent with β-arrestin binding to M 1 muscarinic acetylcholine receptors (M 1 Rs) in two different binding modes, transient and stable. The stable mode persists for minutes after agonist removal. The choice of mode is governed by phosphorylation on key residues in the third intracellular loop of the receptor. We detect a similar intramolecular conformational change in arrestin in either binding mode. It develops within seconds of arrestin binding to the M 1 receptor, and it reverses within seconds of arrestin unbinding from the transient binding mode. Furthermore, we observed that, when stably bound to phosphorylated M 1 R, β-arrestin scaffolds and activates MEK-dependent ERK. In contrast, when transiently bound, β-arrestin reduces ERK activity via recruitment of a protein phosphatase. All this ERK signaling develops at the plasma membrane. In this scaffolding hypothesis, a shifting balance between the two arrestin binding modes determines the degree of ERK activation at the membrane.

Muscarinic receptor regulates extracellular signal regulated kinase by two modes of arrestin binding

PubMed Central

Jung, Seung-Ryoung; Kushmerick, Christopher; Seo, Jong Bae; Koh, Duk-Su

2017-01-01

Binding of agonists to G-protein–coupled receptors (GPCRs) activates heterotrimeric G proteins and downstream signaling. Agonist-bound GPCRs are then phosphorylated by protein kinases and bound by arrestin to trigger desensitization and endocytosis. Arrestin plays another important signaling function. It recruits and regulates activity of an extracellular signal-regulated kinase (ERK) cascade. However, molecular details and timing of ERK activation remain fundamental unanswered questions that limit understanding of how arrestin-dependent GPCR signaling controls cell functions. Here we validate and model a system that tracks the dynamics of interactions of arrestin with receptors and of ERK activation using optical reporters. Our intermolecular FRET measurements in living cells are consistent with β-arrestin binding to M1 muscarinic acetylcholine receptors (M1Rs) in two different binding modes, transient and stable. The stable mode persists for minutes after agonist removal. The choice of mode is governed by phosphorylation on key residues in the third intracellular loop of the receptor. We detect a similar intramolecular conformational change in arrestin in either binding mode. It develops within seconds of arrestin binding to the M1 receptor, and it reverses within seconds of arrestin unbinding from the transient binding mode. Furthermore, we observed that, when stably bound to phosphorylated M1R, β-arrestin scaffolds and activates MEK-dependent ERK. In contrast, when transiently bound, β-arrestin reduces ERK activity via recruitment of a protein phosphatase. All this ERK signaling develops at the plasma membrane. In this scaffolding hypothesis, a shifting balance between the two arrestin binding modes determines the degree of ERK activation at the membrane. PMID:28652372

Action-Effect Associations in Voluntary and Cued Task-Switching.

PubMed

Sommer, Angelika; Lukas, Sarah

2017-01-01

The literature of action control claims that humans control their actions in two ways. In the stimulus-based approach, actions are triggered by external stimuli. In the ideomotor approach, actions are elicited endogenously and controlled by the intended goal. In the current study, our purpose was to investigate whether these two action control modes affect task-switching differently. We combined a classical task-switching paradigm with action-effect learning. Both experiments consisted of two experimental phases: an acquisition phase, in which associations between task, response and subsequent action effects were learned and a test phase, in which the effects of these associations were tested on task performance by presenting the former action effects as preceding effects, prior to the task (called practiced effects ). Subjects either chose freely between tasks (ideomotor action control mode) or they were cued as to which task to perform (sensorimotor action control mode). We aimed to replicate the consistency effect (i.e., task is chosen according to the practiced task-effect association) and non-reversal advantage (i.e., better task performance when the practiced effect matches the previously learned task-effect association). Our results suggest that participants acquired stable action-effect associations independently of the learning mode. The consistency effect (Experiment 1) could be shown, independent of the learning mode, but only on the response-level. The non-reversal advantage (Experiment 2) was only evident in the error rates and only for participants who had practiced in the ideomotor action control mode.

Action-Effect Associations in Voluntary and Cued Task-Switching

PubMed Central

Sommer, Angelika; Lukas, Sarah

2018-01-01

The literature of action control claims that humans control their actions in two ways. In the stimulus-based approach, actions are triggered by external stimuli. In the ideomotor approach, actions are elicited endogenously and controlled by the intended goal. In the current study, our purpose was to investigate whether these two action control modes affect task-switching differently. We combined a classical task-switching paradigm with action-effect learning. Both experiments consisted of two experimental phases: an acquisition phase, in which associations between task, response and subsequent action effects were learned and a test phase, in which the effects of these associations were tested on task performance by presenting the former action effects as preceding effects, prior to the task (called practiced effects). Subjects either chose freely between tasks (ideomotor action control mode) or they were cued as to which task to perform (sensorimotor action control mode). We aimed to replicate the consistency effect (i.e., task is chosen according to the practiced task-effect association) and non-reversal advantage (i.e., better task performance when the practiced effect matches the previously learned task-effect association). Our results suggest that participants acquired stable action-effect associations independently of the learning mode. The consistency effect (Experiment 1) could be shown, independent of the learning mode, but only on the response-level. The non-reversal advantage (Experiment 2) was only evident in the error rates and only for participants who had practiced in the ideomotor action control mode. PMID:29387027

[Risk factors associated with trigger finger. Case-control study].

PubMed

De la Parra-Márquez, Miguel Leonardo; Tamez-Cavazos, Roberto; Zertuche-Cedillo, Luis; Martínez-Pérez, Juan José; Velasco-Rodríguez, Víctor; Cisneros-Pérez, Vicente

2008-01-01

We undertook this study to identify risk factors in our population associated with trigger finger. The study was conducted at the Instituto Mexicano del Seguro Social, UMAE 21, Monterrey, Nuevo Leon, Mexico. This was a case-control, retrospective, and observational study. There were 250 patients in each group. For cases, patients who were operated on for trigger finger from March 2006 to August 2006 were included. Controls included patients admitted to the Emergency Department with hand injuries that fulfilled the selection criteria. Risk factors analyzed were diabetes, hypertension, smoking, sex, age, weight, and 19 different occupations. Mean age of the cases was 52 years (SE +/- 14.19 years) with a median and mode of 53 years. The right hand was the most common with the middle, thumb, ring, index and little fingers, respectively. A significant statistical relationship was found: females (OR 7.57, 95% CI 5.07-11.31); diabetes (OR 3.72, 95% CI 2.43-5.70); obesity (OR 1.49, 95% CI 1.02-2.19). With regard to occupation, a statistical relationship was found: homemaker (OR 2.44, 95% CI 1.62-3.69); seamstress (OR 4.8, 95% CI 1.3-21.6); and secretary (OR 2.74, 95% CI 1.38-5.52). Trigger finger is a common pathology in our population and is more frequent in women >53 years old. It may be related to diabetes, body mass index (obesity) and certain occupations such as secretary, seamstress and homemaker.

Triggering of acute myocardial infarction by different means of transportation.

PubMed

Peters, Annette; von Klot, Stephanie; Mittleman, Murray A; Meisinger, Christine; Hörmann, Allmut; Kuch, Bernhard; Wichmann, H Erich

2013-10-01

Prior studies have reported an association between traffic-related air pollution in urban areas and exacerbation of cardiovascular disease. We assess here whether time spent in different modes of transportation can trigger the onset of acute myocardial infarction (AMI). We performed a case-crossover study. We interviewed consecutive cases of AMI in the KORA Myocardial Infarction Registry in Augsburg, Southern Germany between February 1999 and December 2003 eliciting data on potential triggers in the four days preceding myocardial infarction onset. A total of 1459 cases with known date and time of AMI symptom onset, who had survived 24 hours after the onset, completed the registry's standard interview on potential triggers of AMI. An association between exposure to traffic and AMI onset 1 hour later was observed (odds ratio: 3.2; 95% confidence interval [CI]: 2.7-3.9, p < 0.001). Using a car was the most common source of traffic exposure; nevertheless, times spent in public transport or on a bicycle were similarly associated with AMI onset 1 hour later. While the highest risk for AMI onset was within 1 hour of exposure to traffic, the elevated risk persisted for up to 6 hours. Women, patients aged 65 years or older, patients not part of the workforce, and those with a history of angina or diabetes exhibited the largest associations between times spent in traffic and AMI onset 1 hour later. The data suggest that transient exposure to traffic regardless of the means of transportation may increase the risk of AMI transiently.

Complementary Paired G4FETs as Voltage-Controlled NDR Device

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad; Chen, Suheng; Blalock, Ben; Britton, Chuck; Prothro, Ben; Vandersand, James; Schrimph, Ron; Cristoloveanu, Sorin; Akavardar, Kerem; Gentil, P.

2009-01-01

It is possible to synthesize a voltage-controlled negative-differential-resistance (NDR) device or circuit by use of a pair of complementary G4FETs (four-gate field-effect transistors). [For more information about G4FETs, please see the immediately preceding article]. As shown in Figure 1, the present voltage-controlled NDR device or circuit is an updated version of a prior NDR device or circuit, known as a lambda diode, that contains a pair of complementary junction field-effect transistors (JFETs). (The lambda diode is so named because its current-versus- voltage plot bears some resemblance to an upper-case lambda.) The present version can be derived from the prior version by substituting G4FETs for the JFETs and connecting both JFET gates of each G4FET together. The front gate terminals of the G4FETs constitute additional terminals (that is, terminals not available in the older JFET version) to which one can apply control voltages VN and VP. Circuits in which NDR devices have been used include (1) Schmitt triggers and (2) oscillators containing inductance/ capacitance (LC) resonant circuits. Figure 2 depicts such circuits containing G4FET NDR devices like that of Figure 1. In the Schmitt trigger shown here, the G4FET NDR is loaded with an ordinary inversion-mode, p-channel, metal oxide/semiconductor field-effect transistor (inversion-mode PMOSFET), the VN terminal of the G4FET NDR device is used as an input terminal, and the input terminals of the PMOSFET and the G4FET NDR device are connected. VP can be used as an extra control voltage (that is, a control voltage not available in a typical prior Schmitt trigger) for adjusting the pinch-off voltage of the p-channel G4FET and thereby adjusting the trigger-voltage window. In the oscillator, a G4FET NDR device is loaded with a conventional LC tank circuit. As in other LC NDR oscillators, oscillation occurs because the NDR counteracts the resistance in the tank circuit. The advantage of this G4FET-NDR LC oscillator over a conventional LC NDR oscillator is that one can apply a time-varying signal to one of the extra control input terminals (VN or VP) to modulate the conductance of the NDR device and thereby amplitude-modulate the output signal.

Meteorological Aspects of Two Modes of Lightning Triggered Upward Lightning (LTUL) Events in Sprite-Producing MCSs

NASA Technical Reports Server (NTRS)

Lyons, W. A.; Nelson, T. E.; Warner, T. A.; Lang, T. J.; Cummins, K.; Quick, M.; Rison, W.; Krehbiel, P.; Cummer, S. A.; Meyers, J.;

Filamentation instability in a quantum plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.

2007-08-15

The growth rate of the filamentation instability triggered when a diluted cold electron beam passes through a cold plasma is evaluated using the quantum hydrodynamic equations. Compared with a cold fluid model, quantum effects reduce both the unstable wave vector domain and the maximum growth rate. Stabilization of large wave vector modes is always achieved, but significant reduction of the maximum growth rate depends on a dimensionless parameter that is provided. Although calculations are extended to the relativistic regime, they are mostly relevant to the nonrelativistic one.

External Factors, Produced by Growing Nerves, Trigger a Regenerative Response in a Non-Regenerative Central Nervous System: Purification and Mode of Action

DTIC Science & Technology

1989-06-01

regenerating optic nerve CNS - Central nervous system FCS - Fetal calf serum Galc - Galactocerebroside G AP - Glial fibriliary acidic protein NGF...nent confinment of the casualty to a wheel chair. Laceration in the upper spinal cord leads to paralysis of the four limbs and a cut in the optic...of microtiter plates in Dulbecco’s modified Eagle medium (DVIEM) containing 10% fetal calf serum (FCS). When the cells reached confluency the medium

Realizing Autonomy via Intelligent Hybrid Control: Adaptable Autonomy for Achieving UxV RSTA Team Decision Superiority (also known as Intelligent Multi-UxV Planner with Adaptive Collaborative/Control Technologies (IMPACT))

DTIC Science & Technology

2018-01-30

algorithms. Due to this, Fusion was built with the goal of extensibility throughout the architecture. The Fusion infrastructure enables software...DISTRIBUTION STATEMENT A: Approved for public release. Cleared, 88PA, Case# 2018-0820. b. Trigger a Highly Mobile ...modes were developed in IMPACT (i.e., normal full coverage patrol (NFCP) and highly mobile (HM)). In both NFCP and HM, all UxVs patrol their assigned

Lightning Physics: A Three Year Program

DTIC Science & Technology

1983-01-01

because these aircraft are controlled poeal’ r r o(z’, I- RIC) with low-voltage digital electronics and are in part construct- 4w J(,3 cR "*t • at ed of... millise - limits pretrigger and delayed-trigger mode,. and a variety of sample conds, and hundreds of microseconds, respectively, the time of simple...processes, but we feel it prudent to discontinue use of the Proctor, D. E., A radio study of lightning, Ph.D. thesis , Univ. of designations in order

Rangefinder, Laser AN/GVS-5( )

DTIC Science & Technology

1977-06-01

capacitor, which is proportional to optical energy, is compared to two reference voltages. One comparison is made in the LO power comparator (U1-A...and the other in the NORMAL power comparator (U1-B). 108 OSC. FREQ. RANGE S1A ADJ. ADJ.SB O OSCILLATOR RANGE TIMER MLII:T 2 ELECTRON ICS BOARD PULSE (2...RCVR 1 PULSE and RCVR 2 PULSE modes an oscillator (U4A) is turned on by removal of a short across an integrator. This oscillator triggers the range timer

Bacteria exploit a polymorphic instability of the flagellar filament to escape from traps.

PubMed

Kühn, Marco J; Schmidt, Felix K; Eckhardt, Bruno; Thormann, Kai M

2017-06-13

Many bacterial species swim by rotating single polar helical flagella. Depending on the direction of rotation, they can swim forward or backward and change directions to move along chemical gradients but also to navigate their obstructed natural environment in soils, sediments, or mucus. When they get stuck, they naturally try to back out, but they can also resort to a radically different flagellar mode, which we discovered here. Using high-speed microscopy, we monitored the swimming behavior of the monopolarly flagellated species Shewanella putrefaciens with fluorescently labeled flagellar filaments at an agarose-glass interface. We show that, when a cell gets stuck, the polar flagellar filament executes a polymorphic change into a spiral-like form that wraps around the cell body in a spiral-like fashion and enables the cell to escape by a screw-like backward motion. Microscopy and modeling suggest that this propagation mode is triggered by an instability of the flagellum under reversal of the rotation and the applied torque. The switch is reversible and bacteria that have escaped the trap can return to their normal swimming mode by another reversal of motor direction. The screw-type flagellar arrangement enables a unique mode of propagation and, given the large number of polarly flagellated bacteria, we expect it to be a common and widespread escape or motility mode in complex and structured environments.

Direct generation of all-optical random numbers from optical pulse amplitude chaos.

PubMed

Li, Pu; Wang, Yun-Cai; Wang, An-Bang; Yang, Ling-Zhen; Zhang, Ming-Jiang; Zhang, Jian-Zhong

2012-02-13

We propose and theoretically demonstrate an all-optical method for directly generating all-optical random numbers from pulse amplitude chaos produced by a mode-locked fiber ring laser. Under an appropriate pump intensity, the mode-locked laser can experience a quasi-periodic route to chaos. Such a chaos consists of a stream of pulses with a fixed repetition frequency but random intensities. In this method, we do not require sampling procedure and external triggered clocks but directly quantize the chaotic pulses stream into random number sequence via an all-optical flip-flop. Moreover, our simulation results show that the pulse amplitude chaos has no periodicity and possesses a highly symmetric distribution of amplitude. Thus, in theory, the obtained random number sequence without post-processing has a high-quality randomness verified by industry-standard statistical tests.

Full melting of a two-dimensional complex plasma crystal triggered by localized pulsed laser heating

NASA Astrophysics Data System (ADS)

Couëdel, L.; Nosenko, V.; Rubin-Zuzic, M.; Zhdanov, S.; Elskens, Y.; Hall, T.; Ivlev, A. V.

2018-04-01

The full melting of a two-dimensional plasma crystal was induced in a principally stable monolayer by localized laser stimulation. Two distinct behaviors of the crystal after laser stimulation were observed depending on the amount of injected energy: (i) below a well-defined threshold, the laser melted area recrystallized; (ii) above the threshold, it expanded outwards in a similar fashion to mode-coupling instability-induced melting, rapidly destroying the crystalline order of the whole complex plasma monolayer. The reported experimental observations are due to the fluid mode-coupling instability, which can pump energy into the particle monolayer at a rate surpassing the heat transport and damping rates in the energetic localized melted spot, resulting in its further growth. This behavior exhibits remarkable similarities with impulsive spot heating in ordinary reactive matter.

WHITTIER NARROWS, CALIFORNIA EARTHQUAKE OF OCTOBER 1, 1987-PRELIMINARY ASSESSMENT OF STRONG GROUND MOTION RECORDS.

USGS Publications Warehouse

Brady, A.G.; Etheredge, E.C.; Porcella, R.L.

1988-01-01

More than 250 strong-motion accelerograph stations were triggered by the Whittier Narrows, California earthquake of 1 October 1987. Considering the number of multichannel structural stations in the area of strong shaking, this set of records is one of the more significant in history. Three networks, operated by the U. S. Geological Survey, the California Division of Mines and Geology, and the University of Southern California produced the majority of the records. The excellent performance of the instruments in these and the smaller arrays is attributable to the quality of the maintenance programs. Readiness for a magnitude 8 event is directly related to these maintenance programs. Prior to computer analysis of the analog film records, a number of important structural resonant modes can be identified, and frequencies and simple mode shapes have been scaled.

High-power LED light sources for optical measurement systems operated in continuous and overdriven pulsed modes

NASA Astrophysics Data System (ADS)

Stasicki, Bolesław; Schröder, Andreas; Boden, Fritz; Ludwikowski, Krzysztof

2017-06-01

The rapid progress of light emitting diode (LED) technology has recently resulted in the availability of high power devices with unprecedented light emission intensities comparable to those of visible laser light sources. On this basis two versatile devices have been developed, constructed and tested. The first one is a high-power, single-LED illuminator equipped with exchangeable projection lenses providing a homogenous light spot of defined diameter. The second device is a multi-LED illuminator array consisting of a number of high-power LEDs, each integrated with a separate collimating lens. These devices can emit R, G, CG, B, UV or white light and can be operated in pulsed or continuous wave (CW) mode. Using an external trigger signal they can be easily synchronized with cameras or other devices. The mode of operation and all parameters can be controlled by software. Various experiments have shown that these devices have become a versatile and competitive alternative to laser and xenon lamp based light sources. The principle, design, achieved performances and application examples are given in this paper.

Mode Choice between Private and Public Transport in Klang Valley, Malaysia

PubMed Central

Karim, Mohamed Rehan; Yusoff, Sumiani

2014-01-01

In 2010, Klang Valley has only 17% trips each day were completed using public transport, with the rest of the 83% trips were made through private transport. The inclination towards private car usage will only get worse if the transport policy continues to be inefficient and ineffective. Under the National Key Economic Area, the priority aimed to stimulate the increase of modal share of public transport in the Klang Valley to 50% by 2020. In the 10th Malaysia Plan, the Klang Valley Mass Rapid Transit was proposed, equipped with 141 km of MRT system, and will integrate with the existing rail networks. Nevertheless, adding kilometers into the rail system will not help, if people do not make the shift from private into public transport. This research would like to assess the possible mode shift of travellers in the Klang Valley towards using public transport, based on the utility function of available transport modes. It intends to identify the criteria that will trigger their willingness to make changes in favour of public transport as targeted by the NKEA. PMID:24701165

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, J.D.

1997-05-06

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion. 3 figs.

Ideal kink and neoclassical tearing mode identification in DIII-D with ECE

NASA Astrophysics Data System (ADS)

Zhao, Hailin; Austin, Max; Brookman, Michale; Rowan, William; La Haye, R. J.

2017-10-01

Detection of neoclassical tearing modes (NTMs), which can degrade plasma confinement or cause disruptions, is important in tokamaks. We have developed a code to cross-correlate ECE/magnetics data to get the amplitude and phase profiles of the electron temperature (Te) oscillation caused by the rotating magnetic island and/or a kink. It has been observed that the ΔTe amplitude on the two sides of the island center can be very different in some discharges. Also, a discrepancy often exists between the location of the rational q surface according to MSE-constrained EFIT and the location of island center according to ECE; this can be an issue for ECCD suppression of NTMs. We explore the possible causes of these two phenomena in terms of ECE location and calibration accuracy. By analyzing the Te fluctuation phase evolution after a large sawtooth crash which triggers an NTM, the presence of a kink-like mode before the onset of NTM can be discerned. Work supported by the US DOE under DE-FG02-97ER54415 and DE-FC02-04ER54698.

Mode of action of leucocin K7 produced by Leuconostoc mesenteroides K7 against Listeria monocytogenes and its potential in milk preservation.

PubMed

Shi, Feng; Wang, Yanwei; Li, Yongfu; Wang, Xiaoyuan

2016-09-01

To investigate the mode of action of leucocin K7 against Listeria monocytogenes and to assess its inhibitory effect on Lis. monocytogenes in refrigerated milk. A bacteriocin-producing strain, Leuconostoc mesenteroides K7, was isolated from a fermented pickle. The bacteriocin, leucocin K7, exhibited antagonistic activity against Lis. monocytogenes with an MIC of 28 µg/ml. It was sensitive to proteaseS and displayed good thermal stability and broad active pH range. Leucocin K7 had no effect on the efflux of ATP from Lis. monocytogenes but triggered the efflux of K(+) and the intracellular hydrolysis of ATP. It also dissipated the transmembrane electrical potential completely and transmembrane pH gradient partially. It 80 AU/ml inhibited the growth of Lis. monocytogenes by 2.3-3.9 log units in milk; when combined with glycine (5 mg/ml), it completely eliminated viable Lis. monocytogenes over 7 days Leucocin K7 shows different mode of action from nisin and may have potential application in milk preservation.

First GRB detections with the AGILE Minicalorimeter

NASA Astrophysics Data System (ADS)

Marisaldi, M.; Labanti, C.; Fuschino, F.; Galli, M.; Tavani, M.; Bulgarelli, A.; Gianotti, F.; Trifoglio, M.; Argan, A.

2008-05-01

The Minicalorimeter (MCAL) onboard the AGILE satellite is a 1400 cm2 scintillation detector sensitive in the energy range 0.3-200 MeV. MCAL works both as a slave of the AGILE Silicon Tracker and as an autonomous detector for transient events (BURST mode). A dedicated onboard Burst Search logic scans BURST mode data in search of count rate increase. Peculiar characteristics of the detector are the high energy spectral coverage and a timing resolution of about 2 microseconds. Even if a trigger is not issued, BURST mode data are used to build a broad band energy spectrum (scientific ratemeters) organized in 11 bands for each of the two MCAL detection planes, with a time resolution of 1 second. After the first engineering commissioning phase, following the AGILE launch on 23rd April 2007, between 22nd June and 5th November 2007 eighteen GRBs were detected offline in the scientific ratemeters data, with a detection rate of about one per week. In this paper the capabilities of the detector will be described and an overview of the first detected GRBs will be given.

Concentric core optical fiber with multiple-mode signal transmission

DOEpatents

Muhs, Jeffrey D.

1997-01-01

A concentric core optical fiber provides for the simultaneous but independent transmission of signals over a single optical fiber. The concentric optical fiber is constructed of a single-mode or multimode inner optical fiber defined by a core and a cladding of a lower index of refraction than the core and an outer optical fiber defined by additional cladding concentrically disposed around the cladding and of an index of refraction lower than the first mentioned cladding whereby the latter functions as the core of the outer optical fiber. By employing such an optical fiber construction with a single-mode inner core or optical fiber, highly sensitive interferometric and stable less sensitive amplitude based sensors can be placed along the same length of a concentric core optical fiber. Also, by employing the concentric core optical fiber secure telecommunications can be achieved via the inner optical fiber since an intrusion of the concentric optical fiber will first cause a variation in the light being transmitted through the outer optical fiber and this variation of light being used to trigger a suitable alarm indicative of the intrusion.

The effect of the isotope on the H-mode density limit

NASA Astrophysics Data System (ADS)

Huber, A.; Wiesen, S.; Bernert, M.; Brezinsek, S.; Chankin, A. V.; Sergienko, G.; Huber, V.; Abreu, P.; Boboc, A.; Brix, M.; Carralero, D.; Delabie, E.; Eich, T.; Esser, H. G.; Guillemaut, C.; Jachmich, S.; Joffrin, E.; Kallenbach, A.; Kruezi, U.; Lang, P.; Linsmeier, Ch.; Lowry, C. G.; Maggi, C. F.; Matthews, G. F.; Meigs, A. G.; Mertens, Ph.; Reimold, F.; Schweinzer, J.; Sips, G.; Stamp, M.; Viezzer, E.; Wischmeier, M.; Zohm, H.; contributors, JET; ASDEX Upgrade Team

2017-08-01

In order to understand the mechanisms for the H-mode density limit in machines with fully metallic walls, systematic investigations of H-mode density limit plasmas in experiments with deuterium and hydrogen external gas fuelling have been performed on JET-ILW. The observed H-mode density limit on JET in D- as well as in H-plasmas demonstrates similar operation phases: the stable H-mode phase, degrading H-mode, breakdown of the H-mode with energy confinement deterioration accompanied by a dithering cycling phase, followed by the L-mode phase. The density limit is not related to an inward collapse of the hot core plasma due to an overcooling of the plasma periphery by radiation. Indeed, independently of the isotopic effect, the total radiated power stay almost constant during the H-mode phase until the H-L back transition. It was observed in D- and H-plasmas that neither detachment, nor the X-point MARFE itself do trigger the H-L transition and that they thus do not present a limit on the plasma density. It is the plasma confinement, most likely determined by edge parameters, which is ultimately responsible for the H-mode DL. By comparing similar discharges but fuelled with either deuterium or hydrogen, we have found that the H-mode density limit exhibits a dependence on the isotope mass: the density limit is up to 35% lower in hydrogen compared to similar deuterium plasma conditions (the obtained density limit is in agreement with the Greenwald limit for D-plasma). In addition, the density limit is nearly independent of the applied power both in deuterium or hydrogen fuelling conditions. The measured Greenwald fractions are consistent with the predictions from a theoretical model based on an MHD instability theory in the near-SOL. The JET operational domains are significantly broadened when increasing the plasma effective mass (e.g. tritium or deuterium-tritium operation), i.e. the L to H power threshold is reduced whereas the density limit for the L-mode back transition is increased.

