Science.gov

Sample records for p-wave arrival times

  1. The Residual of the Oki-Daito Plume in the Lower Mantle with the P wave Arrival-time Delays

    NASA Astrophysics Data System (ADS)

    Cui, H.; Zhou, Y.; Li, G.; Wang, X.

    2014-12-01

    The mantle plumes rising from different depths relate to the seismic slow anomaly in the Earth's interior and is significant to understand the geodynamic process. Deep mantle plumes often result as volcano chains or oceanic island chains. The previous EM-2 Oki-Daito mantle plume acted on the Philippine Sea Plate at ~50-35 Ma [Ishizuka et al., 2013]. In order to detect the residual of the Oki-Daito plume in the lower mantle beneath the Philippine Sea Plate, P wave arrival-time delays of seven earthquakes occurred at the subduction zones surrounding the plate and recorded by the Chinese Digital Seismic Network and High Sensitivity Seismograph Network of Japan, are used to map the deep fine structure by using the ray-tracing method [Rawlinson and Sambridge, 2004]. A slow anomaly is found at depths between ~837 and 1007 km beneath the central west Philippine Sea Plate, with the P-wave velocity decrease of 0.35%-0.45% and the related temperature increase of ~117-150K. The slow anomaly should be the residual of Oki-Daito plume. In addition, local fast anomaly of ~200km thickness is also found in the mantle transition zone beneath the northern west Philippine Sea Plate, with the P-wave velocity increase of 1.8-2.0%, which should be the stagnant slab of the Pacific Plate [Fukao et al., 2009]. We also analyze the possible earlier interaction between the Oki-Daito plume and stagnant slab, or the cause of the slow anomaly in the lower mantle. Compared to seismic tomography results [Huang and Zhao, 2006; Fukao and Obayashi, 2013], the slow anomaly obtained by the cross constraint of dense seismic ray-paths shows similar velocity perturbation, but much smaller scales and higher resolution. The phenomenon means that the lower mantle is more homogeneous than that shown in seismic tomography.

  2. A non-parametric method for automatic determination of P-wave and S-wave arrival times: application to local micro earthquakes

    NASA Astrophysics Data System (ADS)

    Rawles, Christopher; Thurber, Clifford

    2015-08-01

    We present a simple, fast, and robust method for automatic detection of P- and S-wave arrivals using a nearest neighbours-based approach. The nearest neighbour algorithm is one of the most popular time-series classification methods in the data mining community and has been applied to time-series problems in many different domains. Specifically, our method is based on the non-parametric time-series classification method developed by Nikolov. Instead of building a model by estimating parameters from the data, the method uses the data itself to define the model. Potential phase arrivals are identified based on their similarity to a set of reference data consisting of positive and negative sets, where the positive set contains examples of analyst identified P- or S-wave onsets and the negative set contains examples that do not contain P waves or S waves. Similarity is defined as the square of the Euclidean distance between vectors representing the scaled absolute values of the amplitudes of the observed signal and a given reference example in time windows of the same length. For both P waves and S waves, a single pass is done through the bandpassed data, producing a score function defined as the ratio of the sum of similarity to positive examples over the sum of similarity to negative examples for each window. A phase arrival is chosen as the centre position of the window that maximizes the score function. The method is tested on two local earthquake data sets, consisting of 98 known events from the Parkfield region in central California and 32 known events from the Alpine Fault region on the South Island of New Zealand. For P-wave picks, using a reference set containing two picks from the Parkfield data set, 98 per cent of Parkfield and 94 per cent of Alpine Fault picks are determined within 0.1 s of the analyst pick. For S-wave picks, 94 per cent and 91 per cent of picks are determined within 0.2 s of the analyst picks for the Parkfield and Alpine Fault data set, respectively. For the Parkfield data set, our method picks 3520 P-wave picks and 3577 S-wave picks out of 4232 station-event pairs. For the Alpine Fault data set, the method picks 282 P-wave picks and 311 S-wave picks out of a total of 344 station-event pairs. For our testing, we note that the vast majority of station-event pairs have analyst picks, although some analyst picks are excluded based on an accuracy assessment. Finally, our tests suggest that the method is portable, allowing the use of a reference set from one region on data from a different region using relatively few reference picks.

  3. Microseismic event location using an inverse method of joint P-S phase arrival difference and P-wave arrival difference in a borehole system

    NASA Astrophysics Data System (ADS)

    Zhou, Wen; Wang, Liangshu; Guan, Luping; Guo, Quanshi; Cui, Shuguo; Yu, Bo

    2015-04-01

    The accuracy of hypocenter location is the essential issue for microseismic monitoring, and is the basis for evaluating the effect of fracture. Although the signal obtained from a borehole monitoring system has a higher signal to noise ratio (SNR) than the surface system, a narrow monitoring aperture makes the location sensitive to noise and tends to be a misguided shape. In order to overcome this disadvantage and obtain a more accurate estimation of the source, we develop a ‘jointing method’, which combines the P-S phase arrival difference and P-wave arrival difference of each receiver pair (PSP) in the objective function. In the synthetic example, we compare the noise responses of three different location methods which are based on P-wave arrival time difference, P-S wave arrival time difference and the PSP method, respectively. This analysis shows that the P-wave arrival difference method is more sensitive to arrival time error than the others and the location results tend to be in a misleading line directed to the receivers. The P-S arrival difference method is more robust than the method using P-wave and its error distribution is perpendicular to the ray-path direction. The PSP method, as expected, is the most stable and accurate. When the P-S method and PSP method are applied to field data of a coal bed methane hydro-fracture process monitoring, the results indicate that the PSP method is preferable. The successful location with the PSP method proves that it is suitable for field data.

  4. Nature of the Vrancea seismic zone (Eastern Carpathians) - New constraints from dispersion of first-arriving P-waves

    NASA Astrophysics Data System (ADS)

    Bokelmann, Götz; Rodler, Fee-Alexandra

    2014-03-01

    The Vrancea region of the southeastern Carpathians is one of the most active seismic zones in Europe and it is well-known for its strong intermediate depth earthquakes. Seismic tomography had revealed a high-velocity body beneath Vrancea and the Moesian platform that extends to a depth of at least 350 km and can be interpreted as descending lithosphere. The strong earthquakes occur within the northeastern part of this high-velocity body, in a very limited seismogenic volume at intermediate depth (70-180 km). Several geodynamic models have been proposed for this area. They can be split into two main categories, in terms of the nature of the high-velocity anomaly, which may (a) be associated with descending relic oceanic lithosphere beneath the bending zone of the SE-Carpathians, either attached or already detached from the continental crust; or (b) it may represent continental lithosphere that has been delaminated, after continental collision and orogenic thickening. Based on currently available information, it appears difficult to distinguish between these two types of models. In this paper we attempt to shed more light on the nature of the seismic anomaly, as well as that of the origin of the intermediate depth seismicity in the Vrancea zone, by investigating the waveform character of P-waves excited by local earthquakes beneath this area, and in particular the dependence of group arrival times on frequency. We present observations of such a dispersion from stations situated at the bending zone of the SE-Carpathians. On the other hand, signals from the same earthquakes, but observed at reference stations outside of the anomalous zone do not show that frequency dependence. A natural explanation for these observations is that it is caused by the presence of a low-velocity channel at the top of the seismic anomaly, which is too thin to be resolved by classical seismic tomographic techniques. Similar observations of dispersed first-arriving P-waves have been made above subduction zones around the world, in which low-velocity layers with a thickness of several kilometers are known to exist. This suggests that a tabular slab of subducted oceanic crust is present within the seismic anomaly under the Vrancea region, and that the anomaly consists of subducted oceanic lithosphere rather than continental lithosphere, at least at depths shallower than the seismically active zone.

  5. An anomalous upper mantle unit beneath southern Norway revealed by P-wave travel time residuals.

    NASA Astrophysics Data System (ADS)

    Bondo, A.; Balling, N.; Jacobsen, B. H.; England, R. W.; Kind, R.; Bödvarsson, R.; Weidle, C.; Gregersen, S.; Voss, P.

    2009-04-01

    We investigate whether high topography in southern Norway is associated with an anomalous upper mantle and we identify the western boundary of thick shield lithosphere. Several studies describe crustal structure in southern Scandinavia, whereas high-resolution information on upper mantle structures is sparse. We present relative P-wave travel time residuals (P-residuals) and preliminary tomography from southern Norway, southern Sweden and northern Denmark. We analyze distant earthquakes registered by seismological stations in projects CENMOVE, CALAS, MAGNUS and SCANLIPS together with selected TOR stations, and permanent stations in southern Sweden, southern Norway and Denmark. Station means of P-residuals corrected for topography and contributions from the crust varies by up to about 1 s across the study area. We associate early arrivals to the east of the Sorgenfrei-Tornquist Zone (STZ) and east of the Oslo Graben with thick shield lithosphere. Late arrivals observed in the Norwegian-Danish Basin southwest of the STZ are consistent with thinned lithosphere related to the basin formation. In southern Norway west of the Oslo Graben area, late arrivals indicate reduced P-wave velocity in the upper mantle and perhaps some regional isostatic buoyancy from the upper mantle. However, arrivals are early in the northern part of southern Norway, still in areas of high topography. Thus, a clear spatial correlation with areas of high topography is not observed. We identify the western boundary of thick shield lithosphere by interpretation of station means of P-residuals, together with the azimuthal dependence of single P-residuals in southern Scandinavia. We find this boundary to follow the STZ from the southeast into the northern part of Jutland. From there it proceed northwards. In southern Norway the western boundary of thick shield lithosphere is found around the Oslo Graben, proceeding to the northwest approaching the Norwegian coast.

  6. Real-Time Prediction of Ground Motion from P-Wave Records

    NASA Astrophysics Data System (ADS)

    Boese, M.; Erdik, M.; Wenzel, F.

    2004-12-01

    Real-time prediction of ground motion parameters, such as peak values, seismic intensity or spectral response, at a critical site or facility as well as on regional scale, can help to reduce losses by strong earthquakes by the automatic triggering of protective steps seconds prior to the arrival of high amplitude seismic waves. We present a concept for an earthquake early warning system designed for real-time processing of information obtained from the low amplitude P-wave that is recorded at a number of accelerographs installed in the epicentral area. To allow for the adaptation to rupture dynamics, the estimation of ground motion parameters starts as soon as the first station is triggered and is continuously up-dated with ongoing time. Our design is in contrast to other earthquake early warning systems that are based on the explicit knowledge of magnitude and hypocenter location for the application of empirical attenuation laws. The level of the cumulative absolute velocity (CAV) of the P-wave as well as relative values of CAV at different seismic stations give a good indicator for the severity of impending ground shaking. The site-specific prediction of ground motion parameters and interpolation for the generation of regional shake maps is achieved by the application of a three-layer feedforward neural network considering local site effects. The procedure is demonstrated for the Istanbul Earthquake Early Warning System in Turkey.

  7. Gaussian modeling of the P-wave morphology time course applied to anticipate paroxysmal atrial fibrillation.

    PubMed

    Martínez, Arturo; Alcaraz, Raúl; Rieta, José Joaquín

    2015-01-01

    This paper introduces a new algorithm to quantify the P-wave morphology time course with the aim of anticipating as much as possible the onset of paroxysmal atrial fibrillation (PAF). The method is based on modeling each P-wave with a single Gaussian function and analyzing the extracted parameters variability over time. The selected Gaussian approaches are associated with the amplitude, peak timing, and width of the P-wave. In order to validate the algorithm, electrocardiogram segments 2 h preceding the onset of PAF episodes from 46 different patients were assessed. According to the expected intermittently disturbed atrial conduction before the onset of PAF, all the analyzed Gaussian metrics showed an increasing variability trend as the PAF onset approximated. Moreover, the Gaussian P-wave width reported a diagnostic accuracy around 80% to discern between healthy subjects, patients far from PAF, and patients less than 1 h close to a PAF episode. This discriminant power was similar to those provided by the most classical time-domain approach, i.e., the P-wave duration. However, this newly proposed parameter presents the advantage of being less sensitive to a precise delineation of the P-wave boundaries. Furthermore, the linear combination of both metrics improved the diagnostic accuracy up to 86.69%. In conclusion, morphological P-wave characterization provides additional information to the metrics based on P-wave timing. PMID:25298113

  8. Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume III P-Wave Measurements in Borehole C4997 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.

    SciTech Connect

    Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

    2007-06-06

    In this volume (III), all P-wave measurements are presented that were performed in Borehole C4997 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 390 to 1220 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 40 ft (later relocated to 27.5 ft due to visibility in borehole after rain) in Borehole C4997, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4997, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

  9. Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume II P-Wave Measurements in Borehole C4996 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.

    SciTech Connect

    Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

    2007-07-06

    In this volume (II), all P-wave measurements are presented that were performed in Borehole C4996 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 360 to 1400 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used, while below about 1180 ft, depth intervals of 20 ft were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 22 ft in Borehole C4996, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4996, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

  10. Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume I P-Wave Measurements in Borehole C4993 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.

    SciTech Connect

    Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

    2007-07-06

    In this volume (I), all P-wave measurements are presented that were performed in Borehole C4993 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 370 to 1400 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used, while below about 1200 ft, depth intervals of 20 ft were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 22 ft in Borehole C4993, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4993, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

  11. Arrival time in quantum field theory

    NASA Astrophysics Data System (ADS)

    Wang, Zhi-Yong; Xiong, Cai-Dong; He, Bing

    2008-09-01

    Via the proper-time eigenstates (event states) instead of the proper-mass eigenstates (particle states), free-motion time-of-arrival theory for massive spin-1/2 particles is developed at the level of quantum field theory. The approach is based on a position-momentum dual formalism. Within the framework of field quantization, the total time-of-arrival is the sum of the single event-of-arrival contributions, and contains zero-point quantum fluctuations because the clocks under consideration follow the laws of quantum mechanics.

  12. HELCATS Prediction of Planetary CME arrival times

    NASA Astrophysics Data System (ADS)

    Boakes, Peter; Moestl, Christian; Davies, Jackie; Harrison, Richard; Byrne, Jason; Barnes, David; Isavnin, Alexey; Kilpua, Emilia; Rollett, Tanja

    2015-04-01

    We present the first results of CME arrival time prediction at different planetary locations and their comparison to the in situ data within the HELCATS project. The EU FP7 HELCATS (Heliospheric Cataloguing, Analysis & Techniques Service) is a European effort to consolidate the exploitation of the maturing field of heliospheric imaging. HELCATS aims to catalogue solar wind transients, observed by the NASA STEREO Heliospheric Imager (HI) instruments, and validate different methods for the determination of their kinematic properties. This validation includes comparison with arrivals at Earth, and elsewhere in the heliosphere, as well as onsets at the Sun (http://www.helcats-fp7.eu/). A preliminary catalogue of manually identified CMEs, with over 1000 separate events, has been created from observations made by the STEREO/HI instruments covering the years 2007-2013. Initial speeds and directions of each CME have been derived through fitting the time elongation profile to the state of the art Self-Similar Expansion Fitting (SSEF) geometric technique (Davies et al., 2012). The technique assumes that, in the plane corresponding to the position angle of interest, CMEs can be modelled as circles subtending a fixed angular width to Sun-center and propagating anti-sunward in a fixed direction at a constant speed (we use an angular width of 30 degrees in our initial results). The model has advantages over previous geometric models (e.g. harmonic mean or fixed phi) as it allows one to predict whether a CME will 'hit' a specific heliospheric location, as well as to what degree (e.g. direct assault or glancing blow). We use correction formulae (Möstl and Davies, 2013) to convert CME speeds, direction and launch time to speed and arrival time at any in situ location. From the preliminary CME dataset, we derive arrival times for over 400 Earth-directed CMEs, and for over 100 Mercury-, Venus-, Mars- and Saturn-directed CMEs predicted to impact each planet. We present statistics of predicted CME arrival properties. In addition, we independently identify CME arrival at in situ locations using magnetic field data from the Venus Express, Messenger, and Ulysses spacecraft and show first comparisons to predicted arrival times. The results hold important implications for space weather prediction at Earth and other locations, allowing model and predicted CME parameters to be compared to their in situ counterparts.

  13. Nonlinear inversion of first-arrival times

    SciTech Connect

    Simmons, J.L. Jr.; Bernitsas, N.

    1994-12-31

    First-arrival times are a valuable source of near-surface velocity information. In the shallow marine environment, the first arrivals are often diving waves which propagate downward to some maximum depth and then continuously refract back to the surface. Diving waves are especially sensitive to slowly varying changes in the velocity structure and are also sensitive to more localized velocity anomalies. The slowly varying features are of a much lower frequency than the traveltime effects produced by the localized anomalies. A maximum-likelihood inversion is applied to the first-arrival times (turning rays) of a shallow-marine seismic reflection data set to estimate the slowly varying components of the near-surface velocity field. The earth model is represented with a low frequency parameterization designed specifically for those components of the data the authors wish to predict. Two-dimensional cubic B-splines represent the velocity field and are adjusted in the inversion. This model parameterization effectively decouples the low frequency components of the first-arrival times from the higher frequency components. This decoupling allows an inherently nonlinear problem to be treated as a linear problem where the solution is obtained in a single iteration.

  14. Acceleration of stable TTI P-wave reverse-time migration with GPUs

    NASA Astrophysics Data System (ADS)

    Kim, Youngseo; Cho, Yongchae; Jang, Ugeun; Shin, Changsoo

    2013-03-01

    When a pseudo-acoustic TTI (tilted transversely isotropic) coupled wave equation is used to implement reverse-time migration (RTM), shear wave energy is significantly included in the migration image. Because anisotropy has intrinsic elastic characteristics, coupling P-wave and S-wave modes in the pseudo-acoustic wave equation is inevitable. In RTM with only primary energy or the P-wave mode in seismic data, the S-wave energy is regarded as noise for the migration image. To solve this problem, we derive a pure P-wave equation for TTI media that excludes the S-wave energy. Additionally, we apply the rapid expansion method (REM) based on a Chebyshev expansion and a pseudo-spectral method (PSM) to calculate spatial derivatives in the wave equation. When REM is incorporated with the PSM for the spatial derivatives, wavefields with high numerical accuracy can be obtained without grid dispersion when performing numerical wave modeling. Another problem in the implementation of TTI RTM is that wavefields in an area with high gradients of dip or azimuth angles can be blown up in the progression of the forward and backward algorithms of the RTM. We stabilize the wavefields by applying a spatial-frequency domain high-cut filter when calculating the spatial derivatives using the PSM. In addition, to increase performance speed, the graphic processing unit (GPU) architecture is used instead of traditional CPU architecture. To confirm the degree of acceleration compared to the CPU version on our RTM, we then analyze the performance measurements according to the number of GPUs employed.

  15. Time arrival of slab avalanche masses

    NASA Astrophysics Data System (ADS)

    McClung, D. M.

    2003-10-01

    One of three criteria to demonstrate self-organized criticality (SOC) for a critical phenomenon is that time arrival of events displays a frequency dependence which is inversely proportional to frequency (f) to some power. That is, for SOC, the power spectrum in the frequency (f) domain is supposed to fall off as 1/fβ, where β is typically a number between 1 and 2. Avalanche phenomena have been used as prototypes for illustrating SOC, and therefore it is of interest as to whether snow avalanches follow the criterion. In this paper, time series analyses of mass arrivals from 20 years of records constituting ˜10,000 avalanches are presented for Bear Pass and Kootenay Pass, British Columbia. The results suggest that the autocorrelation functions and partial autocorrelation functions of the series fall off in an exponential manner so that the implied power spectra in the frequency domain, given by the Fourier transforms of the autocorrelation functions, decay with frequency in a manner which is not strictly consistent with SOC. In common with SOC, the power spectra are suggested to have most content in the low-frequency events and the spectra do not constitute white noise. However, given the limitations on the data sampling and recording, it cannot be definitively stated that the power spectra fall off with 1/f® as required for SOC.

  16. Cascadia tremor located near plate interface constrained by S minus P wave times.

    PubMed

    La Rocca, Mario; Creager, Kenneth C; Galluzzo, Danilo; Malone, Steve; Vidale, John E; Sweet, Justin R; Wech, Aaron G

    2009-01-30

    Nonvolcanic tremor is difficult to locate because it does not produce impulsive phases identifiable across a seismic network. An alternative approach to identifying specific phases is to measure the lag between the S and P waves. We cross-correlate vertical and horizontal seismograms to reveal signals common to both, but with the horizontal delayed with respect to the vertical. This lagged correlation represents the time interval between vertical compressional waves and horizontal shear waves. Measurements of this interval, combined with location techniques, resolve the depth of tremor sources within +/-2 kilometers. For recent Cascadia tremor, the sources locate near or on the subducting slab interface. Strong correlations and steady S-P time differences imply that tremor consists of radiation from repeating sources. PMID:19179527

  17. Investigation of the lithosphere beneath the Vogelsberg volcanic complex with P-wave travel time residuals

    NASA Astrophysics Data System (ADS)

    Braun, T.; Berckhemer, H.

    1993-04-01

    With the aim of investigating the P-wave velocity structure below the Tertiary volcano Vogelsberg, a network of 10 mobile short period seismograph stations was installed in May 1987 for a period of 20 months. P-Wave travel time residuals relative to the station Kleiner Feldberg/Taunus (TNS) were determined for 168 seismic events using the Jeffreys - Bullen travel time tables. At all stations the relative residuals showed a positive sign, indicating a low velocity zone beneath the Vogelsberg. Maxima were found in the northern part of the Vogelsberg (station VAD +0.5 s) and in the region of the Amöneburger Basin (station RAU +0.28 s). The travel time residuals were inverted using the tomographic inversion method of Aki et al. (1977). The slowness perturbations of the single blocks were calculated relative to a crustal and upper mantle model of the Rhenish Massif. The results show an intracrustal low velocity body (about -9%) striking in a Variscan direction and underlying the north-eastern part of the Vogelsberg, and another velocity minimum (about - 6%) in the region of the Am6neburger Basin. In the lower crust and the upper mantle the velocities are reduced by about 4% relative to the starting model. The Variscan alignment of the low velocity zone under the Vogelsberg correlates with results of other geological studies. It can be assumed that during the rifting phase of the Upper Rhinegraben Variscan lineations have been reactivated, favouring uprising of magma along these old structures. The position and extension of the low velocity zone correlate with the assumed sediment distributions in the area of investigation. This may account for about one-half of the observed anomaly. The reason for the velocity reduction of about 4% in the entire underground region of the Vogelsberg down to a depth of about 70 km can be explained by the intensive fracturing of the lithosphere, caused by thermal and pressure gradients during the magma eruption process.

  18. Alternative stable qP wave equations in TTI media with their applications for reverse time migration

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Wang, Huazhong; Liu, Wenqing

    2015-10-01

    Numerical instabilities may arise if the spatial variation of symmetry axis is handled improperly when implementing P-wave modeling and reverse time migration in heterogeneous tilted transversely isotropic (TTI) media, especially in the cases where fast changes exist in TTI symmetry axis’ directions. Based on the pseudo-acoustic approximation to anisotropic elastic wave equations in Cartesian coordinates, alternative second order qP (quasi-P) wave equations in TTI media are derived in this paper. Compared with conventional stable qP wave equations, the proposed equations written in stress components contain only spatial derivatives of wavefield variables (stress components) and are free from spatial derivatives involving media parameters. These lead to an easy and efficient implementation for stable P-wave modeling and imaging. Numerical experiments demonstrate the stability and computational efficiency of the presented equations in complex TTI media.

  19. Fast determination of earthquake magnitude and fault extent from real-time P-wave recordings

    NASA Astrophysics Data System (ADS)

    Colombelli, Simona; Zollo, Aldo

    2015-08-01

    This work is aimed at the automatic and fast characterization of the extended earthquake source, through the progressive measurement of the P-wave displacement amplitude along the recorded seismograms. We propose a straightforward methodology to quickly characterize the earthquake magnitude and the expected length of the rupture, and to provide an approximate estimate of the average stress drop to be used for Earthquake Early Warning and rapid response purposes. We test the methodology over a wide distance and magnitude range using a massive Japan earthquake, accelerogram data set. Our estimates of moment magnitude, source duration/length and stress drop are consistent with the ones obtained by using other techniques and analysing the whole seismic waveform. In particular, the retrieved source parameters follow a self-similar, constant stress-drop scaling (median value of stress drop = 0.71 MPa). For the M 9.0, 2011 Tohoku-Oki event, both magnitude and length are underestimated, due to limited, available P-wave time window (PTWs) and to the low-frequency cut-off of analysed data. We show that, in a simulated real-time mode, about 1-2 seconds would be required for the source parameter determination of M 4-5 events, 3-10 seconds for M 6-7 and 30-40 s for M 8-8.5. The proposed method can also provide a rapid evaluation of the average slip on the fault plane, which can be used as an additional discriminant for tsunami potential, associated to large magnitude earthquakes occurring offshore.

  20. One-dimensional P-wave velocity structure in the northern Red Sea area, deduced from travel time data

    NASA Astrophysics Data System (ADS)

    Mohamed, H.; Miyashita, K.

    2001-07-01

    Travel time inversion of local earthquake data was used to improve a one-dimensional (1-D) P-wave velocity structure model for the northern Red Sea area, including the entrance of the Gulf of Suez and the Gulf of Aqaba. The 1-D velocity model and station corrections were obtained by using 1538 P-arrivals from 216 well-located earthquakes recorded at ten local seismic stations from August 1994 to January 1999. Earthquakes used in the present study were located in depths less than 28 km so that the upper 20 km of the 1-D velocity model was well constrained. The resulting P-velocity model indicated velocities from 5.0 to 6.0 km/sec down to a depth of 10 km, and velocities from 6.0 to 6.8 km/sec with a nearly constant gradient in a depth range from 10 to 20 km. This 1-D velocity model reduced the RMS residual by 47% from 0.21 to 0.11 sec and improved routine earthquake locations, which clearly indicated clusters of hypocenters in the southern tip of the Sinai Peninsula and the entrance of the Gulf of Suez. The resulting station corrections suggested irregular surface geology in the area. Negative and positive station corrections were obtained; the minimum value (-0.35) was observed at the station MAZR, while the maximum value (0.24) at SHRM.

  1. An Exploratory Study of Runway Arrival Procedures: Time Based Arrival and Self-Spacing

    NASA Technical Reports Server (NTRS)

    Houston, Vincent E.; Barmore, Bryan

    2009-01-01

    The ability of a flight crew to deliver their aircraft to its arrival runway on time is important to the overall efficiency of the National Airspace System (NAS). Over the past several years, the NAS has been stressed almost to its limits resulting in problems such as airport congestion, flight delay, and flight cancellation to reach levels that have never been seen before in the NAS. It is predicted that this situation will worsen by the year 2025, due to an anticipated increase in air traffic operations to one-and-a-half to three times its current level. Improved arrival efficiency, in terms of both capacity and environmental impact, is an important part of improving NAS operations. One way to improve the arrival performance of an aircraft is to enable the flight crew to precisely deliver their aircraft to a specified point at either a specified time or specified interval relative to another aircraft. This gives the flight crew more control to make the necessary adjustments to their aircraft s performance with less tactical control from the controller; it may also decrease the controller s workload. Two approaches to precise time navigation have been proposed: Time-Based Arrivals (e.g., required times of arrival) and Self-Spacing. Time-Based Arrivals make use of an aircraft s Flight Management System (FMS) to deliver the aircraft to the runway threshold at a given time. Self-Spacing enables the flight crew to achieve an ATC assigned spacing goals at the runway threshold relative to another aircraft. The Joint Planning and Development Office (JPDO), a multi-agency initiative established to plan and coordinate the development of the Next Generation Air Transportation System (NextGen), has asked for data for both of these concepts to facilitate future research and development. This paper provides a first look at the delivery performance of these two concepts under various initial and environmental conditions in an air traffic simulation environment.

  2. Mobile TV's Time to Shine Has Arrived

    NASA Astrophysics Data System (ADS)

    Kitson, Fred

    MoFilm, the first mobile film festival, achieved some legitimacy when multiple Academy Award-winning actor Kevin Spacey hosted the show in 2009. Spacey commented: "[I]n some countries, this might be the first time they [people] ever see a movie. … They won't see it on that big screen; they'll see it on a small one."1 According to a 2007 Gartner report, sales of cell phones skyrocketed for the first time to more than 1 billion.2 In 2008, the number of worldwide subscribers topped 4 billion, covering 60% of the world population.3 There are more mobile phones than TVs (there are 1.4 billion TVs worldwide4). Spacey concluded: "The quality of work and the simple ability at storytelling, the thing that ignites someone and inspires them to tell a story, can really come from anywhere."5

  3. Shear wave arrival time estimates correlate with local speckle pattern.

    PubMed

    Mcaleavey, Stephen A; Osapoetra, Laurentius O; Langdon, Jonathan

    2015-12-01

    We present simulation and phantom studies demonstrating a strong correlation between errors in shear wave arrival time estimates and the lateral position of the local speckle pattern in targets with fully developed speckle. We hypothesize that the observed arrival time variations are largely due to the underlying speckle pattern, and call the effect speckle bias. Arrival time estimation is a key step in quantitative shear wave elastography, performed by tracking tissue motion via cross-correlation of RF ultrasound echoes or similar methods. Variations in scatterer strength and interference of echoes from scatterers within the tracking beam result in an echo that does not necessarily describe the average motion within the beam, but one favoring areas of constructive interference and strong scattering. A swept-receive image, formed by fixing the transmit beam and sweeping the receive aperture over the region of interest, is used to estimate the local speckle pattern. Metrics for the lateral position of the speckle are found to correlate strongly (r > 0.7) with the estimated shear wave arrival times both in simulations and in phantoms. Lateral weighting of the swept-receive pattern improved the correlation between arrival time estimates and speckle position. The simulations indicate that high RF echo correlation does not equate to an accurate shear wave arrival time estimate-a high correlation coefficient indicates that motion is being tracked with high precision, but the location tracked is uncertain within the tracking beam width. The presence of a strong on-axis speckle is seen to imply high RF correlation and low bias. The converse does not appear to be true-highly correlated RF echoes can still produce biased arrival time estimates. The shear wave arrival time bias is relatively stable with variations in shear wave amplitude and sign (-20 μm to 20 μm simulated) compared with the variation with different speckle realizations obtained along a given tracking vector. We show that the arrival time bias is weakly dependent on shear wave amplitude compared with the variation with axial position/ local speckle pattern. Apertures of f/3 to f/8 on transmit and f/2 and f/4 on receive were simulated. Arrival time error and correlation with speckle pattern are most strongly determined by the receive aperture. PMID:26670847

  4. Time-of-arrival probabilities for general particle detectors

    NASA Astrophysics Data System (ADS)

    Anastopoulos, Charis; Savvidou, Ntina

    2012-07-01

    We develop a general framework for the construction of probabilities for the time of arrival in quantum systems. The time of arrival is identified with the time instant when a transition in the detector's degrees of freedom takes place. Thus, its definition is embedded within the larger issue of defining probabilities with respect to time for general quantum transitions. The key point in our analysis is that we manage to reduce the problem of defining a quantum time observable to a mathematical model where time is associated to a transition from a subspace of the Hilbert space of the total system to its complementary subspace. This property makes it possible to derive a general expression for the probability for the time of transition, valid for any quantum system, with the only requirement that the time of transition is correlated with a definite macroscopic record. The framework developed here allows for the consideration of any experimental configuration for the measurement of the time of arrival, and it also applies to relativistic systems with interactions described by quantum field theory. We use the method in order to describe time-of-arrival measurements in high-energy particle reactions and for a rigorous derivation of the time-integrated probabilities in particle oscillations.

  5. Finding Planets from Variable Star Pulsation Arrival Times with Kepler

    NASA Astrophysics Data System (ADS)

    Mullally, Fergal; Kinemuchi, K.; Thompson, S. E.; Rowe, J. F.

    2011-01-01

    We examine the potential for planet detection using lightcurve arrival times around a variety of stars in the Kepler field. Arrival time analysis has been used to find planets around pulsars and sub-dwarf stars. When a variable star is orbiting the center of mass of a planetary system, its distance from the earth changes periodically. This change in distance is observed as a change in the observed arrival time of otherwise stable pulsations here on Earth. The sensitivity of the technique is set by the jitter of the pulsation period and phase, and the periods of detectable planets by the long term stability of the pulsation modes. We examine the limits that can be placed of a variety of variable stars using public data from the first quarter of observations by the Kepler space telescope. Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate

  6. P-wave tomography of Northeastern China observed with NECESSArray

    NASA Astrophysics Data System (ADS)

    Obayashi, M.; Kawakatsu, H.; Tanaka, S.; Chen, Y. J.; Ning, J.; Grand, S. P.; Niu, F.; Miyakawa, K.; Idehara, K.; Tonegawa, T.; Iritani, R.; Necessarray Project Team

    2011-12-01

    A passive broadband seismic experiment, NorthEast China Extended SeiSmic Array (NECESSArray) has been deployed since 2009 for two years. Northeastern China is a very interesting region because slabs subducting from the south Kuril and Japan trenches are stagnant in the mantle transition zone and extends to northeastern China, and above the stagnant slabs, Sino-Korea craton and unusual volcanism in the continent exist. The relationships between the deep slabs and shallow structures are important clues to understand the tectonic features. P-wave travel-time picks of the NECESSArray stations were made interactively, while the teleseismic arrival time residuals were extracted using the adaptive stacking method. We picked more than 13,000 event-station pairs. Relative travel-times of P-wave between different stations were measured as a function of frequency using deep events of which P-waves separate in time from depth phases and very shallow events of which P-waves and depth phases are completely coincide. We found strong dispersive effect that is not predicted by our previous three dimensional (3D) P-wave model. We will combine the picked travel times and the frequency depended relative travel times to image a 3D P-wave heterogeneities of the northeastern China. We will show our first model at the meeting.

  7. A Comparison of CTAS and Airline Time of Arrival Predictions

    NASA Technical Reports Server (NTRS)

    Heere, Karen R.; Zelenka, Richard E.; Hsu, Rose Y.

    1999-01-01

    A statistically-based comparison of aircraft times of arrival between Center/TRACON Automation System (CTAS) air traffic control scheduling and airline predictions is presented. CTAS is found to provide much improved values, forming the foundation for airline operational improvements, as observed during an airline field trial of a CTAS display.

  8. A geometrical result regarding time-of-arrival lightning location

    NASA Technical Reports Server (NTRS)

    Solakiewicz, Richard

    1996-01-01

    One reason for investigating Lightning Detection And Ranging (LDAR) is to validate data from the Optical Transient Detector (OTD). A Time-Of-Arrival (TOA) procedure may be used with radio wave portions of lighting signatures. An antenna is in place at KSC.

  9. Arrival Time Distribution by the New Observation System at Taro

    NASA Astrophysics Data System (ADS)

    Sakuyama, H.; Obara, Hitoshi; Kuramochi, Hiroshi; Ono, Shunichi; Origasa, Satoru; Mochida, Akinori; Sakuyama, Hiroshi; Suzuki, Noboru

    2003-07-01

    The arrival time distribution of EAS has been observed by using Ultra Fast Cherenkov detector (UFC) and oscilloscope at Taro observatory since 1995 (sea level 200m). The EAS array is arranged 169 sets of 0.25m2 scintillation detectors in the shape of a lattice at intervals of 1.5m and about 40 scintillation detectors which consists of 1m2 and 0.25m2 is arranged in the peripheral part. Then, it consists of 8 fast timing detectors. The UFC detector is installed in the palce of about 20m from the trigger center. The observation system of a UFC detector was changed from the autumn of 2000. The outline of a new observation system and EAS arrival time distribution are reported.

  10. The arrival time distribution of EAS at Taro

    NASA Astrophysics Data System (ADS)

    Maeda, T.; Kuramochi, H.; Ono, S.; Sakuyama, H.; Suzuki, N.

    The arrival time distribution of EAS has been observed since 1995 at Taro cosmicray laboratory (200m above sea level). The EAS arrays consist of 1m2 and 0.25m2 scintillation detectors, 0.25m2 fast timing counters and ultra fast Cherenkov detectors (UFC). 169 0.25m2 scintillation detectors are arranged in alattice configuration with a unit distance of 1.5m. UFC is placed at 20m from the center of lattice array. The arrival time distribution has been analyzed with distance from EAS core (r=10-60m). One of the results shows that the radius of corvature increases as shower size (Ne), near to the EAS core.

  11. Quantum arrival and dwell times via idealized clocks

    SciTech Connect

    Yearsley, J. M.; Downs, D. A.; Halliwell, J. J.; Hashagen, A. K.

    2011-08-15

    A number of approaches to the problem of defining arrival- and dwell-time probabilities in quantum theory makes use of idealized models of clocks. An interesting question is the extent to which the probabilities obtained in this way are related to standard semiclassical results. In this paper, we explore this question using a reasonably general clock model, solved using path-integral methods. We find that, in the weak-coupling regime, where the energy of the clock is much less than the energy of the particle it is measuring, the probability for the clock pointer can be expressed in terms of the probability current in the case of arrival times, and the dwell-time operator in the case of dwell times, the expected semiclassical results. In the regime of strong system-clock coupling, we find that the arrival-time probability is proportional to the kinetic-energy density, consistent with an earlier model involving a complex potential. We argue that, properly normalized, this may be the generically expected result in this regime. We show that these conclusions are largely independent of the form of the clock Hamiltonian.

  12. Empirical estimation of the arrival time of ICME Shocks

    NASA Astrophysics Data System (ADS)

    Shaltout, Mosalam

    Empirical estimation of the arrival time of ICME Shocks Mosalam Shaltout1 ,M.Youssef 1and R.Mawad2 1 National Research Institute of Astronomy and Geophysics (NRIAG) ,Helwan -Cairo-Egypt Email: mosalamshaltout@hotmail.com 2 Faculty of Science-Monifiia University-Physics Department-Shiben Al-Koum -Monifiia-Egypt We are got the Data of the SSC events from Preliminary Reports of the ISGI (Institut de Physique du Globe, France) .Also we are selected the same CME interval 1996-2005 from SOHO/LASCO/C2.We have estimated the arrival time of ICME shocks during solar cycle 23rd (1996-2005), we take the Sudden storm commencement SSC as a indicator of the arrival of CMEs at the Earth's Magnetosphere (ICME).Under our model ,we selected 203 ICME shock-SSC associated events, we got an imperial relation between CME velocity and their travel time, from which we obtained high correlation between them, R=0.75.

  13. Early magnitude estimation for the MW7.9 Wenchuan earthquake using progressively expanded P-wave time window

    PubMed Central

    Peng, Chaoyong; Yang, Jiansi; Zheng, Yu; Xu, Zhiqiang; Jiang, Xudong

    2014-01-01

    More and more earthquake early warning systems (EEWS) are developed or currently being tested in many active seismic regions of the world. A well-known problem with real-time procedures is the parameter saturation, which may lead to magnitude underestimation for large earthquakes. In this paper, the method used to the MW9.0 Tohoku-Oki earthquake is explored with strong-motion records of the MW7.9, 2008 Wenchuan earthquake. We measure two early warning parameters by progressively expanding the P-wave time window (PTW) and distance range, to provide early magnitude estimates and a rapid prediction of the potential damage area. This information would have been available 40 s after the earthquake origin time and could have been refined in the successive 20 s using data from more distant stations. We show the suitability of the existing regression relationships between early warning parameters and magnitude, provided that an appropriate PTW is used for parameter estimation. The reason for the magnitude underestimation is in part a combined effect of high-pass filtering and frequency dependence of the main radiating source during the rupture process. Finally we suggest only using Pd alone for magnitude estimation because of its slight magnitude saturation compared to the τc magnitude. PMID:25346344

  14. Early magnitude estimation for the MW7.9 Wenchuan earthquake using progressively expanded P-wave time window.

    PubMed

    Peng, Chaoyong; Yang, Jiansi; Zheng, Yu; Xu, Zhiqiang; Jiang, Xudong

    2014-01-01

    More and more earthquake early warning systems (EEWS) are developed or currently being tested in many active seismic regions of the world. A well-known problem with real-time procedures is the parameter saturation, which may lead to magnitude underestimation for large earthquakes. In this paper, the method used to the MW9.0 Tohoku-Oki earthquake is explored with strong-motion records of the MW7.9, 2008 Wenchuan earthquake. We measure two early warning parameters by progressively expanding the P-wave time window (PTW) and distance range, to provide early magnitude estimates and a rapid prediction of the potential damage area. This information would have been available 40?s after the earthquake origin time and could have been refined in the successive 20?s using data from more distant stations. We show the suitability of the existing regression relationships between early warning parameters and magnitude, provided that an appropriate PTW is used for parameter estimation. The reason for the magnitude underestimation is in part a combined effect of high-pass filtering and frequency dependence of the main radiating source during the rupture process. Finally we suggest only using Pd alone for magnitude estimation because of its slight magnitude saturation compared to the ?c magnitude. PMID:25346344

  15. Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements

    NASA Astrophysics Data System (ADS)

    Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T.; Carlson, Thomas J.

    2016-04-01

    Locating the position of fixed or mobile sources (i.e., transmitters) based on measurements obtained from sensors (i.e., receivers) is an important research area that is attracting much interest. In this paper, we review several representative localization algorithms that use time of arrivals (TOAs) and time difference of arrivals (TDOAs) to achieve high signal source position estimation accuracy when a transmitter is in the line-of-sight of a receiver. Circular (TOA) and hyperbolic (TDOA) position estimation approaches both use nonlinear equations that relate the known locations of receivers and unknown locations of transmitters. Estimation of the location of transmitters using the standard nonlinear equations may not be very accurate because of receiver location errors, receiver measurement errors, and computational efficiency challenges that result in high computational burdens. Least squares and maximum likelihood based algorithms have become the most popular computational approaches to transmitter location estimation. In this paper, we summarize the computational characteristics and position estimation accuracies of various positioning algorithms. By improving methods for estimating the time-of-arrival of transmissions at receivers and transmitter location estimation algorithms, transmitter location estimation may be applied across a range of applications and technologies such as radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.

  16. Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements.

    PubMed

    Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T; Carlson, Thomas J

    2016-04-01

    Locating the position of fixed or mobile sources (i.e., transmitters) based on measurements obtained from sensors (i.e., receivers) is an important research area that is attracting much interest. In this paper, we review several representative localization algorithms that use time of arrivals (TOAs) and time difference of arrivals (TDOAs) to achieve high signal source position estimation accuracy when a transmitter is in the line-of-sight of a receiver. Circular (TOA) and hyperbolic (TDOA) position estimation approaches both use nonlinear equations that relate the known locations of receivers and unknown locations of transmitters. Estimation of the location of transmitters using the standard nonlinear equations may not be very accurate because of receiver location errors, receiver measurement errors, and computational efficiency challenges that result in high computational burdens. Least squares and maximum likelihood based algorithms have become the most popular computational approaches to transmitter location estimation. In this paper, we summarize the computational characteristics and position estimation accuracies of various positioning algorithms. By improving methods for estimating the time-of-arrival of transmissions at receivers and transmitter location estimation algorithms, transmitter location estimation may be applied across a range of applications and technologies such as radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia. PMID:27131647

  17. The Effects of Predator Arrival Timing on Adaptive Radiation (Invited)

    NASA Astrophysics Data System (ADS)

    Borden, J.; Knope, M. L.; Fukami, T.

    2009-12-01

    Much of Earth’s biodiversity is thought to have arisen by adaptive radiation, the rapid diversification of a single ancestral species to fill a wide-variety of ecological niches. Both theory and empirical evidence have long supported competition for limited resources as a primary driver of adaptive radiation. While predation has also been postulated to be an important selective force during radiation, empirical evidence is surprisingly scant and its role remains controversial. However, two recent empirical studies suggest that predation can promote divergence during adaptive radiation. Using an experimental laboratory microcosm system, we examined how predator arrival timing affects the rate and extent of diversification during adaptive radiation. We varied the introduction timing of a protozoan predator (Tetrahymena thermophila) into populations of the bacteria Pseudomonas flourescens, which is known for its ability to undergo rapid adaptive radiation in aqueous microcosms. While our results show that predator arrival timing may have a significant impact on the rate, but not extent, of diversification, these results are tenuous and should be interpreted with caution, as the protozoan predators died early in the majority of our treatments, hampering our ability for comparison across treatments. Additionally, the abundance of newly derived bacterial genotypes was markedly lower in all treatments than observed in previous experiments utilizing this microbial experimental evolution system. To address these shortcomings, we will be repeating the experiment in the near future to further explore the impact of predator arrival timing on adaptive radiation. Smooth Morph and small-Wrinkly Spreader Pseudomonas flourescens diversification in the 96 hour treatment. Day 10, diluted to 1e-5.

  18. S-P wave travel time residuals and lateral inhomogeneity in the mantle beneath Tibet and the Himalaya

    NASA Technical Reports Server (NTRS)

    Molnar, P.; Chen, W.-P.

    1984-01-01

    S-P wave travel time residuals were measured in earthquakes in Tibet and the Himalaya in order to study lateral inhomogeneities in the earth's mantle. Average S-P residuals, measured with respect to Jeffrey-Bullen (J-B) tables for 11 earthquakes in the Himalaya are less than +1 second. Average J-B S-P from 10 of 11 earthquakes in Tibet, however, are greater than +1 second even when corrected for local crustal thickness. The largest values, ranging between 2.5 and 4.9 seconds are for five events in central and northern Tibet, and they imply that the average velocities in the crust and upper mantle in this part of Tibet are 4 to 10 percent lower than those beneath the Himalaya. On the basis of the data, it is concluded that it is unlikely that a shield structure lies beneath north central Tibet unless the S-P residuals are due to structural variations occurring deeper than 250 km.

  19. Global-scale P wave tomography optimized for prediction of teleseismic and regional travel times for Middle East events: 1. Data set development

    NASA Astrophysics Data System (ADS)

    Myers, S. C.; Johannesson, G.; Simmons, N. A.

    2011-04-01

    We extend the Bayesloc seismic multiple-event location algorithm for application to global arrival time data sets. Bayesloc is a formulation of the joint probability distribution spanning multiple-event location parameters, including hypocenters, travel time corrections, pick precision, and phase labels. Stochastic priors may be used to constrain any of the Bayesloc parameters. Markov Chain Monte Carlo sampling is used to draw samples from the joint probability distribution, and the posteriori samples are summarized to infer conventional location parameters such as the hypocenter. The first application of the broad area Bayesloc algorithm is to a data set consisting of all well-recorded events in the Middle East and the most well-recorded events with 5° spatial sampling globally. This sampling strategy is designed to provide the ray coverage needed to determine lithospheric-scale P wave velocity structure in the Middle East using the complementary ray geometry provided by regional (subhorizontal) and teleseismic (subvertical) raypaths and to determine a consistent, albeit lower-resolution, image of global mantle structure. The data set consists of 5401 events and 878,535 P, Pn, pP, sP, and PcP arrivals recorded at 4606 stations. Relocated epicenters are an average of 16 km from bulletin locations. The data set included events that are known to an accuracy of 1 km (a.k.a. GT1) based on nonseismic information. The average distance between GT1 epicenters and our relocated epicenters is 5.6 km. For arrivals labeled P, Pn, and PcP, ˜92%, ˜90%, and 96% are properly labeled with probability >0.9, respectively. Incorrect phase labels are found to be erroneous at rates of 0.6%, 0.2%, 1.6%, and 2.5% for P, Pn, PcP, and depth phases (pP and sP), respectively. Labels found to be incorrect, but not erroneous, were reassigned to another phase label. P and Pn residual standard deviation with respect to ak135 travel times are dramatically reduced from 3.45 s to 1.01 s. The differences between travel time residuals for nearly reciprocal raypaths are significantly reduced from the input event locations, suggesting that Bayesloc relocation improves data set consistency. The reciprocity tests suggest that the dominant contribution to travel time residuals calculated from information provided in global bulletins is location and picks errors, not travel time prediction errors due to 3-D structure. Modeling the whole multiple-event system results in accurate locations and an internally consistent data set that is ideal for tomography and other travel time calibration studies. Simmons et al. (2011) (companion paper) use the Bayesloc-processed data set to develop a 3-D tomographic image, which further reduces residual standard deviation to 0.50 s.

  20. Equal Arrival Time Surface Effects in GRB Afterglows

    NASA Astrophysics Data System (ADS)

    Huang, Y. F.; Lu, Y.; Cheng, K. S.

    2008-01-01

    Due to the relativistic motion of gamma-ray burst remnant and its deceleration in the circumburst medium, the equal arrival time surface (EATS) is not spherical, but ellipsoidal. Here the EATS effects are studied numerically. A direct comparison for the cases when the effects are or are not included is presented. Generally speaking, the EATS effect slightly hardens the spectra and postpones the peak time of the afterglows, but does not change the shapes of the spectra and light curves significantly In the cases of a density jump or an energy-injection, the effect smears out the variations in the afterglows markedly For the rapid rebrightening observed in the optical afterglow of GRB 030329 at t~1.6 d, the energy-injection model can give a best explanation as compared with the density jump model and two-component jet model. However, the predicted rebrightening is still not as rapid as observations due to EATS effect.

  1. POLENET/LAPNET teleseismic P wave travel time tomography model of the upper mantle beneath northern Fennoscandia

    NASA Astrophysics Data System (ADS)

    Silvennoinen, Hanna; Kozlovskaya, Elena; Kissling, Eduard

    2016-03-01

    The POLENET/LAPNET (Polar Earth Observing Network) broadband seismic network was deployed in northern Fennoscandia (Finland, Sweden, Norway, and Russia) during the third International Polar Year 2007-2009. The array consisted of roughly 60 seismic stations. In our study, we estimate the 3-D architecture of the upper mantle beneath the northern Fennoscandian Shield using high-resolution teleseismic P wave tomography. The P wave tomography method can complement previous studies in the area by efficiently mapping lateral velocity variations in the mantle. For this purpose 111 clearly recorded teleseismic events were selected and the data from the stations hand-picked and analysed. Our study reveals a highly heterogeneous lithospheric mantle beneath the northern Fennoscandian Shield though without any large high P wave velocity area that may indicate the presence of thick depleted lithospheric "keel". The most significant feature seen in the velocity model is a large elongated negative velocity anomaly (up to -3.5 %) in depth range 100-150 km in the central part of our study area that can be followed down to a depth of 200 km in some local areas. This low-velocity area separates three high-velocity regions corresponding to the cratonic units forming the area.

  2. P wave travel times: Stability and change within the source volume of A M = 7. 2 earthquake

    SciTech Connect

    Johnston, A.C.; Wyss, M.; Habermann, R.E.

    1982-08-10

    The dense seismograph network on the south flank of Kilauea afforded a unique opportunity to study travel time changes as a function of space and time within the source volume of the Hawaii earthquake (M/sub S/ = 7.2) of 1975. Careful analysis of more than 600 teleseismic P arrivals from deep Fiji-Tonga earthquakes revealed the following: out of eight stations studied, six showed constant travel times to within +- 0.03 s for up to 10 years with the exception of some small changes of about 0.03 s at the time of the main shock. One station, AHU, showed a highly significant and unique travel time decrease by 0.13 s during 1971/1972. At the beginning of this velocity anomaly a southwest rift intrusion caused closure of surface cracks associated with normal faults located near the station AHU. Also, geodetic measurements revealed that between August and October 1971 compressive strain of 4 x 10/sup -5/ was accumulated perpendicular to the southwest rift in the area of AHU. We conclude that these data show for the first time that in situ velocity increases occur due to the closure of cracks by tectonic forces. The AHU residuals returned to normal approximately at the time of a major earthquake swarm on the fault zone near AHU, during which surface cracks were observed to have opened again.We have interpreted the teleseismic residual change at AHU as due to a P velocity increase of about 10% in the top 3.5-1.5-km of the crust. The only station, WHA, which showed a large (0.2 s) and extended (1972 to 1975) travel time increase was located only 4-km from the main shock epicenter. We interpret this velocity decrease as a precursor to the 1975 main shock, and we hypopthesize that a process reverse from that at AHU caused this anomaly by first opening and then closing cracks in the crust below WHA.