Pulsed vs. CW low level light therapy on osteoarticular signs and symptoms in limited scleroderma (CREST syndrome)

NASA Astrophysics Data System (ADS)

Barolet, Daniel

2012-03-01

Limited cutaneous systemic sclerosis (lcSSc) was formerly known as CREST syndrome in reference to the associated clinical features: Calcinosis, Raynaud's phenomenon, Esophageal dysfunction, Sclerodactyly, and Telangiectasias. The transforming growth factor beta (TGF-β) has been identified has a major player in the pathogenic process, while low level light therapy (LLLT) has been shown to modulate this cytokine superfamily. This case study was conducted to assess the efficacy of 940nm using microsecond domain pulsing and continuous wave mode (CW) on osteoarticular signs and symptoms associated with lcSSc. The patient was treated two to three times a week for 13 weeks, using a sequential pulsing mode on one elbow, and a CW mode on the other. Efficacy assessments included inflammation, symptoms, pain, and health scales, patient satisfaction, clinical global impression, and adverse effects monitoring. Significant functional and morphologic improvements were observed after LLLT, with best results seen with the pulsing mode. No significant adverse effects were noted. Two mechanisms of action may be at play. The 940nm wavelength provides inside-out heating possibly vasodilating capillaries which in turn increases catabolic processes leading to a reduction of in situ calcinosis. LLLT may also improve symptoms by triggering a cascade of cellular reactions, including the modulation of inflammatory mediators.

Magnetic activity and radial electric field during I-phase in ASDEX Upgrade plasmas

NASA Astrophysics Data System (ADS)

Birkenmeier, Gregor; Cavedon, Marco; Conway, Garrard; Manz, Peter; Puetterich, Thomas; Stroth, Ulrich; ASDEX Upgrade Team Team

2016-10-01

At the transition from the low (L-mode) to the high (H-mode) confinement regime, so called limit-cycle oscillations (LCOs) can occur at the edge of a fusion plasma. During the LCO evolution, which is also called I-phase, the relative importance of background flows and turbulence-generated zonal flows can change, and it is still unclear whether a large contribution of zonal flows is a necessary condition for triggering the H-mode. At ASDEX Upgrade, I-phases have been studied in a wide range of parameters. The modulation of flows and gradients during I-phase is accompanied by a strong magnetic activity with a specific poloidal and toroidal structure. The magnetic activity increases during the development of an edge pedestal during I-phase, and is preceded by type-III ELM-like precursors. During all phases of the I-phase, the radial electric field Er is found to be close to the neoclassical prediction of the electric field Er , neo. These results suggest that zonal flows do not contribute significantly to the LCO dynamics, and the burst like behavior is reminiscent of a critical-gradient driven instability like edge localized modes. These observations on ASDEX Upgrade seem to be inconsistent with LCO models based on an interaction between zonal flows and turbulence.

Active control of ECCD-induced tearing mode stabilization in coupled NIMROD/GENRAY HPC simulations

NASA Astrophysics Data System (ADS)

Jenkins, Thomas; Kruger, Scott; Held, Eric

2013-10-01

Actively controlled ECCD applied in or near magnetic islands formed by NTMs has been successfully shown to control/suppress these modes, despite uncertainties in island O-point locations (where induced current is most stabilizing) relative to the RF deposition region. Integrated numerical models of the mode stabilization process can resolve these uncertainties and augment experimental efforts to determine optimal ITER NTM stabilization strategies. The advanced SWIM model incorporates RF effects in the equations/closures of extended MHD as 3D (not toroidal or bounce-averaged) quasilinear diffusion coefficients. Equilibration of driven current within the island geometry is modeled using the same extended MHD dynamics governing the physics of island formation, yielding a more accurate/self-consistent picture of island response to RF drive. Additionally, a numerical active feedback control system gathers data from synthetic diagnostics to dynamically trigger & spatially align the RF fields. Computations which model the RF deposition using ray tracing, assemble the 3D QL operator from ray & profile data, calculate the resultant xMHD forces, and dynamically realign the RF to more efficiently stabilize modes are presented; the efficacy of various control strategies is also discussed. Supported by the SciDAC Center for Extended MHD Modeling (CEMM); see also https://cswim.org.

A 7.8 kV nanosecond pulse generator with a 500 Hz repetition rate

NASA Astrophysics Data System (ADS)

Lin, M.; Liao, H.; Liu, M.; Zhu, G.; Yang, Z.; Shi, P.; Lu, Q.; Sun, X.

2018-04-01

Pseudospark switches are widely used in pulsed power applications. In this paper, we present the design and performance of a 500 Hz repetition rate high-voltage pulse generator to drive TDI-series pseudospark switches. A high-voltage pulse is produced by discharging an 8 μF capacitor through a primary windings of a setup isolation transformer using a single metal-oxide-semiconductor field-effect transistor (MOSFET) as a control switch. In addition, a self-break spark gap is used to steepen the pulse front. The pulse generator can deliver a high-voltage pulse with a peak trigger voltage of 7.8 kV, a peak trigger current of 63 A, a full width at half maximum (FWHM) of ~30 ns, and a rise time of 5 ns to the trigger pin of the pseudospark switch. During burst mode operation, the generator achieved up to a 500 Hz repetition rate. Meanwhile, we also provide an AC heater power circuit for heating a H2 reservoir. This pulse generator can be used in circuits with TDI-series pseudospark switches with either a grounded cathode or with a cathode electrically floating operation. The details of the circuits and their implementation are described in the paper.

Interaction of the Human Contact System with Pathogens-An Update.

PubMed

Oehmcke-Hecht, Sonja; Köhler, Juliane

2018-01-01

The name human contact system is related to its mode of action, as "contact" with artificial negatively charged surfaces triggers its activation. Today, it is generally believed that the contact system is an inflammatory response mechanism not only against artificial material but also against misfolded proteins and foreign organisms. Upon activation, the contact system is involved in at least two distinct (patho)physiologic processes: i . the trigger of the intrinsic coagulation via factor XI and ii . the cleavage of high molecular weight kininogen with release of bradykinin and antimicrobial peptides (AMPs). Bradykinin is involved in the regulation of inflammatory processes, vascular permeability, and blood pressure. Due to the release of AMPs, the contact system is regarded as a branch of the innate immune defense against microorganisms. There is an increasing list of pathogens that interact with contact factors, in addition to bacteria also fungi and viruses bind and activate the system. In spite of that, pathogens have developed their own mechanisms to activate the contact system, resulting in manipulation of this host immune response. In this up-to-date review, we summarize present research on the interaction of pathogens with the human contact system, focusing particularly on bacterial and viral mechanisms that trigger inflammation via contact system activation.

Respirator triggering of electron beam computed tomography (EBCT): evaluation of dynamic changes during mechanical expiration in the traumatized patient

NASA Astrophysics Data System (ADS)

Recheis, Wolfgang A.; Kleinsasser, Axel; Hatschenberger, Robert; Knapp, Rudolf; zur Nedden, Dieter; Hoermann, Christoph

1999-05-01

The purpose of this project is to evaluate the dynamic changes during expiration at different levels of positive end- expiratory pressure (PEEP) in the ventilated patient. We wanted to discriminate between normal lung function and acute respiratory distress syndrome (ARDS). After approval by the local Ethic Committee we studied two ventilated patients: (1) with normal lung function; (2) ARDS). We used the 50 ms scan mode of the EBCT. The beam was positioned 1 cm above the diaphragm. The table position remained unchanged. An electronic trigger was developed, that utilizes the respirators synchronizing signal to start the EBCT at the onset of expiration. During controlled mechanical expiration at two levels of PEEP (0 and 15 cm H2O), pulmonary aeration was rated as: well-aerated (-900HU/-500HU), poorly- aerated (-500HU/-100HU) and non-aerated (-100HU/+100HU). Pathological and normal lung function showed different dynamic changes (FIG.4-12). The different PEEP levels resulted in a significant change of pulmonary aeration in the same patient. Although we studied only a very limited number of patients, respirator triggered EBCT may be accurate in discriminating pathological changes due to the abnormal lung function in the mechanically ventilated patient.

Synchronization of video recording and laser pulses including background light suppression

NASA Technical Reports Server (NTRS)

Kalshoven, Jr., James E. (Inventor); Tierney, Jr., Michael (Inventor); Dabney, Philip W. (Inventor)

2004-01-01

An apparatus for and a method of triggering a pulsed light source, in particular a laser light source, for predictable capture of the source by video equipment. A frame synchronization signal is derived from the video signal of a camera to trigger the laser and position the resulting laser light pulse in the appropriate field of the video frame and during the opening of the electronic shutter, if such shutter is included in the camera. Positioning of the laser pulse in the proper video field allows, after recording, for the viewing of the laser light image with a video monitor using the pause mode on a standard cassette-type VCR. This invention also allows for fine positioning of the laser pulse to fall within the electronic shutter opening. For cameras with externally controllable electronic shutters, the invention provides for background light suppression by increasing shutter speed during the frame in which the laser light image is captured. This results in the laser light appearing in one frame in which the background scene is suppressed with the laser light being uneffected, while in all other frames, the shutter speed is slower, allowing for the normal recording of the background scene. This invention also allows for arbitrary (manual or external) triggering of the laser with full video synchronization and background light suppression.

Magnetohydrodynamic stability at a separatrix. I. Toroidal peeling modes and the energy principle

NASA Astrophysics Data System (ADS)

Webster, A. J.; Gimblett, C. G.

2009-08-01

A potentially serious impediment to the production of energy by nuclear fusion in large tokamaks, such as ITER [R. Aymar, V. A. Chuyanov, M. Huguet, Y. Shimomura, ITER Joint Central Team, and ITER Home Teams, Nucl. Fusion 41, 1301 (2001)] and DEMO [D. Maisonner, I. Cook, S. Pierre, B. Lorenzo, D. Luigi, G. Luciano, N. Prachai, and P. Aldo, Fusion Eng. Des. 81, 1123 (2006)], is the potential for rapid deposition of energy onto plasma facing components by edge localized modes (ELMs). The trigger for ELMs is believed to be the ideal magnetohydrodynamic peeling-ballooning instability, but recent numerical calculations have suggested that a plasma equilibrium with an X-point—as is found in all ITER-like tokamaks, is stable to the peeling mode. This contrasts with analytical calculations [G. Laval, R. Pellat, and J. S. Soule, Phys. Fluids 17, 835 (1974)] that found the peeling mode to be unstable in cylindrical plasmas with arbitrary cross-sectional shape. Here, we re-examine the assumptions made in cylindrical geometry calculations and generalize the calculation to an arbitrary tokamak geometry at marginal stability. The resulting equations solely describe the peeling mode and are not complicated by coupling to the ballooning mode, for example. We find that stability is determined by the value of a single parameter Δ' that is the poloidal average of the normalized jump in the radial derivative of the perturbed magnetic field's normal component. We also find that near a separatrix it is possible for the energy principle's δW to be negative (that is usually taken to indicate that the mode is unstable, as in the cylindrical theory), but the growth rate to be arbitrarily small.

Comparison of gating methods for the real-time analysis of left ventricular function in nonimaging blood pool studies.

PubMed

Beard, B B; Stewart, J R; Shiavi, R G; Lorenz, C H

1995-01-01

Gating methods developed for electrocardiographic-triggered radionuclide ventriculography are being used with nonimaging detectors. These methods have not been compared on the basis of their real-time performance or suitability for determination of load-independent indexes of left ventricular function. This work evaluated the relative merits of different gating methods for nonimaging radionuclude ventriculographic studies, with particular emphasis on their suitability for real-time measurements and the determination of pressure-volume loops. A computer model was used to investigate the relative accuracy of forward gating, backward gating, and phase-mode gating. The durations of simulated left ventricular time-activity curves were randomly varied. Three acquisition parameters were considered: frame rate, acceptance window, and sample size. Twenty-five studies were performed for each combination of acquisition parameters. Hemodynamic and shape parameters from each study were compared with reference parameters derived directly from the random time-activity curves. Backward gating produced the largest errors under all conditions. For both forward gating and phase-mode gating, ejection fraction was underestimated and time to end systole and normalized peak ejection rate were overestimated. For the hemodynamic parameters, forward gating was marginally superior to phase-mode gating. The mean difference in errors between forward and phase-mode gating was 1.47% (SD 2.78%). However, for root mean square shape error, forward gating was several times worse in every case and seven times worse than phase-mode gating on average. Both forward and phase-mode gating are suitable for real-time hemodynamic measurements by nonimaging techniques. The small statistical difference between the methods is not clinically significant. The true shape of the time-activity curve is maintained most accurately by phase-mode gating.

Comparison of gating methods for the real-time analysis of left ventricular function in nonimaging blood pool studies

PubMed Central

Beard, Brian B.; Stewart, James R.; Shiavi, Richard G.; Lorenz, Christine H.

2018-01-01

Background Gating methods developed for electrocardiographic-triggered radionuclide ventriculography are being used with nonimaging detectors. These methods have not been compared on the basis of their real-time performance or suitability for determination of load-independent indexes of left ventricular function. This work evaluated the relative merits of different gating methods for nonimaging radionuclude ventriculographic studies, with particular emphasis on their suitability for real-time measurements and the determination of pressure-volume loops. Methods and Results A computer model was used to investigate the relative accuracy of forward gating, backward gating, and phase-mode gating. The durations of simulated left ventricular time-activity curves were randomly varied. Three acquisition parameters were considered: frame rate, acceptance window, and sample size. Twenty-five studies were performed for each combination of acquisition parameters. Hemodynamic and shape parameters from each study were compared with reference parameters derived directly from the random time-activity curves. Backward gating produced the largest errors under all conditions. For both forward gating and phase-mode gating, ejection fraction was underestimated and time to end systole and normalized peak ejection rate were overestimated. For the hemodynamic parameters, forward gating was marginally superior to phase-mode gating. The mean difference in errors between forward and phase-mode gating was 1.47% (SD 2.78%). However, for root mean square shape error, forward gating was several times worse in every case and seven times worse than phase-mode gating on average. Conclusions Both forward and phase-mode gating are suitable for real-time hemodynamic measurements by nonimaging techniques. The small statistical difference between the methods is not clinically significant. The true shape of the time-activity curve is maintained most accurately by phase-mode gating. PMID:9420820

Backlighting Direct-Drive Cryogenic DT Implosions on OMEGA

NASA Astrophysics Data System (ADS)

Stoeckl, C.

2016-10-01

X-ray backlighting has been frequently used to measure the in-flight characteristics of an imploding shell in both direct- and indirect-drive inertial confinement fusion implosions. These measurements provide unique insight into the early time and stagnation stages of an implosion and guide the modeling efforts to improve the target designs. Backlighting a layered DT implosion on OMEGA is a particular challenge because the opacity of the DT shell is low, the shell velocity is high, the size and wall thickness of the shell is small, and the self-emission from the hot core at the onset of burn is exceedingly bright. A framing-camera-based crystal imaging system with a Si Heα backlighter at 1.865keV driven by 10-ps short pulses from OMEGA EP was developed to meet these radiography challenges. A fast target inserter was developed to accurately place the Si backlighter foil at a distance of 5 mm to the implosion target following the removal of the cryogenic shroud and an ultra-stable triggering system was implemented to reliably trigger the framing camera coincident with the arrival of the OMEGA EP pulse. This talk will report on a series of implosions in which the DT shell is imaged for a range of convergence ratios and in-flight aspect ratios. The images acquired have been analyzed for low-mode shape variations, the DT shell thickness, the level of ablator mixing into the DT fuel (even 0.1% of carbon mix can be reliably inferred), the areal density of the DT shell, and the impact of the support stalk. The measured implosion performance will be compared with hydrodynamic simulations that include imprint (up to mode 200), cross-beam energy transfer, nonlocal thermal transport, and initial low-mode perturbations such as power imbalance and target misalignment. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

An insight into the hepatocellular death induced by amphetamines, individually and in combination: the involvement of necrosis and apoptosis.

PubMed

Dias da Silva, Diana; Carmo, Helena; Lynch, Adam; Silva, Elisabete

2013-12-01

The liver is a vulnerable target for amphetamine toxicity, but the mechanisms involved in the drug's hepatotoxicity remain poorly understood. The purpose of the current research was to characterize the mode of death elicited by four amphetamines and to evaluate whether their combination triggered similar mechanisms in immortalized human HepG2 cells. The obtained data revealed a time- and temperature-dependent mortality of HepG2 cells exposed to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy; 1.3 mM), methamphetamine (3 mM), 4-methylthioamphetamine (0.5 mM) and D-amphetamine (1.7 mM), alone or combined (1.6 mM mixture). At physiological temperature (37 °C), 24-h exposures caused HepG2 death preferentially by apoptosis, while a rise to 40.5 °C favoured necrosis. ATP levels remained unaltered when the drugs where tested at normothermia, but incubation at 40.5 °C provoked marked ATP depletion for all treatments. Further investigations on the apoptotic mechanisms triggered by the drugs (alone or combined) showed a decline in BCL-2 and BCL- XL mRNA levels, with concurrent upregulation of BAX, BIM, PUMA and BID genes. Elevation of Bax, cleaved Bid, Puma, Bak and Bim protein levels was also seen. To the best of our knowledge, Puma, Bim and Bak have never been linked with the toxicity induced by amphetamines. Time-dependent caspase-3/-7 activation, but not mitochondrial membrane potential (∆ψm) disruption, also mediated amphetamine-induced apoptosis. The cell dismantling was confirmed by poly(ADP-ribose)polymerase proteolysis. Overall, for all evaluated parameters, no relevant differences were detected between individual amphetamines and the mixture (all tested at equieffective cytotoxic concentrations), suggesting that the mode of action of the amphetamines in combination does not deviate from the mode of action of the drugs individually, when eliciting HepG2 cell death.

Roles of the distinct electronic structures of the {Fe(NO)(2)}(9) and {Fe(NO)(2)}(10) dinitrosyliron complexes in modulating nitrite binding modes and nitrite activation pathways.

PubMed

Tsai, Fu-Te; Chen, Pei-Lin; Liaw, Wen-Feng

2010-04-14

Nitrosylation of [PPN](2)[(ONO)(2)Fe(eta(2)-ONO)(2)] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}(7) mononitrosyliron complex (MNIC) [PPN](2)[(NO)Fe(ONO)(3)(eta(2)-ONO)] (2). At 4 K, complex 2 exhibits an S = (3)/(2) axial EPR spectrum with principal g values of g( perpendicular) = 3.971 and g( parallel) = 2.000, suggestive of the {Fe(III)(NO(-))}(7) electronic structure. Addition of 1 equiv of PPh(3) to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)(2)}(9) dinitrosyliron complex (DNIC) [PPN][(ONO)(2)Fe(NO)(2)] (3). These results demonstrate that both electronic structure [{Fe(III)(NO(-))}(7), S = (3)/(2)] and redox-active ligands ([RS](-) for [(RS)(3)Fe(NO)](-) and [NO(-)] for complex 2) are required for the transformation of {Fe(NO)}(7) MNICs into {Fe(NO)(2)}(9) DNICs. In comparison with the PPh(3)-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)(2)}(9) DNIC [(1-MeIm)(2)(eta(2)-ONO)Fe(NO)(2)] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)(2)}(10) DNIC [(1-MeIm)(PPh(3))Fe(NO)(2)] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)(2)}(10) DNIC [PPN][(eta(1)-NO(2))(PPh(3))Fe(NO)(2)] (7) produced the {Fe(NO)(2)}(9) DNIC [PPN][(OAc)(2)Fe(NO)(2)] (8), nitric oxide, and H(2)O. These results demonstrate that the distinct electronic structures of {Fe(NO)(2)}(9/10) motifs [{Fe(NO)(2)}(9) vs {Fe(NO)(2)}(10)] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)(2)}(9) DNICs vs N-bound nitro as a pi acceptor for {Fe(NO)(2)}(10) DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh(3) leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)(2)}(9) and {Fe(NO)(2)}(10) DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide.

The slowly reacting mode of combustion of gaseous mixtures in spherical vessels. Part 1: Transient analysis and explosion limits

NASA Astrophysics Data System (ADS)

Liñán, Amable; Moreno-Boza, Daniel; Iglesias, Immaculada; Sánchez, Antonio L.; Williams, Forman A.

2016-11-01

Frank-Kamenetskii's analysis of thermal explosions is revisited, using also a single-reaction model with an Arrhenius rate having a large activation energy, to describe the transient combustion of initially cold gaseous mixtures enclosed in a spherical vessel with a constant wall temperature. The analysis shows two modes of combustion. There is a flameless slowly reacting mode for low wall temperatures or small vessel sizes, when the temperature rise resulting from the heat released by the reaction is kept small by the heat-conduction losses to the wall, so as not to change significantly the order of magnitude of the reaction rate. In the other mode, the slow reaction rates occur only in an initial ignition stage, which ends abruptly when very large reaction rates cause a temperature runaway, or thermal explosion, at a well-defined ignition time and location, thereby triggering a flame that propagates across the vessel to consume the reactant rapidly. Explosion limits are defined, in agreement with Frank-Kamenetskii's analysis, by the limiting conditions for existence of the slowly reacting mode of combustion. In this mode, a quasi-steady temperature distribution is established after a transient reaction stage with small reactant consumption. Most of the reactant is burnt, with nearly uniform mass fraction, in a subsequent long stage during which the temperature follows a quasi-steady balance between the rates of heat conduction to the wall and of chemical heat release. The changes in the explosion limits caused by the enhanced heat-transfer rates associated with buoyant motion are described in an accompanying paper.

Tip Effect of the Tapping Mode of Atomic Force Microscope in Viscous Fluid Environments.

PubMed

Shih, Hua-Ju; Shih, Po-Jen

2015-07-28

Atomic force microscope with applicable types of operation in a liquid environment is widely used to scan the contours of biological specimens. The contact mode of operation allows a tip to touch a specimen directly but sometimes it damages the specimen; thus, a tapping mode of operation may replace the contact mode. The tapping mode triggers the cantilever of the microscope approximately at resonance frequencies, and so the tip periodically knocks the specimen. It is well known that the cantilever induces extra liquid pressure that leads to drift in the resonance frequency. Studies have noted that the heights of protein surfaces measured via the tapping mode of an atomic force microscope are ~25% smaller than those measured by other methods. This discrepancy may be attributable to the induced superficial hydrodynamic pressure, which is worth investigating. In this paper, we introduce a semi-analytical method to analyze the pressure distribution of various tip geometries. According to our analysis, the maximum hydrodynamic pressure on the specimen caused by a cone-shaped tip is ~0.5 Pa, which can, for example, pre-deform a cell by several nanometers in compression before the tip taps it. Moreover, the pressure calculated on the surface of the specimen is 20 times larger than the pressure without considering the tip effect; these results have not been motioned in other papers. Dominating factors, such as surface heights of protein surface, mechanical stiffness of protein increasing with loading velocity, and radius of tip affecting the local pressure of specimen, are also addressed in this study.

Inhibiting ethylene perception with 1-methylcyclopropene triggers molecular responses aimed to cope with cell toxicity and increased respiration in citrus fruits.

PubMed

Establés-Ortiz, Beatriz; Romero, Paco; Ballester, Ana-Rosa; González-Candelas, Luis; Lafuente, María T

2016-06-01

The ethylene perception inhibitor 1-methylcyclopropene (1-MCP) has been critical in understanding the hormone's mode of action. However, 1-MCP may trigger other processes that could vary the interpretation of results related until now to ethylene, which we aim to understand by using transcriptomic analysis. Transcriptomic changes in ethylene and 1-MCP-treated 'Navelate' (Citrus sinensis L. Osbeck) oranges were studied in parallel with changes in ethylene production, respiration and peel damage. The effects of compounds modifying the levels of the ethylene co-product cyanide and nitric oxide (NO) on fruit physiology were also studied. Results suggested that: 1) The ethylene treatment caused sub-lethal stress since it induced stress-related responses and reduced peel damage; 2) 1-MCP induced ethylene-dependent and ethylene-independent responsive networks; 3) 1-MCP triggered ethylene overproduction, stress-related responses and metabolic shifts aimed to cope with cell toxicity, which mostly affected to the inner part of the peel (albedo); 4) 1-MCP increased respiration and drove metabolism reconfiguration for favoring energy conservation but up-regulated genes related to lipid and protein degradation and triggered the over-expression of genes associated with the plasma membrane cellular component; 5) Xenobiotics and/or reactive oxygen species (ROS) might act as signals for defense responses in the ethylene-treated fruit, while their uncontrolled generation would induce processes mimicking cell death and damage in 1-MCP-treated fruit; 6) ROS, the ethylene co-product cyanide and NO may converge in the toxic effects of 1-MCP. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Failure Analysis of Alumina Reinforced Aluminum Microtruss and Tube Composites

NASA Astrophysics Data System (ADS)

Chien, Hsueh Fen (Karen)

The energy absorption capacity of cellular materials can be dramatically increased by applying a structural coating. This thesis examined the failure mechanisms of alumina reinforced 3003 aluminum alloy microtrusses and tubes. Alumina coatings were produced by hard anodizing and by plasma electrolytic oxidation (PEO). The relatively thin and discontinuous oxide coating at the hinge acted as a localized weak spot which triggered a chain reaction of failure, including oxide fracture, oxide spallation, oxide penetration to the aluminum core and severe local plastic deformation of the core. For the PEO microtrusses, delamination occurred within the oxide coating resulting in a global strut buckling failure mode. A new failure mode for the anodized tubes was observed: (i) axisymmetric folding of the aluminum core, (ii) longitudinal fracture, and (iii) alumina pulverization. Overall, the alumina coating enhanced the buckling resistance of the composites, while the aluminum core supported the oxide during the damage propagation.

First results with charmless two-body B-decays at LHCb, and future prospects

ScienceCinema

Vagnoni, Vincenzo

2018-04-27

LHCb is an experiment which is designed to perform flavour physics measurements at the LHC. Charged two-body charmless B decays (e.g. B^0 -> Kpi, pipi, B_s->KK, etc) receive significant contributions from loop diagrams and are thus sensitive probes of New Physics. Study of these modes is therefore an important physics goal of LHCb. First results will be presented, using around 37 pb^{-1} of data collected at \\sqrt{s}=7 TeV in 2010. These results illustrate the power of the LHCb trigger system and particle identification capabilities of the RICH detectors in isolating clean samples of each final state, and include preliminary measurements of direct CP-violation in certain key modes. The prospects for these measurements in the coming run will be presented. A brief survey will also be given of results and prospect in other areas of the LHCb physics programme.

Stellar flare oscillations: evidence for oscillatory reconnection and evolution of MHD modes

NASA Astrophysics Data System (ADS)

Doyle, J. G.; Shetye, J.; Antonova, A. E.; Kolotkov, D. Y.; Srivastava, A. K.; Stangalini, M.; Gupta, G. R.; Avramova, A.; Mathioudakis, M.