  3. Semi-coherent time of arrival estimation using regression.

    PubMed

    Apartsin, Alexander; Cooper, Leon N; Intrator, Nathan

    2012-08-01

    Time of arrival (ToA) estimation is essential for many types of remote sensing applications including radar, sonar, and underground exploration. The standard method for ToA estimation employs a matched filter for computing the maximum likelihood estimator (MLE) for ToA. The accuracy of the MLE decreases rapidly whenever the amount of noise in a received signal rises above a certain threshold. This well-known threshold effect is unavoidable in several important applications due to various limitations on the power and the spectrum of a narrowband source pulse. A measurement performed in the presence of the threshold effect employs a receiver which operates in the semi-coherent state. Therefore, the conventional methods assuming a coherent state receiver should be adapted to the semi-coherent case. In this paper, a biosonar-inspired method for the semi-coherent ToA estimation is described. The method abandons the exploration of an echo signal by a single matched filter in favor of the analysis by multiple phase-shifted unmatched filters. Each phase-shifted unmatched filter gives rise to a biased ToA estimator. The described method uses regression for combining these estimators into a single unbiased ToA estimator that outperform the MLE in the presence of the threshold effect. PMID:22894206

  4. Uppermost mantle P wave velocities beneath Turkey and Iran

    SciTech Connect

    Chen, C.; Chen, W.; Molnar, P.

    1980-01-01

    The uppermost mantle P wave velocities beneath Turkey and Iran were estimated by applying the conventional travel time-distance relation method to arrival times of well located earthquakes recorded at a few stations. The average uppermost mantle P wave velocity under Turkey is estimated from two stations of the World Wide Standardized Seismograph Network (WWSSN), Istanbul and Tabriz. The data are consistent with a crust of uniform, but poorly determined, thickness and an uppermost mantle P wave velocity of 7.73 +- 0.08 km/s. This velocity is very similar to that for the Aegean Sea and suggests that its structure could be closely related to that beneath Turkey. For Iran, the results calculated from travel times to three WWSSN stations, Meshed, Shiraz, and Tabriz, can be explained by a crust dipping toward the south-southeast at about 1/sup 0/ with an uppermost mantle P wave velocity of 8.0 +- 0.1 km/s. If the crustal thickness were 34 km in the north it would reach about 49 km in the south. Based on these uppermost mantle velocities, the temperature at Moho beneath Turkey is probably close to the melting temperature of peridotite but that beneath Iran is probably lower.

  5. Tomography of the western United States from regional arrival times

    NASA Astrophysics Data System (ADS)

    Hearn, Thomas; Beghoul, Noureddine; Barazangi, Muawia

    1991-09-01

    First arrival times from regional distances (200-1200 km) in the western United States extracted from the International Seismological Centre (ISC) data set were inverted in a tomographic study to map the laterally varying Pn velocity structure of the uppermost mantle (i.e., the mantle lid) and to estimate the crustal static delay at each seismograph station. Synthetic data were used to evaluate resolution. Results correlate well with major tectonic features. We find low uppermost mantle velocities (V < 7.9 km/s) centered in the Basin and Range Province surrounded by uppermost mantle of higher, more normal Pn velocities (V > 7.9 km/s). These low apparent Pn velocities are primarily due to the effects of isostasy, hotspot volcanism, and crustal extension. We interpret the low apparent Pn velocities beneath the Sierra Nevada (7.6-7.7 km/s) to be the result of time delays introduced by ray paths tunneling through the deep crustal root. The Yellowstone hotspot, migrating along the Snake River Plain, has left low velocity (<7.6-7.8 km/s), hot upper mantle in its wake. Lower Pn velocities (˜7.8 km/s) beneath the extensional Basin and Range are also presumably due to hotter uppermost mantle. Based on station static delays for the Basin and Range, we infer that Moho depths there do not vary significantly from 30 km. Normal continental Pn velocities (˜8.0 km/s) as well as thicker crust (40-50 km) underlying the Rocky Mountains, Wyoming Basin Province, Colorado Plateau, and the northern Columbia Plateau indicate the presence of relatively cool uppermost mantle beneath these regions.

  6. A Fast-Time Simulation Tool for Analysis of Airport Arrival Traffic

    NASA Technical Reports Server (NTRS)

    Erzberger, Heinz; Meyn, Larry A.; Neuman, Frank

    2004-01-01

    The basic objective of arrival sequencing in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The performance of an automated arrival scheduling system, such as the Traffic Management Advisor developed by NASA for the FAA, can be studied by a fast-time simulation that does not involve running expensive and time-consuming real-time simulations. The fast-time simulation models runway configurations, the characteristics of arrival traffic, deviations from predicted arrival times, as well as the arrival sequencing and scheduling algorithm. This report reviews the development of the fast-time simulation method used originally by NASA in the design of the sequencing and scheduling algorithm for the Traffic Management Advisor. The utility of this method of simulation is demonstrated by examining the effect on delays of altering arrival schedules at a hub airport.

  7. A COMPARISON OF COLLAPSING AND PRECISE ARRIVAL-TIME MAPPING OF MICROSEISMICITY

    SciTech Connect

    RUTLEDGE, JAMES T.; JONES, ROB H.

    2007-01-05

    In this paper they compare the improvements in microseismic location images obtained using precise arrival times with that obtained by the collapsing technique. They first collapse the initial locations for a hydraulic-fracture data set from the Carthage Cotton Valley gas field, they then use the precise-arrival-time locations as measure for the effectiveness of the collapsing. Finally, they examine the changes when applying collapsing to the precise-arrival-time locations.

  8. A particle filtering approach for spatial arrival time tracking in ocean acoustics.

    PubMed

    Jain, Rashi; Michalopoulou, Zoi-Heleni

    2011-06-01

    The focus of this work is on arrival time and amplitude estimation from acoustic signals recorded at spatially separated hydrophones in the ocean. A particle filtering approach is developed that treats arrival times as "targets" and tracks their "location" across receivers, also modeling arrival time gradient. The method is evaluated via Monte Carlo simulations and is compared to a maximum likelihood estimator, which does not relate arrivals at neighboring receivers. The comparison demonstrates a significant advantage in using the particle filter. It is also shown that posterior probability density functions of times and amplitudes become readily available with particle filtering. PMID:21682358

  9. Timing the Random and Anomalous Arrival of Particles in a Geiger Counter with GPS Devices

    ERIC Educational Resources Information Center

    Blanco, F.; La Rocca, P.; Riggi, F.; Riggi, S.

    2008-01-01

    The properties of the arrival time distribution of particles in a detector have been studied by the use of a small Geiger counter, with a GPS device to tag the event time. The experiment is intended to check the basic properties of the random arrival time distribution between successive events and to simulate the investigations carried out by

  10. Timing the Random and Anomalous Arrival of Particles in a Geiger Counter with GPS Devices

    ERIC Educational Resources Information Center

    Blanco, F.; La Rocca, P.; Riggi, F.; Riggi, S.

    2008-01-01

    The properties of the arrival time distribution of particles in a detector have been studied by the use of a small Geiger counter, with a GPS device to tag the event time. The experiment is intended to check the basic properties of the random arrival time distribution between successive events and to simulate the investigations carried out by…

  11. Finite frequency global P wave tomography

    NASA Astrophysics Data System (ADS)

    Montelli, R.; Nolet, G.; Masters, G.; Dahlen, F. A.; Hung, S.-H.

    2003-04-01

    The travel time of a finite frequency wave is sensitive to velocity structure off the geometrical ray within a volume known as the Fresnel zone. We compute 3D travel time sensitivity efficiently by using the paraxial approximation in conjunction with ray theory and the Born approximation (Dahlen et al., 2000) to invert global travel times of long-period compressional waves. Our data set consists of 67540 P and 20266 PP-P travel times measured by cross-correlation. The sensitivity of a broad-band P arrival time resembles a hollow-banana surrounding the unperturbed path with sensitivity being zero on the ray. Typical widths of sensitivity kernels at the turning point are about 1000 km and 1300 km for a P wave at 60o and 80o epicentral distance, respectively. The region of insensitivity around the geometrical ray is small near the source and the receiver but can extend to about 400 km near the turning point for a P wave at 80o epicentral distance. Because of the minimax nature, surface reflected PP waves show a much more complicated shape of the sensitivity region, with the banana-doughnut shape replaced by a saddle-shaped region upon passage of a caustic. Not surprisingly, the introduction of such complicated sensitivity has consequences for the final tomographic images. We compare tomographic models inverted with the new method and with the more standard technique of ray theory for the same data fit (i.e. same χ2) and each smoothed to resolve very similar length scales. Depending on depth and size of the anomaly, amplitudes of the velocity perturbations in finite frequency images are on average 30%-60% higher than those obtained with ray theory. This demonstrates a major shortcoming of ray theory. It is not possible to neglect wavefront healing effect, as ray theory does. The images obtained by inverting long-period waves provide unambiguous evidence that a limited number of hot-spots are fed by plumes originating in the lower mantle. To better constrain the P wave velocity structure in the Earth, we combine the long period data with ISC delays obtained at short period. Inverting a combination of low and high frequency waves allows to properly constrain long wavelength heterogeneity with the kernels, while using the high-frequency data (e.g ISC delays) to constrain smaller-scale structure. We shall present the latest results of this inversion and discuss the improvements brought about by the various improvements in the theory.

  12. Joint Inversion of Geoid Anomaly and Teleseismic P-Wave Delay Times: Modeling Density and Velocity Perturbations Beneath the Parana Magmatic Province

    NASA Astrophysics Data System (ADS)

    Chaves, C. A. M.; Ussami, N.; Ritsema, J.

    2014-12-01

    The Parana Magmatic Province (PMP) is one of the largest continental igneous provinces (LIP) on Earth. It is well dated at 133 Ma preceding the opening of the South Atlantic Ocean, but the causative geodynamic processes are still poorly understood. Although a low-velocity anomaly has been imaged by seismic tomography in the northeast region of the PMP and interpreted as a fossil conduct of a mantle plume that is related to the flood basalt eruptions, geochemical data indicate that such magmatism is caused by the melting of a heterogeneous and enriched lithospheric mantle with no deep plume participation. Models of density perturbations in the upper mantle estimated from joint inversion of geoid anomalies and P-wave delay times will offer important constraints on mantle dynamics. A new generation of accurate global geopotential models derived from satellite-missions (e.g. GRACE, GOCE) allows us to estimate density distribution within the Earth from geoid inversion. In order to obtain the residual geoid anomaly related to the density structure of the mantle, we use the EGM2008 model removing estimated geoid perturbations owing to variations in crustal structure (i.e., topographical masses, Moho depth, thickness of sediments and basalts). Using a spherical-Earth approximation, the density model space is represented by a set of tesseroids and the velocity model is parameterized in nodes of a spherical grid where cubic B-splines are utilized as an interpolation function. To constrain the density inversion, we add more than 10,000 manually picked teleseismic P-wave delay times. During the inversion procedure, density and P-wave velocity are linked through the optimization of a constant linear factor correlating density and velocity perturbation. Such optimization will be performed using a probability density function (PDF) [Tarantola, 2005]. We will present the preliminary results of this joint inversion scheme and hypothesize on the geodynamic processes responsible for the flood basalt eruptions.

  13. Using heliospheric imaging observations to forecast the arrival time of CMEs

    NASA Astrophysics Data System (ADS)

    Mishra, Wageesh; Srivastava, Nandita

    The estimation of arrival time of coronal mass ejections (CMEs) near 1 AU is a crucial problem in the development of any space weather prediction model. For more than twenty years such studies are being done mainly using coronagraphs (SOHO/LASCO) observations near the sun or using empirical, statistical or numerical arrival time models. In both the approaches, we utilize the in-situ measurements of ICMEs as a reference of the actual arrival time of CMEs. But the identification of ICMEs near the earth is based on many signatures and they usually have unclear boundaries, resulting in uncertainties in the actual arrival time too. In this way, our understanding about CME kinematics and estimation of its arrival time based on two point measurements, are not sufficient. In order to understand the CME kinematics throughout the interplanetary medium, we have analyzed the coronagraph (2.5 -15 Rs) and heliospheric imager (15-330 Rs) (SECCHI/HI) data. We applied different methods on imaging (COR and HI) observations to estimate the true kinematics of CMEs in interplanetary medium. We used these estimates as inputs to the drag based model to predict the arrival time as well as transit velocity of CMEs at 1 AU. We also compare the accuracy of different methods implemented on imaging (COR and HI) data on our studied events. Our analysis reveals the importance of heliospheric imager observations in forecasting the CME arrival time near 1 AU.

  14. A self-adjoint arrival time operator inspired by measurement models

    NASA Astrophysics Data System (ADS)

    Halliwell, J. J.; Evaeus, J.; London, J.; Malik, Y.

    2015-10-01

    We introduce an arrival time operator which is self-adjoint and, unlike previously proposed arrival time operators, has a close link to simple measurement models. Its spectrum leads to an arrival time distribution which is a variant of the Kijowski distribution (a re-ordering of the current) in the large momentum regime but is proportional to the kinetic energy density in the small momentum regime, in agreement with measurement models. A brief derivation of the latter distribution is given. We make some simple observations about the physical reasons for self-adjointness, or its absence, in both arrival time operators and the momentum operator on the half-line and we also compare our operator with the dwell time operator.

  15. Time-lapse interpretation of p-wave data for a hydraulically fractured reservoir, Wattenberg Field, Colorado

    NASA Astrophysics Data System (ADS)

    White, Matthew D.

    Hydraulic fracturing technology has contributed to making production from low permeability source rocks economic for oil and gas companies. However, few direct observations have been made regarding the physical modifications of the reservoir resulting from the hydraulic fracturing process. This thesis investigates the time-lapse seismic response generated by hydraulically fracturing an unconventional reservoir. Compressional seismic data sets were acquired before and after completions in a single section in Wattenberg Field, CO. Cross-equalization of the time-lapse seismic data sets was required for the comparison of seismic amplitudes. A time-shift anomaly and amplitude anomaly were observed in the reservoir interval, and time-lapse changes are spatially aligned with the wellbores. To understand the physical change that caused this seismic anomaly, percentage change of acoustic P-impedance was calculated. A decrease in the acoustic P-impedance of up to 7% was observed from the baseline to the monitor survey in the reservoir interval. This observation was put into physical context through interpretation of a structural geologic model, and completions parameter and timing. An increase in pore pressure due to hydraulic fracturing was interpreted as the physical mechanism causing the change in P-impedance. Hydraulic fracturing is highly dependent on local geology, and the integration of geoscience with parameter design is necessary for optimization. Seismic monitoring can assist assist reservoir management of Wattenberg Field.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  17. Perturbation analysis of queueing systems with a time-varying arrival rate

    NASA Technical Reports Server (NTRS)

    Cassandras, Christos G.; Pan, Jie

    1991-01-01

    The authors consider an M/G/1 queuing with a time-varying arrival rate. The objective is to obtain infinitesimal perturbation analysis (IPA) gradient estimates for various performance measures of interest with respect to certain system parameters. In particular, the authors consider the mean system time over n arrivals and an arrival rate alternating between two values. By choosing a convenient sample path representation of this system, they derive an unbiased IPA gradient estimator which, however, is not consistent, and investigate the nature of this problem.

  18. Azimuthal variations in P-wave travel times and shear-wave splitting in the Charlevoix seismic zone

    NASA Astrophysics Data System (ADS)

    Buchbinder, G. G. R.

    1989-08-01

    A significant drop of up to 1% in the seismic P travel times recorded from controlled explosions occurred in the Charlevoix seismic zone (CSZ) between 1979 and 1980. The travel-time data exhibited variations not only with distance but also with azimuth. These variations are interpreted in terms of extensive dilatancy anisotropy (EDA). In 1984 and 1985, shear-wave splitting was observed in the CSZ on micro-earthquake seismograms. Under the assumption of EDA the observations are interpreted in terms of a dominant crack orientation of about 36° and a crack density ɛ of around 0.05 to 0.02. The observations from the P- and S-waves are not incompatible with one another.

  19. The PDV Velocity History and Shock Arrival Time Analyzer

    Energy Science and Technology Software Center (ESTSC)

    2006-08-29

    This software allows the user to analyze heterodyne beat signals generated when a Doppler-shifted laser light interacts with un-shifted laser light. The software analyzes the data in a joint time frequency domain to extract instantaneous velocity.

  20. A Fast-Time Study of Aircraft Reordering in Arrival Sequencing and Scheduling

    NASA Technical Reports Server (NTRS)

    Carr, Greg; Neuman, Frank; Tobias, Leonard (Technical Monitor)

    1998-01-01

    In order to ensure that the safe capacity of the terminal area is not exceeded, Air Traffic Management ATM often places restrictions on arriving flights transitioning from en route airspace to terminal airspace. This restriction of arrival traffic is commonly referred to as arrival flow management, and includes techniques such as metering, vectoring, fix-load balancing, and the imposition of miles-in-trail separations. These restrictions are enacted without regard for the relative priority which airlines may be placing on individual flights based on factors such as crew criticality, passenger connectivity, critical turn times, gate availability, on-time performance, fuel status, or runway preference. The development of new arrival flow management techniques which take into consideration priorities expressed by air carriers will likely reduce the economic impact of ATM restrictions on the airlines and lead to increased airline economic efficiency by allowing airlines to have greater control over their individual arrival banks of aircraft. NASA and the Federal Aviation Administration (FAA) have designed and developed a suite of software decision support tools (DSTs) collectively known as the Center TRACON Automation System (CTAS). One of these tools, the Traffic Management Advisor (TMA) is currently being used at the Fort Worth Air Route Traffic Control Center to perform arrival flow management of traffic into the Dallas/Fort Worth airport (DFW). The TMA is a time-based strategic planning tool that assists Traffic Management Coordinators (TMCs) and En Route Air Traffic Controllers in efficiently balancing arrival demand with airport capacity. The primary algorithm in the TMA is a real-time scheduler which generates efficient landing sequences and landing times for arrivals within about 200 no a. from touchdown. This scheduler will sequence aircraft so that they arrive in a first- come - first-served (FCFS) order. While FCFS sequencing establishes a fair order based on estimated times of arrival, it does not take into account individual airline priorities among incoming flights. NASA is exploring the possibility of allowing airlines to express relative arrival priorities to air traffic management through the development of new CTAS scheduling algorithms which take into consideration airline arrival preferences. The accommodation of airline priorities in arrival sequencing and scheduling would under most circumstances result in a deviation from a "natural" or FCFS arrival order. As a First step toward developing airline influenced sequencing algorithms, an investigation was conducted to determine the feasibility of reordering arrival traffic from a strict FCFS sequence. A fast-time simulation has been developed which allows statistical evaluation of sequencing and scheduling algorithms for arrival traffic at the Dallas/Fort Worth Airport. In contrast to real-time simulation or field tests, which would require on the order of ninety minutes to examine a single traffic rush period, the fast-time simulation allows examination of multiple rush periods in a matter of seconds.

  1. Does winter region affect spring arrival time and body mass of king eiders in northern Alaska?

    USGS Publications Warehouse

    Powell, Abby N.; Oppel, Steffen

    2009-01-01

    Events during the non-breeding season may affect the body condition of migratory birds and influence performance during the following breeding season. Migratory birds nesting in the Arctic often rely on endogenous nutrients for reproductive efforts, and are thus potentially subject to such carry-over effects. We tested whether king eider (Somateria spectabilis) arrival time and body mass upon arrival at breeding grounds in northern Alaska were affected by their choice of a winter region in the Bering Sea. We captured birds shortly after arrival on breeding grounds in early June 2002–2006 at two sites in northern Alaska and determined the region in which individuals wintered using satellite telemetry or stable isotope ratios of head feathers. We used generalized linear models to assess whether winter region explained variation in arrival body mass among individuals by accounting for sex, site, annual variation, and the date a bird was captured. We found no support for our hypothesis that either arrival time or arrival body mass of king eiders differed among winter regions. We conclude that wintering in different regions in the Bering Sea is unlikely to have reproductive consequences for king eiders in our study areas.

  2. A formula relating sojourn times to the time of arrival in Hamiltonian dynamics

    NASA Astrophysics Data System (ADS)

    Gournay, A.; Tiedra de Aldecoa, R.

    2012-06-01

    We consider on a manifold M equipped with a Poisson bracket { ·, ·} a Hamiltonian H with complete flow and a family Φ ≡ (Φ1, …, Φd) of abstract position observables satisfying the condition {{Φj, H}, H} = 0 for each j. Under these assumptions, we prove a new formula relating sojourn times in dilated regions defined in terms of Φ to the time of arrival of classical orbits. The correspondence between this formula and a formula established recently in the framework of quantum mechanics is put into evidence. Among other examples, our theory applies to Stark Hamiltonians, homogeneous Hamiltonians, purely kinetic Hamiltonians, the repulsive harmonic potential, central force systems, the Poincaré ball model, the wave equation, the nonlinear Schrödinger equation, the Korteweg-de Vries equation and quantum Hamiltonians defined via expectation values.

  3. Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain

    SciTech Connect

    Im, M.-Y.; Lee, S.-H.; Kim, D.-H.; Fischer, P.; Shin, S.-C.

    2008-02-04

    We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite their quite different domain evolution patterns. Numerical simulation of the first arrival time with an assumption that the magnetic domain wall traveled as a random walker well matches our experimentally observed scaling behavior, providing an experimental support for the random-walking model of traveling magnetic domain walls.

  4. Predator density and timing of arrival affect reef fish community assembly.

    PubMed

    Stier, Adrian C; Geange, Shane W; Hanson, Kate M; Bolker, Benjamin M

    2013-05-01

    Most empirical studies of predation use simple experimental approaches to quantify the effects of predators on prey (e.g., using constant densities of predators, such as ambient vs. zero). However, predator densities vary in time, and these effects may not be well represented by studies that use constant predator densities. Although studies have independently examined the importance of predator density, temporal variability, and timing of arrival (i.e., early or late relative to prey), the relative contribution of these different predator regimes on prey abundance, diversity, and composition remains poorly understood. The hawkfish (Paracirrhites arcatus), a carnivorous coral reef fish, exhibits substantial variability in patch occupancy, density, and timing of arrival to natural reefs. Our field experiments demonstrated that effects of hawkfish on prey abundance depended on both hawkfish density and the timing of their arrival, but not on variability in hawkfish density. Relative to treatments without hawkfish, hawkfish presence reduced prey abundance by 50%. This effect increased with a doubling of hawkfish density (an additional 33% reduction), and when hawkfish arrived later during community development (a 34% reduction). Hawkfish did not affect within-patch diversity (species richness), but they increased between-patch diversity (beta) based on species incidence (22%), and caused shifts in species composition. Our results suggest that the timing of predator arrival can be as important as predator density in modifying prey abundance and community composition. PMID:23858646

  5. Multi-Mode Lamb Wave Arrival Time Extraction for Improved Tomographic Reconstruction

    SciTech Connect

    Hinders, Mark K.; Hou Jidong; Leonard, Kevin R.

    2005-04-09

    An ultrasonic signal processing technique is applied to multi-mode arrival time estimation from Lamb waveforms. The basic tool is a simplified time-scale projection called a dynamic wavelet fingerprint (DWFP) which enables direct observation of the variation of features of interest in non-stationary ultrasonic signals. The DWFP technique was used to automatically detect and evaluate each candidate through-transmitted Lamb mode. The area of the dynamic wavelet fingerprint was then used as a feature to distinguish false modes caused by noise and other interference from the true modes of interest. The set of estimated arrival times were then used as inputs for tomographic reconstruction. The Lamb wave tomography images generated with these estimated arrival times were able to indicate different defects in aluminum plates.

  6. Continuous measurement of the arrival times of x-ray photon sequence

    SciTech Connect

    Yan Qiurong; Sheng Lizhi; Zhao Baosheng; Liu Yong'an

    2011-05-15

    In order to record x-ray pulse profile for x-ray pulsar-based navigation and timing, this paper presents a continuous, high-precision method for measuring arrival times of photon sequence with a common starting point. In this method, a high stability atomic clock is counted to measure the coarse time of arrival photon. A high resolution time-to-digital converter is used to measure the fine time of arrival photon. The coarse times and the fine times are recorded continuously and then transferred to computer memory by way of memory switch. The pulse profile is obtained by a special data processing method. A special circuit was developed and a low-level x-ray pulse profile measurement experiment system was setup. The arrival times of x-ray photon sequence can be consecutively recorded with a time resolution of 500 ps and the profile of x-ray pulse was constructed. The data also can be used for analysis by many other methods, such as statistical distribution of photon events per time interval, statistical distribution of time interval between two photon events, photon counting histogram, autocorrelation and higher order autocorrelation.