2018-04-01

Here, we report on the detection of a range of quasi-periodic pulsations (20-120 s; QPPs) observed during flaring activity of several magnetically active dMe stars, namely AF Psc, CR Dra, GJ 3685A, Gl 65, SDSS J084425.9+513830, and SDSS J144738.47+035312.1 in the GALEX NUV filter. Based on a solar analogy, this work suggests that many of these flares may be triggered by external drivers creating a periodic reconnection in the flare current sheet or an impulsive energy release giving rise to an avalanche of periodic bursts that occur at time intervals that correspond to the detected periods, thus generating QPPs in their rising and peak phases. Some of these flares also show fast QPPs in their decay phase, indicating the presence of fast sausage mode oscillations either driven externally by periodic reconnection or intrinsically in the post-flare loop system during the flare energy release.

Triggered generation of single guided photons from a single atom in a nanofiber cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Kien, Fam; Hakuta, K.

2011-04-15

We study the deterministic generation of single guided-mode photons from an atom in the vicinity of a nanofiber with two fiber-Bragg-grating (FBG) mirrors. The technique is based on a cavity-enhanced Raman scattering process involving an adiabatic passage. We take into account the scattering of the pump field from the fiber, the multilevel structure of the atom, and the surface-induced van der Waals potential in describing the photon generation process. We find that, due to the confinement of the cavity field in the transverse plane of the fiber and in the space between the FBG mirrors, the probability of the generationmore » of a single guided-mode photon can be close to unity even when the finesse of the nanofiber cavity is moderate. We show the possibilities of saturation and power broadening in the behavior of the number of photons emitted into the nanofiber.« less

Fast, temperature-sensitive and clathrin-independent endocytosis at central synapses

PubMed Central

Delvendahl, Igor; Vyleta, Nicholas P.; von Gersdorff, Henrique; Hallermann, Stefan

2016-01-01

The fusion of neurotransmitter-filled vesicles during synaptic transmission is balanced by endocytotic membrane retrieval. Despite extensive research, the speed and mechanisms of synaptic vesicle endocytosis have remained controversial. Here, we establish low-noise time-resolved membrane capacitance measurements that allow monitoring changes in surface membrane area elicited by single action potentials and stronger stimuli with high-temporal resolution at physiological temperature in individual bonafide mature central synapses. We show that single action potentials trigger very rapid endocytosis, retrieving presynaptic membrane with a time constant of 470 ms. This fast endocytosis is independent of clathrin, but mediated by dynamin and actin. In contrast, stronger stimuli evoke a slower mode of endocytosis that is clathrin-, dynamin-, and actin-dependent. Furthermore, the speed of endocytosis is highly temperature-dependent with a Q10 of ~3.5. These results demonstrate that distinct molecular modes of endocytosis with markedly different kinetics operate at central synapses. PMID:27146271

Investigating the Pressure-Induced Amorphization of Zeolitic Imidazolate Framework ZIF-8: Mechanical Instability Due to Shear Mode Softening.

PubMed

Ortiz, Aurélie U; Boutin, Anne; Fuchs, Alain H; Coudert, François-Xavier

2013-06-06

We provide the first molecular dynamics study of the mechanical instability that is the cause of pressure-induced amorphization of zeolitic imidazolate framework ZIF-8. By measuring the elastic constants of ZIF-8 up to the amorphization pressure, we show that the crystal-to-amorphous transition is triggered by the mechanical instability of ZIF-8 under compression, due to shear mode softening of the material. No similar softening was observed under temperature increase, explaining the absence of temperature-induced amorphization in ZIF-8. We also demonstrate the large impact of the presence of adsorbate in the pores on the mechanical stability and compressibility of the framework, increasing its shear stability. This first molecular dynamics study of ZIF mechanical properties under variations of pressure, temperature, and pore filling opens the way to a more comprehensive understanding of their mechanical stability, structural transitions, and amorphization.

Contact Freezing of Water by Salts.

PubMed

Niehaus, Joseph; Cantrell, Will

2015-09-03

Water is unlikely to crystallize homogeneously at temperatures greater than -34 °C. Freezing at higher temperatures is heterogeneous-catalyzed by the presence of a second substance. If that substance is at an air-water interface, then the mode is called contact freezing, and it typically will trigger nucleation at a higher temperature than if the substance were wholly immersed within the liquid. We find that the impact of salt particles initiates freezing in experiments using water droplets at supercoolings of 9 to 16 °C. These results show that contact freezing nuclei need not be effective as immersion mode nuclei. We discuss our results in the context of proposed mechanisms of contact freezing. Finally, we use the time scales for diffusion of heat and of ions and the propagation of a sound wave through the droplet to estimate that contact freezing occurs within 10 ns of impact.

Do faults trigger folding in the lithosphere?

NASA Astrophysics Data System (ADS)

Gerbault, Muriel; Burov, Eugenii B.; Poliakov, Alexei N. B.; Daignières, Marc

A number of observations reveal large periodic undulations within the oceanic and continental lithospheres. The question if these observations are the result of large-scale compressive instabilities, i.e. buckling, remains open. In this study, we support the buckling hypothesis by direct numerical modeling. We compare our results with the data on three most proeminent cases of the oceanic and continental folding-like deformation (Indian Ocean, Western Gobi (Central Asia) and Central Australia). We demonstrate that under reasonable tectonic stresses, folds can develop from brittle faults cutting through the brittle parts of a lithosphere. The predicted wavelengths and finite growth rates are in agreement with observations. We also show that within a continental lithosphere with thermal age greater than 400 My, either a bi-harmonic mode (two superimposed wavelengths, crustal and mantle one) or a coupled mode (mono-layer deformation) of inelastic folding can develop, depending on the strength and thickness of the lower crust.

Understanding the connection between conformational changes of peptides and equilibrium thermal fluctuations.

PubMed

Soler, Miguel A; Zúñiga, José; Requena, Alberto; Bastida, Adolfo

2017-02-01

Despite the increasing evidence that conformational transitions in peptides and proteins are driven by specific vibrational energy pathways along the molecule, the current experimental techniques of analysis do as yet not allow to study these biophysical processes in terms of anisotropic energy flows. Computational methods offer a complementary approach to obtain a more detailed understanding of the vibrational and conformational dynamics of these systems. Accordingly, in this work we investigate jointly the vibrational energy distribution and the conformational dynamics of trialanine peptide in water solution at room temperature by applying the Instantaneous Normal Mode analysis to the results derived from equilibrium molecular dynamics simulations. It is shown that conformational changes in trialanine are triggered by the vibrational energy accumulated in the low-frequency modes of the molecule, and that excitation is caused exclusively by thermal fluctuations of the solute-solvent system, thus excluding the possibility of an intramolecular vibrational energy redistribution process.

Warning signals for eruptive events in spreading fires

PubMed Central

Fox, Jerome M.; Whitesides, George M.

2015-01-01

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires propagate. Such transitions are rarely captured by predictive models of fire behavior and, thus, complicate efforts in fire suppression. This paper describes a simple, remarkably instructive physical model for examining the eruption of small flames into intense, rapidly moving flames stabilized by feedback between wind and fire (i.e., “wind–fire coupling”—a mechanism of feedback particularly relevant to forest fires), and it presents evidence that characteristic patterns in the dynamics of spreading flames indicate when such transitions are likely to occur. In this model system, flames propagate along strips of nitrocellulose with one of two possible modes of propagation: a slow, structured mode, and a fast, unstructured mode sustained by wind–fire coupling. Experimental examination of patterns in dynamics that emerge near bifurcation points suggests that symptoms of critical slowing down (i.e., the slowed recovery of the system from perturbations as it approaches tipping points) warn of impending transitions to the unstructured mode. Findings suggest that slowing responses of spreading flames to sudden changes in environment (e.g., wind, terrain, temperature) may anticipate the onset of intense, feedback-stabilized modes of propagation (e.g., “blowup fires” in forests). PMID:25675491

Dynamic origin of segment magnetization reversal in thin-film Penrose tilings

NASA Astrophysics Data System (ADS)

Montoncello, F.; Giovannini, L.; Farmer, B.; De Long, L.

2017-02-01

We investigate the low-frequency spin wave dynamics involved in the magnetization reversal of a Penrose P2 tiling using the dynamical matrix method. This system consists of a two-dimensional, connected wire network of elongated thin-film segments, whose complete reversal occurs as a cascade of successive local segment reversals. Using soft mode theory, we interpret the reversal of an individual segment as a first order magnetic transition, in which magnetization curve of the system suffers a small discontinuity. Near this discontinuity a specific mode of the spin wave spectrum goes soft (i.e., its frequency goes to zero), triggering a local instability of the magnetization. We show that this mode is localized, and is at the origin of the local reversal. We discuss the correlation of the mode spatial profile with the ;reversal mechanism;, which is the passage of a domain wall through the segment. This process differs from reversal in periodic square or honeycomb artificial spin ices, where a cascade of reversing segments (e.g., ;Dirac string;) follows an extended (though irregular) path across the sample; here the spatial distribution of successive segment reversals is discontinuous, but strictly associated with the area where a soft mode is localized. The migration of the localization area across the P2 tiling (during reversal in decreasing applied fields) depends on changes in the internal effective field map. We discuss these results in the context of spin wave localization due to the unique topology of the P2 tiling.

Warning signals for eruptive events in spreading fires.

PubMed

Fox, Jerome M; Whitesides, George M

2015-02-24

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires propagate. Such transitions are rarely captured by predictive models of fire behavior and, thus, complicate efforts in fire suppression. This paper describes a simple, remarkably instructive physical model for examining the eruption of small flames into intense, rapidly moving flames stabilized by feedback between wind and fire (i.e., "wind-fire coupling"-a mechanism of feedback particularly relevant to forest fires), and it presents evidence that characteristic patterns in the dynamics of spreading flames indicate when such transitions are likely to occur. In this model system, flames propagate along strips of nitrocellulose with one of two possible modes of propagation: a slow, structured mode, and a fast, unstructured mode sustained by wind-fire coupling. Experimental examination of patterns in dynamics that emerge near bifurcation points suggests that symptoms of critical slowing down (i.e., the slowed recovery of the system from perturbations as it approaches tipping points) warn of impending transitions to the unstructured mode. Findings suggest that slowing responses of spreading flames to sudden changes in environment (e.g., wind, terrain, temperature) may anticipate the onset of intense, feedback-stabilized modes of propagation (e.g., "blowup fires" in forests).

Warning signals for eruptive events in spreading fires

DOE PAGES

Fox, Jerome M.; Whitesides, George M.

2015-02-09

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires propagate. Such transitions are rarely captured by predictive models of fire behavior and, thus, complicate efforts in fire suppression. This study describes a simple, remarkably instructive physical model for examining the eruption of small flames into intense, rapidly moving flames stabilized by feedback between wind and fire (i.e., “wind–firemore » coupling”—a mechanism of feedback particularly relevant to forest fires), and it presents evidence that characteristic patterns in the dynamics of spreading flames indicate when such transitions are likely to occur. Here, in this model system, flames propagate along strips of nitrocellulose with one of two possible modes of propagation: a slow, structured mode, and a fast, unstructured mode sustained by wind–fire coupling. Experimental examination of patterns in dynamics that emerge near bifurcation points suggests that symptoms of critical slowing down (i.e., the slowed recovery of the system from perturbations as it approaches tipping points) warn of impending transitions to the unstructured mode. Lastly, findings suggest that slowing responses of spreading flames to sudden changes in environment (e.g., wind, terrain, temperature) may anticipate the onset of intense, feedback-stabilized modes of propagation (e.g., “blowup fires” in forests).« less

Warning signals for eruptive events in spreading fires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, Jerome M.; Whitesides, George M.

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires propagate. Such transitions are rarely captured by predictive models of fire behavior and, thus, complicate efforts in fire suppression. This study describes a simple, remarkably instructive physical model for examining the eruption of small flames into intense, rapidly moving flames stabilized by feedback between wind and fire (i.e., “wind–firemore » coupling”—a mechanism of feedback particularly relevant to forest fires), and it presents evidence that characteristic patterns in the dynamics of spreading flames indicate when such transitions are likely to occur. Here, in this model system, flames propagate along strips of nitrocellulose with one of two possible modes of propagation: a slow, structured mode, and a fast, unstructured mode sustained by wind–fire coupling. Experimental examination of patterns in dynamics that emerge near bifurcation points suggests that symptoms of critical slowing down (i.e., the slowed recovery of the system from perturbations as it approaches tipping points) warn of impending transitions to the unstructured mode. Lastly, findings suggest that slowing responses of spreading flames to sudden changes in environment (e.g., wind, terrain, temperature) may anticipate the onset of intense, feedback-stabilized modes of propagation (e.g., “blowup fires” in forests).« less

Neurotransmitter-Triggered Transfer of Exosomes Mediates Oligodendrocyte–Neuron Communication

PubMed Central

Kuo, Wen Ping; Amphornrat, Jesa; Thilemann, Sebastian; Saab, Aiman S.; Kirchhoff, Frank; Möbius, Wiebke; Goebbels, Sandra; Nave, Klaus-Armin; Schneider, Anja; Simons, Mikael; Klugmann, Matthias; Trotter, Jacqueline; Krämer-Albers, Eva-Maria

2013-01-01

Reciprocal interactions between neurons and oligodendrocytes are not only crucial for myelination, but also for long-term survival of axons. Degeneration of axons occurs in several human myelin diseases, however the molecular mechanisms of axon-glia communication maintaining axon integrity are poorly understood. Here, we describe the signal-mediated transfer of exosomes from oligodendrocytes to neurons. These endosome-derived vesicles are secreted by oligodendrocytes and carry specific protein and RNA cargo. We show that activity-dependent release of the neurotransmitter glutamate triggers oligodendroglial exosome secretion mediated by Ca2+ entry through oligodendroglial NMDA and AMPA receptors. In turn, neurons internalize the released exosomes by endocytosis. Injection of oligodendroglia-derived exosomes into the mouse brain results in functional retrieval of exosome cargo in neurons. Supply of cultured neurons with oligodendroglial exosomes improves neuronal viability under conditions of cell stress. These findings indicate that oligodendroglial exosomes participate in a novel mode of bidirectional neuron-glia communication contributing to neuronal integrity. PMID:23874151

Neurotransmitter-triggered transfer of exosomes mediates oligodendrocyte-neuron communication.

PubMed

Frühbeis, Carsten; Fröhlich, Dominik; Kuo, Wen Ping; Amphornrat, Jesa; Thilemann, Sebastian; Saab, Aiman S; Kirchhoff, Frank; Möbius, Wiebke; Goebbels, Sandra; Nave, Klaus-Armin; Schneider, Anja; Simons, Mikael; Klugmann, Matthias; Trotter, Jacqueline; Krämer-Albers, Eva-Maria

2013-07-01

Reciprocal interactions between neurons and oligodendrocytes are not only crucial for myelination, but also for long-term survival of axons. Degeneration of axons occurs in several human myelin diseases, however the molecular mechanisms of axon-glia communication maintaining axon integrity are poorly understood. Here, we describe the signal-mediated transfer of exosomes from oligodendrocytes to neurons. These endosome-derived vesicles are secreted by oligodendrocytes and carry specific protein and RNA cargo. We show that activity-dependent release of the neurotransmitter glutamate triggers oligodendroglial exosome secretion mediated by Ca²⁺ entry through oligodendroglial NMDA and AMPA receptors. In turn, neurons internalize the released exosomes by endocytosis. Injection of oligodendroglia-derived exosomes into the mouse brain results in functional retrieval of exosome cargo in neurons. Supply of cultured neurons with oligodendroglial exosomes improves neuronal viability under conditions of cell stress. These findings indicate that oligodendroglial exosomes participate in a novel mode of bidirectional neuron-glia communication contributing to neuronal integrity.

Analysis of operational methane emissions from pressure relief valves from biogas storages of biogas plants.

PubMed

Reinelt, Torsten; Liebetrau, Jan; Nelles, Michael

2016-10-01

The study presents the development of a method for the long term monitoring of methane emissions from pressure relief valves (PRV(1)) of biogas storages, which has been verified during test series at two PRVs of two agricultural biogas plants located in Germany. The determined methane emission factors are 0.12gCH4kWhel(-1) (0.06% CH4-loss, within 106days, 161 triggering events, winter season) from biogas plant A and 6.80/7.44gCH4kWhel(-1) (3.60/3.88% CH4-loss, within 66days, 452 triggering events, summer season) from biogas plant B. Besides the operational state of the biogas plant (e.g. malfunction of the combined heat and power unit), the mode of operation of the biogas flare, which can be manually or automatically operated as well as the atmospheric conditions (e.g. drop of the atmospheric pressure) can also affect the biogas emission from PRVs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simultaneous reconstruction of 3D refractive index, temperature, and intensity distribution of combustion flame by double computed tomography technologies based on spatial phase-shifting method

NASA Astrophysics Data System (ADS)

Guo, Zhenyan; Song, Yang; Yuan, Qun; Wulan, Tuya; Chen, Lei

2017-06-01

In this paper, a transient multi-parameter three-dimensional (3D) reconstruction method is proposed to diagnose and visualize a combustion flow field. Emission and transmission tomography based on spatial phase-shifted technology are combined to reconstruct, simultaneously, the various physical parameter distributions of a propane flame. Two cameras triggered by the internal trigger mode capture the projection information of the emission and moiré tomography, respectively. A two-step spatial phase-shifting method is applied to extract the phase distribution in the moiré fringes. By using the filtered back-projection algorithm, we reconstruct the 3D refractive-index distribution of the combustion flow field. Finally, the 3D temperature distribution of the flame is obtained from the refractive index distribution using the Gladstone-Dale equation. Meanwhile, the 3D intensity distribution is reconstructed based on the radiation projections from the emission tomography. Therefore, the structure and edge information of the propane flame are well visualized.

The LHCb Run Control

NASA Astrophysics Data System (ADS)

Alessio, F.; Barandela, M. C.; Callot, O.; Duval, P.-Y.; Franek, B.; Frank, M.; Galli, D.; Gaspar, C.; Herwijnen, E. v.; Jacobsson, R.; Jost, B.; Neufeld, N.; Sambade, A.; Schwemmer, R.; Somogyi, P.

2010-04-01

LHCb has designed and implemented an integrated Experiment Control System. The Control System uses the same concepts and the same tools to control and monitor all parts of the experiment: the Data Acquisition System, the Timing and the Trigger Systems, the High Level Trigger Farm, the Detector Control System, the Experiment's Infrastructure and the interaction with the CERN Technical Services and the Accelerator. LHCb's Run Control, the main interface used by the experiment's operator, provides access in a hierarchical, coherent and homogeneous manner to all areas of the experiment and to all its sub-detectors. It allows for automated (or manual) configuration and control, including error recovery, of the full experiment in its different running modes. Different instances of the same Run Control interface are used by the various sub-detectors for their stand-alone activities: test runs, calibration runs, etc. The architecture and the tools used to build the control system, the guidelines and components provided to the developers, as well as the first experience with the usage of the Run Control will be presented

ELM Triggering with the New PPPL Lithium Granular Injector

NASA Astrophysics Data System (ADS)

Mansfield, D. K.; Roquemore, A. L.; Maingi, R.; Hu, J. S.; Liang, Y.; Sun, Z.; Zhang, L.; Zou, G.

2012-10-01

A Li granular injector based on a high-speed rotating impeller has been developed at PPPL. The injector is capable of injecting spherical particles with diameters up to 1.3 mm and velocities of up to 100 m/s and has several possible applications. Primarily, the injector was developed as a tool to induce ELMs for ELM pacing experiments in plasmas operating in the H-mode. It can also operate as a real-time wall conditioning tool or as a method to resupply Li during a discharge to devices where Li is applied to the PFC's prior to a discharge. The injector is also capable of horizontally injecting small dust particles of any variety for plasma-dust transport studies. The first injector has recently been successfully installed on the EAST tokamak in Hefei, China where ELMs were induced with near 100% efficiency when 0.7mm spheres were injected at ˜ 40m/s into the midplane SOL. The injector will be described and supporting data for ELM triggering will be presented.

Distributed solid state programmable thermostat/power controller

NASA Technical Reports Server (NTRS)

Smith, Dennis A. (Inventor); Alexander, Jane C. (Inventor); Howard, David E. (Inventor)

2008-01-01

A self-contained power controller having a power driver switch, programmable controller, communication port, and environmental parameter measuring device coupled to a controllable device. The self-contained power controller needs only a single voltage source to power discrete devices, analog devices, and the controlled device. The programmable controller has a run mode which, when selected, upon the occurrence of a trigger event changes the state of a power driver switch and wherein the power driver switch is maintained by the programmable controller at the same state until the occurrence of a second event.

Operation and performance of the LHCb calorimeters

NASA Astrophysics Data System (ADS)

Chefdeville, M.

2018-03-01

The LHCb calorimeters play a key role in the hardware trigger of the experiment. They also serve the measurement of radiative heavy flavor decays and the identification of electrons. Located at twelve meters from the interaction region, they are composed of a plane of scintillating tiles, a preshower detector, an electromagnetic and a hadronic sampling calorimeters using scintillators as active elements. In these proceedings, technical and operational aspects of these detectors are described. Emphasis is then put on calorimeter reconstruction and calibration. Finally, performance for benchmark physics modes are briefly reported.

Virtual environment navigation with look-around mode to explore new real spaces by people who are blind.

PubMed

Lahav, Orly; Gedalevitz, Hadas; Battersby, Steven; Brown, David; Evett, Lindsay; Merritt, Patrick

2018-05-01

This paper examines the ability of people who are blind to construct a mental map and perform orientation tasks in real space by using Nintendo Wii technologies to explore virtual environments. The participant explores new spaces through haptic and auditory feedback triggered by pointing or walking in the virtual environments and later constructs a mental map, which can be used to navigate in real space. The study included 10 participants who were congenitally or adventitiously blind, divided into experimental and control groups. The research was implemented by using virtual environments exploration and orientation tasks in real spaces, using both qualitative and quantitative methods in its methodology. The results show that the mode of exploration afforded to the experimental group is radically new in orientation and mobility training; as a result 60% of the experimental participants constructed mental maps that were based on map model, compared with only 30% of the control group participants. Using technology that enabled them to explore and to collect spatial information in a way that does not exist in real space influenced the ability of the experimental group to construct a mental map based on the map model. Implications for rehabilitation The virtual cane system for the first time enables people who are blind to explore and collect spatial information via the look-around mode in addition to the walk-around mode. People who are blind prefer to use look-around mode to explore new spaces, as opposed to the walking mode. Although the look-around mode requires users to establish a complex collecting and processing procedure for the spatial data, people who are blind using this mode are able to construct a mental map as a map model. For people who are blind (as for the sighted) construction of a mental map based on map model offers more flexibility in choosing a walking path in a real space, accounting for changes that occur in the space.

128-slice Dual-source Computed Tomography Coronary Angiography in Patients with Atrial Fibrillation: Image Quality and Radiation Dose of Prospectively Electrocardiogram-triggered Sequential Scan Compared with Retrospectively Electrocardiogram-gated Spiral Scan.

PubMed

Lin, Lu; Wang, Yi-Ning; Kong, Ling-Yan; Jin, Zheng-Yu; Lu, Guang-Ming; Zhang, Zhao-Qi; Cao, Jian; Li, Shuo; Song, Lan; Wang, Zhi-Wei; Zhou, Kang; Wang, Ming

2013-01-01

Objective To evaluate the image quality (IQ) and radiation dose of 128-slice dual-source computed tomography (DSCT) coronary angiography using prospectively electrocardiogram (ECG)-triggered sequential scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrillation referred for a second-generation 128-slice DSCT coronary angiography were included in the prospective study. Of them, 17 patients (sequential group) were randomly selected to use a prospectively ECG-triggered sequential scan, while the other 15 patients (spiral group) used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel-lent (grade 1) to non-assessable (grade 4), based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each patient were compared between the two groups. Results The mean heart rate (HR) of the sequential group was 96±27 beats per minute (bpm) with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean HR (t=1.91, P=0.243) and HR variation range (t=0.950, P=0.350) had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent (grade 1) in 190/244 (78%) vs. 177/217 (82%) by reader1 and 197/245 (80%) vs. 174/214 (81%) by reader2, as non-assessable (grade 4) in 4/244 (2%) vs. 2/217 (1%) by reader1 and 6/245 (2%) vs. 4/214 (2%) by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good (1.27±0.19 vs. 1.25±0.22, Z=-0.834, P=0.404). The effective radiation dose of the sequential group reduced significantly compared with the spiral group (4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000). Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.

On Three-dimensional Structures in Relativistic Hydrodynamic Jets

NASA Astrophysics Data System (ADS)

Hardee, Philip E.

2000-04-01

The appearance of wavelike helical structures on steady relativistic jets is studied using a normal mode analysis of the linearized fluid equations. Helical structures produced by the normal modes scale relative to the resonant (most unstable) wavelength and not with the absolute wavelength. The resonant wavelength of the normal modes can be less than the jet radius even on highly relativistic jets. High-pressure regions helically twisted around the jet beam may be confined close to the jet surface, penetrate deeply into the jet interior, or be confined to the jet interior. The high-pressure regions range from thin and ribbon-like to thick and tubelike depending on the mode and wavelength. The wave speeds can be significantly different at different wavelengths but are less than the flow speed. The highest wave speed for the jets studied has a Lorentz factor somewhat more than half that of the underlying flow speed. A maximum pressure fluctuation criterion found through comparison between theory and a set of relativistic axisymmetric jet simulations is applied to estimate the maximum amplitudes of the helical, elliptical, and triangular normal modes. Transverse velocity fluctuations for these asymmetric modes are up to twice the amplitude of those associated with the axisymmetric pinch mode. The maximum amplitude of jet distortions and the accompanying velocity fluctuations at, for example, the resonant wavelength decreases as the Lorentz factor increases. Long-wavelength helical surface mode and shorter wavelength helical first body mode generated structures should be the most significant. Emission from high-pressure regions as they twist around the jet beam can vary significantly as a result of angular variation in the flow direction associated with normal mode structures if they are viewed at about the beaming angle θ=1/γ. Variation in the Doppler boost factor can lead to brightness asymmetries by factors up to 6 as long-wavelength helical structure produced by the helical surface mode winds around the jet. Higher order surface modes and first body modes produce less variation. Angular variation in the flow direction associated with the helical mode appears consistent with precessing jet models that have been proposed to explain the variability in 3C 273 and BL Lac object AO 0235+164. In particular, cyclic angular variation in the flow direction produced by the normal modes could produce the activity seen in BL Lac object OJ 287. Jet precession provides a mechanism for triggering the helical modes on multiple length scales, e.g., the galactic superluminal GRO J1655-40.

Power requirements for electron cyclotron current drive and ion cyclotron resonance heating for sawtooth control in ITER

NASA Astrophysics Data System (ADS)

Chapman, I. T.; Graves, J. P.; Sauter, O.; Zucca, C.; Asunta, O.; Buttery, R. J.; Coda, S.; Goodman, T.; Igochine, V.; Johnson, T.; Jucker, M.; La Haye, R. J.; Lennholm, M.; Contributors, JET-EFDA

2013-06-01

13 MW of electron cyclotron current drive (ECCD) power deposited inside the q = 1 surface is likely to reduce the sawtooth period in ITER baseline scenario below the level empirically predicted to trigger neoclassical tearing modes (NTMs). However, since the ECCD control scheme is solely predicated upon changing the local magnetic shear, it is prudent to plan to use a complementary scheme which directly decreases the potential energy of the kink mode in order to reduce the sawtooth period. In the event that the natural sawtooth period is longer than expected, due to enhanced α particle stabilization for instance, this ancillary sawtooth control can be provided from >10MW of ion cyclotron resonance heating (ICRH) power with a resonance just inside the q = 1 surface. Both ECCD and ICRH control schemes would benefit greatly from active feedback of the deposition with respect to the rational surface. If the q = 1 surface can be maintained closer to the magnetic axis, the efficacy of ECCD and ICRH schemes significantly increases, the negative effect on the fusion gain is reduced, and off-axis negative-ion neutral beam injection (NNBI) can also be considered for sawtooth control. Consequently, schemes to reduce the q = 1 radius are highly desirable, such as early heating to delay the current penetration and, of course, active sawtooth destabilization to mediate small frequent sawteeth and retain a small q = 1 radius. Finally, there remains a residual risk that the ECCD + ICRH control actuators cannot keep the sawtooth period below the threshold for triggering NTMs (since this is derived only from empirical scaling and the control modelling has numerous caveats). If this is the case, a secondary control scheme of sawtooth stabilization via ECCD + ICRH + NNBI, interspersed with deliberate triggering of a crash through auxiliary power reduction and simultaneous pre-emptive NTM control by off-axis ECCD has been considered, permitting long transient periods with high fusion gain. The power requirements for the necessary degree of sawtooth control using either destabilization or stabilization schemes are expected to be within the specification of anticipated ICRH and ECRH heating in ITER, provided the requisite power can be dedicated to sawtooth control.

Southern Hemisphere origins for interannual variations of Tibetan Plateau snow cover in boreal summer

NASA Astrophysics Data System (ADS)

Wu, Z.

2017-12-01

The climate response to the Tibetan Plateau (TP) snow cover (TPSC) has been receiving extensive concern. However, relatively few studies have devoted to revealing the potential factors that can contribute to the TPSC variability on the interannual time scale. Especially during the boreal summer, snow cover can persist over the TP at high elevations, which exerts profound influences on the local and remote climate change. The present study finds that May Southern Hemisphere (SH) annular mode (SAM), the dominating mode of atmospheric circulation variability in the SH extratropics, exhibits a significant positive relationship with the boreal summer TPSC interannual variability. Observational analysis and numerical experiments manifest that the signal of May SAM can be "prolonged" by a meridional Indian Ocean tripole (IOT) sea surface temperature anomaly (SSTA) via atmosphere-ocean interaction. The IOT SSTA pattern persists into the following summer and excites anomalous local-scale zonal vertical circulation. Subsequently, a positive (or negative) tropical dipole rainfall (TDR) mode is induced with deficient (or sufficient) precipitation in tropical western Indian Ocean and sufficient (or deficient) precipitation in eastern Indian Ocean-Maritime continent. Rossby wave source diagnosis reveals that the wave energies, generated by the latent heat release of the TDR mode, propagate northward into western TP. As a response, abnormal cyclonic circulation and upward movement are triggered and prevail over western TP, providing favorable dynamical conditions for more TPSC, and vice versa. Hence, the IOT SSTA plays an "ocean bridge" role and the TDR mode acts as an "atmosphere bridge" role in the process of May SAM impacting the following summer TPSC variability. The results of our work may provide new insight about the cross-equatorial propagation of the SAM influence. Keywords Southern Hemisphere annular mode; Tibetan Plateau snow cover; Rossby wave source

ASTEROSEISMOLOGY OF THE NEARBY SN II PROGENITOR RIGEL. II. {epsilon}-MECHANISM TRIGGERING GRAVITY-MODE PULSATIONS?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moravveji, Ehsan; Moya, Andres; Guinan, Edward F., E-mail: moravveji@iasbs.ac.ir

2012-04-10

The cores of luminous B- and A-type (BA) supergiant stars are the seeds of later core-collapse supernovae. Thus, constraining the near-core conditions in this class of stars can place tighter constraints on the size, mass, and chemical composition of supernova remnants. Asteroseismology of these massive stars is one possible approach into such investigations. Recently, Moravveji et al. in 2012 (hereafter Paper I) extracted 19 significant frequencies from a 6-year radial velocity monitoring of Rigel ({beta} Ori, B8 Ia). The periods they determined broadly range from 1.22 to 74.74 days. Based on our differentially rotating stellar structure and evolution model, Rigel,more » at its current evolutionary state, is undergoing core He burning and shell H burning. Linear fully non-adiabatic non-radial stability analyses result in the excitation of a dense spectrum of non-radial gravity-dominated mixed modes. The fundamental radial mode (l = 0) and its overtones are all stable. When the hydrogen-burning shell is located even partially in the radiative zone, a favorable condition for destabilization of g-modes through the so-called {epsilon}-mechanism becomes viable. Only those g-modes that have high relative amplitudes in the hydrogen-burning (radiative) zone can survive the strong radiative damping. From the entire observed range of variability periods of Rigel (found in Paper I), and based on our model, only those modes with periods ranging between 21 and 127 days can be theoretically explained by the {epsilon}-mechanism. The origin of the short-period variations (found in Paper I) still remains unexplained. Because Rigel is similar to other massive BA supergiants, we believe that the {epsilon}-mechanism may be able to explain the long-period variations in {alpha} Cygni class of pulsating stars.« less

Gyro-Landau-Fluid Theory and Simulations of Edge-Localized-Modes

NASA Astrophysics Data System (ADS)

Xu, X. Q.

2012-10-01

We report on the theory and simulations of edge-localized-modes (ELMs) using a gyro-Landau-fluid (GLF) extension of the BOUT++ code. Consistent with the two-fluid model (including 1st order FLR corrections), large ELMs, which are low-to-intermediate toroidal mode number (n) peeling-ballooning (P-B) modes, are suppressed by finite Larmor radius (FLR) effects as the ion temperature increases, while small ELMs (at intermediate n's) remain unstable. This result is good news for high ion temperatures in ITER due to the large stabilizing effects of FLR. Because the FLR effects are proportional to both Ti and n, the maximum growth rate is inversely proportional to Ti and the P-B mode is stabilized at high n. Nonlinear gyro-fluid simulations show results similar to those from the two-fluid model, namely that the P-B modes trigger magnetic reconnection, which drives the collapse of the pedestal pressure. Hyper-resistivity limits the radial spreading of ELMs by facilitating magnetic reconnection. The gyro-fluid ion model further limits the radial spreading of ELMs due to FLR-corrected nonlinear ExB convection of the ion gyro-center density. A gyro-fluid ETG model is being developed to self-consistently calculate the hyper-resistivity. Zonal magnetic fields arise from an ELM event and finite beta drift-wave turbulence when electron inertia effects are included. These lead to current generation and self-consistent current transport as a result of ExB convection in the generalized Ohm's law. Because edge plasmas have significant spatial inhomogeneities and complicated boundary conditions, we have developed a fast non-Fourier method for the computation of Landau-fluid closure terms based on an accurate and tunable approximation. The accuracy and the fast computational scaling of the method are demonstrated.

Data acquisition electronics for gamma ray emission tomography using width-modulated leading-edge discriminators

NASA Astrophysics Data System (ADS)

Lage, E.; Tapias, G.; Villena, J.; Desco, M.; Vaquero, J. J.

2010-08-01

We present a new high-performance and low-cost approach for implementing radiation detection acquisition systems. The basic elements used are charge-integrating ADCs and a set of components encapsulated in an HDL (hardware definition language) library which makes it possible to implement several acquisition tasks such as time pickoff and coincidence detection using a new and simple trigger technique that we name WMLET (width-modulated leading-edge timing). As proof of concept, a 32-channel hybrid PET/SPECT acquisition system based on these elements was developed and tested. This demonstrator consists of a master module responsible for the generation and distribution of trigger signals, 2 × 16-channel ADC cards (12-bit resolution) for data digitization and a 32-bit digital I/O PCI card for handling data transmission to a personal computer. System characteristics such as linearity, maximum transmission rates or timing resolution in coincidence mode were evaluated with test and real detector signals. Imaging capabilities of the prototype were also evaluated using different detector configurations. The performance tests showed that this implementation is able to handle data rates in excess of 600k events s-1 when acquiring simultaneously 32 channels (96-byte events). ADC channel linearity is >98.5% in energy quantification. Time resolution in PET mode for the tested configurations ranges from 3.64 ns FWHM to 7.88 ns FWHM when signals from LYSO-based detectors are used. The measured energy resolution matched the expected values for the detectors evaluated and single elements of crystal matrices can be neatly separated in the acquired flood histograms.

Data acquisition electronics for gamma ray emission tomography using width-modulated leading-edge discriminators.

PubMed

Lage, E; Tapias, G; Villena, J; Desco, M; Vaquero, J J

2010-08-07

We present a new high-performance and low-cost approach for implementing radiation detection acquisition systems. The basic elements used are charge-integrating ADCs and a set of components encapsulated in an HDL (hardware definition language) library which makes it possible to implement several acquisition tasks such as time pickoff and coincidence detection using a new and simple trigger technique that we name WMLET (width-modulated leading-edge timing). As proof of concept, a 32-channel hybrid PET/SPECT acquisition system based on these elements was developed and tested. This demonstrator consists of a master module responsible for the generation and distribution of trigger signals, 2 x 16-channel ADC cards (12-bit resolution) for data digitization and a 32-bit digital I/O PCI card for handling data transmission to a personal computer. System characteristics such as linearity, maximum transmission rates or timing resolution in coincidence mode were evaluated with test and real detector signals. Imaging capabilities of the prototype were also evaluated using different detector configurations. The performance tests showed that this implementation is able to handle data rates in excess of 600k events s(-1) when acquiring simultaneously 32 channels (96-byte events). ADC channel linearity is >98.5% in energy quantification. Time resolution in PET mode for the tested configurations ranges from 3.64 ns FWHM to 7.88 ns FWHM when signals from LYSO-based detectors are used. The measured energy resolution matched the expected values for the detectors evaluated and single elements of crystal matrices can be neatly separated in the acquired flood histograms.

iPad2(R) use in patients with implantable cardioverter defibrillators causes electromagnetic interference: the EMIT Study.

PubMed

Kozik, Teri M; Chien, Gianna; Connolly, Therese F; Grewal, Gurinder S; Liang, David; Chien, Walter

2014-04-10

Over 140 million iPads(®) have been sold worldwide. The iPad2(®), with magnets embedded in its frame and Smart Cover and 3G cellular data capability, can potentially cause electromagnetic interference in implantable cardioverter defibrillators. This can lead to potentially life-threatening situations in patients. The goal of this study was to determine whether the iPad2(®) can cause electromagnetic interference in patients with implantable cardioverter defibrillators. Twenty-seven patients with implantable cardioverter defibrillators were studied. The iPad2(®) was held at reading distance and placed directly over the device with cellular data capability activated and deactivated. The manufacturers/models of devices and the patients' body mass index were noted. The presence of electromagnetic interference was detected by using a programmer supplied by each manufacturer. Magnet mode with suspension of anti-tachycardia therapy was triggered in 9 (33%) patients. All occurred when the iPad2(®) was placed directly over the device. The cellular data status did not cause interference and no noise or oversensing was noted. There was no significant difference between the mean body mass index of the groups with or without interference. The iPad2(®) can trigger magnet mode in implantable cardioverter defibrillators when laid directly over the device. This is potentially dangerous if patients should develop life-threatening arrhythmias at the same time. As new electronic products that use magnets are produced, the potential risk to patients with implantable defibrillators needs to be addressed.

An Extreme-ultraviolet Wave Generating Upward Secondary Waves in a Streamer-like Solar Structure

NASA Astrophysics Data System (ADS)

Zheng, Ruisheng; Chen, Yao; Feng, Shiwei; Wang, Bing; Song, Hongqiang

2018-05-01

Extreme-ultraviolet (EUV) waves, spectacular horizontally propagating disturbances in the low solar corona, always trigger horizontal secondary waves (SWs) when they encounter the ambient coronal structure. We present the first example of upward SWs in a streamer-like structure after the passing of an EUV wave. This event occurred on 2017 June 1. The EUV wave happened during a typical solar eruption including a filament eruption, a coronal mass ejection (CME), and a C6.6 flare. The EUV wave was associated with quasi-periodic fast propagating (QFP) wave trains and a type II radio burst that represented the existence of a coronal shock. The EUV wave had a fast initial velocity of ∼1000 km s‑1, comparable to high speeds of the shock and the QFP wave trains. Intriguingly, upward SWs rose slowly (∼80 km s‑1) in the streamer-like structure after the sweeping of the EUV wave. The upward SWs seemed to originate from limb brightenings that were caused by the EUV wave. All of the results show that the EUV wave is a fast-mode magnetohydrodynamic (MHD) shock wave, likely triggered by the flare impulses. We suggest that part of the EUV wave was probably trapped in the closed magnetic fields of the streamer-like structure, and upward SWs possibly resulted from the release of slow-mode trapped waves. It is believed that the interplay of the strong compression of the coronal shock and the configuration of the streamer-like structure is crucial for the formation of upward SWs.

Combined system for high-time-resolution dual-excitation fluorescence photometry and fluorescence imaging of calcium transients in single normal and diseased skeletal muscle fibers

NASA Astrophysics Data System (ADS)

Uttenweiler, Dietmar; Wojciechowski, Reinhold; Makabe, Makoto; Veigel, Claudia; Fink, Rainer H.

1994-12-01

Fast photometric measurements and video-imaging of fluorescent indicators both are powerful tools in measuring the intracellular free calcium concentration of muscle and many other cells. as photometric systems yield a high temporal resolution, calcium imaging systems have high spatial but significantly reduced temporal resolution. Therefore we have developed an integrated system combining both methods and based mostly on standard components. As a common, sensitive Ca2+- indicator we used the fluorescent probe Fura-2, which is alternatingly excited for ratio measurements at 340/380 nm. We used a commercially available dual excitation photometric system (OSP-3; Olympus) for attaching a CCD-camera and a frame grabber board. To achieve the synchronization we had to design circuitries for external triggering, synchronization and accurate control of the filter changer, which we added to the system. Additionally, the software for a triggered image acquisition was developed. With this integrated setup one can easily switch between the fast photometric mode (ratio frequency 100 Hz) and the imaging mode (ratio frequency 4.17 Hz). The calcium images are correlated with the 25 times faster spot measurements and are analyzed by means of image processing. With this combined system we study release and uptake of calcium ions of normal and diseased skeletal muscle from mdx mice. Such a system will also be important for other cellular studies in which fluorescence indicators are used to monitor similar time dependent alterations as well as changes in cellular distributions of calcium.

Development of a hybrid mode linear transformer driver stage

NASA Astrophysics Data System (ADS)

Zhang, Le; Wang, Meng; Zhou, Liangji; Tian, Qing; Guo, Fan; Wang, Lingyun; Qing, Yanling; Zhao, Yue; Dai, Yingmin; Han, Wenhui; Chen, Lin; Xie, Weiping

2018-02-01

At present, the mainstream technologies of primary power sources of large pulse power devices adopt Marx or linear transformer driver (LTD) designs. Based on the analysis of the characteristics of these two types of circuit topologies, the concept of a hybrid mode LTD stage based on Marx branches is proposed. The analysis shows that the hybrid mode LTD stage can realize the following goals: (a) to reduce the energy and power handled by the basic components (switch and capacitor) to lengthen their lifetime; (b) to reduce the requirements of the multipath synchronous trigger system; and (c) to improve the maintainability of the LTD stage by using independent Marx generators instead of "traditional LTD bricks." To verify the technique, a hybrid mode LTD stage consisting of 50 branches (four-stage compact Marx generators) was designed, manufactured and tested. The stage has a radius of about 3.3 m and a height of 0.6 m. The single Marx circuit's load current is about 21 kA, with a rise time of ˜90 ns (10%-90%), under the conditions of capacitors charged to ±40 kV and a 6.9 Ω matched load. The whole stage's load current is ˜1 MA , with a rise time of ˜112 ns (10%-90%), when the capacitors are charged to ±45 kV and the matched load is 0.14 Ω .

Development of an advanced mobile base for personal mobility and manipulation appliance generation II robotic wheelchair.

PubMed

Wang, Hongwu; Candiotti, Jorge; Shino, Motoki; Chung, Cheng-Shiu; Grindle, Garrett G; Ding, Dan; Cooper, Rory A

2013-07-01

This paper describes the development of a mobile base for the Personal Mobility and Manipulation Appliance Generation II (PerMMA Gen II robotic wheelchair), an obstacle-climbing wheelchair able to move in structured and unstructured environments, and to climb over curbs as high as 8 inches. The mechanical, electrical, and software systems of the mobile base are presented in detail, and similar devices such as the iBOT mobility system, TopChair, and 6X6 Explorer are described. The mobile base of PerMMA Gen II has two operating modes: "advanced driving mode" on flat and uneven terrain, and "automatic climbing mode" during stair climbing. The different operating modes are triggered either by local and dynamic conditions or by external commands from users. A step-climbing sequence, up to 0.2 m, is under development and to be evaluated via simulation. The mathematical model of the mobile base is introduced. A feedback and a feed-forward controller have been developed to maintain the posture of the passenger when driving over uneven surfaces or slopes. The effectiveness of the controller has been evaluated by simulation using the open dynamics engine tool. Future work for PerMMA Gen II mobile base is implementation of the simulation and control on a real system and evaluation of the system via further experimental tests.

Regulatory Mode and Risk-Taking: The Mediating Role of Anticipated Regret

PubMed Central

Panno, Angelo; Lauriola, Marco; Pierro, Antonio

2015-01-01

We propose that decision maker’s regulatory mode affects risk-taking through anticipated regret. In the Study 1 either a locomotion or an assessment orientation were experimentally induced, and in the Studies 2 and 3 these different orientations were assessed as chronic individual differences. To assess risk-taking we used two behavioral measures of risk: BART and hot-CCT. The results show that experimentally induced assessment orientation–compared to locomotion–leads to decreased risk-taking through increased anticipated regret (Study 1). People chronically predisposed to be in the assessment state take less risk through increased anticipated regret (Study 2 and Study 3). Study 2 results also show a marginally non-significant indirect effect of chronic locomotion mode on BART through anticipated regret. Differently, Study 3 shows that people chronically predisposed to be in the locomotion state take greater risk through decreased anticipated regret, when play a dynamic risk task triggering stronger emotional arousal. Through all three studies, the average effect size for the relationship of assessment with anticipated regret was in the moderate-large range, whereas for risk-taking was in the moderate range. The average effect size for the relationship of locomotion with anticipated regret was in the moderate range, whereas for risk-taking was in the small-moderate range. These results increase our understanding of human behavior under conditions of risk obtaining novel insights into regulatory mode theory and decision science. PMID:26580960

Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lunsford, R.; Bortolon, A.; Roquemore, A. L.

Here, by employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s –1 are presented for NSTX-U L-mode type plasmas, as well as H-mode dischargesmore » with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s –1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.« less

Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

DOE PAGES

Lunsford, R.; Bortolon, A.; Roquemore, A. L.; ...

2017-05-16

Here, by employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s –1 are presented for NSTX-U L-mode type plasmas, as well as H-mode dischargesmore » with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50–150 m s –1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.« less

Stability of surface plastic flow in large strain deformation of metals

NASA Astrophysics Data System (ADS)

Viswanathan, Koushik; Udapa, Anirduh; Sagapuram, Dinakar; Mann, James; Chandrasekar, Srinivasan

We examine large-strain unconstrained simple shear deformation in metals using a model two-dimensional cutting system and high-speed in situ imaging. The nature of the deformation mode is shown to be a function of the initial microstructure state of the metal and the deformation geometry. For annealed metals, which exhibit large ductility and strain hardening capacity, the commonly assumed laminar flow mode is inherently unstable. Instead, the imposed shear is accommodated by a highly rotational flow-sinuous flow-with vortex-like components and large-amplitude folding on the mesoscale. Sinuous flow is triggered by a plastic instability on the material surface ahead of the primary region of shear. On the other hand, when the material is extensively strain-hardened prior to shear, laminar flow again becomes unstable giving way to shear banding. The existence of these flow modes is established by stability analysis of laminar flow. The role of the initial microstructure state in determining the change in stability from laminar to sinuous / shear-banded flows in metals is elucidated. The implications for cutting, forming and wear processes for metals, and to surface plasticity phenomena such as mechanochemical Rehbinder effects are discussed.

Repeated bubble breakup and coalescence in perturbed Hele-Shaw channels

NASA Astrophysics Data System (ADS)

Thompson, Alice; Franco-Gomez, Andres; Hazel, Andrew; Juel, Anne

2017-11-01

The introduction of an axially-uniform, centred constriction in a Hele-Shaw channel leads to multiple propagation modes for both air fingers and bubbles, including symmetric and asymmetric steadily propagating modes along with oscillations. These multiple modes correspond to a non-trivial bifurcation structure, and relate to the plethora of steadily propagating bubbles and fingers which exist in the Saffman-Taylor system. In both experiments and depth-averaged computations, a very small centred occlusion can be enough to trigger bubble breakup, with a single large centred bubble splitting into two smaller bubbles which propagate along each side of the channel. We present numerical simulations for the depth-averaged model, implementing geometric criteria for pinchoff and coalescence in order to track the bubble before and beyond breakup. We find that the two-bubble state is itself unstable, with finger competition causing one bubble to move ahead; the trailing bubble then moves across the channel to merge with the leading bubble. However, the story is not always so simple, enabling complicated cascades of splitting and merging bubbles. We compare the general dynamical behaviour, basins of attraction, and the details of merging and splitting, to experimental observations.

Control dynamics of interaction quenched ultracold bosons in periodically driven lattices

NASA Astrophysics Data System (ADS)

Mistakidis, Simeon; Schmelcher, Peter; Group of Fundamental Processes in Quantum Physics Team

2016-05-01

The out-of-equilibrium dynamics of ultracold bosons following an interaction quench upon a periodically driven optical lattice is investigated. It is shown that an interaction quench triggers the inter-well tunneling dynamics, while for the intra-well dynamics breathing and cradle-like processes can be generated. In particular, the occurrence of a resonance between the cradle and tunneling modes is revealed. On the other hand, the employed periodic driving enforces the bosons in the mirror wells to oscillate out-of-phase and to exhibit a dipole mode, while in the central well the cloud experiences a breathing mode. The dynamical behaviour of the system is investigated with respect to the driving frequency revealing a resonant behaviour of the intra-well dynamics. To drive the system in a highly non-equilibrium state an interaction quench upon the driving is performed giving rise to admixtures of excitations in the outer wells, an enhanced breathing in the center and an amplification of the tunneling dynamics. As a result of the quench the system experiences multiple resonances between the inter- and intra-well dynamics at different quench amplitudes. Deutsche Forschungsgemeinschaft, SFB 925 ``Light induced dynamics and control of correlated quantum systems''.

Overview of Recent DIII-D Experimental Results

NASA Astrophysics Data System (ADS)

Fenstermacher, Max

2015-11-01

Recent DIII-D experiments have added to the ITER physics basis and to physics understanding for extrapolation to future devices. ELMs were suppressed by RMPs in He plasmas consistent with ITER non-nuclear phase conditions, and in steady state hybrid plasmas. Characteristics of the EHO during both standard high torque, and low torque enhanced pedestal QH-mode with edge broadband fluctuations were measured, including edge localized density fluctuations with a microwave imaging reflectometer. The path to Super H-mode was verified at high beta with a QH-mode edge, and in plasmas with ELMs triggered by Li granules. ITER acceptable TQ mitigation was obtained with low Ne fraction Shattered Pellet Injection. Divertor ne and Te data from Thomson Scattering confirm predicted drift-driven asymmetries in electron pressure, and X-divertor heat flux reduction and detachment were characterized. The crucial mechanisms for ExB shear control of turbulence were clarified. In collaboration with EAST, high beta-p scenarios were obtained with 80 % bootstrap fraction, high H-factor and stability limits, and large radius ITBs leading to low AE activity. Work supported by the US Department of Energy under DE-FC02-04ER54698 and DE-AC52-07NA27344.

Towards the control of the modal energy transfer in transverse mode instabilities

NASA Astrophysics Data System (ADS)

Stihler, Christoph; Jauregui, Cesar; Tünnermann, Andreas; Limpert, Jens

2018-02-01

Thermally-induced refractive index gratings (RIG) in high-power fiber laser systems lead to transverse mode instabilities (TMI) above a certain average power threshold. The effect of TMI is currently the main limitation for the further average power scaling of fiber lasers and amplifiers with nearly diffraction-limited beam quality. In this work we experimentally investigate, for the first time, the growth of the RIG strength by introducing a phase-shift between the RIG and the modal interference pattern in a fiber amplifier. The experiments reveal that the RIG is strong enough to couple energy between different transverse modes even at powers significantly below the TMI threshold, provided that the introduced phase-shift is high enough. This indicates that, as the strength of the RIG further increases with increasing average output power, the RIG becomes more and more sensitive to even small noise-induced phase-shifts, which ultimately trigger TMI. Furthermore, it is shown that a beam cleaning also occurs when a positive phase-shift is introduced, even above the TMI threshold. This finding will pave the way for the development of a new class of mitigation strategies for TMI, which key feature is the control of the introduced phase-shift.

Decentralized semi-active damping of free structural vibrations by means of structural nodes with an on/off ability to transmit moments

NASA Astrophysics Data System (ADS)

Poplawski, Blazej; Mikułowski, Grzegorz; Mróz, Arkadiusz; Jankowski, Łukasz

2018-02-01

This paper proposes, tests numerically and verifies experimentally a decentralized control algorithm with local feedback for semi-active mitigation of free vibrations in frame structures. The algorithm aims at transferring the vibration energy of low-order, lightly-damped structural modes into high-frequency modes of vibration, where it is quickly damped by natural mechanisms of material damping. Such an approach to mitigation of vibrations, known as the prestress-accumulation release (PAR) strategy, has been earlier applied only in global control schemes to the fundamental vibration mode of a cantilever beam. In contrast, the decentralization and local feedback allows the approach proposed here to be applied to more complex frame structures and vibration patterns, where the global control ceases to be intuitively obvious. The actuators (truss-frame nodes with controllable ability to transmit moments) are essentially unblockable hinges that become unblocked only for very short time periods in order to trigger local modal transfer of energy. The paper proposes a computationally simple model of the controllable nodes, specifies the control performance measure, yields basic characteristics of the optimum control, proposes the control algorithm and then tests it in numerical and experimental examples.