  7. Changes in the timing of departure and arrival of Irish migrant waterbirds.

    PubMed

    Donnelly, Alison; Geyer, Heather; Yu, Rong

    2015-01-01

    There have been many recent reports across Europe and North America of a change in the timing of arrival and departure of a range of migrant bird species to their breeding grounds. These studies have focused primarily on passerine birds and climate warming has been found to be one of the main drivers of earlier arrival and departure in spring. In Ireland, rising spring temperature has been shown to result in the earlier arrival of sub-Saharan passerine species and the early departure of the Whooper Swan. In order to investigate changes in spring arrival and departure dates of waterbirds to Ireland, we extracted latest dates as an indicator of the timing of departure of winter visitors (24 species) and earliest dates as an indicator of the timing of arrival of spring/summer migrants (2 species) from BirdWatch Ireland's East Coast Bird reports (1980-2003). Three of the winter visitors showed evidence of later departure and one of earlier departure whereas one of the spring/summer visitors showed evidence of earlier arrival. In order to determine any influence of local temperature on these trends, we analysed data from two synoptic weather stations within the study area and found that spring (average February, March and April) air temperature significantly (P < 0.05) increased at a rate of 0.03 °C per year, which was strongly correlated with changes in latest and earliest records. We also tested the sensitivity of bird departure/arrival to temperature and found that Northern Pintail would leave 10 days earlier in response to a 1 °C increase in spring temperature. In addition, we investigated the impact of a large-scale circulation pattern, the North Atlantic Oscillation (NAO), on the timing of arrival and departure which correlated with both advances and delays in departure and arrival. We conclude that the impact of climate change on earliest and latest records of these birds is, as expected, species specific and that local temperature had less of an influence than large-scale circulation patterns. PMID:25653907

  8. Changes in the timing of departure and arrival of Irish migrant waterbirds

    PubMed Central

    Geyer, Heather; Yu, Rong

    2015-01-01

    There have been many recent reports across Europe and North America of a change in the timing of arrival and departure of a range of migrant bird species to their breeding grounds. These studies have focused primarily on passerine birds and climate warming has been found to be one of the main drivers of earlier arrival and departure in spring. In Ireland, rising spring temperature has been shown to result in the earlier arrival of sub-Saharan passerine species and the early departure of the Whooper Swan. In order to investigate changes in spring arrival and departure dates of waterbirds to Ireland, we extracted latest dates as an indicator of the timing of departure of winter visitors (24 species) and earliest dates as an indicator of the timing of arrival of spring/summer migrants (2 species) from BirdWatch Ireland’s East Coast Bird reports (1980–2003). Three of the winter visitors showed evidence of later departure and one of earlier departure whereas one of the spring/summer visitors showed evidence of earlier arrival. In order to determine any influence of local temperature on these trends, we analysed data from two synoptic weather stations within the study area and found that spring (average February, March and April) air temperature significantly (P < 0.05) increased at a rate of 0.03 °C per year, which was strongly correlated with changes in latest and earliest records. We also tested the sensitivity of bird departure/arrival to temperature and found that Northern Pintail would leave 10 days earlier in response to a 1 °C increase in spring temperature. In addition, we investigated the impact of a large-scale circulation pattern, the North Atlantic Oscillation (NAO), on the timing of arrival and departure which correlated with both advances and delays in departure and arrival. We conclude that the impact of climate change on earliest and latest records of these birds is, as expected, species specific and that local temperature had less of an influence than large-scale circulation patterns. PMID:25653907

  9. Time-of-Arrival Lightning Location Retrieval Using an Oblate Spheroidal Earth Model

    NASA Technical Reports Server (NTRS)

    Solakiewicz, Richard

    1999-01-01

    The problem of retrieving lightning ground strike location on an oblate spheroidal Earth using a network of 4 or more time-of-arrival sensors is considered. A recently developed analytic method for obtaining such retrievals on a spherical Earth surface is perturbed resulting in an iterative procedure to get correction terms. The perturbation procedure consists of applying a vector Newton's method to eqs. relating the distances from the lightning location to each sensor along a geodesic and the times of arrival of the wave produced by the lightning source at each sensor.

  10. Primary energy spectrum of cosmic rays obtained by arrival time spread of particles in EAS

    NASA Astrophysics Data System (ADS)

    Okita, M.; Wada, T.; Yamashita, Y.; Okei, K.; Morita, T.; Liang, S.; Takahashi, N.; Iyono, A.; Matsumoto, H.; Noda, C.; Masuda, M.; Yamamoto, I.; Kohata, M.; Ochi, N.; Nakatsuka, T.; Tsuji, S.

    2008-01-01

    The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) by using compact arrays. According to J. Linsley, the primary energy of EAS can be estimated from the spread of the arrival times of EAS particles, even with a small array. A shift register system for clocking the arrival times was installed in an array (OUS1) which is located in Okayama University of Science. Analyzing the OUS1 data, we obtained the primary energies of large air showers.

  11. Validation of a priori CME arrival predictions made using real-time heliospheric imager observations

    NASA Astrophysics Data System (ADS)

    Tucker-Hood, Kimberley; Scott, Chris; Owens, Mathew; Jackson, David; Barnard, Luke; Davies, Jackie A.; Crothers, Steve; Lintott, Chris; Simpson, Robert; Savani, Neel P.; Wilkinson, J.; Harder, B.; Eriksson, G. M.; L Baeten, E. M.; Wan Wah, Lily Lau

    2015-01-01

    Between December 2010 and March 2013, volunteers for the Solar Stormwatch (SSW) Citizen Science project have identified and analyzed coronal mass ejections (CMEs) in the near real-time Solar Terrestrial Relations Observatory Heliospheric Imager observations, in order to make "Fearless Forecasts" of CME arrival times and speeds at Earth. Of the 60 predictions of Earth-directed CMEs, 20 resulted in an identifiable Interplanetary CME (ICME) at Earth within 1.5-6 days, with an average error in predicted transit time of 22 h, and average transit time of 82.3 h. The average error in predicting arrival speed is 151 km s-1, with an average arrival speed of 425km s-1. In the same time period, there were 44 CMEs for which there are no corresponding SSW predictions, and there were 600 days on which there was neither a CME predicted nor observed. A number of metrics show that the SSW predictions do have useful forecast skill; however, there is still much room for improvement. We investigate potential improvements by using SSW inputs in three models of ICME propagation: two of constant acceleration and one of aerodynamic drag. We find that taking account of interplanetary acceleration can improve the average errors of transit time to 19 h and arrival speed to 77 km s-1.

  12. From 3-Hz P Waves to 0-S-2: Real-time and deferred estimates of the moment of the Honshu event across the full frequency spectrum

    NASA Astrophysics Data System (ADS)

    Andre, O. E.

    2011-12-01

    In the hours following the 2011 Honshu event, and as part of tsunami warning procedures at the Laboratoire de Geophysique in Papeete, Tahiti, the seismic source of the event was analyzed using a number of real-time procedures. The ultra-long period mantle magnitude algorithm suggests a static moment of 4.2E29 dyn*cm, not signifcantly different from the NEIC value obtained by W-phase inversion. The slowness parameter, THETA = -5.65, is slightly deficient, but characteristic of other large subduction events such as Nias (2005) or Peru (2001); it remains significantly larger than for slow earthquakes such as Sumatra (2004) or Mentawai (2010). Similarly, the duration of high-frequency (2-4 Hz) P waves in relation to seismic moment or estimated energy fails to document any slowness in the seismic source. These results were confirmed in the ensuing weeks by the analysis of the lowest-frequency spheroidal modes of the Earth. A dataset of 109 fits for 8 modes (including the gravest one, 0s2, and the breathing mode, 0s0) yields a remarkably flat spectrum, with an average moment of 3.5E29 dyn*cm (*/1.07). This textbook behavior of the Sendai earthquake explains the generally successful real-time modeling of its teleseismic tsunami, based on available seismic source scaling laws. On the other hand, it confirms the dichotomy, amongst mega-quakes (M sub 0 > 10 sup 29 dyn*cm) between regular events (Nias, 2005; Chile, 2010; Sendai, 2011) and slow ones (Chile, 1960; Alaska, 1964; Sumatra, 2004; and probably Rat Island, 1965), whose origin remains unexplained.

  13. Multiple mantle upwellings in the transition zone beneath the northern East-African Rift system from relative P-wave travel-time tomography

    NASA Astrophysics Data System (ADS)

    Civiero, Chiara; Hammond, James O. S.; Goes, Saskia; Fishwick, Stewart; Ahmed, Abdulhakim; Ayele, Atalay; Doubre, Cecile; Goitom, Berhe; Keir, Derek; Kendall, J.-Michael; Leroy, Sylvie; Ogubazghi, Ghebrebrhan; Rümpker, Georg; Stuart, Graham W.

    2015-09-01

    Mantle plumes and consequent plate extension have been invoked as the likely cause of East African Rift volcanism. However, the nature of mantle upwelling is debated, with proposed configurations ranging from a single broad plume connected to the large low-shear-velocity province beneath Southern Africa, the so-called African Superplume, to multiple lower-mantle sources along the rift. We present a new P-wave travel-time tomography model below the northern East-African, Red Sea, and Gulf of Aden rifts and surrounding areas. Data are from stations that span an area from Madagascar to Saudi Arabia. The aperture of the integrated data set allows us to image structures of ˜100 km length-scale down to depths of 700-800 km beneath the study region. Our images provide evidence of two clusters of low-velocity structures consisting of features with diameter of 100-200 km that extend through the transition zone, the first beneath Afar and a second just west of the Main Ethiopian Rift, a region with off-rift volcanism. Considering seismic sensitivity to temperature, we interpret these features as upwellings with excess temperatures of 100 ± 50 K. The scale of the upwellings is smaller than expected for lower mantle plume sources. This, together with the change in pattern of the low-velocity anomalies across the base of the transition zone, suggests that ponding or flow of deep-plume material below the transition zone may be spawning these upper mantle upwellings. This article was corrected on 28 SEP 2015. See the end of the full text for details.

  14. Optimal Time Advance In Terminal Area Arrivals: Throughput vs. Fuel Savings

    NASA Technical Reports Server (NTRS)

    Sadovsky, Alexander V .; Swenson, Harry N.; Haskell, William B.; Rakas, Jasenka

    2011-01-01

    The current operational practice in scheduling air traffic arriving at an airport is to adjust flight schedules by delay, i.e. a postponement of an aircrafts arrival at a scheduled location, to manage safely the FAA-mandated separation constraints between aircraft. To meet the observed and forecast growth in traffic demand, however, the practice of time advance (speeding up an aircraft toward a scheduled location) is envisioned for future operations as a practice additional to delay. Time advance has two potential advantages. The first is the capability to minimize, or at least reduce, the excess separation (the distances between pairs of aircraft immediately in-trail) and thereby to increase the throughput of the arriving traffic. The second is to reduce the total traffic delay when the traffic sample is below saturation density. A cost associated with time advance is the fuel expenditure required by an aircraft to speed up. We present an optimal control model of air traffic arriving in a terminal area and solve it using the Pontryagin Maximum Principle. The admissible controls allow time advance, as well as delay, some of the way. The cost function reflects the trade-off between minimizing two competing objectives: excess separation (negatively correlated with throughput) and fuel burn. A number of instances are solved using three different methods, to demonstrate consistency of solutions.

  15. Maximum Likelihood Time-of-Arrival Estimation of Optical Pulses via Photon-Counting Photodetectors

    NASA Technical Reports Server (NTRS)

    Erkmen, Baris I.; Moision, Bruce E.

    2010-01-01

    Many optical imaging, ranging, and communications systems rely on the estimation of the arrival time of an optical pulse. Recently, such systems have been increasingly employing photon-counting photodetector technology, which changes the statistics of the observed photocurrent. This requires time-of-arrival estimators to be developed and their performances characterized. The statistics of the output of an ideal photodetector, which are well modeled as a Poisson point process, were considered. An analytical model was developed for the mean-square error of the maximum likelihood (ML) estimator, demonstrating two phenomena that cause deviations from the minimum achievable error at low signal power. An approximation was derived to the threshold at which the ML estimator essentially fails to provide better than a random guess of the pulse arrival time. Comparing the analytic model performance predictions to those obtained via simulations, it was verified that the model accurately predicts the ML performance over all regimes considered. There is little prior art that attempts to understand the fundamental limitations to time-of-arrival estimation from Poisson statistics. This work establishes both a simple mathematical description of the error behavior, and the associated physical processes that yield this behavior. Previous work on mean-square error characterization for ML estimators has predominantly focused on additive Gaussian noise. This work demonstrates that the discrete nature of the Poisson noise process leads to a distinctly different error behavior.

  16. Improvements of the shock arrival times at the Earth model STOA

    NASA Astrophysics Data System (ADS)

    Liu, H.-L.; Qin, G.

    2015-07-01

    Prediction of the shocks' arrival times (SATs) at the Earth is very important for space weather forecast. There is a well-known SAT model, Shock Time of Arrival (STOA), which is widely used in the space weather forecast. However, the shock transit time from STOA model usually has a relative large error compared to the real measurements. In addition, STOA tends to yield too much "yes" prediction, which causes a large number of false alarms. Therefore, in this work, we work on the modification of STOA model. First, we give a new method to calculate the shock transit time by modifying the way to use the solar wind speed in STOA model. Second, we develop new criteria for deciding whether the shock will arrive at the Earth with the help of the sunspot numbers and the angle distances of the flare events. It is shown that our work can improve the SATs prediction significantly, especially the prediction of flare events without shocks arriving at the Earth.

  17. Techniques for measuring arrival times of pulsar signals 1: DSN observations from 1968 to 1980

    NASA Technical Reports Server (NTRS)

    Downs, G. S.; Reichley, P. E.

    1980-01-01

    Techniques used in the ground based observations of pulsars are described, many of them applicable in a navigation scheme. The arrival times of the pulses intercepting Earth are measured at time intervals from a few days to a few months. Low noise, wide band receivers, amplify signals intercepted by 26 m, 34, and 64 m antennas. Digital recordings of total received signal power versus time are cross correlated with the appropriate pulse template.

  18. High-speed quantum-random number generation by continuous measurement of arrival time of photons

    SciTech Connect

    Yan, Qiurong; Zhao, Baosheng; Hua, Zhang; Liao, Qinghong; Yang, Hao

    2015-07-15

    We demonstrate a novel high speed and multi-bit optical quantum random number generator by continuously measuring arrival time of photons with a common starting point. To obtain the unbiased and post-processing free random bits, the measured photon arrival time is converted into the sum of integral multiple of a fixed period and a phase time. Theoretical and experimental results show that the phase time is an independent and uniform random variable. A random bit extraction method by encoding the phase time is proposed. An experimental setup has been built and the unbiased random bit generation rate could reach 128 Mb/s, with random bit generation efficiency of 8 bits per detected photon. The random numbers passed all tests in the statistical test suite.

  19. Monitoring molecular interactions using photon arrival-time interval distribution analysis

    DOEpatents

    Laurence, Ted A.; Weiss, Shimon

    2009-10-06

    A method for analyzing/monitoring the properties of species that are labeled with fluorophores. A detector is used to detect photons emitted from species that are labeled with one or more fluorophores and located in a confocal detection volume. The arrival time of each of the photons is determined. The interval of time between various photon pairs is then determined to provide photon pair intervals. The number of photons that have arrival times within the photon pair intervals is also determined. The photon pair intervals are then used in combination with the corresponding counts of intervening photons to analyze properties and interactions of the molecules including brightness, concentration, coincidence and transit time. The method can be used for analyzing single photon streams and multiple photon streams.

  20. Method for Identifying Micro-seismic P-Arrival by Time-frequency Analysis Using Intrinsic Time-Scale Decomposition

    NASA Astrophysics Data System (ADS)

    Zhang, Ruihong; Zhang, Lihua

    2015-04-01

    A method to identify the P-arrival of microseismic signals is proposed in this work, based on the algorithm of intrinsic timescale decomposition (ITD). Using the results of ITD decomposition of observed data, information of instantaneous amplitude and frequency can be determined. The improved ratio function of short-time average over long-time average and the information of instantaneous frequency are applied to the time-frequency-energy denoised signal for picking the P-arrival of the microseismic signal. We compared the proposed method with the wavelet transform method based on the denoised signal resulting from the best basis wavelet packet transform and the single-scale reconstruction of the wavelet transform. The comparison results showed that the new method is more effective and reliable for identifying P-arrivals of microseismic signals.

  1. A Comparison of Center/TRACON Automation System and Airline Time of Arrival Predictions

    NASA Technical Reports Server (NTRS)

    Heere, Karen R.; Zelenka, Richard E.

    2000-01-01

    Benefits from information sharing between an air traffic service provider and a major air carrier are evaluated. Aircraft arrival time schedules generated by the NASA/FAA Center/TRACON Automation System (CTAS) were provided to the American Airlines System Operations Control Center in Fort Worth, Texas, during a field trial of a specialized CTAS display. A statistical analysis indicates that the CTAS schedules, based on aircraft trajectories predicted from real-time radar and weather data, are substantially more accurate than the traditional airline arrival time estimates, constructed from flight plans and en route crew updates. The improvement offered by CTAS is especially advantageous during periods of heavy traffic and substantial terminal area delay, allowing the airline to avoid large predictive errors with serious impact on the efficiency and profitability of flight operations.

  2. High resolution time of arrival estimation for a cooperative sensor system

    NASA Astrophysics Data System (ADS)

    Morhart, C.; Biebl, E. M.

    2010-09-01

    Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.

  3. Breaking the fixed-arrival-time restriction in reaching movements of neural prosthetic devices.

    PubMed

    Srinivasan, Lakshminarayan; da Silva, Marco

    2011-06-01

    We routinely generate reaching arm movements to function independently. For paralyzed users of upper extremity neural prosthetic devices, flexible, high-performance reaching algorithms will be critical to restoring quality-of-life. Previously, algorithms called real-time reach state equations (RSE) were developed to integrate the user's plan and execution-related neural activity to drive reaching movements to arbitrary targets. Preliminary validation under restricted conditions suggested that RSE might yield dramatic performance improvements. Unfortunately, real-world applications of RSE have been impeded because the RSE assumes a fixed, known arrival time. Recent animal-based prototypes attempted to break the fixed-arrival-time assumption by proposing a standard model (SM) that instead restricted the user's movements to a fixed, known set of targets. Here, we leverage general purpose filter design (GPFD) to break both of these critical restrictions, freeing the paralyzed user to make reaching movements to arbitrary target sets with various arrival times and definitive stopping. In silico validation predicts that the new approach, GPFD-RSE, outperforms the SM while offering greater flexibility. We demonstrate the GPFD-RSE against SM in the simulated control of an overactuated 3-D virtual robotic arm with a real-time inverse kinematics engine. PMID:21189232

  4. UNCERTAINTY IN PHASE ARRIVAL TIME PICKS FOR REGIONAL SEISMIC EVENTS: AN EXPERIMENTAL DESIGN

    SciTech Connect

    A. VELASCO; ET AL

    2001-02-01

    The detection and timing of seismic arrivals play a critical role in the ability to locate seismic events, especially at low magnitude. Errors can occur with the determination of the timing of the arrivals, whether these errors are made by automated processing or by an analyst. One of the major obstacles encountered in properly estimating travel-time picking error is the lack of a clear and comprehensive discussion of all of the factors that influence phase picks. This report discusses possible factors that need to be modeled to properly study phase arrival time picking errors. We have developed a multivariate statistical model, experimental design, and analysis strategy that can be used in this study. We have embedded a general form of the International Data Center(IDC)/U.S. National Data Center (USNDC) phase pick measurement error model into our statistical model. We can use this statistical model to optimally calibrate a picking error model to regional data. A follow-on report will present the results of this analysis plan applied to an implementation of an experiment/data-gathering task.

  5. Cerebral arterial bolus arrival time is prolonged in multiple sclerosis and associated with disability

    PubMed Central

    Paling, David; Thade Petersen, Esben; Tozer, Daniel J; Altmann, Daniel R; Wheeler-Kingshott, Claudia AM; Kapoor, Raju; Miller, David H; Golay, Xavier

    2014-01-01

    Alterations in the overall cerebral hemodynamics have been reported in multiple sclerosis (MS); however, their cause and significance is unknown. While potential venous causes have been examined, arterial causes have not. In this study, a multiple delay time arterial spin labeling magnetic resonance imaging sequence at 3T was used to quantify the arterial hemodynamic parameter bolus arrival time (BAT) and cerebral blood flow (CBF) in normal-appearing white matter (NAWM) and deep gray matter in 33 controls and 35 patients with relapsing–remitting MS. Bolus arrival time was prolonged in MS in NAWM (1.0±0.2 versus 0.9±0.2 seconds, P=0.031) and deep gray matter (0.90±0.18 versus 0.80±0.14 seconds, P=0.001) and CBF was increased in NAWM (14±4 versus 10±2 mL/100 g/min, P=0.001). Prolonged BAT in NAWM (P=0.042) and deep gray matter (P=0.01) were associated with higher expanded disability status score. This study demonstrates alteration in cerebral arterial hemodynamics in MS. One possible cause may be widespread inflammation. Bolus arrival time was longer in patients with greater disability independent of atrophy and T2 lesion load, suggesting alterations in cerebral arterial hemodynamics may be a marker of clinically relevant pathology. PMID:24045400

  6. Observation of arrival times of EAS with energies or = 6 x 10 (14) eV

    NASA Technical Reports Server (NTRS)

    Sun, L.

    1985-01-01

    The Earth's atmosphere is continually being bombarded by primary cosmic ray particles which are generally believed to be high-energy nuclei. The fact that the majority of cosmic ray primaries are charged particles and that space is permeated with random magnetic fields, means that the particles do not travel in straight lines. The arrival time distribution of EAS may also transfer some information about the primary particles. Actually, if the particles come to our Earth in a completely random process, the arrival time distribution of pairs of successive particles should fit an exponential law. The work reported here was arried out at Sydney University from May 1982 to January 1983. All the data are used to plot the arrival-time distribution of the events, that is, the distribution of time-separation between consecutive events on a 1 minute bin size. During this period more than 2300 showers were recorded. The results are discussed and compared with that of some other experiments.

  7. p-Wave Feshbach Molecules

    SciTech Connect

    Gaebler, J. P.; Stewart, J. T.; Bohn, J. L.; Jin, D. S.

    2007-05-18

    We have produced and detected molecules using a p-wave Feshbach resonance between {sup 40}K atoms. We have measured the binding energy and lifetime for these molecules and we find that the binding energy scales approximately linearly with the magnetic field near the resonance. The lifetime of bound p-wave molecules is measured to be 1.0{+-}0.1 ms and 2.3{+-}0.2 ms for the m{sub l}={+-}1 and m{sub l}=0 angular momentum projections, respectively. At magnetic fields above the resonance, we detect quasibound molecules whose lifetime is set by the tunneling rate through the centrifugal barrier.

  8. Acoustic source localization using time-difference of arrival and neural-network analysis

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Dong, Jiancheng; Ying, Ren D.

    2013-03-01

    The developing embedded technology requires revolutions in human-machine interaction. In this paper, we propose a novel method using localization of the taping sound on the table to replace the keyboard as manual input device. The method is applicable with a quad-channel-array collection of acoustic signals, from which the time-of-arrival differences and the position information could be estimated. In practice, as our table is in a limited size and the material properties are complex, the traditional localization algorithm based on time-of-arrival differences contains a sizable margin for error. Furthermore, we use neural-network analysis to improve recognition accuracy. Then experiments and simulations are carried out to verify this signal processing algorithm.

  9. Optimal merging of multiple aircrafts to waypoints via controlled time of arrival windows

    NASA Astrophysics Data System (ADS)

    Poolla, C.; Ishihara, A. K.

    This paper presents an algorithm that computes the optimal arrival times and velocities required for maximizing worst case mutual separation in a multiple aircraft optimal merging scenario. The approach leverages the Pontryagin Maximum Principle (PMP) to rapidly generate locally optimal trajectories per aircraft and an outer-loop Particle Swarm Optimization (PSO) scheme to search for globally optimal merging dynamics. The subset of feasible Controlled Time of Arrival (CTA) and velocity windows is estimated based on an asymptotic approximation of the locally optimal trajectory generated by the PMP. The Particle Swarm Optimization (PSO) scheme maximizes the minimum separation between all aircrafts over all instances of the trajectory. The cost functional has been chosen to minimize load factor (enhance comfort) and maximize worst case mutual separation (improve safety). Simulations based on a simplified lateral aircraft model subject to bounded control inputs are provided to illustrate the concept.

  10. Dead on Arrival: Adapting Games to Finish at a Given Time or Location

    NASA Astrophysics Data System (ADS)

    von Öhsen, Arne; Loviscach, Jörn

    Casual and other games often serve as time-killing applications, be it on the commuter train or in the back seat of a shared car. When one arrives at the destination, the game has to be interrupted or aborted, which is annoying or even frustrating. Hence, we propose to continuously adapt the game’s level of difficulty to the estimated remaining time to arrival. This can be preset as a number of minutes or can continuously be estimated from the player’s position in relation to a predefined destination. Our dungeon-style prototype is based on an automated engine for content placement and can also make use of GPS data. We report on preliminary results from user tests.

  11. AIMBAT: A Python/Matplotlib Tool for Measuring Teleseismic Arrival Times

    NASA Astrophysics Data System (ADS)

    Lou, X.; van der Lee, S.; Lloyd, S.

    2013-12-01

    Python is an open-source, platform-independent, and object-oriented scripting language. It became more popular in the seismologist community since the appearance of ObsPy (Beyreuther et al. 2010, Megies et al. 2011), which provides a powerful framework for seismic data access and processing. This study introduces a new Python-based tool named AIMBAT (Automated and Interactive Measurement of Body-wave Arrival Times) for measuring teleseismic body-wave arrival times on large-scale seismic event data (Lou et al. 2013). Compared to ObsPy, AIMBAT is a lighter tool that is more focused on a particular aspect of seismic data processing. It originates from the widely used MCCC (Multi-Channel Cross-Correlation) method developed by VanDecar and Crosson (1990). On top of the original MCCC procedure, AIMBAT is automated in initial phase picking and is interactive in quality control. The core cross-correlation function is implemented in Fortran to boost up performance in addition to Python. The GUI (graphical user interface) of AIMBAT depends on Matplotlib's GUI-neutral widgets and event-handling API. A number of sorting and (de)selecting options are designed to facilitate the quality control of seismograms. By using AIMBAT, both relative and absolute teleseismic body-wave arrival times are measured. AIMBAT significantly improves efficiency and quality of the measurements. User interaction is needed only to pick the target phase arrival and to set a time window on the array stack. The package is easy to install and use, open-source, and is publicly available. Graphical user interface of AIMBAT.

  12. Optimal first-arrival times in Lévy flights with resetting

    NASA Astrophysics Data System (ADS)

    Kuśmierz, Łukasz; Gudowska-Nowak, Ewa

    2015-11-01

    We consider the diffusive motion of a particle performing a random walk with Lévy distributed jump lengths and subject to a resetting mechanism, bringing the walker to an initial position at uniformly distributed times. In the limit of an infinite number of steps and for long times, the process converges to superdiffusive motion with replenishment. We derive a formula for the mean first arrival time (MFAT) to a predefined target position reached by a meandering particle and we analyze the efficiency of the proposed searching strategy by investigating criteria for an optimal (a shortest possible) MFAT.