Physical modeling of Tibetan bowls

NASA Astrophysics Data System (ADS)

Antunes, Jose; Inacio, Octavio

2004-05-01

Tibetan bowls produce rich penetrating sounds, used in musical contexts and to induce a state of relaxation for meditation or therapy purposes. To understand the dynamics of these instruments under impact and rubbing excitation, we developed a simulation method based on the modal approach, following our previous papers on physical modeling of plucked/bowed strings and impacted/bowed bars. This technique is based on a compact representation of the system dynamics, in terms of the unconstrained bowl modes. Nonlinear contact/friction interaction forces, between the exciter (puja) and the bowl, are computed at each time step and projected on the bowl modal basis, followed by step integration of the modal equations. We explore the behavior of two different-sized bowls, for extensive ranges of excitation conditions (contact/friction parameters, normal force, and tangential puja velocity). Numerical results and experiments show that various self-excited motions may arise depending on the playing conditions and, mainly, on the contact/friction interaction parameters. Indeed, triggering of a given bowl modal frequency mainly depends on the puja material. Computed animations and experiments demonstrate that self-excited modes spin, following the puja motion. Accordingly, the sensed pressure field pulsates, with frequency controlled by the puja spinning velocity and the spatial pattern of the singing mode.

Control of edge localized modes by pedestal deposited impurity in the HL-2A tokamak

NASA Astrophysics Data System (ADS)

Zhang, Y. P.; Mazon, D.; Zou, X. L.; Zhong, W. L.; Gao, J. M.; Zhang, K.; Sun, P.; Dong, C. F.; Cui, Z. Y.; Liu, Yi; Shi, Z. B.; Yu, D. L.; Cheng, J.; Jiang, M.; Xu, J. Q.; Isobe, M.; Xiao, G. L.; Chen, W.; Song, S. D.; Bai, X. Y.; Zhang, P. F.; Yuan, G. L.; Ji, X. Q.; Li, Y. G.; Zhou, Y.; Delpech, L.; Ekedahl, A.; Giruzzi, G.; Hoang, T.; Peysson, Y.; Song, X. M.; Song, X. Y.; Li, X.; Ding, X. T.; Dong, J. Q.; Yang, Q. W.; Xu, M.; Duan, X. R.; Liu, Y.; the HL-2A Team

2018-04-01

Effect of the pedestal deposited impurity on the edge-localized mode (ELM) behaviour has been observed and intensively investigated in the HL-2A tokamak. Impurities have been externally seeded by a newly developed laser blow-off (LBO) system. Both mitigation and suppression of ELMs have been realized by LBO-seeded impurity. Measurements have shown that the LBO-seeded impurity particles are mainly deposited in the pedestal region. During the ELM mitigation phase, the pedestal density fluctuation is significantly increased, indicating that the ELM mitigation may be achieved by the enhancement of the pedestal transport. The transition from ELM mitigation to ELM suppression was triggered when the number of the LBO-seeded impurity exceeds a threshold value. During the ELM suppression phase, a harmonic coherent mode (HCM) is excited by the LBO-seeded impurity, and the pedestal density fluctuation is significantly decreased, the electron density is continuously increased, implying that HCM may reduce the pedestal turbulence, suppress ELMs, increase the pedestal pressure, thus extending the Peeling-Ballooning instability limit. It has been found that the occurance of the ELM mitigation and ELM suppression closely depends on the LBO laser spot diameter.

Airborne signals from Trichoderma fungi stimulate iron uptake responses in roots resulting in priming of jasmonic acid-dependent defences in shoots of Arabidopsis thaliana and Solanum lycopersicum.

PubMed

Martínez-Medina, Ainhoa; Van Wees, Saskia C M; Pieterse, Corné M J

2017-11-01

Root colonization by Trichoderma fungi can trigger induced systemic resistance (ISR). In Arabidopsis, Trichoderma-ISR relies on the transcription factor MYB72, which plays a dual role in the onset of ISR and the activation of Fe uptake responses. Volatile compounds (VCs) from rhizobacteria are important elicitors of MYB72 in Arabidopsis roots. Here, we investigated the mode of action of VCs from Trichoderma fungi in the onset of ISR and Fe uptake responses. VCs from Trichoderma asperellum and Trichoderma harzianum were applied in an in vitro split-plate system with Arabidopsis or tomato seedlings. Locally, Trichoderma-VCs triggered MYB72 expression and molecular, physiological and morphological Fe uptake mechanisms in Arabidopsis roots. In leaves, Trichoderma-VCs primed jasmonic acid-dependent defences, leading to an enhanced resistance against Botrytis cinerea. By using Arabidopsis micrografts of VCs-exposed rootstocks and non-exposed scions, we demonstrated that perception of Trichoderma-VCs by the roots leads to a systemic signal that primes shoots for enhanced defences. Trichoderma-VCs also elicited Fe deficiency responses and shoot immunity in tomato, suggesting that this phenomenon is expressed in different plant species. Our results indicate that Trichoderma-VCs trigger locally a readjustment of Fe homeostasis in roots, which links to systemic elicitation of ISR by priming of jasmonic acid-dependent defences. © 2017 John Wiley & Sons Ltd.

Optical techniques for biological triggers and identifiers

NASA Astrophysics Data System (ADS)

Grant, Bruce A. C.

2004-12-01

Optical techniques for the classification and identification of biological particles provide a number of advantages over traditional 'Wet Chemistry" methods, amongst which are speed of response and the reduction/elimination of consumables. These techniques can be employed in both 'Trigger" and 'Identifier" systems. Trigger systems monitor environmental particulates with the aim of detecting 'unusual" changes in the overall environmental composition and providing an indication of threat. At the present time there is no single optical measurement that can distinguish between benign and hostile events. Therefore, in order to distinguish between these 2 classifications, a number of different measurements must be effected and a decision made on the basis of the 'integrated" data. Smiths Detection have developed a data gathering platform capable of measuring multiple optical, physical and electrical parameters of individual airborne biological particles. The data from all these measurements are combined in a hazard classification algorithm based on Bayesian Inference techniques. Identifier systems give a greater level of information and confidence than triggers, -- although they require reagents and are therefore much more expensive to operate -- and typically take upwards of 20 minutes to respond. Ideally, in a continuous flow mode, identifier systems would respond in real-time, and identify a range of pathogens specifically and simultaneously. The results of recent development work -- carried out by Smiths Detection and its collaborators -- to develop an optical device that meets most of these requirements, and has the stretch potential to meet all of the requirements in a 3-5 year time frame will be presented. This technology enables continuous stand-alone operation for both civil and military defense applications and significant miniaturisation can be achieved with further development.

In Silico Identification of Mimicking Molecules as Defense Inducers Triggering Jasmonic Acid Mediated Immunity against Alternaria Blight Disease in Brassica Species

PubMed Central

Pathak, Rajesh K.; Baunthiyal, Mamta; Shukla, Rohit; Pandey, Dinesh; Taj, Gohar; Kumar, Anil

2017-01-01

Alternaria brassicae and Alternaria brassicicola are two major phytopathogenic fungi which cause Alternaria blight, a recalcitrant disease on Brassica crops throughout the world, which is highly destructive and responsible for significant yield losses. Since no resistant source is available against Alternaria blight, therefore, efforts have been made in the present study to identify defense inducer molecules which can induce jasmonic acid (JA) mediated defense against the disease. It is believed that JA triggered defense response will prevent necrotrophic mode of colonization of Alternaria brassicae fungus. The JA receptor, COI1 is one of the potential targets for triggering JA mediated immunity through interaction with JA signal. In the present study, few mimicking compounds more efficient than naturally occurring JA in terms of interaction with COI1 were identified through virtual screening and molecular dynamics simulation studies. A high quality structural model of COI1 was developed using the protein sequence of Brassica rapa. This was followed by virtual screening of 767 analogs of JA from ZINC database for interaction with COI1. Two analogs viz. ZINC27640214 and ZINC43772052 showed more binding affinity with COI1 as compared to naturally occurring JA. Molecular dynamics simulation of COI1 and COI1-JA complex, as well as best screened interacting structural analogs of JA with COI1 was done for 50 ns to validate the stability of system. It was found that ZINC27640214 possesses efficient, stable, and good cell permeability properties. Based on the obtained results and its physicochemical properties, it is capable of mimicking JA signaling and may be used as defense inducers for triggering JA mediated resistance against Alternaria blight, only after further validation through field trials. PMID:28487711

Development of instrumentation with application to sounding rocket electric and magnetic field measurements above thunderstorms

NASA Astrophysics Data System (ADS)

Baker, Steven D.

1999-06-01

The thunderstorm campaigns led by Cornell University in 1981 and 1988 both measured large-amplitude (10 to 40 mV/m), long duration (1 ms) electric-field pulses parallel to the earth's magnetic field. To investigate the mechanism responsible for these pulses, the instrumentation bandwidth was increased from the VLF range to MF frequencies. The design for a Helmholtz coil developed to calibrate magnetometers from DC to 10 MHz is given in Chapter 3. This coil generates a spatially uniform field with for frequencies up to at least 10 MHz with amplitudes of up to 1.1 mA/m. Coincident with the need for higher bandwidth sensors, a burst-memory data acquisition system was developed to intelligently select the 1.25% of the available data to send to the telemetry encoder. This system uses the optical flash of the lightning as a trigger and has a back-up mode to ensure data is transmitted in the event no triggers occur. The higher-frequency instruments allowed the first rocket-borne measurement of nose- whistlers caused by the plasma frequency resonance (as opposed to the more common electron cyclotron frequency resonance), and what may have been the first observation of a TIPP at MF frequencies. Triggered emission from the second campaign, Thunderstorm-II, are identified as lower hybrid emissions. These emissions enhanced the whistler by several decibels in the lower hybrid frequency band and in bands above the emission. No emissions seen above the lower hybrid frequency. The Thunderstorm-III payloads also measured triggered emissions and long-duration pulses. The former were found in several altitude-independent frequency bands for which the source could not be identified. The long duration pulses, while of interest, have not been studied in sufficient depth for inclusion in this work.

Evaluation of GPUs as a level-1 track trigger for the High-Luminosity LHC

NASA Astrophysics Data System (ADS)

Mohr, H.; Dritschler, T.; Ardila, L. E.; Balzer, M.; Caselle, M.; Chilingaryan, S.; Kopmann, A.; Rota, L.; Schuh, T.; Vogelgesang, M.; Weber, M.

2017-04-01

In this work, we investigate the use of GPUs as a way of realizing a low-latency, high-throughput track trigger, using CMS as a showcase example. The CMS detector at the Large Hadron Collider (LHC) will undergo a major upgrade after the long shutdown from 2024 to 2026 when it will enter the high luminosity era. During this upgrade, the silicon tracker will have to be completely replaced. In the High Luminosity operation mode, luminosities of 5-7 × 1034 cm-2s-1 and pileups averaging at 140 events, with a maximum of up to 200 events, will be reached. These changes will require a major update of the triggering system. The demonstrated systems rely on dedicated hardware such as associative memory ASICs and FPGAs. We investigate the use of GPUs as an alternative way of realizing the requirements of the L1 track trigger. To this end we implemeted a Hough transformation track finding step on GPUs and established a low-latency RDMA connection using the PCIe bus. To showcase the benefits of floating point operations, made possible by the use of GPUs, we present a modified algorithm. It uses hexagonal bins for the parameter space and leads to a more truthful representation of the possible track parameters of the individual hits in Hough space. This leads to fewer duplicate candidates and reduces fake track candidates compared to the regular approach. With data-transfer latencies of 2 μs and processing times for the Hough transformation as low as 3.6 μs, we can show that latencies are not as critical as expected. However, computing throughput proves to be challenging due to hardware limitations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guidarelli, Andrea; Fiorani, Mara; Carloni, Silvia

We herein report the results from a comparative study of arsenite toxicity in respiration-proficient (RP) and -deficient (RD) U937 cells. An initial characterization of these cells led to the demonstration that the respiration-deficient phenotype is not associated with apparent changes in mitochondrial mass and membrane potential. In addition, similar levels of superoxide (O{sub 2}{sup .-}) were generated by RP and RD cells in response to stimuli specifically triggering respiratory chain-independent mitochondrial mechanisms or extramitochondrial, NADPH-oxidase dependent, mechanisms. At the concentration of 2.5 μM, arsenite elicited selective formation of O{sub 2}{sup .-} in the respiratory chain of RP cells, with hardlymore » any contribution of the above mechanisms. Under these conditions, O{sub 2}{sup .-} triggered downstream events leading to endoplasmic reticulum (ER) stress, autophagy and apoptosis. RD cells challenged with similar levels of arsenite failed to generate O{sub 2}{sup .-} because of the lack of a functional respiratory chain and were therefore resistant to the toxic effects mediated by the metalloid. Their resistance, however, was lost after exposure to four fold greater concentrations of arsenite, coincidentally with the release of O{sub 2}{sup .-} mediated by NADPH oxidase. Interestingly, extramitochondrial O{sub 2}{sup .-} triggered the same downstream events and an identical mode of death previously observed in RP cells. Taken together, the results obtained in this study indicate that arsenite toxicity is strictly dependent on O{sub 2}{sup .-} availability that, regardless of whether generated in the mitochondrial or extramitochondrial compartments, triggers similar downstream events leading to ER stress, autophagy and apoptosis. - Highlights: • Mitochondrial superoxide mediates arsenite toxicity in respiration-proficient cells. • NADPH-derived superoxide mediates arsenite toxicity in respiration-deficient cells. • Arsenite causes apoptosis in respiration-proficient and -deficient cells. • Apoptosis is in both circumstances associated with ER stress and autophagy.« less

Intermode Breather Solitons in Optical Microresonators

NASA Astrophysics Data System (ADS)

Guo, Hairun; Lucas, Erwan; Pfeiffer, Martin H. P.; Karpov, Maxim; Anderson, Miles; Liu, Junqiu; Geiselmann, Michael; Jost, John D.; Kippenberg, Tobias J.

2017-10-01

Dissipative solitons can be found in a variety of systems resulting from the double balance between dispersion and nonlinearity, as well as gain and loss. Recently, they have been observed to spontaneously form in Kerr nonlinear microresonators driven by a continuous wave laser, providing a compact source of coherent optical frequency combs. As optical microresonators are commonly multimode, intermode interactions, which give rise to avoided mode crossings, frequently occur and can alter the soliton properties. Recent works have shown that avoided mode crossings cause the soliton to acquire a single-mode dispersive wave, a recoil in the spectrum, or lead to soliton decay. Here, we show that avoided mode crossings can also trigger the formation of breather solitons, solitons that undergo a periodic evolution in their amplitude and duration. This new breather soliton, referred to as an intermode breather soliton, occurs within a laser detuning range where conventionally stationary (i.e., stable) dissipative Kerr solitons are expected. We experimentally demonstrate the phenomenon in two microresonator platforms (crystalline magnesium fluoride and photonic chip-based silicon nitride microresonators) and theoretically describe the dynamics based on a pair of coupled Lugiato-Lefever equations. We show that the breathing is associated with a periodic energy exchange between the soliton and a second optical mode family, a behavior that can be modeled by a response function acting on dissipative solitons described by the Lugiato-Lefever model. The observation of breathing dynamics in the conventionally stable soliton regime is relevant to applications in metrology such as low-noise microwave generation, frequency synthesis, or spectroscopy.

Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poli, Francesca M.; Fredrickson, Eric; Henderson, Mark A.

Time-dependent simulations are used to evolve plasma discharges in combination with a Modified Rutherford equation (MRE) for calculation of Neoclassical Tearing Mode (NTM) stability in response to Electron Cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. These simulations indicate that it is critical to detect the island as soon asmore » possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2,1). A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2,1)-NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in the ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the Upper Launcher during the entire flattop phase. By assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10.« less

Meta-analysis of fish early life stage tests-Association of toxic ratios and acute-to-chronic ratios with modes of action.

PubMed

Scholz, Stefan; Schreiber, Rene; Armitage, James; Mayer, Philipp; Escher, Beate I; Lidzba, Annegret; Léonard, Marc; Altenburger, Rolf

2018-04-01

Fish early life stage (ELS) tests (Organisation for Economic Co-operation and Development test guideline 210) are widely conducted to estimate chronic fish toxicity. In these tests, fish are exposed from the embryonic to the juvenile life stages. To analyze whether certain modes of action are related to high toxic ratios (i.e., ratios between baseline toxicity and experimental effect) and/or acute-to-chronic ratios (ACRs) in the fish ELS test, effect concentrations (ECs) for 183 compounds were extracted from the US Environmental Protection Agency's ecotoxicity database. Analysis of ECs of narcotic compounds indicated that baseline toxicity could be observed in the fish ELS test at similar concentrations as in the acute fish toxicity test. All nonnarcotic modes of action were associated with higher toxic ratios, with median values ranging from 4 to 9.3 × 10 4 (uncoupling < reactivity < neuromuscular toxicity < methemoglobin formation < endocrine disruption < extracellular matrix formation inhibition). Four modes of action were also found to be associated with high ACRs: 1) lysyl oxidase inhibition leading to notochord distortion, 2) putative methemoglobin formation or hemolytic anemia, 3) endocrine disruption, and 4) compounds with neuromuscular toxicity. For the prediction of ECs in the fish ELS test with alternative test systems, endpoints targeted to the modes of action of compounds with enhanced toxic ratios or ACRs could be used to trigger fish ELS tests or even replace these tests. Environ Toxicol Chem 2018;37:955-969. © 2018 SETAC. © 2018 SETAC.

Electron cyclotron power management for control of neoclassical tearing modes in the ITER baseline scenario

NASA Astrophysics Data System (ADS)

Poli, F. M.; Fredrickson, E. D.; Henderson, M. A.; Kim, S.-H.; Bertelli, N.; Poli, E.; Farina, D.; Figini, L.

2018-01-01

Time-dependent simulations are used to evolve plasma discharges in combination with a modified Rutherford equation for calculation of neoclassical tearing mode (NTM) stability in response to electron cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. Simulations indicate that it is critical to detect the island as soon as possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2, 1) . A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2, 1)- NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in the ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the upper launcher during the entire flattop phase. Assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10 .

Electron Cyclotron power management for control of Neoclassical Tearing Modes in the ITER baseline scenario

DOE PAGES

Poli, Francesca M.; Fredrickson, Eric; Henderson, Mark A.; ...

2017-09-21

Time-dependent simulations are used to evolve plasma discharges in combination with a Modified Rutherford equation (MRE) for calculation of Neoclassical Tearing Mode (NTM) stability in response to Electron Cyclotron (EC) feedback control in ITER. The main application of this integrated approach is to support the development of control algorithms by analyzing the plasma response with physics-based models and to assess how uncertainties in the detection of the magnetic island and in the EC alignment affect the ability of the ITER EC system to fulfill its purpose. These simulations indicate that it is critical to detect the island as soon asmore » possible, before its size exceeds the EC deposition width, and that maintaining alignment with the rational surface within half of the EC deposition width is needed for stabilization and suppression of the modes, especially in the case of modes with helicity (2,1). A broadening of the deposition profile, for example due to wave scattering by turbulence fluctuations or not well aligned beams, could even be favorable in the case of the (2,1)-NTM, by relaxing an over-focussing of the EC beam and improving the stabilization at the mode onset. Pre-emptive control reduces the power needed for suppression and stabilization in the ITER baseline discharge to a maximum of 5 MW, which should be reserved and available to the Upper Launcher during the entire flattop phase. By assuming continuous triggering of NTMs, with pre-emptive control ITER would be still able to demonstrate a fusion gain of Q=10.« less

Where is the breathing mode? High voltage Hall effect thruster studies with EMD method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurzyna, J.; Makowski, K.; Mazouffre, S.

2008-03-19

Discharge current and local plasma oscillations are studied in a high voltage Hall effect thruster PPS registered -X000. Characteristic time scales that appear in different operating conditions are resolved with the use of Hilbert-Huang spectra (HHS) which display time dependenc of instantaneous frequency and power. Sets of intrinsic mode functions (imfs) that are used for HHS calculation result due to application of empirical mode decomposition method (EMD) to nonstationary multicomponent signals. In the experiment the signals are captured in the electric circuit of the thruster as well locally, in the vicinity of the thruster exhaust region. Classical electric probes spacedmore » along the azimuth and/or thruster axis let us study correlations of signals which were captured in different locations. In this way azimuthal and axial propagation of disturbances is inspected. The discharge voltage is varied in the range of 200 divide 900 V while xenon mas flow rate of 5 divide 9 mg/s. LF, MF, and HF characteristic bands that are known from previous studies of PPS registered -100 thruster have been also detected here. However, expanding discharge current onto a set of intrinsic modes we can resolve MF mode more reliably than before. Moreover, for higher discharge voltages, this irregular mode turns into more regular waveform and tends to dominate in the discharge current masking almost completely the breathing mode (LF oscillations of the discharge current). In such a case triggering of HF oscillations is correlated with the phase of MF mode while in the case of PPS registered -100 thruster it was correlated with the appropriate phase of the breathing mode (LF band). Regular HF emission that can be unambiguously interpreted as azimuthal electrostatic wave now is observed only in the specific operating conditions of the thruster. However, even if irregular HF emission is observed the time delay of cross-correlated signals which are captured in different azimuthal locations corresponds to the velocity of azimuthal electron drift in the field of magnetic barrier.« less

Generation of whistler waves by continuous HF heating of the upper ionosphere

NASA Astrophysics Data System (ADS)

Vartanyan, A.; Milikh, G. M.; Eliasson, B. E.; Sharma, A.; Chang, C.; Parrot, M.; Papadopoulos, K.

2013-12-01

We report observations of VLF waves by the DEMETER satellite overflying the HAARP facility during ionospheric heating experiments. The detected VLF waves were in the range 8-17 kHz and coincided with times of continuous heating. The experiments indicate whistler generation due to conversion of artificial lower hybrid waves to whistlers on small scale field-aligned plasma density striations. The observations are compared with theoretical models, taking into account both linear and nonlinear processes. Implications of the mode conversion technique on VLF generation with subsequent injection into the radiation belts to trigger particle precipitation are discussed.

High performance thyratron driver with low jitter.

PubMed

Verma, Rishi; Lee, P; Springham, S V; Tan, T L; Rawat, R S

2007-08-01

We report the design and development of insulated gate bipolar junction transistor based high performance driver for operating thyratrons in grounded grid mode. With careful design, the driver meets the specification of trigger output pulse rise time less than 30 ns, jitter less than +/-1 ns, and time delay less than 160 ns. It produces a -600 V pulse of 500 ns duration (full width at half maximum) at repetition rate ranging from 1 Hz to 1.14 kHz. The developed module also facilitates heating and biasing units along with protection circuitry in one complete package.

Broad band energy spectrum and a low frequency QPO from H1743-322 in the hard state revealed by INTEGRAL and Swift observations

NASA Astrophysics Data System (ADS)

Rodriguez, J.; Cadolle Bel, M.; Tomsick, J. A.; Hannikainen, D.; Pottschmidt, K.; Kuulkers, E.; Corbel, S.; Coriat, M.; Goldwurm, A.; Russell, D. M.; Wilms, J.

2011-04-01

Following the report of renewed activity of the microquasar H1743-322 (aka IGR J17464-3213, ATels #3263, #3267) we have triggered a Swift ToO. The observation was performed on April 10, 2011 between 7.9h UT and 16.12h UT, therefore in quasi-simultaneity with the INTEGRAL bulge monitoring program (April 10, 2011 18.0h UT to 21.7h UT). The Swift/XRT was operated in Window Timing mode.

Robust calibration of an optical-lattice depth based on a phase shift

NASA Astrophysics Data System (ADS)

Cabrera-Gutiérrez, C.; Michon, E.; Brunaud, V.; Kawalec, T.; Fortun, A.; Arnal, M.; Billy, J.; Guéry-Odelin, D.

2018-04-01

We report on a method to calibrate the depth of an optical lattice. It consists of triggering the intrasite dipole mode of the cloud by a sudden phase shift. The corresponding oscillatory motion is directly related to the interband frequencies on a large range of lattice depths. Remarkably, for a moderate displacement, a single frequency dominates the oscillation of the zeroth and first orders of the interference pattern observed after a sufficiently long time of flight. The method is robust against atom-atom interactions and the exact value of the extra weak external confinement superimposed to the optical lattice.

Modes of Paramyxovirus Fusion: a Henipavirus perspective

PubMed Central

Lee, Benhur; Akyol-Ataman, Zeynep

2011-01-01

Henipavirus is a new genus of paramyxovirus that uses protein-based receptors (EphrinB2 and EphrinB3) for virus entry. Paramyxovirus entry requires the coordinated action of the fusion (F) and attachment viral envelope glycoproteins. Receptor binding to the attachment protein triggers F to undergo a conformational cascade that results in membrane fusion. The accumulation of structural and functional studies on many paramyxoviral fusion and attachment proteins, including recent structures of Nipah and Hendra virus G bound and unbound to cognate ephrinB receptors, indicate that henipavirus entry and fusion differs mechanistically from paramyxoviruses that use glycan-based receptors. PMID:21511478

Polymorphic transformation of helical flagella of bacteria

NASA Astrophysics Data System (ADS)

Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

2016-11-01

Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

Metal vapor arc switch electromagnetic accelerator technology

NASA Technical Reports Server (NTRS)

Mongeau, P. P.

1984-01-01

A multielectrode device housed in an insulator vacuum vessel, the metal vapor vacuum switch has high power capability and can hold off voltages up to the 100 kilovolt level. Such switches can be electronically triggered and can interrupt or commutate at a zero current crossing. The physics of arc initiation, arc conduction, and interruption are examined, including material considerations; inefficiencies; arc modes; magnetic field effects; passive and forced extinction; and voltage recovery. Heating, electrode lifetime, device configuration, and external circuit configuration are discussed. The metal vapor vacuum switch is compared with SCRs, GTOs, spark gaps, ignitrons, and mechanical breakers.

American cutaneous leishmaniasis triggered by electrocoagulation.

PubMed

Martins, Sofia Sales; Santos, Adriana de Oliveira; Lima, Beatriz Dolabela; Gomes, Ciro Martins; Sampaio, Raimunda Nonata Ribeiro

2018-01-01

Cutaneous leishmaniasis is usually transmitted by infected phlebotomine sand fly bites that initiate local cutaneous lesions. Few reports in the literature describe other modes of transmission. We report a case of a previously healthy 59-year-old woman who underwent electrocoagulation to remove seborrheic keratosis confirmed by dermatoscopy. Three months later, a skin fragment tested positive for Leishmania culture; the parasite was identified as L. (V.) braziliensis. Trauma may generate inflammatory cascades that favor Leishmania growth and lesion formation in previously infected patients. American cutaneous leishmaniasis is a dynamic disease with unclear pathophysiology because of continually changing environments, demographics, and human behaviors.