  13. Spatial factors in visual attention: some compensatory effects of location and time of arrival of nontargets.

    PubMed

    Gathercole, S E; Broadbent, D E

    1987-01-01

    It is well established that the identity of nontarget events may affect reaction to a target event, but that spatial separation between the two will reduce such an influence. Two experiments are reported in which an attempt was made to distinguish between two accounts of this effect. On one, some of the information about events spatially distant from the target is shut out from analysis altogether. On the other, such events are fully analysed, but either the analysis proceeds more slowly or else it starts only after a delay. In the experiments the time of arrival of, and the distance between, the target and nontarget events were systematically varied. The conventional effects of the distance of nontargets from target were greatly reduced when the target and nontarget events were asynchronous. If the nontargets arrived first, they had an effect on reaction to the target whether they were near to or far from it. If they arrived second, their identity had no effect at either separation. These results appear to rule out any simple view of attention according to which information outside the target region is denied analysis. Rather, distant nontarget events are analysed, but produce their effects at a later time than less peripheral events. PMID:3444724

  14. Badge size and arrival time predict mating success of red-breasted flycatcher Ficedula parva males.

    PubMed

    Mitrus, Cezary; Mitrus, Joanna; Sikora, Magdalena

    2012-12-01

    Older red-breasted flycatcher males (after the second year) have an orange patch on the throat and breast. To date, the occurrence of this ornament has been explained in terms of male-male interactions. In this paper, we show that badge size also influences the mating success of red-breasted-flycatcher males. In addition to the size of the ornament, arrival time was a second factor related to the males' mating success, but no effects of body parameters such as wing length, tarsus length, and body mass were observed. Mated males arrived significantly earlier than unmated ones. The arrival time of males was negatively correlated to body mass and positively correlated to tarsus length but no relation to wing length or badge size was observed. No correlations between badge size and body parameters were observed. This ornament was evolved through sexual selection, with both male-male interaction and selection pressure arising from female preference for males with larger badges. PMID:23215969

  15. Simulated Obstructive Sleep Apnea Increases P-Wave Duration and P-Wave Dispersion

    PubMed Central

    Wons, Annette M.; Rossi, Valentina; Bratton, Daniel J.; Schlatzer, Christian; Schwarz, Esther I.; Camen, Giovanni; Kohler, Malcolm

    2016-01-01

    Background A high P-wave duration and dispersion (Pd) have been reported to be a prognostic factor for the occurrence of paroxysmal atrial fibrillation (PAF), a condition linked to obstructive sleep apnea (OSA). We tested the hypothesis of whether a short-term increase of P-wave duration and Pd can be induced by respiratory manoeuvres simulating OSA in healthy subjects and in patients with PAF. Methods 12-lead-electrocardiography (ECG) was recorded continuously in 24 healthy subjects and 33 patients with PAF, while simulating obstructive apnea (Mueller manoeuvre, MM), obstructive hypopnea (inspiration through a threshold load, ITH), central apnea (AP), and during normal breathing (BL) in randomized order. The P-wave duration and Pd was calculated by using dedicated software for ECG-analysis. Results P-wave duration and Pd significantly increased during MM and ITH compared to BL in all subjects (+13.1ms and +13.8ms during MM; +11.7ms and +12.9ms during ITH; p<0.001 for all comparisons). In MM, the increase was larger in healthy subjects when compared to patients with PAF (p<0.05). Conclusion Intrathoracic pressure swings through simulated obstructive sleep apnea increase P-wave duration and Pd in healthy subjects and in patients with PAF. Our findings imply that intrathoracic pressure swings prolong the intra-atrial and inter-atrial conduction time and therefore may represent an independent trigger factor for the development for PAF. PMID:27071039

  16. Accurate tremor locations from coherent S and P waves

    NASA Astrophysics Data System (ADS)

    Armbruster, John G.; Kim, Won-Young; Rubin, Allan M.

    2014-06-01

    Nonvolcanic tremor is an important component of the slow slip processes which load faults from below, but accurately locating tremor has proven difficult because tremor rarely contains clear P or S wave arrivals. Here we report the observation of coherence in the shear and compressional waves of tremor at widely separated stations which allows us to detect and accurately locate tremor events. An event detector using data from two stations sees the onset of tremor activity in the Cascadia tremor episodes of February 2003, July 2004, and September 2005 and confirms the previously reported south to north migration of the tremor. Event detectors using data from three and four stations give Sand P arrival times of high accuracy. The hypocenters of the tremor events fall at depths of ˜30 to ˜40 km and define a narrow plane dipping at a shallow angle to the northeast, consistent with the subducting plate interface. The S wave polarizations and P wave first motions define a source mechanism in agreement with the northeast convergence seen in geodetic observations of slow slip. Tens of thousands of locations determined by constraining the events to the plate interface show tremor sources highly clustered in space with a strongly similar pattern of sources in the three episodes examined. The deeper sources generate tremor in minor episodes as well. The extent to which the narrow bands of tremor sources overlap between the three major episodes suggests relative epicentral location errors as small as 1-2 km.

  17. Fast-Time Evaluations of Airborne Merging and Spacing in Terminal Arrival Operations

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, Karthik; Barmore, Bryan; Bussink, Frank; Weitz, Lesley; Dahlene, Laura

    2005-01-01

    NASA researchers are developing new airborne technologies and procedures to increase runway throughput at capacity-constrained airports by improving the precision of inter-arrival spacing at the runway threshold. In this new operational concept, pilots of equipped aircraft are cleared to adjust aircraft speed to achieve a designated spacing interval at the runway threshold, relative to a designated lead aircraft. A new airborne toolset, prototypes of which are being developed at the NASA Langley Research Center, assists pilots in achieving this objective. The current prototype allows precision spacing operations to commence even when the aircraft and its lead are not yet in-trail, but are on merging arrival routes to the runway. A series of fast-time evaluations of the new toolset were conducted at the Langley Research Center during the summer of 2004. The study assessed toolset performance in a mixed fleet of aircraft on three merging arrival streams under a range of operating conditions. The results of the study indicate that the prototype possesses a high degree of robustness to moderate variations in operating conditions.

  18. Temporal dispersion of the emergence of intelligence: an inter-arrival time analysis

    NASA Astrophysics Data System (ADS)

    Hair, Thomas W.

    2011-02-01

    Many reasons for why extraterrestrial intelligences might avoid communications with our civilization have been proposed. One possible scenario is that all civilizations follow the lead of some particularly distinguished civilization. This paper will examine the impact the first successful civilization could have on all other subsequent civilizations within its sphere of influence and the ramifications of this as it relates to the Fermi Paradox. Monte Carlo simulation is used to map the inter-arrival times of early civilizations and to highlight the immense epochs of time that the earliest civilizations could have had the Galaxy to themselves.

  19. Time-dependent solution for the manufacturing line with unreliable machine and batched arrivals

    NASA Astrophysics Data System (ADS)

    Kempa, W. M.; Paprocka, I.; Grabowik, C.; Kalinowski, K.

    2015-11-01

    Time-dependent queue-size distribution in a finite-buffer manufacturing line with unreliable machine is investigated. Successive jobs arrive in batches (groups) with sizes being generally distributed random variables, and are being processed individually with exponential service times. Applying the approach based on the memory less property of exponential distribution and the total probability law, a system of integral equations for the transient queue- size distribution conditioned by the initial level of buffer saturation is derived. The solution of the corresponding system written for Laplace transforms is found via linear-algebraic approach.

  20. Predicting Ambulance Time of Arrival to the Emergency Department Using Global Positioning System and Google Maps

    PubMed Central

    Fleischman, Ross J.; Lundquist, Mark; Jui, Jonathan; Newgard, Craig D.; Warden, Craig

    2014-01-01

    Objective To derive and validate a model that accurately predicts ambulance arrival time that could be implemented as a Google Maps web application. Methods This was a retrospective study of all scene transports in Multnomah County, Oregon, from January 1 through December 31, 2008. Scene and destination hospital addresses were converted to coordinates. ArcGIS Network Analyst was used to estimate transport times based on street network speed limits. We then created a linear regression model to improve the accuracy of these street network estimates using weather, patient characteristics, use of lights and sirens, daylight, and rush-hour intervals. The model was derived from a 50% sample and validated on the remainder. Significance of the covariates was determined by p < 0.05 for a t-test of the model coefficients. Accuracy was quantified by the proportion of estimates that were within 5 minutes of the actual transport times recorded by computer-aided dispatch. We then built a Google Maps-based web application to demonstrate application in real-world EMS operations. Results There were 48,308 included transports. Street network estimates of transport time were accurate within 5 minutes of actual transport time less than 16% of the time. Actual transport times were longer during daylight and rush-hour intervals and shorter with use of lights and sirens. Age under 18 years, gender, wet weather, and trauma system entry were not significant predictors of transport time. Our model predicted arrival time within 5 minutes 73% of the time. For lights and sirens transports, accuracy was within 5 minutes 77% of the time. Accuracy was identical in the validation dataset. Lights and sirens saved an average of 3.1 minutes for transports under 8.8 minutes, and 5.3 minutes for longer transports. Conclusions An estimate of transport time based only on a street network significantly underestimated transport times. A simple model incorporating few variables can predict ambulance time of arrival to the emergency department with good accuracy. This model could be linked to global positioning system data and an automated Google Maps web application to optimize emergency department resource use. Use of lights and sirens had a significant effect on transport times. PMID:23865736

  1. Analytical arrival and persistence time distributions for flow thresholds in seasonally dry climates

    NASA Astrophysics Data System (ADS)

    Dralle, D.; Thompson, S. E.

    2014-12-01

    Seasonally dry ecosystems, which include Mediterranean, tropical monsoonal and tropical savannah climates, cover approximately 30% of the planet's land area and are globally significant biodiversity hotspots. Due to a highly variable climate, the streamflow available for ecosystems and ecosystems services in these regions is typified by large inter-annual variability. Methods to quantify this variability could shed light on stream ecosystem stress, particularly new stresses imposed by human activity or climate change. This study develops a probabilistic framework to examine controls on dry season flow characteristics in seasonally dry climates. Assuming a typical recession pattern, which is conditioned on an initial value that is sampled from the wet season flows [1,2], analytical PDFs for the arrival time of a given dry season flow threshold can be obtained. Below-flow-threshold persistence time distributions are computed as the difference between an (assumed) normally distributed dry season length and the mean flow threshold arrival time. A number of hypotheses are proposed to explain unexpected sources of variability in the empirical arrival time distributions. The ecologic implications of extended low flow persistence, such as the hydrologic fragmentation of lower order watersheds, are discussed. [1] Müller, M. F., D. N. Dralle, and S. E. Thompson (2014), Analytical model for flow duration curves in seasonally dry climates, Water Resour. Res., 50, doi:10.1002/2014WR015301 [2] Botter, G., A. Porporato, I. Rodriguez-Iturbe, and A. Rinaldo (2007), Basin-scale soil moisture dynamics and the probabilistic characterization of carrier hydrologic flows: Slow, leaching-prone components of the hydrologic response, Water Resour. Res., 43, W02417, doi:10.1029/2006WR005043

  2. Correlating index properties of rocks with P-wave measurements

    NASA Astrophysics Data System (ADS)

    Khandelwal, Manoj; Ranjith, P. G.

    2010-05-01

    The determination of index properties of rock, such as Cerchar Abrasivity Index, Shore Hardness, Protodyakonov Index and Vickers Hardness in laboratory or insitu conditions is time-consuming and requires special equipment and expertise. However, the use of P-wave technology to measure the P-wave velocity of rock is a relatively simple task because the portable equipment can be used in the laboratory or in the field without tedious preparation of rock cores and it is non-destructive. This paper presents an experimental study of the measurement of P-waves of several types of igneous, sedimentary and metamorphic rock. The index properties were also determined in the laboratory to obtain correlations between P-waves and various index properties. Good linear relationships were found between all the index properties determined and the P-wave measurements.

  3. Crustal parameters estimated from P-waves of earthquakes recorded at a small array

    USGS Publications Warehouse

    Murdock, J.N.; Steppe, J.A.

    1980-01-01

    The P-arrival times of local and regional earthquakes that are outside of a small network of seismometers can be used to interpret crustal parameters beneath the network by employing the time-term technique. Even when the estimate of the refractor velocity is poorly determined, useful estimates of the station time-terms can be made. The method is applied to a 20 km diameter network of eight seismic stations which was operated near Castaic, California, during the winter of 1972-73. The stations were located in sedimentary basins. Beneath the network, the sedimentary rocks of the basins are known to range from 1 to more than 4 km in thickness. Relative time-terms are estimated from P-waves assumed to be propagated by a refractor in the mid-crust, and again from P-waves propagated by a refractor in the upper basement. For the range of velocities reported by others, the two sets of time-terms are very similar. They suggest that both refractors dip to the southwest, and the geology also indicates that the basement dips in this direction. In addition, the P-wave velocity estimated for the refractor of mid-crustal depths, roughly 6.7 km/sec, agrees with values reported by others. Thus, even in this region of complicated geologic structure, the method appears to give realistic results. ?? 1980 Birkha??user Verlag.

  4. Time-of-arrival analysis applied to ELF/VLF wave generation experiments at HAARP

    NASA Astrophysics Data System (ADS)

    Moore, R. C.; Fujimaru, S.

    2012-12-01

    Time-of-arrival (TOA) analysis is applied to observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska. In 2012, a variety of ELF/VLF wave generation techniques were employed to identify the dominant source altitude for each case. Observations were performed for beat-wave modulation, AM modulation, STF modulation, ICD modulation, and cubic frequency modulation, among others. For each of these cases, we identify the dominant ELF/VLF source altitude and compare the experimental results with theoretical HF heating predictions.

  5. Marginal Bayesian nonparametric model for time to disease arrival of threatened amphibian populations.

    PubMed

    Zhou, Haiming; Hanson, Timothy; Knapp, Roland

    2015-12-01

    The global emergence of Batrachochytrium dendrobatidis (Bd) has caused the extinction of hundreds of amphibian species worldwide. It has become increasingly important to be able to precisely predict time to Bd arrival in a population. The data analyzed herein present a unique challenge in terms of modeling because there is a strong spatial component to Bd arrival time and the traditional proportional hazards assumption is grossly violated. To address these concerns, we develop a novel marginal Bayesian nonparametric survival model for spatially correlated right-censored data. This class of models assumes that the logarithm of survival times marginally follow a mixture of normal densities with a linear-dependent Dirichlet process prior as the random mixing measure, and their joint distribution is induced by a Gaussian copula model with a spatial correlation structure. To invert high-dimensional spatial correlation matrices, we adopt a full-scale approximation that can capture both large- and small-scale spatial dependence. An efficient Markov chain Monte Carlo algorithm with delayed rejection is proposed for posterior computation, and an R package spBayesSurv is provided to fit the model. This approach is first evaluated through simulations, then applied to threatened frog populations in Sequoia-Kings Canyon National Park. PMID:26148536

  6. VLF long-range lightning location using the arrival time difference technique (ATD)

    NASA Technical Reports Server (NTRS)

    Ierkic, H. Mario

    1996-01-01

    A new network of VLF receiving systems is currently being developed in the USA to support NASA's Tropical Rain Measuring Mission (TRMM). The new network will be deployed in the east coast of the US, including Puerto Rico, and will be operational in late 1995. The system should give affordable, near real-time, accurate lightning locating capabilities at long ranges and with extended coverage. It is based on the Arrival Time Difference (ATD) method of Lee (1986; 1990). The ATD technique is based on the estimation of the time of arrival of sferics detected over an 18 kHz bandwith. The ground system results will be compared and complemented with satellite optical measurements gathered with the already operational Optical Transient Detector (OTD) instrument and in due course with its successor the Lightning Imaging Sensor (LIS). Lightning observations are important to understand atmospheric electrification phenomena, discharge processes, associated phenomena on earth (e.g. whistlers, explosive Spread-F) and other planets. In addition, lightning is a conspicuous indicator of atmospheric activity whose potential is just beginning to be recognized and utilized. On more prosaic grounds, lightning observations are important for protection of life, property and services.

  7. Parametric estimation of pulse arrival time: a robust approach to pulse wave velocity.

    PubMed

    Solà, Josep; Vetter, Rolf; Renevey, Philippe; Chételat, Olivier; Sartori, Claudio; Rimoldi, Stefano F

    2009-07-01

    Pulse wave velocity (PWV) is a surrogate of arterial stiffness and represents a non-invasive marker of cardiovascular risk. The non-invasive measurement of PWV requires tracking the arrival time of pressure pulses recorded in vivo, commonly referred to as pulse arrival time (PAT). In the state of the art, PAT is estimated by identifying a characteristic point of the pressure pulse waveform. This paper demonstrates that for ambulatory scenarios, where signal-to-noise ratios are below 10 dB, the performance in terms of repeatability of PAT measurements through characteristic points identification degrades drastically. Hence, we introduce a novel family of PAT estimators based on the parametric modeling of the anacrotic phase of a pressure pulse. In particular, we propose a parametric PAT estimator (TANH) that depicts high correlation with the Complior(R) characteristic point D1 (CC = 0.99), increases noise robustness and reduces by a five-fold factor the number of heartbeats required to obtain reliable PAT measurements. PMID:19491457

  8. Determination of differential arrival times by cross-correlating worldwide seismological data

    NASA Astrophysics Data System (ADS)

    Godano, M.; Nolet, G.; Zaroli, C.

    2012-12-01

    Cross-correlation delays are the preferred body wave observables in global tomography. Heterogeneity is the main factor influencing delay times found by cross-correlation. Not only the waveform, but also the arrival time itself is affected by differences in seismic velocity encountered along the way. An accurate method for estimating differential times of seismic arrivals across a regional array by cross-correlation was developed by VanDecar and Crosson [1990]. For the estimation of global travel time delays in different frequency bands, Sigloch and Nolet [2006] developed a method for the estimation of body wave delays using a matched filter, which requires the separate estimation of the source time function. Sigloch et al. [2008] found that waveforms often cluster in and opposite the direction of rupture propagation on the fault, confirming that the directivity effect is a major factor in shaping the waveform of large events. We propose a generalization of the VanDecar-Crosson method to which we add a correction for the directivity effect in the seismological data. The new method allows large events to be treated without the need to estimate the source time function for the computation of a matched synthetic waveform. The procedure consists in (1) the detection of the directivity effect in the data and the determination of a rupture model (unilateral or bilateral) explaining the differences in pulse duration among the stations, (2) the determination of an apparent fault rupture length explaining the pulse durations, (3) the removal of the delay due to the directivity effect in the pulse duration , by stretching or contracting the seismograms for directive and anti-directive stations respectively and (4) the application of a generalized VanDecar and Crosson method using only delays between pairs of stations that have an acceptable correlation coefficient. We validate our method by performing tests on synthetic data. Results show that the error between theoretical and measured differential arrival time are significantly reduced for the corrected data. We illustrate our method on data from several real earthquakes.

  9. Simultaneous elastic parameter inversion in 2-D/3-D TTI medium combined later arrival times

    NASA Astrophysics Data System (ADS)

    Bai, Chao-ying; Wang, Tao; Yang, Shang-bei; Li, Xing-wang; Huang, Guo-jiao

    2016-04-01

    Traditional traveltime inversion for anisotropic medium is, in general, based on a "weak" assumption in the anisotropic property, which simplifies both the forward part (ray tracing is performed once only) and the inversion part (a linear inversion solver is possible). But for some real applications, a general (both "weak" and "strong") anisotropic medium should be considered. In such cases, one has to develop a ray tracing algorithm to handle with the general (including "strong") anisotropic medium and also to design a non-linear inversion solver for later tomography. Meanwhile, it is constructive to investigate how much the tomographic resolution can be improved by introducing the later arrivals. For this motivation, we incorporated our newly developed ray tracing algorithm (multistage irregular shortest-path method) for general anisotropic media with a non-linear inversion solver (a damped minimum norm, constrained least squares problem with a conjugate gradient approach) to formulate a non-linear inversion solver for anisotropic medium. This anisotropic traveltime inversion procedure is able to combine the later (reflected) arrival times. Both 2-D/3-D synthetic inversion experiments and comparison tests show that (1) the proposed anisotropic traveltime inversion scheme is able to recover the high contrast anomalies and (2) it is possible to improve the tomographic resolution by introducing the later (reflected) arrivals, but not as expected in the isotropic medium, because the different velocity (qP, qSV and qSH) sensitivities (or derivatives) respective to the different elastic parameters are not the same but are also dependent on the inclination angle.

  10. Periodic modulation in pulse arrival times from young pulsars: a renewed case for neutron star precession

    NASA Astrophysics Data System (ADS)

    Kerr, M.; Hobbs, G.; Johnston, S.; Shannon, R. M.

    2016-01-01

    In a search for periodic variation in the arrival times of pulses from 151 young, energetic pulsars, we have identified seven cases of modulation consistent with one or two harmonics of a single fundamental with time-scale 0.5-1.5 yr. We use simulations to show that these modulations are statistically significant and of high quality (sinusoidal) even when contaminated by the strong stochastic timing noise common to young pulsars. Although planetary companions could induce such modulation, the large implied masses and 2:1 mean motion resonances challenge such an explanation. Instead, the modulation is likely to be intrinsic to the pulsar, arising from quasi-periodic switching between stable magnetospheric states, and we propose that precession of the neutron star may regulate this switching.

  11. Preliminary result of P-wave speed tomography beneath North Sumatera region

    SciTech Connect

    Jatnika, Jajat; Nugraha, Andri Dian; Wandono

    2015-04-24

    The structure of P-wave speed beneath the North Sumatra region was determined using P-wave arrival times compiled by MCGA from time periods of January 2009 to December 2012 combining with PASSCAL data for February to May 1995. In total, there are 2,246 local earthquake events with 10,666 P-wave phases from 63 stations seismic around the study area. Ray tracing to estimate travel time from source to receiver in this study by applying pseudo-bending method while the damped LSQR method was used for the tomographic inversion. Based on assessment of ray coverage, earthquakes and stations distribution, horizontal grid nodes was set up of 30×30 km2 for inside the study area and 80×80 km2 for outside the study area. The tomographic inversion results show low Vp anomaly beneath Toba caldera complex region and around the Sumatra Fault Zones (SFZ). These features are consistent with previous study. The low Vp anomaly beneath Toba caldera complex are observed around Mt. Pusuk Bukit at depths of 5 km down to 100 km. The interpretation is these anomalies may be associated with ascending hot materials from subduction processes at depths of 80 km down to 100 km. The obtained Vp structure from local tomography will give valuable information to enhance understanding of tectonic and volcanic in this study area.

  12. Airborne Evaluation and Demonstration of a Time-Based Airborne Inter-Arrival Spacing Tool

    NASA Technical Reports Server (NTRS)

    Lohr, Gary W.; Oseguera-Lohr, Rosa M.; Abbott, Terence S.; Capron, William R.; Howell, Charles T.

    2005-01-01

    An airborne tool has been developed that allows an aircraft to obtain a precise inter-arrival time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) data to compute speed commands for the ATAAS-equipped aircraft to obtain this inter-arrival spacing behind another aircraft. The tool was evaluated in an operational environment at the Chicago O'Hare International Airport and in the surrounding terminal area with three participating aircraft flying fixed route area navigation (RNAV) paths and vector scenarios. Both manual and autothrottle speed management were included in the scenarios to demonstrate the ability to use ATAAS with either method of speed management. The results on the overall delivery precision of the tool, based on a target spacing of 90 seconds, were a mean of 90.8 seconds with a standard deviation of 7.7 seconds. The results for the RNAV and vector cases were, respectively, M=89.3, SD=4.9 and M=91.7, SD=9.0.

  13. High bandwidth pickup design for bunch arrival-time monitors for free-electron laser

    NASA Astrophysics Data System (ADS)

    Angelovski, Aleksandar; Kuhl, Alexander; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M.; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-11-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high (>500pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  14. Seismicity and arrival-time residuals from the Victoria Earthquake of June 9, 1980

    SciTech Connect

    Wong, V.; Frez, J.

    1981-01-01

    Hypocenter distribution in space and time of the aftershock activity from the Victoria Earthquake of June 9, 1980 was studied. It was concluded that the main event excited aftershocks in several pre-existing nests at the northwest end of the Cerro Prieto Fault, but no significant activity occurred at the immediate neighborhood of the main event. The depth of the aftershocks increases with the distance from the northwest end of the fault and this feature might be related with the higher temperatures and the spreading center located between the ends of the Imperial and Cerro Prieto Faults. The significance of the arrival-times residuals for local and regional stations is discussed both for P and S-waves and the importance of obtaining station corrections is emphasized. The non-uniqueness in determining a structure which minimizes the residuals is illustrated. Two different structures which satisfy the local data are presented.

  15. Extracting Time-Lapsed Velocity Changes From The Direct Arrival Of Ambient Noise Correlation Functions

    NASA Astrophysics Data System (ADS)

    Seats, K.; Lawrence, J. F.

    2013-12-01

    This study investigates methods for observing temporal subsurface velocity variations from ambient seismic noise, which provides an exciting opportunity to generate 4D tomographic images. In geologically active regions, the time lag of the ambient Noise Correlation Function (NCF) can change or migrate, reflecting associated changes in the subsurface velocity structure. Unfortunately, this time lag also reflects apparent velocity changes due to seasonal variations in the ambient seismic field as well. Recently, studies have begun observing these temporal variations in volcanic regions by analyzing the changes in the coda of the NCF, and attempting to spatially locate these changes though the examination of the complex scattering regime. Here, we examine time-lagged differences of the main arrival, with the signal to noise ratio of these NCFs being drastically improved by the development of the adaptive covariance filter (ACF). By utilizing velocity variations in these main arrivals, it becomes more straightforward to spatially locate these changes and understand their temporal resolution. We examine two case studies that have different spatial and temporal scales. First, we use all available data near the Yellowstone caldera, including permanent and temporary networks such as the USArray and NOISY projects. We attempt to correct for, and remove, seasonal velocity variations in the NCFs to directly observe decreased velocities at surface wave periods consistent with depths of the magma chamber beneath Yellowstone. Second, we use data from 2009-2011 around Piton de la Fournaise shield volcano on Réunion Island to observe temporal velocity variations associated with eruptive phases. We compare our results of the magnitude and location of these velocity variations to studies observing time-lapsed velocity changes from NCF coda waves.

  16. Effects of territory competition and climate change on timing of arrival to breeding grounds: a game-theory approach.