Track and mode controller (TMC): a software executive for a high-altitude pointing and tracking experiment

NASA Astrophysics Data System (ADS)

Michnovicz, Michael R.

1997-06-01

A real-time executive has been implemented to control a high altitude pointing and tracking experiment. The track and mode controller (TMC) implements a table driven design, in which the track mode logic for a tracking mission is defined within a state transition diagram (STD). THe STD is implemented as a state transition table in the TMC software. Status Events trigger the state transitions in the STD. Each state, as it is entered, causes a number of processes to be activated within the system. As these processes propagate through the system, the status of key processes are monitored by the TMC, allowing further transitions within the STD. This architecture is implemented in real-time, using the vxWorks operating system. VxWorks message queues allow communication of status events from the Event Monitor task to the STD task. Process commands are propagated to the rest of the system processors by means of the SCRAMNet shared memory network. The system mode logic contained in the STD will autonomously sequence in acquisition, tracking and pointing system through an entire engagement sequence, starting with target detection and ending with aimpoint maintenance. Simulation results and lab test results will be presented to verify the mode controller. In addition to implementing the system mode logic with the STD, the TMC can process prerecorded time sequences of commands required during startup operations. It can also process single commands from the system operator. In this paper, the author presents (1) an overview, in which he describes the TMC architecture, the relationship of an end-to-end simulation to the flight software and the laboratory testing environment, (2) implementation details, including information on the vxWorks message queues and the SCRAMNet shared memory network, (3) simulation results and lab test results which verify the mode controller, and (4) plans for the future, specifically as to how this executive will expedite transition to a fully functional system.

Two aspects of feedforward postural control: anticipatory postural adjustments and anticipatory synergy adjustments.

PubMed

Klous, Miriam; Mikulic, Pavle; Latash, Mark L

2011-05-01

We used the framework of the uncontrolled manifold hypothesis to explore the relations between anticipatory synergy adjustments (ASAs) and anticipatory postural adjustments (APAs) during feedforward control of vertical posture. ASAs represent a drop in the index of a multimuscle-mode synergy stabilizing the coordinate of the center of pressure in preparation to an action. ASAs reflect early changes of an index of covariation among variables reflecting muscle activation, whereas APAs reflect early changes in muscle activation levels averaged across trials. The assumed purpose of ASAs is to modify stability of performance variables, whereas the purpose of APAs is to change magnitudes of those variables. We hypothesized that ASAs would be seen before APAs and that this finding would be consistent with regard to the muscle-mode composition defined on the basis of different tasks and phases of action. Subjects performed a voluntary body sway task and a quick, bilateral shoulder flexion task under self-paced and reaction time conditions. Surface muscle activity of 12 leg and trunk muscles was analyzed to identify sets of 4 muscle modes for each task and for different phases within the shoulder flexion task. Variance components in the muscle-mode space and indexes of multimuscle-mode synergy stabilizing shift of the center of pressure were computed. ASAs were seen ∼ 100-150 ms prior to the task initiation, before APAs. The results were consistent with respect to different sets of muscle modes defined over the two tasks and different shoulder flexion phases. We conclude that the preparation for a self-triggered postural perturbation is associated with two types of anticipatory adjustments, ASAs and APAs. They reflect different feedforward processes within the hypothetical hierarchical control scheme, resulting in changes in patterns of covariation of elemental variables and in their patterns averaged across trials, respectively. The results show that synergies quantified using dissimilar sets of muscle modes show similar feedforward changes in preparation to action.

Cell cycle entry triggers a switch between two modes of Cdc42 activation during yeast polarization

PubMed Central

Witte, Kristen; Strickland, Devin; Glotzer, Michael

2017-01-01

Cell polarization underlies many cellular and organismal functions. The GTPase Cdc42 orchestrates polarization in many contexts. In budding yeast, polarization is associated with a focus of Cdc42•GTP which is thought to self sustain by recruiting a complex containing Cla4, a Cdc42-binding effector, Bem1, a scaffold, and Cdc24, a Cdc42 GEF. Using optogenetics, we probe yeast polarization and find that local recruitment of Cdc24 or Bem1 is sufficient to induce polarization by triggering self-sustaining Cdc42 activity. However, the response to these perturbations depends on the recruited molecule, the cell cycle stage, and existing polarization sites. Before cell cycle entry, recruitment of Cdc24, but not Bem1, induces a metastable pool of Cdc42 that is sustained by positive feedback. Upon Cdk1 activation, recruitment of either Cdc24 or Bem1 creates a stable site of polarization that induces budding and inhibits formation of competing sites. Local perturbations have therefore revealed unexpected features of polarity establishment. DOI: http://dx.doi.org/10.7554/eLife.26722.001 PMID:28682236

A 32-channel front-end ASIC for GEM detectors used in beam monitoring applications

NASA Astrophysics Data System (ADS)

Ciciriello, F.; Altieri, P. R.; Corsi, F.; De Robertis, G.; Felici, G.; Loddo, F.; Lorusso, L.; Marzocca, C.; Matarrese, G.; Ranieri, A.; Stamerra, A.

2017-11-01

A multichannel, mixed-signal, front-end ASIC for GEM detectors, intended for beam monitoring in hadron therapy applications, has been designed and prototyped in a standard 0.35 μm CMOS technology. The analog channels are based on the classic CSA + shaper processing chain, followed by a peak detector which can work as an analog memory, to simplifiy the analog-to-digital conversion of the peak voltage of the output pulse, proportional to the energy of the detected event. The available hardware resources include an 8-bit A/D converter and a standard-cell digital part, which manages the read-out procedure, in sparse or serial mode. The ASIC is self-triggered and transfers energy and address data to the external DAQ via a fast 100 MHz LVDS link. Preliminary characterization results show that the non-linearity error is limited to 5% for a maximum input charge of about 70 fC, the measured ENC is about 1400e- and the time jitter of the trigger signal generated in response to an injected charge of 60 fC is close to 200 ps.

β-glucans and eicosapolyenoic acids as MAMPs in plant–oomycete interactions: past and present

PubMed Central

Robinson, Sara M.; Bostock, Richard M.

2015-01-01

Branched β-1,3-glucans and the eicosapolyenoic acids (EP) are among the best characterized oomycete elicitors that trigger innate immune responses in plants. These elicitors were identified over three decades ago, and they were useful in the study of the sequence of physiological, biochemical and molecular events that induce resistance in plants. However, in spite of the cross-kingdom parallels where these molecules are well-characterized as immune system modulators in animals, their perception and modes of action in plants remains obscure. Oomycetes are among the most important plant pathogens, responsible for diseases that devastate crops, ornamentals, and tree species worldwide. With the recent interest and advances in our understanding of innate immunity in plants, and the redefining of many of the classical elicitors as microbe-associated molecular patterns (MAMPs), it seems timely and important to reexamine β-glucans and EP using contemporary approaches. In this review, we highlight early studies of β-glucans and EP, discuss their roles as evolutionarily conserved signals, and consider their action in relation to current models of MAMP-triggered immunity. PMID:25628639

Current Multistage Drug Delivery Systems Based on the Tumor Microenvironment

PubMed Central

Chen, Binlong; Dai, Wenbing; He, Bing; Zhang, Hua; Wang, Xueqing; Wang, Yiguang; Zhang, Qiang

2017-01-01

The development of traditional tumor-targeted drug delivery systems based on EPR effect and receptor-mediated endocytosis is very challenging probably because of the biological complexity of tumors as well as the limitations in the design of the functional nano-sized delivery systems. Recently, multistage drug delivery systems (Ms-DDS) triggered by various specific tumor microenvironment stimuli have emerged for tumor therapy and imaging. In response to the differences in the physiological blood circulation, tumor microenvironment, and intracellular environment, Ms-DDS can change their physicochemical properties (such as size, hydrophobicity, or zeta potential) to achieve deeper tumor penetration, enhanced cellular uptake, timely drug release, as well as effective endosomal escape. Based on these mechanisms, Ms-DDS could deliver maximum quantity of drugs to the therapeutic targets including tumor tissues, cells, and subcellular organelles and eventually exhibit the highest therapeutic efficacy. In this review, we expatiate on various responsive modes triggered by the tumor microenvironment stimuli, introduce recent advances in multistage nanoparticle systems, especially the multi-stimuli responsive delivery systems, and discuss their functions, effects, and prospects. PMID:28255348

Structural Basis for Inhibitor-Induced Hydrogen Peroxide Production by Kynurenine 3-Monooxygenase.

PubMed

Kim, Hyun Tae; Na, Byeong Kwan; Chung, Jiwoung; Kim, Sulhee; Kwon, Sool Ki; Cha, Hyunju; Son, Jonghyeon; Cho, Joong Myung; Hwang, Kwang Yeon

2018-04-19

Kynurenine 3-monooxygenase (KMO) inhibitors have been developed for the treatment of neurodegenerative disorders. The mechanisms of flavin reduction and hydrogen peroxide production by KMO inhibitors are unknown. Herein, we report the structure of human KMO and crystal structures of Saccharomyces cerevisiae (sc) and Pseudomonas fluorescens (pf) KMO with Ro 61-8048. Proton transfer in the hydrogen bond network triggers flavin reduction in p-hydroxybenzoate hydroxylase, but the mechanism triggering flavin reduction in KMO is different. Conformational changes via π-π interactions between the loop above the flavin and substrate or non-substrate effectors lead to disorder of the C-terminal α helix in scKMO and shifts of domain III in pfKMO, stimulating flavin reduction. Interestingly, Ro 61-8048 has two different binding modes. It acts as a competitive inhibitor in scKMO and as a non-substrate effector in pfKMO. These findings provide understanding of the catalytic cycle of KMO and insight for structure-based drug design of KMO inhibitors. Copyright © 2018 Elsevier Ltd. All rights reserved.

Psychiatric Illness in Takotsubo (Stress) Cardiomyopathy: A Review.

PubMed

Nayeri, Arash; Rafla-Yuan, Eric; Krishnan, Srikanth; Ziaeian, Boback; Cadeiras, Martin; McPherson, John A; Wells, Quinn S

Takotsubo cardiomyopathy (TC), also known as stress-induced cardiomyopathy, has been increasingly described in relation to psychiatric illness. We performed a literature review to identify the key findings related to psychiatric illness in TC that may be relevant to the practice of mental health and other health care providers. The association of psychiatric illness with TC in addition to the spectrum of psychiatric illness found in TC, the role of exacerbation or treatment of psychiatric illness in triggering TC, different modes of presentation, prognostic implications, and long-term management of psychiatric illness in TC are discussed. Additionally, we review the limitations of the pre-existing literature and suggest areas of future research. There is a strong association between pre-existing psychiatric illness, particularly anxiety and mood spectrum disorders, and TC. Acute exacerbation of psychiatric illness, rapid uptitration or overdose of certain psychotropic agents, and electroconvulsive therapy may trigger TC. Further studies are needed to better evaluate the prognostic significance and long-term management of psychiatric illness in TC. Copyright © 2018 Academy of Consultation-Liaison Psychiatry. Published by Elsevier Inc. All rights reserved.

Measuring Apoptosis by Microscopy and Flow Cytometry.

PubMed

Hollville, Emilie; Martin, Seamus J

2016-02-02

Apoptosis is a mode of programmed cell death that plays an important role during development and in the maintenance of tissue homeostasis. Numerous physiological as well as pathological stimuli trigger apoptosis such as engagement of Fas, TRAIL, or TNF receptors, growth factor deprivation, hypoxia, or exposure to cytotoxic drugs. Apoptosis is coordinated from within by members of the caspase family of cysteine proteases that, upon activation, trigger a series of morphological changes including cell shrinkage, extensive plasma membrane blebbing, chromatin condensation, DNA hydrolysis, and nuclear fragmentation. These dramatic structural and biochemical alterations result not only in the controlled dismantling of the cell, but also in the efficient recognition and removal of apoptotic cells by phagocytes. Necrosis, which is typically nonprogrammed or imposed upon the cell by overwhelming membrane or organelle damage, is characterized by rapid plasma membrane rupture followed by organelle and cell swelling. Necrosis is often provoked by infectious agents or a severe departure from physiological conditions. This unit describes protocols for the measurement of apoptosis and for distinguishing apoptosis from necrosis. Copyright © 2016 John Wiley & Sons, Inc.

Optical GRB Afterglows Detected with UVOT

NASA Astrophysics Data System (ADS)

Marshall, F. E.

2008-05-01

The automated response of the UltraViolet and Optical Telescope (UVOT) on Swift to new GRBs has several parameters, including exposure time, filter sequence and data mode, that can be adjusted to optimize the science return of early afterglow observations. After some initial changes, the response has remained stable since March 15, 2006. From then through August 10, 2007, UVOT observed 122 of the 130 GRBs detected with Swift's Burst Alert Telescope (BAT). UVOT typically takes an initial 100-s exposure with the White filter (160-650 nm) starting 60-180 s after the trigger and then takes exposures with the other 6 filters. In its first finding chart exposure UVOT detected 39% of the 84 long (T90>2.0 s) GRBs that were not heavily reddened in the Milky Way (EB-V<0.5) and were observed within 500 seconds of the trigger. Another 4% were detected after including subsequent exposures. Afterglow magnitudes ranged from 12.8 to the sensitivity limit of ~21. Only 1 of 11 short GRBs were detected, and its magnitude was near the sensitivity limit. We also report correlations of afterglow magnitudes with other GRB properties.

Current Multistage Drug Delivery Systems Based on the Tumor Microenvironment.

PubMed

Chen, Binlong; Dai, Wenbing; He, Bing; Zhang, Hua; Wang, Xueqing; Wang, Yiguang; Zhang, Qiang

2017-01-01

The development of traditional tumor-targeted drug delivery systems based on EPR effect and receptor-mediated endocytosis is very challenging probably because of the biological complexity of tumors as well as the limitations in the design of the functional nano-sized delivery systems. Recently, multistage drug delivery systems (Ms-DDS) triggered by various specific tumor microenvironment stimuli have emerged for tumor therapy and imaging. In response to the differences in the physiological blood circulation, tumor microenvironment, and intracellular environment, Ms-DDS can change their physicochemical properties (such as size, hydrophobicity, or zeta potential) to achieve deeper tumor penetration, enhanced cellular uptake, timely drug release, as well as effective endosomal escape. Based on these mechanisms, Ms-DDS could deliver maximum quantity of drugs to the therapeutic targets including tumor tissues, cells, and subcellular organelles and eventually exhibit the highest therapeutic efficacy. In this review, we expatiate on various responsive modes triggered by the tumor microenvironment stimuli, introduce recent advances in multistage nanoparticle systems, especially the multi-stimuli responsive delivery systems, and discuss their functions, effects, and prospects.

Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bortolon, A.; Maingi, R.; Mansfield, D. K.

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 10 19 m –3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation.more » Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.« less

Intermittent bursts induced by double tearing mode reconnection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Lai; Wang, Zheng-Xiong, E-mail: zxwang@dlut.edu.cn

Reversed magnetic shear (RMS) configuration is assumed to be the steady-state operation scenario for the future advanced tokamaks like International Thermonuclear Experimental Reactor. In this work, we numerically discover a phenomenon of violent intermittent bursts induced by self-organized double tearing mode (DTM) reconnection in the RMS configuration during the very long evolution, which may continuously lead to annular sawtooth crashes and thus badly impact the desired steady-state operation of the future advanced RMS tokamaks. The key process of the intermittent bursts in the off-axis region is similar to that of the typical sawtooth relaxation oscillation in the positive magnetic shearmore » configuration. It is interestingly found that in the decay phase of the DTM reconnection, the zonal field significantly counteracts equilibrium field to make the magnetic shear between the two rational surfaces so weak that the residual self-generated vortices of the previous DTM burst are able to trigger a reverse DTM reconnection by curling the field lines.« less

Spatio-temporal mapping of variation potentials in leaves of Helianthus annuus L. seedlings in situ using multi-electrode array

PubMed Central

Zhao, Dong-Jie; Wang, Zhong-Yi; Huang, Lan; Jia, Yong-Peng; Leng, John Q.

2014-01-01

Damaging thermal stimuli trigger long-lasting variation potentials (VPs) in higher plants. Owing to limitations in conventional plant electrophysiological recording techniques, recorded signals are composed of signals originating from all of the cells that are connected to an electrode. This limitation does not enable detailed spatio-temporal distributions of transmission and electrical activities in plants to be visualised. Multi-electrode array (MEA) enables the recording and imaging of dynamic spatio-temporal electrical activities in higher plants. Here, we used an 8 × 8 MEA with a polar distance of 450 μm to measure electrical activities from numerous cells simultaneously. The mapping of the data that were recorded from the MEA revealed the transfer mode of the thermally induced VPs in the leaves of Helianthus annuus L. seedlings in situ. These results suggest that MEA can enable recordings with high spatio-temporal resolution that facilitate the determination of the bioelectrical response mode of higher plants under stress. PMID:24961469

Spatio-temporal mapping of variation potentials in leaves of Helianthus annuus L. seedlings in situ using multi-electrode array.

PubMed

Zhao, Dong-Jie; Wang, Zhong-Yi; Huang, Lan; Jia, Yong-Peng; Leng, John Q

2014-06-25

Damaging thermal stimuli trigger long-lasting variation potentials (VPs) in higher plants. Owing to limitations in conventional plant electrophysiological recording techniques, recorded signals are composed of signals originating from all of the cells that are connected to an electrode. This limitation does not enable detailed spatio-temporal distributions of transmission and electrical activities in plants to be visualised. Multi-electrode array (MEA) enables the recording and imaging of dynamic spatio-temporal electrical activities in higher plants. Here, we used an 8 × 8 MEA with a polar distance of 450 μm to measure electrical activities from numerous cells simultaneously. The mapping of the data that were recorded from the MEA revealed the transfer mode of the thermally induced VPs in the leaves of Helianthus annuus L. seedlings in situ. These results suggest that MEA can enable recordings with high spatio-temporal resolution that facilitate the determination of the bioelectrical response mode of higher plants under stress.

Mitigation of divertor heat flux by high-frequency ELM pacing with non-fuel pellet injection in DIII-D

DOE PAGES

Bortolon, A.; Maingi, R.; Mansfield, D. K.; ...

2017-03-23

Experiments have been conducted on DIII-D investigating high repetition rate injection of non-fuel pellets as a tool for pacing Edge Localized Modes (ELMs) and mitigating their transient divertor heat loads. Effective ELM pacing was obtained with injection of Li granules in different H-mode scenarios, at frequencies 3–5 times larger than the natural ELM frequency, with subsequent reduction of strike-point heat flux. However, in scenarios with high pedestal density (~6 × 10 19 m –3), the magnitude of granule triggered ELMs shows a broad distribution, in terms of stored energy loss and peak heat flux, challenging the effectiveness of ELM mitigation.more » Furthermore, transient heat-flux deposition correlated with granule injections was observed far from the strike-points. As a result, field line tracing suggest this phenomenon to be consistent with particle loss into the mid-plane far scrape-off layer, at toroidal location of the granule injection.« less

Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms.

PubMed

de Ceglia, Domenico; Scalora, Michael; Vincenti, Maria A; Campione, Salvatore; Kelley, Kyle; Runnerstrom, Evan L; Maria, Jon-Paul; Keeler, Gordon A; Luk, Ting S

2018-06-19

Optical nonlocalities are elusive and hardly observable in traditional plasmonic materials like noble and alkali metals. Here we report experimental observation of viscoelastic nonlocalities in the infrared optical response of epsilon-near-zero nanofilms made of low-loss doped cadmium-oxide. The nonlocality is detectable thanks to the low damping rate of conduction electrons and the virtual absence of interband transitions at infrared wavelengths. We describe the motion of conduction electrons using a hydrodynamic model for a viscoelastic fluid, and find excellent agreement with experimental results. The electrons' elasticity blue-shifts the infrared plasmonic resonance associated with the main epsilon-near-zero mode, and triggers the onset of higher-order resonances due to the excitation of electron-pressure modes above the bulk plasma frequency. We also provide evidence of the existence of nonlocal damping, i.e., viscosity, in the motion of optically-excited conduction electrons using a combination of spectroscopic ellipsometry data and predictions based on the viscoelastic hydrodynamic model.

Giant thermo-optical relaxation oscillations in millimeter-size whispering gallery mode disk resonators.

PubMed

Diallo, Souleymane; Lin, Guoping; Chembo, Yanne K

2015-08-15

In this Letter, we show that giant thermo-optical oscillations can be triggered in millimeter (mm)-size whispering gallery mode (WGM) disk resonators when they are pumped by a resonant continuous-wave laser. Our resonator is an ultrahigh-Q barium fluoride cavity that features a positive thermo-optic coefficient and a negative thermo-elastic coefficient. We demonstrate for the first time, to our knowledge, that the complex interplay between these two thermic coefficients and the intrinsic Kerr nonlinearity yields very sharp slow-fast relaxation oscillations with a slow timescale that can be exceptionally large, typically of the order of 1 s. We use a time-domain model to gain understanding into this instability, and we find that both the experimental and theoretical results are in excellent agreement. The understanding of these thermal effects is an essential requirement for every WGM-related application and our study demonstrates that even in the case of mm-size resonators, such effects can still be accurately analyzed using nonlinear time-domain models.

Calibration of Herschel SPIRE FTS observations at different spectral resolutions

NASA Astrophysics Data System (ADS)

Marchili, N.; Hopwood, R.; Fulton, T.; Polehampton, E. T.; Valtchanov, I.; Zaretski, J.; Naylor, D. A.; Griffin, M. J.; Imhof, P.; Lim, T.; Lu, N.; Makiwa, G.; Pearson, C.; Spencer, L.

2017-01-01

The SPIRE Fourier Transform Spectrometer on-board the Herschel Space Observatory had two standard spectral resolution modes for science observations: high resolution (HR) and low resolution (LR), which could also be performed in sequence (H+LR). A comparison of the HR and LR resolution spectra taken in this sequential mode revealed a systematic discrepancy in the continuum level. Analysing the data at different stages during standard pipeline processing demonstrates that the telescope and instrument emission affect HR and H+LR observations in a systematically different way. The origin of this difference is found to lie in the variation of both the telescope and instrument response functions, while it is triggered by fast variation of the instrument temperatures. As it is not possible to trace the evolution of the response functions using housekeeping data from the instrument subsystems, the calibration cannot be corrected analytically. Therefore, an empirical correction for LR spectra has been developed, which removes the systematic noise introduced by the variation of the response functions.

Fast, Temperature-Sensitive and Clathrin-Independent Endocytosis at Central Synapses.

PubMed

Delvendahl, Igor; Vyleta, Nicholas P; von Gersdorff, Henrique; Hallermann, Stefan

2016-05-04

The fusion of neurotransmitter-filled vesicles during synaptic transmission is balanced by endocytotic membrane retrieval. Despite extensive research, the speed and mechanisms of synaptic vesicle endocytosis have remained controversial. Here, we establish low-noise time-resolved membrane capacitance measurements that allow monitoring changes in surface membrane area elicited by single action potentials and stronger stimuli with high-temporal resolution at physiological temperature in individual bona-fide mature central synapses. We show that single action potentials trigger very rapid endocytosis, retrieving presynaptic membrane with a time constant of 470 ms. This fast endocytosis is independent of clathrin but mediated by dynamin and actin. In contrast, stronger stimuli evoke a slower mode of endocytosis that is clathrin, dynamin, and actin dependent. Furthermore, the speed of endocytosis is highly temperature dependent with a Q10 of ∼3.5. These results demonstrate that distinct molecular modes of endocytosis with markedly different kinetics operate at central synapses. Copyright © 2016 Elsevier Inc. All rights reserved.

Strigolactones: new plant hormones in action.

PubMed

Zwanenburg, Binne; Pospíšil, Tomáš; Ćavar Zeljković, Sanja

2016-06-01

The key step in the mode of action of strigolactones is the enzymatic detachment of the D-ring. The thus formed hydroxy butenolide induces conformational changes of the receptor pocket which trigger a cascade of reactions in the signal transduction. Strigolactones (SLs) constitute a new class of plant hormones which are of increasing importance in plant science. For the last 60 years, they have been known as germination stimulants for parasitic plants. Recently, several new bio-properties of SLs have been discovered such as the branching factor for arbuscular mycorrhizal fungi, regulation of plant architecture (inhibition of bud outgrowth and of shoot branching) and the response to abiotic factors, etc. To broaden horizons and encourage new ideas for identifying and synthesising new and structurally simple SLs, this review is focused on molecular aspects of this new class of plant hormones. Special attention has been given to structural features, the mode of action of these phytohormones in various biological actions, the design of SL analogs and their applications.

Subduction of a low-salinity water mass around the Xisha Islands in the South China Sea.

PubMed

Huang, Zhida; Zhuang, Wei; Liu, Hailong; Hu, Jianyu

2018-02-15

Based on three climatologically observed temperature and salinity datasets (i.e., GDEM-V3, SCSPOD14 and WOA13), this paper reports a low-salinity (~34.32) water mass in the subsurface-to-intermediate layer around the Xisha Islands in the South China Sea. This water mass mainly subducts from the surface layer into the intermediate layer, characterized by a relatively low potential vorticity tongue extending from the bottom of mixed layer to the thermocline, and accompanied by a thermocline ventilation in spring (especially in April). The potential dynamics are the joint effects of negative wind stress curl, and an anticyclonic eddy triggered by the inherent topographic effect of the Xisha Islands, reflecting that downward vertical motion dominates the subduction. Despite lacking of the homogenous temperature and density, the low-salinity water mass is to some extent similar to the classic mode water and can be regarded as a deformed mode water in the South China Sea.

Investigation of numerical simulation on all-optical flip-flop stability maps of 1550nm vertical-cavity surface-emitting laser

NASA Astrophysics Data System (ADS)

Li, Jun; Xia, Qing; Wang, Xiaofa

2017-10-01

Based on the extended spin-flip model, the all-optical flip-flop stability maps of the 1550nm vertical-cavity surface-emitting laser have been studied. Theoretical results show that excellent agreement is found between theoretical and the reported experimental results in polarization switching point current which is equal to 1.95 times threshold. Furthermore, the polarization bistable region is wide which is from 1.05 to 1.95 times threshold. A new method is presented that uses power difference between two linear polarization modes as the judging criterion of trigger degree and stability maps of all-optical flip-flop operation under different injection parameters are obtained. By alternately injecting set and reset pulse with appropriate parameters, the mutual conversion switching between two polarization modes is realized, the feasibility of all-optical flip-flop operation is checked theoretically. The results show certain guiding significance on the experimental study on all optical buffer technology.

Counterstreaming beams and flat-top electron distributions observed with Langmuir, Whistler, and compressional Alfvén waves in earth's magnetic tail.

PubMed

Teste, Alexandra; Parks, George K

2009-02-20

Relevant new clues to wave-particle interactions have been obtained in Earth's plasma sheet (PS). The plasma measurements made on Cluster spacecraft show that broadband (approximately 2-6 kHz) electrostatic emissions, in the PS boundary layer, are associated with cold counterstreaming electrons flowing at 5-12x10(3) km s(-1) through hot Maxwellian plasma. In the current sheet (CS), electromagnetic whistler mode waves (approximately 10-80 Hz) and compressional Alfvén waves (<2 Hz) are detected with flat-topped electron distributions whose cutoff speeds are approximately 15-17x10(3) km s(-1). These waves are damped in the central CS where |B|

Intermittent bursts induced by double tearing mode reconnection

NASA Astrophysics Data System (ADS)

Wei, Lai; Wang, Zheng-Xiong

2014-06-01

Reversed magnetic shear (RMS) configuration is assumed to be the steady-state operation scenario for the future advanced tokamaks like International Thermonuclear Experimental Reactor. In this work, we numerically discover a phenomenon of violent intermittent bursts induced by self-organized double tearing mode (DTM) reconnection in the RMS configuration during the very long evolution, which may continuously lead to annular sawtooth crashes and thus badly impact the desired steady-state operation of the future advanced RMS tokamaks. The key process of the intermittent bursts in the off-axis region is similar to that of the typical sawtooth relaxation oscillation in the positive magnetic shear configuration. It is interestingly found that in the decay phase of the DTM reconnection, the zonal field significantly counteracts equilibrium field to make the magnetic shear between the two rational surfaces so weak that the residual self-generated vortices of the previous DTM burst are able to trigger a reverse DTM reconnection by curling the field lines.

Low-intensity focused ultrasound (LIFU)-induced acoustic droplet vaporization in phase-transition perfluoropentane nanodroplets modified by folate for ultrasound molecular imaging.

PubMed

Liu, Jianxin; Shang, Tingting; Wang, Fengjuan; Cao, Yang; Hao, Lan; Ren, JianLi; Ran, Haitao; Wang, Zhigang; Li, Pan; Du, Zhiyu

2017-01-01

The commonly used ultrasound (US) molecular probes, such as targeted microbubbles and perfluorocarbon emulsions, present a number of inherent problems including the conflict between US visualization and particle penetration. This study describes the successful fabrication of phase changeable folate-targeted perfluoropentane nanodroplets (termed FA-NDs), a novel US molecular probe for tumor molecular imaging with US. Notably, these FA-NDs can be triggered by low-intensity focused US (LIFU) sonication, providing excellent US enhancement in B-mode and contrast-enhanced US mode in vitro. After intravenous administration into nude mice bearing SKOV3 ovarian carcinomas, 1,1'-dioctadecyl-3,3,3',3' -tetramethylindotricarbocya-nine iodide-labeled FA-NDs were found to accumulate in the tumor region. FA-NDs injection followed by LIFU sonication exhibited remarkable US contrast enhancement in the tumor region. In conclusion, combining our elaborately developed FA-NDs with LIFU sonication provides a potential protocol for US molecular imaging in folate receptor-overexpressing tumors.

Low-intensity focused ultrasound (LIFU)-induced acoustic droplet vaporization in phase-transition perfluoropentane nanodroplets modified by folate for ultrasound molecular imaging

PubMed Central

Liu, Jianxin; Shang, Tingting; Wang, Fengjuan; Cao, Yang; Hao, Lan; Ren, JianLi; Ran, Haitao; Wang, Zhigang; Li, Pan; Du, Zhiyu

2017-01-01

The commonly used ultrasound (US) molecular probes, such as targeted microbubbles and perfluorocarbon emulsions, present a number of inherent problems including the conflict between US visualization and particle penetration. This study describes the successful fabrication of phase changeable folate-targeted perfluoropentane nanodroplets (termed FA-NDs), a novel US molecular probe for tumor molecular imaging with US. Notably, these FA-NDs can be triggered by low-intensity focused US (LIFU) sonication, providing excellent US enhancement in B-mode and contrast-enhanced US mode in vitro. After intravenous administration into nude mice bearing SKOV3 ovarian carcinomas, 1,1′-dioctadecyl-3,3,3′,3′ -tetramethylindotricarbocya-nine iodide-labeled FA-NDs were found to accumulate in the tumor region. FA-NDs injection followed by LIFU sonication exhibited remarkable US contrast enhancement in the tumor region. In conclusion, combining our elaborately developed FA-NDs with LIFU sonication provides a potential protocol for US molecular imaging in folate receptor-overexpressing tumors. PMID:28184161

On the correlation between phase-locking modes and Vibrational Resonance in a neuronal model

NASA Astrophysics Data System (ADS)

Morfu, S.; Bordet, M.

2018-02-01

We numerically and experimentally investigate the underlying mechanism leading to multiple resonances in the FitzHugh-Nagumo model driven by a bichromatic excitation. Using a FitzHugh-Nagumo circuit, we first analyze the number of spikes triggered by the system in response to a single sinusoidal wave forcing. We build an encoding diagram where different phase-locking modes are identified according to the amplitude and frequency of the sinusoidal excitation. Next, we consider the bichromatic driving which consists in a low frequency sinusoidal wave perturbed by an additive high frequency signal. Beside the classical Vibrational Resonance phenomenon, we show in real experiments that multiple resonances can be reached by an appropriate setting of the perturbation parameters. We clearly establish a correlation between these resonances and the encoding diagram of the low frequency signal free FitzHugh-Nagumo model. We show with realistic parameters that sharp transitions of the encoding diagram allow to predict the main resonances. Our experiments are confirmed by numerical simulations of the system response.

Anisotropic MoS2 Nanosheets Grown on Self-Organized Nanopatterned Substrates.

PubMed

Martella, Christian; Mennucci, Carlo; Cinquanta, Eugenio; Lamperti, Alessio; Cappelluti, Emmanuele; Buatier de Mongeot, Francesco; Molle, Alessandro

2017-05-01

Manipulating the anisotropy in 2D nanosheets is a promising way to tune or trigger functional properties at the nanoscale. Here, a novel approach is presented to introduce a one-directional anisotropy in MoS 2 nanosheets via chemical vapor deposition (CVD) onto rippled patterns prepared on ion-sputtered SiO 2 /Si substrates. The optoelectronic properties of MoS 2 are dramatically affected by the rippled MoS 2 morphology both at the macro- and the nanoscale. In particular, strongly anisotropic phonon modes are observed depending on the polarization orientation with respect to the ripple axis. Moreover, the rippled morphology induces localization of strain and charge doping at the nanoscale, thus causing substantial redshifts of the phonon mode frequencies and a topography-dependent modulation of the MoS 2 workfunction, respectively. This study paves the way to a controllable tuning of the anisotropy via substrate pattern engineering in CVD-grown 2D nanosheets. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sneaker Male Squid Produce Long-lived Spermatozoa by Modulating Their Energy Metabolism *

PubMed Central

Hirohashi, Noritaka; Tamura-Nakano, Miwa; Nakaya, Fumio; Iida, Tomohiro; Iwata, Yoko

2016-01-01

Spermatozoa released by males should remain viable until fertilization. Hence, sperm longevity is governed by intrinsic and environmental factors in accordance with the male mating strategy. However, whether intraspecific variation of insemination modes can impact sperm longevity remains to be elucidated. In the squid Heterololigo bleekeri, male dimorphism (consort and sneaker) is linked to two discontinuous insemination modes that differ in place and time. Notably, only sneaker male spermatozoa inseminated long before egg spawning can be stored in the seminal receptacle. We found that sneaker spermatozoa exhibited greater persistence in fertilization competence and flagellar motility than consort ones because of a larger amount of flagellar glycogen. Sneaker spermatozoa also showed higher capacities in glucose uptake and lactate efflux. Lactic acidosis was considered to stabilize CO2-triggered self-clustering of sneaker spermatozoa, thus establishing hypoxia-induced metabolic changes and sperm survival. These results, together with comparative omics analyses, suggest that postcopulatory reproductive contexts define sperm longevity by modulating the inherent energy levels and metabolic pathways. PMID:27385589

Mechanism for verification of mismatched and homoduplex DNAs by nucleotides-bound MutS analyzed by molecular dynamics simulations.

PubMed

Ishida, Hisashi; Matsumoto, Atsushi

2016-09-01

In order to understand how MutS recognizes mismatched DNA and induces the reaction of DNA repair using ATP, the dynamics of the complexes of MutS (bound to the ADP and ATP nucleotides, or not) and DNA (with mismatched and matched base-pairs) were investigated using molecular dynamics simulations. As for DNA, the structure of the base-pairs of the homoduplex DNA which interacted with the DNA recognition site of MutS was intermittently disturbed, indicating that the homoduplex DNA was unstable. As for MutS, the disordered loops in the ATPase domains, which are considered to be necessary for the induction of DNA repair, were close to (away from) the nucleotide-binding sites in the ATPase domains when the nucleotides were (not) bound to MutS. This indicates that the ATPase domains changed their structural stability upon ATP binding using the disordered loop. Conformational analysis by principal component analysis showed that the nucleotide binding changed modes which have structurally solid ATPase domains and the large bending motion of the DNA from higher to lower frequencies. In the MutS-mismatched DNA complex bound to two nucleotides, the bending motion of the DNA at low frequency modes may play a role in triggering the formation of the sliding clamp for the following DNA-repair reaction step. Moreover, MM-PBSA/GBSA showed that the MutS-homoduplex DNA complex bound to two nucleotides was unstable because of the unfavorable interactions between MutS and DNA. This would trigger the ATP hydrolysis or separation of MutS and DNA to continue searching for mismatch base-pairs. Proteins 2016; 84:1287-1303. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts. I. Bursts Detected in the Triggered Mode

NASA Astrophysics Data System (ADS)

Tsvetkova, A.; Frederiks, D.; Golenetskii, S.; Lysenko, A.; Oleynik, P.; Pal'shin, V.; Svinkin, D.; Ulanov, M.; Cline, T.; Hurley, K.; Aptekar, R.

2017-12-01

In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological GRBs studied to date over a broad energy band. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with two model functions, the total energy fluences, and the peak energy fluxes. Based on the GRB redshifts, which span the range 0.1≤slant z≤slant 5, we estimate the rest-frame, isotropic-equivalent energy, and peak luminosity. For 32 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. We consider the behavior of the rest-frame GRB parameters in the hardness-duration and hardness-intensity planes, and confirm the “Amati” and “Yonetoku” relations for Type II GRBs. The correction for the jet collimation does not improve these correlations for the KW sample. We discuss the influence of instrumental selection effects on the GRB parameter distributions and estimate the KW GRB detection horizon, which extends to z˜ 16.6, stressing the importance of GRBs as probes of the early universe. Accounting for the instrumental bias, we estimate the KW GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which are in general agreement with those obtained in previous studies.

Doxorubicin loaded superparamagnetic PLGA-iron oxide multifunctional microbubbles for dual-mode US/MR imaging and therapy of metastasis in lymph nodes.

PubMed

Niu, Chengcheng; Wang, Zhigang; Lu, Guangming; Krupka, Tianyi M; Sun, Yang; You, Yufang; Song, Weixiang; Ran, Haitao; Li, Pan; Zheng, Yuanyi

2013-03-01

Current strategies for tumor-induced sentinel lymph node detection and metastasis therapy have limitations. In this work, we co-encapsulated iron oxide nanoparticles and chemotherapeutic drug into poly(lactic-co-glycolic acid) (PLGA) microbubbles to form multifunctional polymer microbubbles (MPMBs) for both tumor lymph node imaging and therapy. Fe(3)O(4) nanoparticles and doxorubicin (DOX) co-encapsulated PLGA microbubbles were prepared and filled with perfluorocarbon gas. Enhancement of ultrasound (US)/magnetic resonance (MR) imaging and US triggered drug delivery were evaluated both in vitro and in vivo. The MPMBs exhibited characters like narrow size distribution and smooth surface with a mean diameter of 868.0 ± 68.73 nm. In addition, varying the concentration of Fe(3)O(4) nanoparticles in the bubbles did not significantly influence the DOX encapsulation efficiency or drug loading efficiency. Our in vitro results demonstrated that these MPMBs could enhance both US and MR imaging which was further validated in vivo showing that these MPMBs enhanced tumor lymph nodes signals. The anti-tumor effect of MPMBs mediated chemotherapy was assessed in vivo using end markers like tumor proliferation index, micro blood vessel density and micro lymphatic vessel density, which were shown consistently the lowest after the MPMBs plus sonication treatment compared to controls. In line with these findings, the tumor cell apoptotic index was found the largest after the MPMBs plus sonication treatment. In conclusion, we have successfully developed a doxorubicin loaded superparamagnetic PLGA-Iron Oxide multifunctional theranostic agent for dual-mode US/MR Imaging of lymph node, and for low frequency US triggered therapy of metastasis in lymph nodes, which might provide a strategy for the imaging and chemotherapy of primary tumor and their metastases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stochastically-forced Decadal Variability in Australian Rainfall

NASA Astrophysics Data System (ADS)

Taschetto, A.

2015-12-01

Iconic Australian dry and wet periods were driven by anomalous conditions in the tropical oceans, such as the worst short-term drought in the southeast in 1982 associated with the strong El Niño and the widespread "Big Wet" in 1974 linked with a La Niña event. The association with oceanic conditions makes droughts predictable to some extent. However, prediction can be difficult when there is no clear external forcing such as El Niños. Can dry spells be triggered and maintained with no ocean memory? In this study, we investigate the potential role of internal multi-century atmospheric variability in controlling the frequency, duration and intensity of long-term dry and wet spells over Australia. Two multi-century-scale simulations were performed with the NCAR CESM: (1) a fully-coupled simulation (CPLD) and (2) an atmospheric simulation forced by a seasonal SST climatology derived from the coupled experiment (ACGM). Results reveal that droughts and wet spells can indeed be generated by internal variability of the atmosphere. Those internally generated events are less severe than those forced by oceanic variability, however the duration of dry and wet spells longer than 3 years is comparable with and without the ocean memory. Large-scale ocean modes of variability seem to play an important role in producing continental-scale rainfall impacts over Australia. While the Pacific Decadal Oscillation plays an important role in generating droughts in the fully coupled model, perturbations of monsoonal winds seem to be the main trigger of dry spells in the AGCM case. Droughts in the mid-latitude regions such as Tasmania can be driven by perturbations in the Southern Annular Mode, not necessarily linked to oceanic conditions even in the fully-coupled model. The mechanisms behind internally-driven mega-droughts and mega-wets will be discussed.

Curcumin induces the apoptotic intrinsic pathway via upregulation of reactive oxygen species and JNKs in H9c2 cardiac myoblasts.

PubMed

Zikaki, Kyriaki; Aggeli, Ioanna-Katerina; Gaitanaki, Catherine; Beis, Isidoros

2014-06-01

Curcumin derived from the rhizome of turmeric (Curcuma longa L.), is a well known coloring culinary agent, that has therapeutic properties against diverse pathologies such as cancer, atherosclerosis and heart failure. Given the salutary potential of curcumin, deciphering its mode of action particularly in cardiac cells, is of outstanding value. Accumulating evidence implicates curcumin in the regulation of multiple signaling pathways leading to cell survival or apoptosis. Therefore, the present study aimed at elucidating the molecular mechanisms triggered by curcumin in H9c2 cells. Curcumin was found to activate p38-mitogen-activated protein kinase (p38-MAPK) as well as c-jun NH2 terminal kinases (JNKs), in a dose- and time-dependent manner. We also observed curcumin to impair cell survival by promoting apoptosis, evidenced by chromatin condensation, poly(ADP-ribose) polymerase (PARP) and caspase-3 cleavage, as well as Bax translocation and cytochrome c release into the cytosol. Curcumin-induced apoptosis was ascribed to JNKs, since hindering their activity abolished PARP fragmentation. Furthermore, we identified curcumin to exert a pro-oxidative activity, with 2',7'-dichlorofluorescin diacetate (DCFH-DA) staining revealing up-regulation of reactive oxygen species (ROS) levels and anti-oxidants found to abrogate PARP cleavage. In conclusion, curcumin was found to stimulate the apoptotic cell death of H9c2 cells by upregulating ROS generation and triggering activation of JNKs. With reports underscoring the capacity of curcumin to perturb the cellular redox balance ensuring survival or enhancing apoptosis, determination of its mode of action appears to be critical. Future studies should assess the appropriate administration conditions of curcumin, so as to optimize its therapeutic potential against cardiovascular pathologies.

Mechanics of rainfall-induced flow failure in unsaturated shallow slopes (Invited)

NASA Astrophysics Data System (ADS)

Buscarnera, G.

2013-12-01

The increase in pore water pressure due to rain infiltration can be a dominant component in the activation of slope instabilities. This work shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of rain infiltration promotes instabilities of the flow-type in the soil covers. The interplay between increase in pore water pressure and failure mechanisms is investigated at material point level. To account for multiple failure mechanisms, the second-order energy input is linked to the controllability theory and used to define different types of stability indices, each associated with a specific mode of slope failure. It is shown that the theory can be used to assess both shear failure and static liquefaction in saturated and unsaturated soil covers. In particular, it is shown that these instability modes are regulated by the hydro-mechanical characteristics of the soil covers, as well as by their mutual coupling. This finding discloses the importance of the constitutive functions that simulate the interaction between the response of the solid skeleton and the fluid-retention characteristics of the soil. As a consequence, they suggest that even material properties that are not be to directly associated with the shearing resistance (e.g., the potential for wetting compaction) may play a role in the initiation of catastrophic slope failures. According to the proposed interpretation, the process of pore pressure increase can be seen as the trigger of uncontrolled strains, which can anticipate the onset of frictional failure and promote a solid-to-fluid transition.

Clustering, Cosmology and a New Era of Black Hole Demographics: The Conditional Luminosity Function of AGNs

NASA Astrophysics Data System (ADS)

Ballantyne, David R.

2016-04-01

Deep X-ray surveys have provided a comprehensive and largely unbiased view of AGN evolution stretching back to z˜5. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, we present a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific z. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function - all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method is demonstrated at z ≈0 and 0.9, and clear luminosity dependence in the AGN bias and mean halo mass is predicted at both z. The results support the idea that there are at least two different modes of AGN triggering: one, at high luminosity, that only occurs in high mass, highly biased haloes, and one that can occur over a wide range of halo masses and leads to luminosities that are correlated with halo mass. This latter mode dominates at z<0.9. The CLFs for Type 2 and Type 1 AGNs are also constrained at z ≈0, and we find evidence that unobscured quasars are more likely to be found in higher mass halos than obscured quasars. Thus, the AGN unification model seems to fail at quasar luminosities.

Magnetometer Application for GAMMA-400 Telescope Switching into the Mode with Increased Low Energy Charged Particles Intensity Registration

NASA Astrophysics Data System (ADS)

Khyzhniak, E. V.; Arkhangelskaja, I. V.; Chasovikov, E. N.; Arkhangelskiy, A. I.; Topchiev, N. P.

GAMMA-400 is an international project of a high apogee orbital astrophysical observatory for studying the characteristics of high-energy gamma-emission, electrons/positrons and light nuclei fluxes. The energy range for γ-rays and electrons/positrons registration in the main aperture is from ∼0.1 GeV to ∼3.0 TeV. Also, this aperture allows high energy light nuclei fluxes characteristics investigation. Moreover, special aperture configuration allows registering of gamma-quanta, electrons (positrons) and light nuclei from the lateral directions too. The spacecraft GAMMA-400 orbit will be located in the Earth's magnetosphere and will pass front shock wave from magnetosphere interaction with the solar wind, turbulent-transition region, magnetopause and so on. During the satellite's movement through various Earth's magnetosphere regions its anticoincidence detectors will register high intensity fluxes of low energy charged particles captured by the magnetic field. The working area sections of GAMMA-400 detector systems used as anticoincidence shield are about 1 m2 each. The high intensity low energy charged particles flux influence on anticoincidence detectors should be taken into account during particle identification. This article presents a comparison between Earth's magnetosphere theoretical model according to SPENVIIS package and real data measured by detectors onboard THEMIS series satellites. The differences between these two datasets indicate that the calculated data are not sufficient to make short time predictions of variations of magnetic induction in the outer magnetosphere. A special trigger marker flag will be produced by GAMMA-400 counting and triggers signals formation system accordingly to the data of two onboard magnetometers. This flag's presence leads to special algorithms execution start, putting the plastic detectors into a dedicated working mode taking into account possible high count rates of external detector layers.

Structure and Mode-of-Action of the Two-Peptide (Class-IIb) Bacteriocins.

PubMed

Nissen-Meyer, Jon; Oppegård, Camilla; Rogne, Per; Haugen, Helen Sophie; Kristiansen, Per Eugen

2010-03-01

This review focuses on the structure and mode-of-action of the two-peptide (class-IIb) bacteriocins that consist of two different peptides whose genes are next to each other in the same operon. Optimal antibacterial activity requires the presence of both peptides in about equal amounts. The two peptides are synthesized as preforms that contain a 15-30 residue double-glycine-type N-terminal leader sequence that is cleaved off at the C-terminal side of two glycine residues by a dedicated ABC-transporter that concomitantly transfers the bacteriocin peptides across cell membranes. Two-peptide bacteriocins render the membrane of sensitive bacteria permeable to a selected group of ions, indicating that the bacteriocins form or induce the formation of pores that display specificity with respect to the transport of molecules. Based on structure-function studies, it has been proposed that the two peptides of two-peptide bacteriocins form a membrane-penetrating helix-helix structure involving helix-helix-interacting GxxxG-motifs that are present in all characterized two-peptide bacteriocins. It has also been suggested that the membrane-penetrating helix-helix structure interacts with an integrated membrane protein, thereby triggering a conformational alteration in the protein, which in turn causes membrane-leakage. This proposed mode-of-action is similar to the mode-of-action of the pediocin-like (class-IIa) bacteriocins and lactococcin A (a class-IId bacteriocin), which bind to a membrane-embedded part of the mannose phosphotransferase permease in a manner that causes membrane-leakage and cell death.

Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall

NASA Astrophysics Data System (ADS)

Bowman, C.; Dickinson, D.; Horvath, L.; Lunniss, A. E.; Wilson, H. R.; Cziegler, I.; Frassinetti, L.; Gibson, K.; Kirk, A.; Lipschultz, B.; Maggi, C. F.; Roach, C. M.; Saarelma, S.; Snyder, P. B.; Thornton, A.; Wynn, A.; Contributors, JET

2018-01-01

The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that controls the evolution of the JET pedestal between ELMs is analysed for 1.4 MA, 1.7 T, low triangularity, δ  =  0.2, discharges with the ITER-like wall, finding that the pressure gradient typically tracks the ideal magneto-hydrodynamic ballooning limit, consistent with a role for the kinetic ballooning mode. Furthermore, the pedestal width is often influenced by the region of plasma that has second stability access to the ballooning mode, which can explain its sometimes complex evolution between ELMs. A local gyrokinetic analysis of a second stable flux surface reveals stability to kinetic ballooning modes; global effects are expected to provide a destabilising mechanism and need to be retained in such second stable situations. As well as an electron-scale electron temperature gradient mode, ion scale instabilities associated with this flux surface include an electro-magnetic trapped electron branch and two electrostatic branches propagating in the ion direction, one with high radial wavenumber. In these second stability situations, the ELM is triggered by a peeling-ballooning mode; otherwise the pedestal is somewhat below the peeling-ballooning mode marginal stability boundary at ELM onset. In this latter situation, there is evidence that higher frequency ELMs are paced by an oscillation in the plasma, causing a crash in the pedestal before the peeling-ballooning boundary is reached. A model is proposed in which the oscillation is associated with hot plasma filaments that are pushed out towards the plasma edge by a ballooning mode, draining their free energy into the cooler plasma there, and then relaxing back to repeat the process. The results suggest that avoiding the oscillation and maximising the region of plasma that has second stability access will lead to the highest pedestal heights and, therefore, best confinement—a key result for optimising the fusion performance of JET and future tokamaks, such as ITER.

New cryogenic temperature monitor: PLT-HPT-32

NASA Astrophysics Data System (ADS)

Viera Curbelo, Teodora Aleida; Martín-Fernández, Sergio Gonzáles; Hoyland, R.; Vega-Moreno, A.; Cozar Castellano, Juan; Gómez Reñasco, M. F.; Aguiar-González, M.; Pérez de Taoro, Angeles; Sánchez-de la Rosa, V.; Rubiño-Martín, J. A.; Génova-Santos, R.

2016-07-01

The PLT-HPT-32, a new cryogenic temperature monitor, has been developed by the Institute of Astrophysics of the Canary Islands (IAC) and an external engineering company (Sergio González Martín-Fernandez). The PLT-HPT-32 temperature monitor offers precision measurement in a wide range of cryogenic and higher-temperature applications with the ability to easily monitor up to 32 sensor channels. It provides better measurement performance in applications where researchers need to ensure accuracy and precision in their low cryogenic temperature monitoring. The PLT-HPT-32 supports PTC RTDs such as platinum sensors, and diodes such as the Lake Shore DT-670 Series. Used with silicon diodes, it provides accurate measurements in cryo-cooler applications from 16 K to above room temperature. The resolution of the measurement is less than 0.1K. Measurements can be displayed in voltage units or Kelvin units. For it, two different tables can be used. One can be programmed by the user, and the other one corresponds to Lake Shore DT670 sensor that comes standard. There are two modes of measuring, the instantaneous mode and averaged mode. In this moment, all channels must work in the same mode but in the near future it expected to be used in blocks of eight channels. The instantaneous mode takes three seconds to read all channels. The averaged mode takes one minute to average twenty samples in all channels. Alarm thresholds can be configured independently for each input. The alarm events, come from the first eight channels, can activate the unit's relay outputs for hard-wired triggering of other systems or audible annunciators. Activate relays on high, low, or both alarms for any input. For local monitoring, "Stand-Alone Mode", the front panel of the PLT-HPT-32 features a bright liquid crystal display with an LED backlight that shows up to 32 readings simultaneously. Plus, monitoring can be done over a network "Remote Control Mode". Using the Ethernet port on the PLT-HPT-32, you can keep an eye on temperatures, log measurement and configured remotely via a Networked local PC or even remotely over a TCP/IP Internet connection from anywhere.

Development of robust and multi-mode control of tearing in DIII-D

DOE PAGES

Welander, A. S.; La Haye, R.J.; Humphreys, D. A.; ...