    PubMed

    Johansson, Jacob; Jonzn, Niclas

    2012-04-01

    Phenology is an important part of life history that is gaining increased attention because of recent climate change. We use game theory to model phenological adaptation in migratory birds that compete for territories at their breeding grounds. We investigate how the evolutionarily stable strategy (ESS) for the timing of arrival is affected by changes in the onset of spring, the timing of the resource peak, and the season length. We compare the ESS mean arrival date with the environmental optimum, that is, the mean arrival date that maximizes fitness in the absence of competition. When competition is strong, the ESS mean arrival date responds less than the environmental optimum to shifts in the resource peak but more to changes in the onset of spring. Increased season length may not necessarily affect the environmental optimum but can still advance the ESS mean arrival date. Conversely, shifting a narrow resource distribution may change the environmental optimum without affecting the ESS mean arrival date. The ESS mean arrival date and the environmental optimum may even shift in different directions. Hence, treating phenology as an evolutionary game rather than an optimization problem fundamentally changes what we predict to be an adaptive response to environmental changes. PMID:22437176

  17. Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.

    PubMed

    Sanders, Geoff; Sinclair, Kamila

    2011-12-01

    We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering. PMID:21125324

  18. Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

    SciTech Connect

    Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Glownia, J. M.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Nicholson, D. J.; Cryan, J. P.; Baker, K.; Kane, D. J.; and others

    2014-08-15

    The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10–100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for “measure-and-sort” at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses.

  19. Constrained Optimization of Average Arrival Time via a Probabilistic Approach to Transport Reliability.

    PubMed

    Namazi-Rad, Mohammad-Reza; Dunbar, Michelle; Ghaderi, Hadi; Mokhtarian, Payam

    2015-01-01

    To achieve greater transit-time reduction and improvement in reliability of transport services, there is an increasing need to assist transport planners in understanding the value of punctuality; i.e. the potential improvements, not only to service quality and the consumer but also to the actual profitability of the service. In order for this to be achieved, it is important to understand the network-specific aspects that affect both the ability to decrease transit-time, and the associated cost-benefit of doing so. In this paper, we outline a framework for evaluating the effectiveness of proposed changes to average transit-time, so as to determine the optimal choice of average arrival time subject to desired punctuality levels whilst simultaneously minimizing operational costs. We model the service transit-time variability using a truncated probability density function, and simultaneously compare the trade-off between potential gains and increased service costs, for several commonly employed cost-benefit functions of general form. We formulate this problem as a constrained optimization problem to determine the optimal choice of average transit time, so as to increase the level of service punctuality, whilst simultaneously ensuring a minimum level of cost-benefit to the service operator. PMID:25992902

  20. Constrained Optimization of Average Arrival Time via a Probabilistic Approach to Transport Reliability

    PubMed Central

    Namazi-Rad, Mohammad-Reza; Dunbar, Michelle; Ghaderi, Hadi; Mokhtarian, Payam

    2015-01-01

    To achieve greater transit-time reduction and improvement in reliability of transport services, there is an increasing need to assist transport planners in understanding the value of punctuality; i.e. the potential improvements, not only to service quality and the consumer but also to the actual profitability of the service. In order for this to be achieved, it is important to understand the network-specific aspects that affect both the ability to decrease transit-time, and the associated cost-benefit of doing so. In this paper, we outline a framework for evaluating the effectiveness of proposed changes to average transit-time, so as to determine the optimal choice of average arrival time subject to desired punctuality levels whilst simultaneously minimizing operational costs. We model the service transit-time variability using a truncated probability density function, and simultaneously compare the trade-off between potential gains and increased service costs, for several commonly employed cost-benefit functions of general form. We formulate this problem as a constrained optimization problem to determine the optimal choice of average transit time, so as to increase the level of service punctuality, whilst simultaneously ensuring a minimum level of cost-benefit to the service operator. PMID:25992902

  1. Timing of arrival and pre-acclimatization strategies for the endurance athlete competing at moderate to high altitudes.

    PubMed

    Chapman, Robert F; Laymon, Abigail S; Levine, Benjamin D

    2013-12-01

    With the wide array of endurance sport competition offerings at moderate and high altitudes, clinicians are frequently asked about best practice recommendations regarding arrival times prior to the event and acclimatization guidelines. This brief review will offer data and current advice on when to arrive at altitude and various potential sea level-based pre-acclimatization strategies in an effort to maximize performance and minimize the risk of altitude sickness. PMID:24377334

  2. P wave azimuthal and radial anisotropy of the Hokkaido subduction zone

    NASA Astrophysics Data System (ADS)

    Niu, Xiongwei; Zhao, Dapeng; Li, Jiabiao; Ruan, Aiguo

    2016-04-01

    We present the first three-dimensional P wave radial anisotropy tomography of the Hokkaido subduction zone, as well as P wave azimuthal anisotropy and S wave tomography, which are determined by inverting 298,430 P wave and 233,934 S wave arrival times from 14,245 local earthquakes recorded by 344 seismic stations. Our results reveal significant velocity heterogeneity, seismic anisotropy, and upwelling flows beneath the study region. In the mantle wedge, prominent low-velocity (low-V) anomalies exhibit trench-normal fast-velocity directions (FVDs) and a negative radial anisotropy (i.e., vertical velocity > horizontal velocity), which may reflect upwelling mantle flows. Fan-shaped FVDs are found at depths of 65-90 km, and a detailed 3-D mantle flow pattern is revealed, which may be caused by a combination of oblique subduction of the Pacific plate and collision of the Kuril arc with the Honshu arc beneath southern Hokkaido. The radial anisotropy changes at ~100 km depth, which may reflect variations in temperature and fluid conditions there. The subducting Pacific slab exhibits a positive radial anisotropy (i.e., horizontal velocity > vertical velocity), which may reflect the original fossil anisotropy when the Pacific plate formed at the mid-ocean ridge.

  3. On the Retrieval of Lightning Radio Sources from Time-of-Arrival Data

    NASA Technical Reports Server (NTRS)

    Koshak, William J.; Solakiewicz, Richard J.

    1996-01-01

    We examine the problem of retrieving three-dimensional lightning locations from radio frequency Time-Of-Arrival (TOA) measurements. Arbitrary antenna locations are considered. By judiciously differencing measurements that are related to the location of the antennas and their excitation times, the problem is converted from the initial spherical nonlinear form to a system of linear equations. In the linear formalism, the source location and time-of-occurrence is viewed geometrically as an intersection of hyperplanes in the four-dimensional Minkowski space (x,y,z,t). The linear equations are solved to obtain explicit analytic expressions for the location and time variables. Retrieval errors are not interpreted with conventional Geometrical Dilution of Precision (GDOP) arguments as discussed by Holmes and Reedy (1951), but with more recent inversion analyses considered by Twomey (1977). Measurement errors are propagated analytically so that the specific effect of these errors on the solution is clarified. The sensitivity of the solution on the number of antennas used, antenna network geometry, source position, and measurement differencing schemes are discussed in terms of the eigenvalues of the linear system.

  4. The NANOGrav Nine-year Data Set: Noise Budget for Pulsar Arrival Times on Intraday Timescales

    NASA Astrophysics Data System (ADS)

    Lam, M. T.; Cordes, J. M.; Chatterjee, S.; Arzoumanian, Z.; Crowter, K.; Demorest, P. B.; Dolch, T.; Ellis, J. A.; Ferdman, R. D.; Fonseca, E. F.; Gonzalez, M. E.; Jones, G.; Jones, M. L.; Levin, L.; Madison, D. R.; McLaughlin, M. A.; Nice, D. J.; Pennucci, T. T.; Ransom, S. M.; Siemens, X.; Stairs, I. H.; Stovall, K.; Swiggum, J. K.; Zhu, W. W.

    2016-03-01

    The use of pulsars as astrophysical clocks for gravitational wave (GW) experiments demands the highest possible timing precision. Pulse times of arrival (TOAs) are limited by stochastic processes that occur in the pulsar itself, along the line of sight through the interstellar medium, and in the measurement process. On timescales of seconds to hours, the TOA variance exceeds that from template-fitting errors due to additive noise. We assess contributions to the total variance from two additional effects: amplitude and phase jitter intrinsic to single pulses and changes in the interstellar impulse response from scattering. The three effects have different dependencies on time, frequency, and pulse signal-to-noise ratio. We use data on 37 pulsars from the North American Nanohertz Observatory for GWs to assess the individual contributions to the overall intraday noise budget for each pulsar. We detect jitter in 22 pulsars and estimate the average value of rms jitter in our pulsars to be ∼ 1% of pulse phase. We examine how jitter evolves as a function of frequency and find evidence for evolution. Finally, we compare our measurements with previous noise parameter estimates and discuss methods to improve GW detection pipelines.

  5. Measurement of arrival time of particles in extensive air showers using TDC32

    NASA Astrophysics Data System (ADS)

    Gupta, S. K.; Christiansen, J.; Hayashi, Y.; Jain, A.; Mohanty, P. K.; Ravindran, K. C.; Satyanarayana, B.

    2013-04-01

    Arrival time of particles in an extensive air shower (EAS) is a key physical parameter to determine its direction. EAS direction is useful for studies of anisotropy and composition of cosmic rays, and search for multi-TeV γ-rays sources. Accurate timing may be used to search exotic phenomena such as production of new particles at extremely high energies available during early stages of development of EAS and also for detecting sub-relativistic hadrons in EAS. Time to digital converters (TDCs) are used to perform this task. Traditional TDCs operate in the START-STOP mode with limited dynamic range and single-hit capability. With the advent of high luminosity collider LHC, need for TDCs with large dynamic range, multi-hit capability and TRIGGERED mode of operation became necessary. A 32 channel TDC was designed for the GRAPES-3 experiment on a CAMAC platform around TDC32, an ASIC developed by micro-electronics group at CERN, Geneva. Four modules were operated in the GRAPES-3 experiment. Here, we present details of the circuit design and their performance over several years. The multi-hit feature of this device was used to study the time structure of particles in the EAS on time scale of ~1 μs. The distribution of time intervals in the multi-hit data shows an exponential profile with a time constant of ~370 ns. These delayed particles are likely to be neutrons produced in the EAS core that were recorded in the scintillator detectors following the relativistic EAS front.

  6. Estimating permeability from quasi-static deformation: Temporal variations and arrival time inversion

    SciTech Connect

    Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio

    2008-05-01

    Transient pressure variations within a reservoir can be treated as a propagating front and analyzed using an asymptotic formulation. From this perspective one can define a pressure 'arrival time' and formulate solutions along trajectories, in the manner of ray theory. We combine this methodology and a technique for mapping overburden deformation into reservoir volume change as a means to estimate reservoir flow properties, such as permeability. Given the entire 'travel time' or phase field, obtained from the deformation data, we can construct the trajectories directly, there-by linearizing the inverse problem. A numerical study indicates that, using this approach, we can infer large-scale variations in flow properties. In an application to Interferometric Synthetic Aperture (InSAR) observations associated with a CO{sub 2} injection at the Krechba field, Algeria, we image pressure propagation to the northwest. An inversion for flow properties indicates a linear trend of high permeability. The high permeability correlates with a northwest trending fault on the flank of the anticline which defines the field.

  7. Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

    2010-01-01

    This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

  8. Priority effects of time of arrival of plant functional groups override sowing interval or density effects: a grassland experiment.

    PubMed

    von Gillhaussen, Philipp; Rascher, Uwe; Jablonowski, Nicolai D; Plückers, Christine; Beierkuhnlein, Carl; Temperton, Vicky M

    2014-01-01

    Priority effects occur when species that arrive first in a habitat significantly affect the establishment, growth, or reproduction of species arriving later and thus affect functioning of communities. However, we know little about how the timing of arrival of functionally different species may alter structure and function during assembly. Even less is known about how plant density might interact with initial assembly. In a greenhouse experiment legumes, grasses or forbs were sown a number of weeks before the other two plant functional types were sown (PFT) in combination with a sowing density treatment. Legumes, grasses or non-legume forbs were sown first at three different density levels followed by sowing of the remaining PFTs after three or six-weeks. We found that the order of arrival of different plant functional types had a much stronger influence on aboveground productivity than sowing density or interval between the sowing events. The sowing of legumes before the other PFTs produced the highest aboveground biomass. The larger sowing interval led to higher asymmetric competition, with highest dominance of the PFT sown first. It seems that legumes were better able to get a head-start and be productive before the later groups arrived, but that their traits allowed for better subsequent establishment of non-legume PFTs. Our study indicates that the manipulation of the order of arrival can create priority effects which favour functional groups of plants differently and thus induce different assembly routes and affect community composition and functioning. PMID:24497995

  9. Evaluation of Operational Procedures for Using a Time-Based Airborne Inter-arrival Spacing Tool

    NASA Technical Reports Server (NTRS)

    Oseguera-Lohr, Rosa M.; Lohr, Gary W.; Abbott, Terence S.; Eischeid, Todd M.

    2002-01-01

    An airborne tool has been developed based on the concept of an aircraft maintaining a time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) aircraft state data to compute a speed command for the ATAAS-equipped aircraft to obtain a required time interval behind another aircraft. The tool and candidate operational procedures were tested in a high-fidelity, full mission simulator with active airline subject pilots flying an arrival scenario using three different modes for speed control. The objectives of this study were to validate the results of a prior Monte Carlo analysis of the ATAAS algorithm and to evaluate the concept from the standpoint of pilot acceptability and workload. Results showed that the aircraft was able to consistently achieve the target spacing interval within one second (the equivalent of approximately 220 ft at a final approach speed of 130 kt) when the ATAAS speed guidance was autothrottle-coupled, and a slightly greater (4-5 seconds), but consistent interval with the pilot-controlled speed modes. The subject pilots generally rated the workload level with the ATAAS procedure as similar to that with standard procedures, and also rated most aspects of the procedure high in terms of acceptability. Although pilots indicated that the head-down time was higher with ATAAS, the acceptability of head-down time was rated high. Oculometer data indicated slight changes in instrument scan patterns, but no significant change in the amount of time spent looking out the window between the ATAAS procedure versus standard procedures.

  10. P-wave dispersion: What we know till now?

    PubMed Central

    Aytemir, Kudret; Oto, Ali

    2016-01-01

    P-wave dispersion is defined as the difference between the maximum and the minimum P-wave duration recorded from multiple different-surface ECG leads. It has been known that increased P-wave duration and P-wave dispersion reflect prolongation of intraatrial and interatrial conduction time and the inhomogeneous propagation of sinus impulses, which are well-known electrophysiologic characteristics in patients with atrial arrhythmias and especially paroxysmal atrial fibrillation. Extensive clinical evaluation of P-wave dispersion has been performed in the assessment of the risk for atrial fibrillation in patients without apparent heart disease, in hypertensives, in patients with coronary artery disease, in patients undergoing coronary artery bypass surgery, in patients with congenital heart diseases, as well as in other groups of patients suffering from various cardiac or non-cardiac diseases. In this paper, we aimed to summarize the measurement methods, current use in different clinical situations, strengths and limitations of the of P-wave dispersion. PMID:27081484

  11. Arrival time of solar eruptive CMEs associated with ICMEs of magnetic cloud and ejecta

    NASA Astrophysics Data System (ADS)

    Shanmugaraju, A.; Syed Ibrahim, M.; Moon, Y.-J.; Kasro Lourdhina, K.; Dharanya, M.

    2015-05-01

    The Coronal Mass Ejection (CME) is an eruptive event in which magnetic plasma is ejected from the Sun into space through the solar corona. We considered a set of 51 Interplanetary Coronal Mass Ejections (ICMEs) listed by Kim et al. (Solar Phys. 184:77, 2013) from Coordinated Data Analysis Workshop (CDAW, Gopalswamy et al. in Astrophys. J. 710:1111, 2010). Among the 51 events, 22 events are classified as Magnetic Clouds (MC) and 29 events are classified as Ejecta (EJ) where the MC and EJ are subsets of ICMEs. We have analyzed the physical properties of CMEs and ICMEs associated with MC and EJ, and correlated them with the CME's transit time/arrival time from the Sun to the Earth. Main aims of the present study are to examine (a) dependence of transit time on the properties of CMEs and ICMEs, and (b) differences between MC and EJ. It is found that CME's initial speed decides the transit time which is in support of the known results in literature. Apart from this, some important results from the present study are: (i) transit time predicted using an empirical relation obtained in the present work is found comparable with the observations (correlation coefficient=0.70). (ii) The transit time of MC and EJ-associated CMEs ranges from 20 to 120 hours and IP acceleration lies between -10 m/s2 to 5 m/s2. (iii) There are certain differences between MC and EJ such as: (a) Ejecta takes slightly more time to travel and only 30 % of them are accelerated in the interplanetary medium. Whereas, MC takes less time to travel and nearly 50 % of them are accelerated, (b) The correlations of IP acceleration and speed with transit time are higher for MC than that of EJ, (c) A weak relationship between the deflection and transit time is found for MC, but it is absent in the case of EJ and (d) Only EJ-type CMEs have wider range of direction parameter and acceleration. Further, we checked the solar wind speed as another parameter has any influence on CME acceleration and it shows that there is no clear dependence between the two parameters. While it is observed that the average acceleration of MC-associated CME is larger for lower direction parameter values (<0.2), it is larger for EJ-associated CME for higher direction parameter values (>0.6).

  12. Fault zone structure determined through the analysis of earthquake arrival times

    SciTech Connect

    Michelini, A.

    1991-10-01

    This thesis develops and applies a technique for the simultaneous determination of P and S wave velocity models and hypocenters from a set of arrival times. The velocity models are parameterized in terms of cubic B-splines basis functions which permit the retrieval of smooth models that can be used directly for generation of synthetic seismograms using the ray method. In addition, this type of smoothing limits the rise of instabilities related to the poor resolving power of the data. V{sub P}/V{sub S} ratios calculated from P and S models display generally instabilities related to the different ray-coverages of compressional and shear waves. However, V{sub P}/V{sub S} ratios are important for correct identification of rock types and this study introduces a new methodology based on adding some coupling (i.e., proportionality) between P and S models which stabilizes the V{sub P}/V{sub S} models around some average preset value determined from the data. Tests of the technique with synthetic data show that this additional coupling regularizes effectively the resulting models.

  13. How Do Vision and Hearing Impact Pedestrian Time-to-Arrival Judgments?

    PubMed Central

    Roper, JulieAnne M.; Hassan, Shirin E.

    2014-01-01

    Purpose To determine how accurate normally-sighted male and female pedestrians were at making time-to-arrival (TTA) judgments of approaching vehicles when using just their hearing or both their hearing and vision. Methods Ten male and 14 female subjects with confirmed normal vision and hearing estimated the TTA of approaching vehicles along an unsignalized street under two sensory conditions: (i) using both habitual vision and hearing; and (ii) using habitual hearing only. All subjects estimated how long the approaching vehicle would take to reach them (ie the TTA). The actual TTA of vehicles was also measured using custom made sensors. The error in TTA judgments for each subject under each sensory condition was calculated as the difference between the actual and estimated TTA. A secondary timing experiment was also conducted to adjust each subject’s TTA judgments for their “internal metronome”. Results Error in TTA judgments changed significantly as a function of both the actual TTA (p<0.0001) and sensory condition (p<0.0001). While no main effect for gender was found (p=0.19), the way the TTA judgments varied within each sensory condition for each gender was different (p<0.0001). Females tended to be as accurate under either condition (p≥0.01) with the exception of TTA judgments made when the actual TTA was two seconds or less and eight seconds or longer, during which the vision and hearing condition was more accurate (p≤0.002). Males made more accurate TTA judgments under the hearing only condition for actual TTA values five seconds or less (p<0.0001), after which there were no significant differences between the two conditions (p≥0.01). Conclusions Our data suggests that males and females use visual and auditory information differently when making TTA judgments. While the sensory condition did not affect the females’ accuracy in judgments, males initially tended to be more accurate when using their hearing only. PMID:24509543

  14. Landscape-scale pest suppression is mediated by timing of predator arrival.

    PubMed

    Costamagna, Alejandro C; Venables, William N; Schellhorn, Nancy A

    2015-06-01

    There is increasing evidence that biological control of agricultural pests is affected by the landscape context, although the mechanisms behind this pattern have received little attention. Ecological theory predicts that one key mechanism mediating successful pest suppression is early predator immigration to agricultural fields. However, the importance of this population process under different landscape contexts remains unknown. Here, we elucidate the relative importance of landscape context and timing of predator immigration on aphid suppression by manipulating exposure to predation in agroecosystems located across a gradient of landscape complexity in a subtropical horticultural region in Australia. Aphid suppression varied with landscape context, from populations escaping control to almost complete pest suppression. In general, we found higher aphid suppression when predators were allowed immediate and continuous access to aphids than when predators were delayed or excluded for a week, but responses varied in each landscape. Contrary to previous reports from temperate agricultural landscapes, aphid suppression was neutral or negatively associated with natural and seminatural vegetation, whereas aphid suppression was positively associated with landscapes with a higher proportion of alfalfa. When landscapes were classified according to their levels of complexity, we showed that early predation resulted in similar levels of pest suppression in simplified landscapes (i.e., with low proportions of alfalfa and habitat diversity) as late predation in complex landscapes (i.e., with high proportions of alfalfa and habitat diversity). Our data show that timing of predator arrival to agricultural fields is as important as landscape complexity for mediating pest control in agroecosystems. Furthermore, our results suggest that key distributions of suitable habitats that facilitate natural enemy movement can enhance biological control in simplified landscapes. PMID:26465046

  15. Design and Performance Evaluation on Ultra-Wideband Time-Of-Arrival 3D Tracking System

    NASA Technical Reports Server (NTRS)

    Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Dusl, John

    2012-01-01

    A three-dimensional (3D) Ultra-Wideband (UWB) Time--of-Arrival (TOA) tracking system has been studied at NASA Johnson Space Center (JSC) to provide the tracking capability inside the International Space Station (ISS) modules for various applications. One of applications is to locate and report the location where crew experienced possible high level of carbon-dioxide and felt upset. In order to accurately locate those places in a multipath intensive environment like ISS modules, it requires a robust real-time location system (RTLS) which can provide the required accuracy and update rate. A 3D UWB TOA tracking system with two-way ranging has been proposed and studied. The designed system will be tested in the Wireless Habitat Testbed which simulates the ISS module environment. In this presentation, we discuss the 3D TOA tracking algorithm and the performance evaluation based on different tracking baseline configurations. The simulation results show that two configurations of the tracking baseline are feasible. With 100 picoseconds standard deviation (STD) of TOA estimates, the average tracking error 0.2392 feet (about 7 centimeters) can be achieved for configuration Twisted Rectangle while the average tracking error 0.9183 feet (about 28 centimeters) can be achieved for configuration Slightly-Twisted Top Rectangle . The tracking accuracy can be further improved with the improvement of the STD of TOA estimates. With 10 picoseconds STD of TOA estimates, the average tracking error 0.0239 feet (less than 1 centimeter) can be achieved for configuration "Twisted Rectangle".

  16. Characterizing the nonlinear interaction of S- and P-waves in a rock sample

    NASA Astrophysics Data System (ADS)

    Gallot, Thomas; Malcolm, Alison; Szabo, Thomas L.; Brown, Stephen; Burns, Daniel; Fehler, Michael

    2015-01-01

    The nonlinear elastic response of rocks is known to be caused by the rocks' microstructure, particularly cracks and fluids. This paper presents a method for characterizing the nonlinearity of rocks in a laboratory scale experiment with a unique configuration. This configuration has been designed to open up the possibility of using the nonlinear characterization of rocks as an imaging tool in the field. In our experiment, we study the nonlinear interaction of two traveling waves: a low-amplitude 500 kHz P-wave probe and a high-amplitude 50 kHz S-wave pump in a room-dry 15 × 15 × 3 cm slab of Berea sandstone. Changes in the arrival time of the P-wave probe as it passes through the perturbation created by the traveling S-wave pump were recorded. Waveforms were time gated to simulate a semi-infinite medium. The shear wave phase relative to the P-wave probe signal was varied with resultant changes in the P-wave probe arrival time of up to 100 ns, corresponding to a change in elastic properties of 0.2%. In order to estimate the strain in our sample, we also measured the particle velocity at the sample surface to scale a finite difference linear elastic simulation to estimate the complex strain field in the sample, on the order of 10-6, induced by the S-wave pump. We derived a fourth order elastic model to relate the changes in elasticity to the pump strain components. We recover quadratic and cubic nonlinear parameters: β ˜ = - 872 and δ ˜ = - 1.1 × 10 10 , respectively, at room-temperature and when particle motions of the pump and probe waves are aligned. Temperature fluctuations are correlated to changes in the recovered values of β ˜ and δ ˜ , and we find that the nonlinear parameter changes when the particle motions are orthogonal. No evidence of slow dynamics was seen in our measurements. The same experimental configuration, when applied to Lucite and aluminum, produced no measurable nonlinear effects. In summary, a method of selectively determining the local nonlinear characteristics of rock quantitatively has been demonstrated using traveling sound waves.

  17. Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease

    PubMed Central

    Al-Bachari, Sarah; Parkes, Laura M.; Vidyasagar, Rishma; Hanby, Martha F.; Tharaken, Vivek; Leroi, Iracema; Emsley, Hedley C.A.

    2014-01-01

    Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD. PMID:25379411

  18. `Inter-Arrival Time' Inspired Algorithm and its Application in Clustering and Molecular Phylogeny

    NASA Astrophysics Data System (ADS)

    Kolekar, Pandurang S.; Kale, Mohan M.; Kulkarni-Kale, Urmila

    2010-10-01

    Bioinformatics, being multidisciplinary field, involves applications of various methods from allied areas of Science for data mining using computational approaches. Clustering and molecular phylogeny is one of the key areas in Bioinformatics, which help in study of classification and evolution of organisms. Molecular phylogeny algorithms can be divided into distance based and character based methods. But most of these methods are dependent on pre-alignment of sequences and become computationally intensive with increase in size of data and hence demand alternative efficient approaches. `Inter arrival time distribution' (IATD) is a popular concept in the theory of stochastic system modeling but its potential in molecular data analysis has not been fully explored. The present study reports application of IATD in Bioinformatics for clustering and molecular phylogeny. The proposed method provides IATDs of nucleotides in genomic sequences. The distance function based on statistical parameters of IATDs is proposed and distance matrix thus obtained is used for the purpose of clustering and molecular phylogeny. The method is applied on a dataset of 3' non-coding region sequences (NCR) of Dengue virus type 3 (DENV-3), subtype III, reported in 2008. The phylogram thus obtained revealed the geographical distribution of DENV-3 isolates. Sri Lankan DENV-3 isolates were further observed to be clustered in two sub-clades corresponding to pre and post Dengue hemorrhagic fever emergence groups. These results are consistent with those reported earlier, which are obtained using pre-aligned sequence data as an input. These findings encourage applications of the IATD based method in molecular phylogenetic analysis in particular and data mining in general.