2016-06-02

Neoclassical tearing modes (NTMs) are instabilities that can produce undesirable magnetic islands in tokamak plasmas. They can be stabilized by applying electron cyclotron current drive (ECCD) at the island. The NTM control system on DIII-D can now control multiple modes. Each of 6 mirrors that reflect ECCD beams into the plasma can be assigned to different surfaces in the plasma where NTMs are unstable. The control system then steers the mirrors to keep the beams aimed at the surfaces. The system routinely stabilizes one NTM preemptively and has now also been used to control two modes in the same discharge.more » With the “catch-and-subdue” function, ECCD-generating gyrotrons can be turned on when NTMs appear and off after suppression. Newly triggered NTMs can be promptly suppressed if mode onset is detected early and ECCD immediately applied. Early mode detection is achieved in this paper by spectral analysis of Mirnov probes with a band-pass filter for the expected mode frequency. Targeted surfaces are tracked by equilibrium reconstructions (that include measurements of the motional Stark effect). The ECCD position is tracked by ray-tracing using the TORBEAM code. Several techniques are being explored for fine-tuning alignment when NTMs occur. One method adjusts ECCD alignment in steps until the island decays fast enough. A second method sweeps the alignment to find the optimum. A third method pulses gyrotrons and uses electron cyclotron emission to compare where the resulting temperature pulses are relative to temperature fluctuations from a rotating NTM. NTM control in ITER is expected to use active profile regulation to maximize controllability, followed by repeated catch-and-subdue actions if modes are retriggered, in order to maintain island size below the disruptive threshold while maximizing confinement and fusion gain. Between events, real-time tracking will be performed to maintain alignment and readiness for subsequent catch-andsubdue actions. Methods for active probing of stability boundaries will be studied as possible diagnostics for the profile regulation. Finally, selected elements of this ITER NTM control vision will be discussed and assessed.« less

Triggered instabilities in rocket motors and active combustion control for an incinerator afterburner

NASA Astrophysics Data System (ADS)

Wicker, Josef M.

1999-11-01

Two branches of research are conducted in this thesis. The first deals with nonlinear combustion response as a mechanism for triggering combustion instabilities in solid rocket motors. A nonlinear wave equation is developed to study a wide class of combustion response functions to second-order in fluctuation amplitude. Conditions for triggering are derived from analysis of limit cycles, and regions of triggering are found in parametric space. Introduction of linear cross-coupling and quadratic self-coupling among the acoustic modes appears to be how the nonlinear combustion response produces triggering to a stable limit cycle. Regions of initial conditions corresponding to stable pulses were found, suggesting that stability depends on initial phase angle and harmonic content, as well as the composite amplitude, of the pulse. Also, dependence of nonlinear stability upon system parameters is considered. The second part of this thesis presents research for a controller to improve the emissions of an incinerator afterburner. The developed controller was experimentally tested at the Naval Air Warfare Center (NAWC), on a 50kW-scale model of an afterburner for Naval shipboard incinerator applications. Acoustic forcing of the combustor's reacting shear layer is used to control the formation of coherent vortical structures, within which favorable fuel-air mixing and efficient combustion can occur. Laser-based measurements of CO emissions are used as the performance indicator for the combustor. The controller algorithm is based on the downhill simplex method and adjusts the shear layer forcing parameters in order to minimize the CO emissions. The downhill simplex method was analyzed with respect to its behavior in the face of time-variation of the plant and noise in the sensor signal, and was modified to account for these difficulties. The control system has experimentally demonstrated the ability (1) to find optimal control action for single- and multi-variable control, (2) to maintain optimal control for time-varying operating states, and (3) to automatically adjust auxiliary fuel in response to changing stoichiometry of the incoming waste pyrolysis gas. Also presented but not tested in the experiments are an expert-type model-guidance feature to aid convergence of the controller to optimum control, and methodology for maintaining flammability.

Investigation of MHD instabilities and control in KSTAR preparing for high beta operation

NASA Astrophysics Data System (ADS)

Park, Y. S.; Sabbagh, S. A.; Bialek, J. M.; Berkery, J. W.; Lee, S. G.; Ko, W. H.; Bak, J. G.; Jeon, Y. M.; Park, J. K.; Kim, J.; Hahn, S. H.; Ahn, J.-W.; Yoon, S. W.; Lee, K. D.; Choi, M. J.; Yun, G. S.; Park, H. K.; You, K.-I.; Bae, Y. S.; Oh, Y. K.; Kim, W.-C.; Kwak, J. G.

2013-08-01

Initial H-mode operation of the Korea Superconducting Tokamak Advanced Research (KSTAR) is expanded to higher normalized beta and lower plasma internal inductance moving towards design target operation. As a key supporting device for ITER, an important goal for KSTAR is to produce physics understanding of MHD instabilities at long pulse with steady-state profiles, at high normalized beta, and over a wide range of plasma rotation profiles. An advance from initial plasma operation is a significant increase in plasma stored energy and normalized beta, with Wtot = 340 kJ, βN = 1.9, which is 75% of the level required to reach the computed ideal n = 1 no-wall stability limit. The internal inductance was lowered to 0.9 at sustained H-mode duration up to 5 s. In ohmically heated plasmas, the plasma current reached 1 MA with prolonged pulse length up to 12 s. Rotating MHD modes are observed in the device with perturbations having tearing rather than ideal parity. Modes with m/n = 3/2 are triggered during the H-mode phase but are relatively weak and do not substantially reduce Wtot. In contrast, 2/1 modes to date only appear when the plasma rotation profiles are lowered after H-L back-transition. Subsequent 2/1 mode locking creates a repetitive collapse of βN by more than 50%. Onset behaviour suggests the 3/2 mode is close to being neoclassically unstable. A correlation between the 2/1 mode amplitude and local rotation shear from an x-ray imaging crystal spectrometer suggests that the rotation shear at the mode rational surface is stabilizing. As a method to access the ITER-relevant low plasma rotation regime, plasma rotation alteration by n = 1, 2 applied fields and associated neoclassical toroidal viscosity (NTV) induced torque is presently investigated. The net rotation profile change measured by a charge exchange recombination diagnostic with proper compensation of plasma boundary movement shows initial evidence of non-resonant rotation damping by the n = 1, 2 applied field configurations. The result addresses perspective on access to low rotation regimes for MHD instability studies applicable to ITER. Computation of active RWM control using the VALEN-3D code examines control performance using midplane locked mode detection sensors. The LM sensors are found to be strongly affected by mode and control coil-induced vessel current, and consequently lead to limited control performance theoretically.

Combined Effects of Ventilation Mode and Positive End-Expiratory Pressure on Mechanics, Gas Exchange and the Epithelium in Mice with Acute Lung Injury

PubMed Central

Thammanomai, Apiradee; Hamakawa, Hiroshi; Bartolák-Suki, Erzsébet; Suki, Béla

2013-01-01

The accepted protocol to ventilate patients with acute lung injury is to use low tidal volume (VT) in combination with recruitment maneuvers or positive end-expiratory pressure (PEEP). However, an important aspect of mechanical ventilation has not been considered: the combined effects of PEEP and ventilation modes on the integrity of the epithelium. Additionally, it is implicitly assumed that the best PEEP-VT combination also protects the epithelium. We aimed to investigate the effects of ventilation mode and PEEP on respiratory mechanics, peak airway pressures and gas exchange as well as on lung surfactant and epithelial cell integrity in mice with acute lung injury. HCl-injured mice were ventilated at PEEPs of 3 and 6 cmH2O with conventional ventilation (CV), CV with intermittent large breaths (CVLB) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VVN). Mechanics and gas exchange were measured during ventilation and surfactant protein (SP)-B, proSP-B and E-cadherin levels were determined from lavage and lung homogenate. PEEP had a significant effect on mechanics, gas exchange and the epithelium. The higher PEEP reduced lung collapse and improved mechanics and gas exchange but it also down regulated surfactant release and production and increased epithelial cell injury. While CVLB was better than CV, VVN outperformed CVLB in recruitment, reduced epithelial injury and, via a dynamic mechanotransduction, it also triggered increased release and production of surfactant. For long-term outcome, selection of optimal PEEP and ventilation mode may be based on balancing lung physiology with epithelial injury. PMID:23326543

Search for Gravitational Wave Bursts from Six Magnetars

NASA Astrophysics Data System (ADS)

Abadie, J.; Abbott, B. P.; Abbott, R.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Antonucci, F.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Barker, D.; Barnum, S.; Barone, F.; Barr, B.; Barriga, P.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Bauchrowitz, J.; Bauer, Th. S.; Behnke, B.; Beker, M. G.; Bell, A. S.; Belletoile, A.; Belopolski, I.; Benacquista, M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birindelli, S.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Boyle, M.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brummit, A.; Budzyński, R.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cain, J.; Calloni, E.; Camp, J. B.; Campagna, E.; Campsie, P.; Cannizzo, J.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chaibi, O.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chassande-Mottin, E.; Chelkowski, S.; Chen, Y.; Chincarini, A.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Clara, F.; Clark, D.; Clark, J.; Clayton, J. H.; Cleva, F.; Coccia, E.; Colacino, C. N.; Colas, J.; Colla, A.; Colombini, M.; Conte, R.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Culter, R. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; D'Antonio, S.; Danzmann, K.; Das, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; del Prete, M.; Dent, T.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Emilio, M. Di Paolo; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Dorsher, S.; Douglas, E. S. D.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Engel, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Flaminio, R.; Flanigan, M.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garofoli, J. A.; Garufi, F.; Gáspár, M. E.; Gemme, G.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Greverie, C.; Grosso, R.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Hayler, T.; Heefner, J.; Heitmann, H.; Hello, P.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Hosken, D. J.; Hough, J.; Howell, E. J.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Jaranowski, P.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Kelner, M.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, H.; Kim, N.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, R.; Kwee, P.; Landry, M.; Lantz, B.; Lastzka, N.; Lazzarini, A.; Leaci, P.; Leong, J.; Leonor, I.; Leroy, N.; Letendre, N.; Li, J.; Li, T. G. F.; Liguori, N.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lu, P.; Luan, J.; Lubiński, M.; Lück, H.; Lundgren, A. P.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marandi, A.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McKechan, D. J. A.; Meadors, G.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Mercer, R. A.; Merill, L.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mino, Y.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Moesta, P.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mosca, S.; Moscatelli, V.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murray, P. G.; Nash, T.; Nawrodt, R.; Nelson, J.; Neri, I.; Newton, G.; Nishida, E.; Nishizawa, A.; Nocera, F.; Nolting, D.; Ochsner, E.; O'Dell, J.; Ogin, G. H.; Oldenburg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Pagliaroli, G.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Papa, M. A.; Parameswaran, A.; Pardi, S.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patel, P.; Pathak, D.; Pedraza, M.; Pekowsky, L.; Penn, S.; Peralta, C.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pietka, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Podkaminer, J.; Poggiani, R.; Pöld, J.; Postiglione, F.; Prato, M.; Predoi, V.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C. R.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Redwine, K.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, P.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rolland, L.; Rollins, J.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sakata, S.; Sakosky, M.; Salemi, F.; Salit, M.; Sammut, L.; Sancho de la Jordana, L.; Sandberg, V.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saraf, S.; Sassolas, B.; Sathyaprakash, B. S.; Sato, S.; Satterthwaite, M.; Saulson, P. R.; Savage, R.; Schilling, R.; Schlamminger, S.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Searle, A. C.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shihan Weerathunga, T.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, N. D.; Smith, R.; Somiya, K.; Sorazu, B.; Soto, J.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Stein, A. J.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szokoly, G. P.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, J. R.; Taylor, R.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Trias, M.; Tseng, K.; Turner, L.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vaishnav, B.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Veltkamp, C.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vocca, H.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Wanner, A.; Ward, R. L.; Was, M.; Wei, P.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wen, S.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, H. R.; Williams, L.; Willke, B.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yu, P.; Yvert, M.; Zanolin, M.; Zhang, L.; Zhang, Z.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Aptekar, R. L.; Boynton, W. V.; Briggs, M. S.; Cline, T. L.; Connaughton, V.; Frederiks, D. D.; Gehrels, N.; Goldsten, J. O.; Golovin, D.; van der Horst, A. J.; Hurley, K. C.; Kaneko, Y.; von Kienlin, A.; Kouveliotou, C.; Krimm, H. A.; Lin, L.; Mitrofanov, I.; Ohno, M.; Pal'shin, V. D.; Rau, A.; Sanin, A.; Tashiro, M. S.; Terada, Y.; Yamaoka, K.

2011-06-01

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >1044 erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 × 1044 d 2 1 erg and 1.4 × 1047 d 2 1 erg, respectively, where d_{1} = \\frac{d_{{0501}}}{1\\,{kpc}} and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.

Interactive simulation system for artificial ventilation on the internet: virtual ventilator.

PubMed

Takeuchi, Akihiro; Abe, Tadashi; Hirose, Minoru; Kamioka, Koichi; Hamada, Atsushi; Ikeda, Noriaki

2004-12-01

To develop an interactive simulation system "virtual ventilator" that demonstrates the dynamics of pressure and flow in the respiratory system under the combination of spontaneous breathing, ventilation modes, and ventilator options. The simulation system was designed to be used by unexperienced health care professionals as a self-training tool. The system consists of a simulation controller and three modules: respiratory, spontaneous breath, and ventilator. The respiratory module models the respiratory system by three resistances representing the main airway, the right and left lungs, and two compliances also representing the right and left lungs. The spontaneous breath module generates inspiratory negative pressure produced by a patient. The ventilator module generates driving force of pressure or flow according to the combination of the ventilation mode and options. These forces are given to the respiratory module through the simulation controller. The simulation system was developed using HTML, VBScript (3000 lines, 100 kB) and ActiveX control (120 kB), and runs on Internet Explorer (5.5 or higher). The spontaneous breath is defined by a frequency, amplitude and inspiratory patterns in the spontaneous breath module. The user can construct a ventilation mode by setting a control variable, phase variables (trigger, limit, and cycle), and options. Available ventilation modes are: controlled mechanical ventilation (CMV), continuous positive airway pressure, synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), SIMV + PSV, pressure-controlled ventilation (PCV), pressure-regulated volume control (PRVC), proportional assisted ventilation, mandatory minute ventilation (MMV), bilevel positive airway pressure (BiPAP). The simulation system demonstrates in a graph and animation the airway pressure, flow, and volume of the respiratory system during mechanical ventilation both with and without spontaneous breathing. We developed a web application that demonstrated the respiratory mechanics and the basic theory of ventilation mode.

Theoretical and experimental study of bent fully aperiodic large-pitch fibers for enhancing the high-order modes delocalization

NASA Astrophysics Data System (ADS)

du Jeu, Rémi; Dauliat, Romain; Darwich, Dia; Auguste, Jean-Louis; Benoît, Aurélien; Leconte, Baptiste; Malleville, Marie-Alicia; Jamier, Raphaël.; Schuster, Kay; Roy, Philippe

2018-02-01

The power scaling of fiber lasers and amplifiers has triggered an extensive development of large-mode area fibers among which the most promising are the distributed mode filtering fibers and the large-pitch fibers. These structures enable for an effective higher-order modes delocalization and subsequently a singlemode emission. An interesting alternative consists in using the fully-aperiodic large-pitch fibers, into which the standard air-silica photonic crystal cladding is replaced by an aperiodic pattern made of solid low-index inclusions cladding. However, in such a structure, the core and the background cladding material surrounding it must have rigorously the same refractive index. Current synthesis processes and measurement techniques offer respectively a maximum resolution of 5×10-4 and 1×10-4 while the indexmatching must be as precise as 1×10-5 . Lately a gain material with a refractive index 1.5×10-4 higher than that of the background cladding material was fabricated, thus re-confining the first higher-order modes in the core. A numerical study is carried out on the benefit of bending such fully-aperiodic fiber to counteract this phenomenon. Optimized bending axis and radius have been determined. Experiments are done in a laser cavity operating at 1030 nm using an 88cm-long 51μm core diameter ytterbium-doped fiber. Results demonstrate an improvement of the M2 from 1.7 when the fiber is kept straight to 1.2 when it is bent with a 100 to 60 cm bend radius. These primary results are promising for future power scaling.

Noise-induced creation and annihilation of dissipative solitons (DS) in a passively mode-locked laser

NASA Astrophysics Data System (ADS)

Teamir, Tesfay; Elahi, Parviz; Makey, Ghaith; Fatih, Ilday

Passive mode-locking, resulting in self-organized formation of femtoseconds-long laser pulses, constitutes a far-from-equilibrium steady state. Mode-locking is not only important for laser technology, but also of fundamental interest for broad class of systems. Despite numerous studies on their nonlinear dynamics, there is little understanding of the transitions that intrinsic noise can induce. We show that transitions between single-DS and multi-DS states can be triggered. Near critical points, DS states are observed to repeatedly exchange energy among themselves, form DS clusters with varying or vibrating temporal separation, often followed by random transformations among different states. This critical behavior appears to be caused by soliton-soliton or soliton-generated dispersive wave interactions. Irrespective of the specifics of the state, the measured noise level of the laser starts at a moderate value, is then reduced, as the DS's energy is increased. Further increases in power (nonlinearity) drives it towards a noisy critical state, where creation or annihilation of pulses occurs just before a new steady state is formed. These noise-induced transitions between steady states can shed light on the thermodynamics of far-from-equilibrium systems. TàBITAK (113F319) and ERC CoG (617521).

Dopaminergic modulation of multi-muscle synergies in postural tasks performed by patients with Parkinson’s disease

PubMed Central

Falaki, Ali; Huang, Xuemei; Lewis, Mechelle M.; Latash, Mark L.

2017-01-01

Background Postural instability is one of most disabling motor symptoms in Parkinson’s disease. Indices of multi-muscle synergies are new measurements of postural stability. Objectives We explored the effects of dopamine-replacement drugs on multi-muscle synergies stabilizing center of pressure coordinate and their adjustments prior to a self-triggered perturbation in patients with Parkinson’s disease. We hypothesized that both synergy indices and synergy adjustments would be improved on dopaminergic drugs. Methods Patients at Hoehn-Yahr stages II and III performed whole-body tasks both off- and on-drugs while standing. Muscle modes were identified as factors in the muscle activation space. Synergy indices stabilizing center of pressure in the anterior-posterior direction were quantified in the muscle mode space during a load-release task. Results Dopamine-replacement drugs led to more consistent organization of muscles in stable groups (muscle modes). On-drugs patients showed larger indices of synergies and anticipatory synergy adjustments. In contrast, no medication effects were seen on anticipatory postural adjustments or other performance indices. Conclusions Dopamine-replacement drugs lead to significant changes in characteristics of multi-muscle synergies in Parkinson’s disease. Studies of synergies may provide a biomarker sensitive to problems with postural stability and agility and to efficacy of dopamine-replacement therapy. PMID:28110044

Studies in Astronomical Time Series Analysis. VI. Bayesian Block Representations

NASA Technical Reports Server (NTRS)

Scargle, Jeffrey D.; Norris, Jay P.; Jackson, Brad; Chiang, James

2013-01-01

This paper addresses the problem of detecting and characterizing local variability in time series and other forms of sequential data. The goal is to identify and characterize statistically significant variations, at the same time suppressing the inevitable corrupting observational errors. We present a simple nonparametric modeling technique and an algorithm implementing it-an improved and generalized version of Bayesian Blocks [Scargle 1998]-that finds the optimal segmentation of the data in the observation interval. The structure of the algorithm allows it to be used in either a real-time trigger mode, or a retrospective mode. Maximum likelihood or marginal posterior functions to measure model fitness are presented for events, binned counts, and measurements at arbitrary times with known error distributions. Problems addressed include those connected with data gaps, variable exposure, extension to piece- wise linear and piecewise exponential representations, multivariate time series data, analysis of variance, data on the circle, other data modes, and dispersed data. Simulations provide evidence that the detection efficiency for weak signals is close to a theoretical asymptotic limit derived by [Arias-Castro, Donoho and Huo 2003]. In the spirit of Reproducible Research [Donoho et al. (2008)] all of the code and data necessary to reproduce all of the figures in this paper are included as auxiliary material.

An integrated perspective of the continuum between earthquakes and slow-slip phenomena

USGS Publications Warehouse

Peng, Zhigang; Gomberg, Joan

2010-01-01

The discovery of slow-slip phenomena has revolutionized our understanding of how faults accommodate relative plate motions. Faults were previously thought to relieve stress either through continuous aseismic sliding, or as earthquakes resulting from instantaneous failure of locked faults. In contrast, slow-slip events proceed so slowly that slip is limited and only low-frequency (or no) seismic waves radiate. We find that slow-slip phenomena are not unique to the depths (tens of kilometres) of subduction zone plate interfaces. They occur on faults in many settings, at numerous scales and owing to various loading processes, including landslides and glaciers. Taken together, the observations indicate that slowly slipping fault surfaces relax most of the accrued stresses through aseismic slip. Aseismic motion can trigger more rapid slip elsewhere on the fault that is sufficiently fast to generate seismic waves. The resulting radiation has characteristics ranging from those indicative of slow but seismic slip, to those typical of earthquakes. The mode of seismic slip depends on the inherent characteristics of the fault, such as the frictional properties. Slow-slip events have previously been classified as a distinct mode of fault slip compared with that seen in earthquakes. We conclude that instead, slip modes span a continuum and are of common occurrence.

Green and ultraviolet pulse generation with a compact, fiber laser, chirped-pulse amplification system for aerosol fluorescence measurements.

PubMed

Lou, Janet W; Currie, Marc; Sivaprakasam, Vasanthi; Eversole, Jay D

2010-10-01

We use a compact chirped-pulse amplified system to harmonically generate ultrashort pulses for aerosol fluorescence measurements. The seed laser is a compact, all-normal dispersion, mode-locked Yb-doped fiber laser with a 1050 nm center wavelength operating at 41 MHz. Average powers of more than 1.2 W at 525 nm and 350 mW at 262 nm are generated with <500 fs pulse durations. The pulses are time-stretched with high-dispersion fiber, amplified by a high-power, large-mode-area fiber amplifier, and recompressed using a chirped volume holographic Bragg grating. The resulting high-peak-power pulses allow for highly efficient harmonic generation. We also demonstrate for the first time to our knowledge, the use of a mode-locked ultraviolet source to excite individual biological particles and other calibration particles in an inlet air flow as they pass through an optical chamber. The repetition rate is ideal for biofluorescence measurements as it allows faster sampling rates as well as the higher peak powers as compared to previously demonstrated Q-switched systems while maintaining a pulse period that is longer than the typical fluorescence lifetimes. Thus, the fluorescence excitation can be considered to be quasicontinuous and requires no external synchronization and triggering.

Counter-facing plasma guns for efficient extreme ultra-violet plasma light source

NASA Astrophysics Data System (ADS)

Kuroda, Yusuke; Yamamoto, Akiko; Kuwabara, Hajime; Nakajima, Mitsuo; Kawamura, Tohru; Horioka, Kazuhiko

2013-11-01

A plasma focus system composed of a pair of counter-facing coaxial guns was proposed as a long-pulse and/or repetitive high energy density plasma source. We applied Li as the source of plasma for improvement of the conversion efficiency, the spectral purity, and the repetition capability. For operation of the system with ideal counter-facing plasma focus mode, we changed the system from simple coaxial geometry to a multi-channel configuration. We applied a laser trigger to make synchronous multi-channel discharges with low jitter. The results indicated that the configuration is promising to make a high energy density plasma with high spectral efficiency.

How kinetics drives the two- to three-dimensional transition in semiconductor strained heterostructures: The case of InAs/GaAs(001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arciprete, F.; Placidi, E.; Sessi, V.

2006-07-24

The two- to three-dimensional growth mode transition in the InAs/GaAs(001) heterostructure has been investigated by means of atomic force microscopy. The kinetics of the density of three-dimensional islands indicates two transition onsets at 1.45 and 1.59 ML of InAs coverage, corresponding to two separate families, small and large dots. According to the scaling analysis and volume measurements, the transition between the two families of quantum dots and the explosive nucleation of the large ones is triggered by the erosion of the step edges.

How hairpin vortices emerge from exact invariant solutions

NASA Astrophysics Data System (ADS)

Schneider, Tobias M.; Farano, Mirko; de Palma, Pietro; Robinet, Jean-Christoph; Cherubini, Stefania

2017-11-01

Hairpin vortices are among the most commonly observed flow structures in wall-bounded shear flows. However, within the dynamical system approach to turbulence, those structures have not yet been described. They are not captured by known exact invariant solutions of the Navier-Stokes equations nor have other state-space structures supporting hairpins been identified. We show that hairpin structures are observed along an optimally growing trajectory leaving a well known exact traveling wave solution of plane Poiseuille flow. The perturbation triggering hairpins does not correspond to an unstable mode of the exact traveling wave but lies in the stable manifold where non-normality causes strong transient amplification.

VizieR Online Data Catalog: The second Konus-Wind short GRB catalog (Svinkin+, 2016)

NASA Astrophysics Data System (ADS)

Svinkin, D. S.; Frederiks, D. D.; Aptekar, R. L.; Golenetskii, S. V.; Pal'Shin, V. D.; Oleynik, P. P.; Tsvetkova, A. E.; Ulanov, M. V.; Cline, T. L.; Hurley, K.

2016-07-01

Between 1994 November and 2010 December, the Konus-Wind spectrometer (KW; see section 2 for details) detected 1939 GRBs in the triggered mode, 295 of which were classified as short-duration GRBs or short bursts with extended emission (EE). The count rates are recorded in three energy windows G1 (13-50keV), G2 (50-200keV), and G3 (200-760keV) with 2.944s time resolution. The catalog includes about twice the number of bursts as the first Konus catalog of short GRBs (Mazets et al. arXiv:astro-ph/0209219). (6 data files).

Ethoscopes: An open platform for high-throughput ethomics.

PubMed

Geissmann, Quentin; Garcia Rodriguez, Luis; Beckwith, Esteban J; French, Alice S; Jamasb, Arian R; Gilestro, Giorgio F

2017-10-01

Here, we present the use of ethoscopes, which are machines for high-throughput analysis of behavior in Drosophila and other animals. Ethoscopes provide a software and hardware solution that is reproducible and easily scalable. They perform, in real-time, tracking and profiling of behavior by using a supervised machine learning algorithm, are able to deliver behaviorally triggered stimuli to flies in a feedback-loop mode, and are highly customizable and open source. Ethoscopes can be built easily by using 3D printing technology and rely on Raspberry Pi microcomputers and Arduino boards to provide affordable and flexible hardware. All software and construction specifications are available at http://lab.gilest.ro/ethoscope.

Abolishment of Spontaneous Flight Turns in Visually Responsive Drosophila.

PubMed

Ferris, Bennett Drew; Green, Jonathan; Maimon, Gaby

2018-01-22

Animals react rapidly to external stimuli, such as an approaching predator, but in other circumstances, they seem to act spontaneously, without any obvious external trigger. How do the neural processes mediating the execution of reflexive and spontaneous actions differ? We studied this question in tethered, flying Drosophila. We found that silencing a large but genetically defined set of non-motor neurons virtually eliminates spontaneous flight turns while preserving the tethered flies' ability to perform two types of visually evoked turns, demonstrating that, at least in flies, these two modes of action are almost completely dissociable. Copyright © 2017 Elsevier Ltd. All rights reserved.