  19. Effects of a Longer Detection Window in VHF Time-of-Arrival Lightning Detection Systems

    NASA Astrophysics Data System (ADS)

    Murphy, M.; Holle, R.; Demetriades, N.

    2003-12-01

    Lightning detection systems that operate by measuring the times of arrival (TOA) of short bursts of radiation at VHF can produce huge volumes of data. The first automated system of this kind, the NASA Kennedy Space Center LDAR network, is capable of producing one detection every 100 usec from each of seven sensors (Lennon and Maier, 1991), where each detection consists of the time and amplitude of the highest-amplitude peak observed within the 100 usec window. More modern systems have been shown to produce very detailed information with one detection every 10 usec (Rison et al., 2001). Operating such systems in real time, however, can become expensive because of the large data communications rates required. One solution to this problem is to use a longer detection window, say 500 usec. In principle, this has little or no effect on the flash detection efficiency because each flash typically produces a very large number of these VHF bursts (known as sources). By simply taking the largest-amplitude peak from every 500-usec interval instead of every 100-usec interval, we should detect the largest 20{%} of the sources that would have been detected using the 100-usec window. However, questions remain about the exact effect of a longer detection window on the source detection efficiency with distance from the network, its effects on how well flashes are represented in space, and how well the reduced information represents the parent thunderstorm. The latter issue is relevant for automated location and tracking of thunderstorm cells using data from VHF TOA lightning detection networks, as well as for understanding relationships between lightning and severe weather. References Lennon, C.L. and L.M. Maier, Lightning mapping system. Proceedings, Intl. Aerospace and Ground Conf. on Lightning and Static Elec., Cocoa Beach, Fla., NASA Conf. Pub. 3106, vol. II, pp. 89-1 - 89-10, 1991. Rison, W., P. Krehbiel, R. Thomas, T. Hamlin, J. Harlin, High time resolution lightning mapping observations of a small thunderstorm during STEPS. Eos Trans. AGU, 82 (47), Fall Meet. Suppl., Abstract AE12A-83, 2001.

  20. The Development of a General Associative Learning Account of Skill Acquisition in a Relative Arrival-Time Judgment Task

    ERIC Educational Resources Information Center

    Loft, Shayne; Neal, Andrew; Humphreys, Michael S.

    2007-01-01

    Current theory assumes that individuals only use information from the immediate environment to perform relative arrival-time judgment tasks. This article presents a theoretical analysis of the memory requirements of this task. The authors present an analysis of the inputs to the memory system and the processes that map those inputs onto outputs.…

  1. Time difference of arrival to blast localization of potential chemical/biological event on the move

    NASA Astrophysics Data System (ADS)

    Morcos, Amir; Desai, Sachi; Peltzer, Brian; Hohil, Myron E.

    2007-10-01

    Integrating a sensor suite with ability to discriminate potential Chemical/Biological (CB) events from high-explosive (HE) events employing a standalone acoustic sensor with a Time Difference of Arrival (TDOA) algorithm we developed a cueing mechanism for more power intensive and range limited sensing techniques. Enabling the event detection algorithm to locate to a blast event using TDOA we then provide further information of the event as either Launch/Impact and if CB/HE. The added information is provided to a range limited chemical sensing system that exploits spectroscopy to determine the contents of the chemical event. The main innovation within this sensor suite is the system will provide this information on the move while the chemical sensor will have adequate time to determine the contents of the event from a safe stand-off distance. The CB/HE discrimination algorithm exploits acoustic sensors to provide early detection and identification of CB attacks. Distinct characteristics arise within the different airburst signatures because HE warheads emphasize concussive and shrapnel effects, while CB warheads are designed to disperse their contents over large areas, therefore employing a slower burning, less intense explosive to mix and spread their contents. Differences characterized by variations in the corresponding peak pressure and rise time of the blast, differences in the ratio of positive pressure amplitude to the negative amplitude, and variations in the overall duration of the resulting waveform. The discrete wavelet transform (DWT) is used to extract the predominant components of these characteristics from air burst signatures at ranges exceeding 3km. Highly reliable discrimination is achieved with a feed-forward neural network classifier trained on a feature space derived from the distribution of wavelet coefficients and higher frequency details found within different levels of the multiresolution decomposition. The development of an adaptive noise floor to provide early event detection assists in minimizing the false alarm rate and increasing the confidence whether the event is blast event or back ground noise. The integration of these algorithms with the TDOA algorithm provides a complex suite of algorithms that can give early warning detection and highly reliable look direction from a great stand-off distance for a moving vehicle to determine if a candidate blast event is CB and if CB what is the composition of the resulting cloud.

  2. P-wave Receiver Functions reveal the Bohemian Massif crust

    NASA Astrophysics Data System (ADS)

    Kampfova Exnerova, Hana; Plomerova, Jaroslava; Vecsey, Ludek

    2015-04-01

    In this study we present initial results of P-wave Receiver Functions (RF) calculated from broad-band waveforms of teleseismic events recorded by temporary and permanent stations in the Bohemian Massif (BM, Central Europe). Temporary arrays BOHEMA I (2001-2003), BOHEMA II (2004-2005) and BOHEMA III (2005-2006) operated during passive seismic experiments oriented towards studying velocity structure of the lithosphere and the upper mantle. Receiver Functions show relative response of the Earth structure under a seismic station and nowadays represent frequently-used method to retrieve structure of the crust, whose knowledge is needed in various studies of the upper mantle. The recorded waveforms are composites of direct P and P-to-S converted waves that reverberate in the structure beneath the receiver (Ammon, 1997). The RFs are sensitive to seismic velocity contrast and are thus suited to identifying velocity discontinuities in the crust, including the Mohorovi?i? discontinuity (Moho). Relative travel-time delays of the converted phases detected in the RFs are transformed into estimates of discontinuity depths assuming external information on the vp/vs and P velocity. To evaluate RFs we use the Multiple-taper spectral correlation (MTC) method (Park and Levin, 2000) and process signals from teleseismic events at epicentral distances of 30 - 100 with magnitude Mw > 5.5. Recordings are filtered with Butterworth band-pass filter of 2 - 8 s. To select automatically signals which are strong enough, we calculate signal-to-noise ratios (SNR) in two steps. In the first step we calculate SNR for signals from intervals (-1s, 3s)/(-10s, -2s), where P-arrival time represent time zero. In the second step we broaden the intervals and calculate SNR for (-1s, 9s)/(-60s, -2s). We also employ forward modelling of the RFs using Interactive Receiver Functions Forward Modeller (IRFFM) (Tkal?i? et al., 2010) to produce, in the first step, one-dimensional velocity models under individual seismic station. Stacked traces of the RFs show strong conversions with positive polarity (indicating a velocity increase across the discontinuity) between 3.3 and 4.5 s after the P-wave arrival at almost all stations. We relate these pulses to conversions at the Moho discontinuity. Assuming a constant crustal vp/vs ratio (1.73) and average crustal velocity vp=6.3 km/s for all stations, analogically to Geissler et al (2012), we multiply the evaluated Ps delay times by factor of 8.3 km/s and estimate the Moho beneath the Bohemian Massif at depths between 27 and 37 km. The crust is thinnest in the western part of the BM, beneath the SW end of the Eger Rift. The Moldanubian part of the BM exhibits the thickest crust. At most of the stations we also see one or two intra-crustal conversions, sometimes stronger than that related to the Moho. Several stations exhibit significant variations of the RF with back-azimuth. The aim of this study is to update existing three dimensional P-velocity crustal model of the Bohemian Massif (Karousov et al., 2012) compiled from control-source seismic results.

  3. The Great "Non-Event" of 7 January 2014: Challenges in CME Arrival Time and Geomagnetic Storm Strength Prediction

    NASA Astrophysics Data System (ADS)

    Mays, M. L.; Thompson, B. J.; Jian, L.; Evans, R. M.; Savani, N.; Odstrcil, D.; Nieves-Chinchilla, T.; Richardson, I. G.

    2014-12-01

    We present a case study of the 7 January 2014 event in order to highlight current challenges in space weather forecasting of CME arrival time and geomagnetic storm strength. On 7 January 2014 an X1.2 flare and CME with a radial speed ~2400 km/s was observed from active region 11943. The flaring region was only ten degrees southwest of disk center with extensive dimming south of the active region and preliminary analysis indicated a fairly rapid arrival at Earth (~36 hours). Of the eleven forecasting groups world-wide who participated in CCMC's Space Weather Scoreboard (http://kauai.ccmc.gsfc.nasa.gov/SWScoreBoard), nine predicted early arrivals and six predicted dramatic geomagnetic storm impacts (Kp predictions ranged from 6 to 9). However, the CME only had a glancing blow arrival at Earth - Kp did not rise above 3 and there was no geomagnetic storm. What happened? One idea is that the large coronal hole to the northeast of the active region could have deflected the CME. This coronal hole produced a high speed stream near Earth reaching an uncommon speed of 900 km/s four days after the observed CME arrival. However, no clear CME deflection was observed in the outer coronagraph fields of view (~5-20Rs) where CME measurements are derived to initiate models, therefore deflection seems unlikely. Another idea is the effect of the CME flux rope orientation with respect to Earth orbit. We show that using elliptical major and minor axis widths obtained by GCS fitting for the initial CME parameters in ENLIL would have improved the forecast to better reflect the observed glancing blow in-situ signature. We also explore the WSA-ENLIL+Cone simulations, the background solar wind solution, and compare with the observed CME arrival at Venus (from Venus Express) and Earth.

  4. YO!-A Time-of-Arrival Receiver for Removal of Femtosecond Helicity-Correlated Beam Effects

    SciTech Connect

    John Musson; Trent Allison; Arne Freyberger; Joachim Kuhn; Brian Quinn

    2004-05-02

    The G0 parity violation experiment at Jefferson Lab is based on time-of-flight measurements, and is sensitive to timing effects between the two electron helicity states of the beam. Photon counters triggered by time-of-arrival at the target mandate that timing must be independent of delays associated with different orbits taken by the two helicity states. In addition, the standard 499 MHz beam structure is altered such that 1 of every 16 microbunches are filled, resulting in an arrival frequency of 31.1875 (31) MHz, and an average current of 40 {micro}A. Helicity correction involves identifying and tracking the 31 MHz subharmonic, applying a fast/fine phase correction, and finally producing a clean 31 MHz trigger and a 499 MHz clock train. These signals are phase-matched to the beam arrival at the target on the order of femtoseconds. The 10 kHz output bandwidth is sufficiently greater than the 30 Hz helicity flip settling time (500 {micro}s). This permits the system to correct each helicity bin for any orbit-induced timing inequalities. A sampling phase detection scheme is used in order to eliminate the unavoidable 2n/n phase shifts associated with frequency dividers. Conventional receiver architecture and DSP techniques are combined for maximum sensitivity, bandwidth, and flexibility. Results of bench tests, commissioning and production data will be presented.

  5. P-wave propagation heterogeneity and earthquake location in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Piromallo, Claudia; Morelli, Andrea

    1998-10-01

    We analyse P-wave traveltimes for the Mediterranean area, using both teleseismic and regional arrivals for shallow earthquakes reported in the Bulletins of the International Seismological Centre. We model delays between pairs of 0.5° × 0.5° cells, obtaining a detailed representation of the P traveltime heterogeneities. Examination of these anomalies shows the clear presence of geographically coherent patterns-consistent with known geological features-due to significant structure in the upper mantle. We present a scheme, based on an empirical heterogeneity correction (EHC) to P-wave traveltimes, to improve earthquake location. This method provides similar benefits to those of a location procedure based on ray tracing in a 3-D model, but it is simpler and computationally more efficient. The definition of the traveltime heterogeneity model, being based on a statistical procedure, bypasses most of the critical points and possible instabilities involved in model inversion. EHC relocation, applied to Mediterranean earthquakes, allows one to predict about 70 per cent of the estimated signal due to heterogeneity and produces epicentral and origin time-shifts of, respectively, 4.22 km and 0.35 s (rms). From a synthetic experiment, in which we use the proposed algorithm to retrieve known source locations, we estimate that the rms improvement achieved by the EHC relocation over a simpler, standard, 1-D location is more than 20 per cent for both epicentral mislocation and origin time-shifts.

  6. Search for Non-Random Features in Arrival Time Series of Air Showers Observed at Mt.Chacaltaya

    NASA Astrophysics Data System (ADS)

    Ochi, N.; Aoki, H.; Hashimoto, K.; Honda, K.; Inoue, N.; Kawasumi, N.; Ohmori, N.; Ohsawa, A.; Shinozaki, K.; Tamada, M.; Tsushima, I.; Yokoi, K.; Aguirre, C.; Martinic, N.; Ticona, R.

    2003-07-01

    Using arrival time series of air showers observed at Mt. Chacaltaya during 1991-1995, we have performed a time series analysis to search for non-random features of UHE cosmic rays. The location of the Chacaltaya air shower array (5200m a.s.l. and in the Southern hemisphere) is expected to reveal new asp ects of UHE cosmic rays which cannot be observed by Northern, sea-level detectors. The arrival time structure of air showers is carefully examined in method of the cluster analysis. In this analysis, we count the number of air showers (N ) observed within short time windows and compare the N distribution with the Poisson/Gaussian distribution. The discrepancy between the distributions possibly implies the existence of non-random components in UHE cosmic rays. From the Chacaltaya data, we picked up one cluster event, consisting of 182 EAS within 10min., though the significance was not enough. The arrival direction of the event was consistent with the Galactic plane, possibly implying the existence of sporadic UHE γ -ray emission from it.

  7. Three-dimensional P-wave velocity structure of Mt. Etna, Italy

    USGS Publications Warehouse

    Villasenor, A.; Benz, H.M.; Filippi, L.; De Luca, G.; Scarpa, R.; Patane, G.; Vinciguerra, S.

    1998-01-01

    The three-dimensional P-wave velocity structure of Mt. Etna is determined to depths of 15 km by tomographic inversion of first arrival times from local earthquakes recorded by a network of 29 permanent and temporary seismographs. Results show a near-vertical low-velocity zone that extends from beneath the central craters to a depth of 10 km. This low-velocity region is coincident with a band of steeply-dipping seismicity, suggesting a magmatic conduit that feeds the summit eruptions. The most prominent structure is an approximately 8-km-diameter high-velocity body located between 2 and 12 km depth below the southeast flank of the volcano. This high-velocity body is interpreted as a remnant mafic intrusion that is an important structural feature influencing both volcanism and east flank slope stability and faulting.

  8. P wave tomography and anisotropy beneath Southeast Asia: Insight into mantle dynamics

    NASA Astrophysics Data System (ADS)

    Huang, Zhouchuan; Zhao, Dapeng; Wang, Liangshu

    2015-07-01

    Southeast Asia is surrounded by subduction zones resulting from the interactions of several lithospheric plates. Its evolution has been also influenced by active tectonics due to the Indo-Asian collision in the Cenozoic. In this study, we use a large number of arrival-time data of local and regional earthquakes to determine 3-D P wave tomography and azimuthal anisotropy in the mantle beneath SE Asia. High-velocity (high-V) anomalies representing the subducting slabs are clearly visible in the upper mantle and the mantle transition zone (MTZ). Low-velocity (low-V) zones with trench-normal anisotropy are revealed in the uppermost mantle, which indicate back-arc spreading or secondary mantle-wedge flow induced by the slab subduction. In contrast, trench-parallel anisotropy dominates in the deep upper mantle and reflects structures either in the subducting slab or in the upper mantle surrounding the slab. The trench-parallel anisotropy is also significant in the lower MTZ, which may contribute to shear wave splitting observations. A low-V body extending down to the lower mantle is visible under the Hainan volcano far away from the plate boundaries, suggesting that Hainan is a hot spot fed by a lower-mantle plume. The low-V body under Hainan is connected with low-V zones in the upper mantle under SE Tibet and Vietnam. Our P wave anisotropy results reflect significant mantle flow existing in the asthenosphere from SE Tibet to Hainan and further southwestward to Vietnam. The present study, especially the 3-D P wave anisotropy results, provides important new insight into mantle dynamics in SE Asia.

  9. P wave anisotropic tomography of the Nankai subduction zone in Southwest Japan

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zhao, Dapeng

    2012-05-01

    The active subduction of the young Philippine Sea (PHS) plate and the old Pacific plate has resulted in significant seismic heterogeneity and anisotropy in Southwest (SW) Japan. In this work we determined a detailed 3-D P wave anisotropic tomography of the crust and upper mantle beneath SW Japan using ˜540,000 P wave arrival times from 5,249 local earthquakes recorded by 1095 stations. The PHS slab is imaged clearly as a high-velocity (high-V) anomaly which exhibits considerable lateral variations. Significant low-velocity (low-V) anomalies are revealed above and below the PHS slab. The low-V anomalies above the PHS slab may reflect the upwelling flow in the mantle wedge and the PHS slab dehydration, and they form the source zone of the arc volcanoes in SW Japan. The low-V zones under the PHS slab may reflect the upwelling flow in the big mantle wedge above the Pacific slab. The anisotropy in the crust and upper mantle is complex. In Kyushu, the P wave fast velocity direction (FVD) is generally trench-normal in the mantle wedge under the back-arc, which is consistent with the corner flow driven by the PHS slab subduction. The FVD is trench-parallel in the subducting PHS slab under Kyushu. We think that the intraslab seismicity is a potential indicator to the slab anisotropy. That is, the PHS slab with seismicity has kept its original fossil anisotropy formed at the mid-ocean ridge, while the aseismic PHS slab has reproduced the anisotropy according to its current deformation.

  10. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM).

    PubMed

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission. PMID:26754955

  11. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    PubMed Central

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission. PMID:26754955

  12. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    NASA Astrophysics Data System (ADS)

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.

  13. Using soft X-ray observations to help the prediction of flare related interplanetary shocks arrival times at the Earth

    NASA Astrophysics Data System (ADS)

    Liu, H.-L.; Qin, G.

    2012-04-01

    It is very important to predict the shock arrival times (SATs) at Earth for space weather practice. In this paper we use the energy of soft X-ray during solar flare events to help predict the SATs at Earth. We combine the soft X-ray energy and SAT prediction models previously developed by researchers to obtain two new methods. By testing the methods with the total of 585 solar flare events following the generation of a metric type II radio burst during the Solar Cycle 23 from September 1997 to December 2006, we find that the predictions of SATs at Earth could be improved by significantly increasing PODn, the proportion of events without shock detection that were correctly forecast. PODn represents a method's ability in forecasting the solar flare events without shocks arriving at the Earth, which is important for operational predictions.

  14. The NANOGrav Nine-year Data Set: Observations, Arrival Time Measurements, and Analysis of 37 Millisecond Pulsars

    NASA Astrophysics Data System (ADS)

    The NANOGrav Collaboration; Arzoumanian, Zaven; Brazier, Adam; Burke-Spolaor, Sarah; Chamberlin, Sydney; Chatterjee, Shami; Christy, Brian; Cordes, James M.; Cornish, Neil; Crowter, Kathryn; Demorest, Paul B.; Dolch, Timothy; Ellis, Justin A.; Ferdman, Robert D.; Fonseca, Emmanuel; Garver-Daniels, Nathan; Gonzalez, Marjorie E.; Jenet, Fredrick A.; Jones, Glenn; Jones, Megan L.; Kaspi, Victoria M.; Koop, Michael; Lam, Michael T.; Lazio, T. Joseph W.; Levin, Lina; Lommen, Andrea N.; Lorimer, Duncan R.; Luo, Jing; Lynch, Ryan S.; Madison, Dustin; McLaughlin, Maura A.; McWilliams, Sean T.; Nice, David J.; Palliyaguru, Nipuni; Pennucci, Timothy T.; Ransom, Scott M.; Siemens, Xavier; Stairs, Ingrid H.; Stinebring, Daniel R.; Stovall, Kevin; Swiggum, Joseph K.; Vallisneri, Michele; van Haasteren, Rutger; Wang, Yan; Zhu, Weiwei

    2015-11-01

    We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In conjunction with the timing model fit, we have performed a Bayesian analysis of a parameterized timing noise model for each source, and detect evidence for excess low-frequency, or “red,” timing noise in 10 of the pulsars. For 5 of these cases this is likely due to interstellar medium propagation effects rather than intrisic spin variations. Subsequent papers in this series will present further analysis of this data set aimed at detecting or limiting the presence of nanohertz-frequency gravitational wave signals.

  15. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1983-10-18

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  16. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, Robert F.

    1987-01-01

    An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

  17. Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles

    DOEpatents

    Benjamin, R.F.

    1987-03-10

    An apparatus is disclosed for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously. 3 figs.

  18. Dual subduction tectonics and plate dynamics of central Japan shown by three-dimensional P-wave anisotropic structure

    NASA Astrophysics Data System (ADS)

    Ishise, Motoko; Miyake, Hiroe; Koketsu, Kazuki

    2015-07-01

    The central Japanese subduction zone is characterized by a complex tectonic setting affected by the dual subduction of oceanic plates and collisions between the island arcs. To better understand of the subduction system, we performed an anisotropic tomography analysis using P-wave arrival times from local earthquakes to determine the three-dimensional structure of P-wave azimuthal anisotropy in the overriding plate and the Pacific and Philippine Sea (PHS) slabs. The principal characteristics of anisotropy in the subducted and subducting plates are (1) in the overriding plate, the distribution pattern of fast direction of crustal anisotropy coincides with that of the strike of geological structure, (2) in the two oceanic plates, fast propagation directions of P-wave were sub-parallel to the directions of seafloor spreading. Additionally, our tomographic images demonstrate that (1) the bottom of the Median Tectonic Line, the longest fault zone in Japan, reaches to the lower crust, and seems to link to the source region of an inter-plate earthquake along the PHS slab, (2) the segmentation of the PHS slab - the Izu Islands arc, the Nishi-Shichito ridge, and the Shikoku basin - due to the formation history, is reflected in the regional variation of anisotropy. The tomographic study further implies that there might be a fragment of the Pacific slab suggested by a previous study beneath the Tokyo metropolitan area. The overall findings strongly indicate that seismic anisotropy analysis provide potentially useful information to understand a subduction zone.

  19. P-wave anisotropic velocity tomography beneath the Japan islands: Large-scale images and details in the Kanto district

    NASA Astrophysics Data System (ADS)

    Ishise, M.; Koketsu, K.; Miyake, H.; Oda, H.

    2006-12-01

    The Japan islands arc is located in the convergence zone of the North American (NA), Amurian (AM), Pacific (PAC) and Philippine Sea (PHS) plates, and its parts are exposed to various tectonic settings. For example, at the Kanto district in its central part, these four plates directly interact with each, so that disastrous future earthquakes are expected along the plate boundaries and within the inland areas. In order to understand this sort of complex tectonic setting, it is necessary to know the seismological structure in various perspectives. We investigate the seismic velocity structure beneath the Japan islands in view of P-wave anisotropy. We improved a hitherto-known P-wave tomography technique so that the 3-D structure of isotropic and anisotropic velocities and earthquake hypocenter locations are determined from P-wave arrival times of local earthquakes [Ishise and Oda, 2005]. In the tomography technique, P-wave anisotropy is assumed to hold hexagonal symmetry with horizontal symmetry axis. The P-wave arrival times used in this study are complied in the Japan University Network Earthquake Catalog. The results obtained are summarized as follows; (1) the upper crust anisotropy is governed by the present-day stress field arising from the interaction between the plates surrounding the Japan islands arc, (2) the mantle anisotropy is caused by the present-day mantle flow induced by slab subduction and continental plate motion, (3) the old PAC slab keeps its original slab anisotropy which was captured when the plate was formed, while the youngest part of the PHS slab has lost the original anisotropy during its subduction and has gained new anisotropy which is controlled by the present-day stress field. We also carried out a further study on high-resolution seismic tomography for understanding the specific characteristics of the Kanto district. We mostly focused on the elucidation of the dual subduction formed by the PHS and PAC slabs using seismological data compiled by the Natural Research Institute for Earth Science and Japan Meteorological Agency. This will lead to more accurate source modeling of future plate- boundary earthquakes.

  20. 3D P-Wave Velocity Structure of the Crust and Relocation of Earthquakes in 21 the Lushan Source Area

    NASA Astrophysics Data System (ADS)

    Yu, X.; Wang, X.; Zhang, W.

    2014-12-01

    The double difference seismic tomography method is applied to the absolute first arrival P wave arrival times and high quality relative P arrival times of the Lushan seismic sequence to determine the detailed crustal 3D P wave velocity structure and the hypocenter parameters in the Lushan seismic area. The results show that the Lushan mainshock locates at 30.28 N, 103.98 E, with the depth of 16.38 km. The leading edge of aftershock in the northeast of mainshock present a spade with a steep dip angle, the aftershocks' extended length is about 12 km. In the southwest of the Lushan mainshock, the leading edge of aftershock in low velocity zone slope gently, the aftershocks' extended length is about 23 km. The P wave velocity structure of the Lushan seismic area shows obviously lateral heterogeneity. The P wave velocity anomalies represent close relationship with topographic relief and geological structure. In Baoxing area the complex rocks correspond obvious high-velocity anomalies extending down to 15 km depth,while the Cenozoic rocks are correlated with low-velocity anomalies. Our high-resolution tomographic model not only displays the general features contained in the previous models, but also reveals some new features. An obvious high-velocity anomaly is visible in Daxing area. The high-velocity anomalies beneath Baoxing and Daxing connect each other in 10 km depth, which makes the contrast between high and low velocity anomalies more sharp. Above 20 km depth the velocity structure in southwest and northeast segment of the mainshock shows a big difference: low-velocity anomalies are dominated the southwest segment, while high-velocity anomalies rule the northeast segment. The Lushan mainshock locates at the leading edge of a low-velocity anomaly surrounded by the Baoxing and Daxing high-velocity anomalies. The Lushan aftershocks in southwest are distributed in low-velocity anomalies or the transition belt: the footwall represents low-velocity anomalies, while the hanging wall shows high-velocity anomalies. The northeastern aftershocks are distributed at the boundary between high-velocity anomalies in Baoxing and Daxing area. The main seismogenic layer dips to northwest.

  1. Catching audiovisual mice: predicting the arrival time of auditory-visual motion signals.

    PubMed

    Hofbauer, M; Wuerger, S M; Meyer, G F; Roehrbein, F; Schill, K; Zetzsche, C

    2004-06-01

    We investigated the extent to which auditory and visual motion signals are combined when observers are asked to predict the location of a virtually moving target. In Condition 1, the unimodal and bimodal signals were noisy, but the target object was continuously visible and audible; in Condition 2, the virtually moving object was hidden (invisible and inaudible) for a short period prior to its arrival at the target location. Our main finding was that the facilitation due to simultaneous visual and auditory input is very different for the two conditions. When the target is continuously visible and audible (Condition 1), the bimodal performance is twice as good as the unimodal performances, thus suggesting a very effective integration mechanism. On the other hand, if the object is hidden for a short period (Condition 2) and the task therefore requires the extrapolation of motion speed over a temporal and spatial period, the facilitation due to both sensory inputs is almost absent, and the bimodal performance is limited by the visual performance. PMID:15460930

  2. Connecting speeds, directions and arrival times of 22 coronal mass ejections from the sun to 1 AU

    SciTech Connect

    Möstl, C.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V.; Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong, E. M.; Colaninno, R. C.; Davies, J. A.; Harrison, R. A.; Lugaz, N.; Farrugia, C. J.; Galvin, A. B.; Liu, Y. D.; Luhmann, J. G.; Vršnak, B.

    2014-06-01

    Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s{sup –1}). We track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of –26.4 ± 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ± 288 km s{sup –1}. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 ± 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 ± 50 km s{sup –1}. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line.

  3. Sex-Specific Arrival Times on the Breeding Grounds: Hybridizing Migratory Skuas Provide Empirical Support for the Role of Sex Ratios.

    PubMed

    Lisovski, Simeon; Fröhlich, Anne; von Tersch, Matthew; Klaassen, Marcel; Peter, Hans-Ulrich; Ritz, Markus S

    2016-04-01

    In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio. PMID:27028080

  4. Alignment of leading-edge and peak-picking time of arrival methods to obtain accurate source locations

    SciTech Connect

    Roussel-Dupre, R.; Symbalisty, E.; Fox, C.; and Vanderlinde, O.

    2009-08-01

    The location of a radiating source can be determined by time-tagging the arrival of the radiated signal at a network of spatially distributed sensors. The accuracy of this approach depends strongly on the particular time-tagging algorithm employed at each of the sensors. If different techniques are used across the network, then the time tags must be referenced to a common fiducial for maximum location accuracy. In this report we derive the time corrections needed to temporally align leading-edge, time-tagging techniques with peak-picking algorithms. We focus on broadband radio frequency (RF) sources, an ionospheric propagation channel, and narrowband receivers, but the final results can be generalized to apply to any source, propagation environment, and sensor. Our analytic results are checked against numerical simulations for a number of representative cases and agree with the specific leading-edge algorithm studied independently by Kim and Eng (1995) and Pongratz (2005 and 2007).

  5. A New Version of the Shock Propagation Model (SPM2) for Predicting the Arrival Time of Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Feng, X.

    2012-12-01

    Forecasting the arrival time at the near Earth space of interplanetary (IP) shocks following the solar disturbances is one of the important ingredients of space weather prediction. Shock Propagation Model (SPM), based on the analytic solution of the blast wave theory, is one of the models to predict the shock arrival time (SAT). The input parameters of SPM include the initial shock speed, the duration time of the X-ray flare, and the background solar wind speed. Considering the fact that the measurement errors exist in the input parameters as well as the shortage of the theoretical model in real applications, a new version of SPM, called SPM2 is presented with the aim of overcome these shortages. Firstly, SPM is used to train the input data, and an empirical relationship is established to correct for the error in the initial shock speed (computed from the type II burst drafting speed). And the corrected shock speed is used is the SPM2 model. Secondly, a large number of data set during solar cycle 23 are adopted to train the model, and an additional acceleration/deceleration relation is added in SPM2. Thirdly, the propagating direction is introduced as one of the contributing factors to the shock's arrival at Earth, which overcomes the shortage of the isotropy of the blast wave theory in the practice of real prediction. Finally, SPM2 adopts an equivalent Mach number of the shock at 1 AU in order to judge whether or not the shock could reach the Earth. 584 flare-type II related shock events during Solar Cycle 23 are used to test the prediction capability of the SPM2 model. Several standard meteorological forecast skill scores of SPM2 are also computed. The corresponding success rates of SPM2 for both shock and non-shock events at Earth are above 60%, and the application of a x2 test demonstrates that the predictions of the model are statistically significant. As for the predicting accuracy in shock arrival time, the root-mean-square err of △T of SPM2 is less than 12 hours, and its mean-absolute err is below 10 hours.

  6. Position surveillance using one active ranging satellite and time-of-arrival of a signal from an independent satellite

    NASA Technical Reports Server (NTRS)

    Anderson, R. E.; Frey, R. L.; Lewis, J. R.

    1980-01-01

    Position surveillance using one active ranging/communication satellite and the time-of-arrival of signals from an independent satellite was shown to be feasible and practical. A towboat on the Mississippi River was equipped with a tone-code ranging transponder and a receiver tuned to the timing signals of the GOES satellite. A similar transponder was located at the office of the towing company. Tone-code ranging interrogations were transmitted from the General Electric Earth Station Laboratory through ATS-6 to the towboat and to the ground truth transponder office. Their automatic responses included digital transmissions of time-of-arrival measurements derived from the GOES signals. The Earth Station Laboratory determined ranges from the satellites to the towboat and computed position fixes. The ATS-6 lines-of-position were more precise than 0.1 NMi, 1 sigma, and the GOES lines-of-position were more precise than 1.6 NMi, 1 sigma. High quality voice communications were accomplished with the transponders using a nondirectional antenna on the towboat. The simple and effective surveillance technique merits further evaluation using operational maritime satellites.

  7. IEEE 802.15.4 ZigBee-Based Time-of-Arrival Estimation for Wireless Sensor Networks.

    PubMed

    Cheon, Jeonghyeon; Hwang, Hyunsu; Kim, Dongsun; Jung, Yunho

    2016-01-01

    Precise time-of-arrival (TOA) estimation is one of the most important techniques in RF-based positioning systems that use wireless sensor networks (WSNs). Because the accuracy of TOA estimation is proportional to the RF signal bandwidth, using broad bandwidth is the most fundamental approach for achieving higher accuracy. Hence, ultra-wide-band (UWB) systems with a bandwidth of 500 MHz are commonly used. However, wireless systems with broad bandwidth suffer from the disadvantages of high complexity and high power consumption. Therefore, it is difficult to employ such systems in various WSN applications. In this paper, we present a precise time-of-arrival (TOA) estimation algorithm using an IEEE 802.15.4 ZigBee system with a narrow bandwidth of 2 MHz. In order to overcome the lack of bandwidth, the proposed algorithm estimates the fractional TOA within the sampling interval. Simulation results show that the proposed TOA estimation algorithm provides an accuracy of 0.5 m at a signal-to-noise ratio (SNR) of 8 dB and achieves an SNR gain of 5 dB as compared with the existing algorithm. In addition, experimental results indicate that the proposed algorithm provides accurate TOA estimation in a real indoor environment. PMID:26861331

  8. Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory and Ulysses

    NASA Technical Reports Server (NTRS)

    Laros, J. G.; Boynton, W. V.; Hurley, K.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.

    1997-01-01

    Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to approximately 2 deg accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at approximately 1 min x 4 min, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.

  9. IEEE 802.15.4 ZigBee-Based Time-of-Arrival Estimation for Wireless Sensor Networks

    PubMed Central

    Cheon, Jeonghyeon; Hwang, Hyunsu; Kim, Dongsun; Jung, Yunho

    2016-01-01

    Precise time-of-arrival (TOA) estimation is one of the most important techniques in RF-based positioning systems that use wireless sensor networks (WSNs). Because the accuracy of TOA estimation is proportional to the RF signal bandwidth, using broad bandwidth is the most fundamental approach for achieving higher accuracy. Hence, ultra-wide-band (UWB) systems with a bandwidth of 500 MHz are commonly used. However, wireless systems with broad bandwidth suffer from the disadvantages of high complexity and high power consumption. Therefore, it is difficult to employ such systems in various WSN applications. In this paper, we present a precise time-of-arrival (TOA) estimation algorithm using an IEEE 802.15.4 ZigBee system with a narrow bandwidth of 2 MHz. In order to overcome the lack of bandwidth, the proposed algorithm estimates the fractional TOA within the sampling interval. Simulation results show that the proposed TOA estimation algorithm provides an accuracy of 0.5 m at a signal-to-noise ratio (SNR) of 8 dB and achieves an SNR gain of 5 dB as compared with the existing algorithm. In addition, experimental results indicate that the proposed algorithm provides accurate TOA estimation in a real indoor environment. PMID:26861331

  10. A one-particle time of arrival operator for a free relativistic spin- 0 charged particle in (1 + 1) dimensions

    NASA Astrophysics Data System (ADS)

    Bunao, Joseph; Galapon, Eric A.

    2015-02-01

    We construct a one-particle TOA operator T ˆ canonically conjugate with the Hamiltonian describing a free, charged, spin- 0, relativistic particle in one spatial dimension and show that it is maximally symmetric. We solve for its eigenfunctions and show that they form a complete and non-orthogonal set. Plotting the time evolution of their corresponding probability densities, it implies that the eigenfunctions become more localized at the origin at the time equal to their eigenvalues. That is, a particle being described by an eigenfunction of T ˆ is in a state of definite arrival time at the origin and at the corresponding eigenvalue. We also calculate the TOA probability distribution of a particle in some initial state.

  11. Magnetotelluric apparent conductivity and seismic p-wave tomography comparison, Rio Grande Rift, Southwestern USA

    NASA Astrophysics Data System (ADS)

    Harding, J.; Sheehan, A. F.; Feucht, D. W.; Bedrosian, P.; O'Rourke, C. T.

    2013-12-01

    During the summers of 2012 and 2013, magnetotelluric (MT) data was collected in three transects across the Rio Grande Rift in Colorado and New Mexico. Previous seismological studies, including both regional deployments and EarthScope USArray Transportable Array (TA), have shown that a wide area of upper mantle below the Rio Grande Rift is seismically slow, but the cause of this is unclear. MT has the potential to help reduce the ambiguity in determining the cause of the seismically slow anomaly. Electrical conductivity determined from MT and elastic parameters determined from seismic experiments have different sensitivities to temperature, partial melt, hydration and composition; together these methods can be used to constrain the physical, chemical, and thermal state of the lithosphere, and to investigate changes in it throughout the rift. These constraints can help distinguish between different rift opening models such as the rift unzipping south to north or being rotated open. We have used a cross correlation algorithm to pick teleseismic P-wave arrival times from twenty-two events recorded by TA stations in Colorado and New Mexico from 2008 - 2010. Our teleseismic picks were used to create maps and profiles of travel time residuals that can be compared with existing tomographic images and with our new MT data. We have forward modeled select MT data to produce 1-D models of conductivity versus depth, which can then be compared to the average travel time residuals at TA stations in proximity to the MT profile. The travel time residuals across the three MT lines are also qualitatively compared to cross-sections of the Schmandt & Humphreys (2010) P-wave tomography model.

  12. On the possibility to discriminate the mass of the primary cosmic ray using the muon arrival times from extensive air showers: Application for Pierre Auger Observatory

    SciTech Connect

    Arsene, N.; Rebel, H.; Sima, O.

    2012-11-20

    In this paper we study the possibility to discriminate the mass of the primary cosmic ray by observing the muon arrival times in ground detectors. We analyzed extensive air showers (EAS) induced by proton and iron nuclei with the same energy 8 Multiplication-Sign 10{sup 17} eV simulated with CORSIKA, and analyzed the muon arrival times at ground measured by the infill array detectors of the Pierre Auger Observatory (PAO). From the arrival times of the core and of the muons the atmospheric depth of muon generation locus is evaluated. The results suggest a potential mass discrimination on the basis of muon arrival times and of the reconstructed atmospheric depth of muon production. An analysis of a larger set of CORSIKA simulations carried out for primary energies above 10{sup 18} eV is in progress.

  13. Lightning First Pulses Used in the "Last" (Time-of-Arrival) and "Atlas" (Single Station) Total Lightning Mapping Systems

    NASA Technical Reports Server (NTRS)

    Markson, Ralph; Ruhnke, Lothar

    1999-01-01

    The first RF pulse from "total lightning' discharges (cloud and ground flashes) has been used in different ways to locate the origin of flashes in two new types of lightning detection systems. The multisensor LASI time-of-arrival (TOA) system uses GPS timing of the first pulse. The ATLAS single sensor system uses the amplitude of the first pulse, which is invariant in magnitude and polarization for all lightning discharges, to determine distance from the sensor. It is significantly more accurate than past single sensor lightning mapping systems. The polarity of the first pulse generally identifies lightning type (IC or CG). Both systems utilize only the first pulse which makes signal processing much simpler than with previous lightning locating systems. Knowing the position where lightning begins (maximum electric fields, mixed phase hydrometeors and updrafts) is valuable for identifying convective cells producing the hazardous meteorological conditions caused by thunderstorms. It is also important for research studying thunderstorm electrification and associated microphysical problems.

  14. Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1987 Annual Report.

    SciTech Connect

    Buettner, Edwin W.; Nelson, V. Lance

    1990-01-01

    This project monitored the daily passage of smolts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clearwater rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time. 10 figs, 15 tabs.

  15. Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1988 Annual Report.

    SciTech Connect

    Buettner, Edwin W.; Nelson, William R.

    1989-10-01

    This project monitored the daily passage of smelts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clear-water rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time.

  16. Zero-bias anomaly in p-wave superconductor

    NASA Astrophysics Data System (ADS)

    Rosenstein, Baruch; Shapiro, B. Ya.; Shapiro, I.; Li, Dingping

    2015-11-01

    It was shown some time ago that a magnetic field penetrates a triplet non-chiral superconductor described by the (three-dimensional) vector order parameter as an array of magnetic skyrmions, a texture carrying two units of magnetic flux. Magnetic skyrmions do not have a normal core in contrast to Abrikosov vortices. The spectrum of Andreev midgap states of this coreless topological defect in p-wave isotropic superconductors with single parabolic band is calculated. It is shown that a magnetic field can be used to tune the Andreev state energy precisely to zero (these states are not topologically protected). They can be further stabilized and manipulated by pinning of the skyrmions on columnar defects or nanoholes. In contrast to Majorana modes in chiral p-wave superconductor, the tunneling between ZES within neighboring skyrmions is prohibited due to their high angular momentum. Experimental signatures of these states are discussed.

  17. Practical and fast quantum random number generation based on photon arrival time relative to external reference

    SciTech Connect

    Nie, You-Qi; Zhang, Jun Pan, Jian-Wei; Zhang, Hong-Fei; Wang, Jian; Zhang, Zhen; Ma, Xiongfeng

    2014-02-03

    We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

  18. Smolt Condition and Timing of Arrival at Lower Granite Dam, 1983 Annual Report.

    SciTech Connect

    Scully, Richard J.; Buettner, Edwin W.; Cummins, Clay

    1984-05-01

    Migration rate and condition of salmon and steelhead smolts in the Salmon and Clearwater Rivers were investigated. Hatchery-raised fish were released at various points along the rivers and their travel times to the upper end of Granite Reservoir determined. Rates of descaling were recorded as an indication of fish condition. (ACR). 8 references, 33 figures, 18 tables.

  19. Effect of method and timing of castration on newly arrived stocker cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted to determine the effects of castration method and timing on the performance and health of newly received stocker cattle. Two hundred and seventy-one crossbred male calves (184 bulls, 87 steers; 210 ± 14.7 kg) were purchased at auction barns and shipped in three groups. ...

  20. Estimating the Arrival Time of Earth-directed Coronal Mass Ejections at in Situ Spacecraft Using COR and HI Observations from STEREO

    NASA Astrophysics Data System (ADS)

    Mishra, Wageesh; Srivastava, Nandita

    2013-07-01

    Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient for accurate forecasting of the arrival time at Earth of a majority of CMEs. This uncertainty is due to many factors that change CME kinematics, such as the interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagation of CMEs, we have used the three-dimensional triangulation method on SECCHI coronagraph (COR2) images and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 data for eight Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and implementing the drag-based model for the distance where the CMEs could not be tracked unambiguously in the interplanetary (IP) medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival times as observed by in situ instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the IP medium.

  1. ESTIMATING THE ARRIVAL TIME OF EARTH-DIRECTED CORONAL MASS EJECTIONS AT IN SITU SPACECRAFT USING COR AND HI OBSERVATIONS FROM STEREO

    SciTech Connect

    Mishra, Wageesh; Srivastava, Nandita

    2013-07-20

    Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient for accurate forecasting of the arrival time at Earth of a majority of CMEs. This uncertainty is due to many factors that change CME kinematics, such as the interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagation of CMEs, we have used the three-dimensional triangulation method on SECCHI coronagraph (COR2) images and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 data for eight Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and implementing the drag-based model for the distance where the CMEs could not be tracked unambiguously in the interplanetary (IP) medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival times as observed by in situ instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the IP medium.

  2. Post-Arrival Screening for Malaria in Asymptomatic Refugees Using Real-Time PCR

    PubMed Central

    Matisz, Chelsea E.; Naidu, Prenilla; Shokoples, Sandra E.; Grice, Diane; Krinke, Valerie; Brown, Stuart Z.; Kowalewska-Grochowska, Kinga; Houston, Stan; Yanow, Stephanie K.

    2011-01-01

    Malaria is a significant health risk to refugee populations originating from endemic areas, but there is little consensus on screening and/or treatment approaches for malaria in this population. Furthermore, detection of malaria in semi-immune asymptomatic refugees is limited by the sensitivity of diagnostic tests used for screening. We determined the prevalence of malaria by microscopy and real-time polymerase chain reaction (PCR) in a consecutive population of 324 asymptomatic refugees examined in Edmonton, Canada, during 20092010. Although all thick and thin blood smear results were negative, 10 subjects (3.1%) tested PCR positive for Plasmodium DNA. Interestingly, 6 of 10 PCR positive subjects are at risk of malaria relapse by P. vivax or P. ovale infections. These results suggest that appropriate guidelines for malaria screening should consider the risk of relapsing infections, and they highlight the potential usefulness of real-time PCR in the diagnosis of asymptomatic malaria. PMID:21212221

  3. Development of the town data base: Estimates of exposure rates and times of fallout arrival near the Nevada Test Site

    SciTech Connect

    Thompson, C.B.; McArthur, R.D.; Hutchinson, S.W.

    1994-09-01

    As part of the U.S. Department of Energy`s Off-Site Radiation Exposure Review Project, the time of fallout arrival and the H+12 exposure rate were estimated for populated locations in Arizona, California, Nevada, and Utah that were affected by fallout from one or more nuclear tests at the Nevada Test Site. Estimates of exposure rate were derived from measured values recorded before and after each test by fallout monitors in the field. The estimate for a given location was obtained by retrieving from a data base all measurements made in the vicinity, decay-correcting them to H+12, and calculating an average. Estimates were also derived from maps produced after most events that show isopleths of exposure rate and time of fallout arrival. Both sets of isopleths on these maps were digitized, and kriging was used to interpolate values at the nodes of a 10-km grid covering the pattern. The values at any location within the grid were then estimated from the values at the surrounding grid nodes. Estimates of dispersion (standard deviation) were also calculated. The Town Data Base contains the estimates for all combinations of location and nuclear event for which the estimated mean H+12 exposure rate was greater than three times background. A listing of the data base is included as an appendix. The information was used by other project task groups to estimate the radiation dose that off-site populations and individuals may have received as a result of exposure to fallout from Nevada nuclear tests.

  4. The energy radiated by the 26 December 2004 Sumatra-Andaman earthquake estimated from 10-minute P-wave windows

    USGS Publications Warehouse

    Choy, G.L.; Boatwright, J.

    2007-01-01

    The rupture process of the Mw 9.1 Sumatra-Andaman earthquake lasted for approximately 500 sec, nearly twice as long as the teleseismic time windows between the P and PP arrival times generally used to compute radiated energy. In order to measure the P waves radiated by the entire earthquake, we analyze records that extend from the P-wave to the S-wave arrival times from stations at distances ?? >60??. These 8- to 10-min windows contain the PP, PPP, and ScP arrivals, along with other multiply reflected phases. To gauge the effect of including these additional phases, we form the spectral ratio of the source spectrum estimated from extended windows (between TP and TS) to the source spectrum estimated from normal windows (between TP and TPP). The extended windows are analyzed as though they contained only the P-pP-sP wave group. We analyze four smaller earthquakes that occurred in the vicinity of the Mw 9.1 mainshock, with similar depths and focal mechanisms. These smaller events range in magnitude from an Mw 6.0 aftershock of 9 January 2005 to the Mw 8.6 Nias earthquake that occurred to the south of the Sumatra-Andaman earthquake on 28 March 2005. We average the spectral ratios for these four events to obtain a frequency-dependent operator for the extended windows. We then correct the source spectrum estimated from the extended records of the 26 December 2004 mainshock to obtain a complete or corrected source spectrum for the entire rupture process (???600 sec) of the great Sumatra-Andaman earthquake. Our estimate of the total seismic energy radiated by this earthquake is 1.4 ?? 1017 J. When we compare the corrected source spectrum for the entire earthquake to the source spectrum from the first ???250 sec of the rupture process (obtained from normal teleseismic windows), we find that the mainshock radiated much more seismic energy in the first half of the rupture process than in the second half, especially over the period range from 3 sec to 40 sec.

  5. A relativistic one-particle Time of Arrival operator for a free spin- 1 / 2 particle in (1 + 1) dimensions

    NASA Astrophysics Data System (ADS)

    Bunao, Joseph; Galapon, Eric A.

    2015-05-01

    As a follow-up to a recent study in the spin-0 case (Bunao and Galapon, 2015), we construct a one-particle Time of Arrival (TOA) operator conjugate to a Hamiltonian describing a free relativistic spin- 1 / 2 particle in one spatial dimension. Upon transformation in a representation where the Hamiltonian is diagonal, it turns out that the constructed operator consists of an operator term T ˆ whose action is the same as in the spin-0 case, and another operator term Tˆ0 which commutes with the Hamiltonian but breaks invariance under parity inversion. If we must impose this symmetry on our TOA operator, then we can throw away Tˆ0 so that the TOA operator is just T ˆ .

  6. The analyses of P-wave velocity structures in the Manila subduction system

    NASA Astrophysics Data System (ADS)

    Liang, C.; Chen, H.; Wu, H.; Lee, C.

    2011-12-01

    During the TAIGER project in 2009, we deployed 260 OBSs around offshore Taiwan, and recorded the refracted wave from the deep crust. The seismic source was provided by a 6000 cu-in airgun array from R/V Langseth. During leg 1 and 4 of TAIGER experiment, 3 OBS lines, T1 (consists of MGL0908_05 and MGL0908_07), T2 (consists of MGL0908_01 and MGL0908_09), and MGL0905_27, were shot in the Manila subduction system. We picked OBS first arrivals and inversed the P-wave velocity model to demonstrate the major feactures such as the Manila subduction zone, Luzon arc and part of West Philippine Basin. In the results, the oceanic crust thickness of the northeast part of the South China Sea was identified which is about 10-12 km thick in west of the LRTPB (Luzon-Ryukyu Transform Plate Boundary). But the thickness of the crust thins across the LRTPB to Manila Trench (6-8km), and start to subduct into the Philippine Sea Plate beneath the Manila Trench. Both sides of the Gagua Ridge are the oceanic crust, and their thickness is about 8 km. Even the P-wave velocity model cannot demonstrates the subducting angle very well along Manila Trench, but the depth of the Moho can be showed about 16 km at west of the Manila Trench, and about 25 km deep beneath the accretionary prism. In addition, we also used the earthquake data from CWB, IRIS, and Philippine. The subduction zone of the Benioff zone can be extended up to 100 km. Several splay faults and out-of-sequence thrusts (OOST) are also detected from multi-beam echo sounder and multi-channel seismic data. The stress of the splay faults and the OOST increases from collision and compression. If the stress accumulates for a long time, the mega earthquake and tsunami probably may be occurred.

  7. P-Wave Electron-Hydrogen Scattering

    NASA Technical Reports Server (NTRS)

    Bhtia, Anand

    2012-01-01

    A variational wave function incorporating short range correlations via Hylleraas type functions plus long-range polarization terms of the polarized orbital type but with smooth cut-off factors has been used to calculate P-wave phase shifts for electron-hydrogen scattering. This approach gives the direct r(exp -4) potential and a non-local optical potential which is definite. The resulting phase shifts have rigorous lower bounds and the convergence is much faster than those obtained without the modification of the target function. Final results will be presented at the conference.

  8. Magnitude estimation using high-frequency acceleration of initial P-wave

    NASA Astrophysics Data System (ADS)

    Korenaga, M.; Yamamoto, S.; Noda, S.; Iwata, N.

    2011-12-01

    Recently various methods to estimate earthquake parameters (epicentral location and magnitude) have been proposed, and some of those are applied to an earthquake early warning system. For example, the method to estimate epicentral location using single station data (the B-delta method (Odaka et al., 2003) and the Principal component analysis (Meteorological Research Institute, 1985)) is used by Japan Meteorological Agency(JMA) EEW system and the Shinkansen EEW system. Improvement of its accuracy and rapidness is discussed by Noda et al., 2011. As for estimating a magnitude from the initial phase data, the method using the maximum amplitude (Odaka et al., 2003) and the ?c method (Wu and Kanamori, 2005) are proposed. The present JMA EEW and the Shinkansen EEW system use the maximum displacement amplitude for estimating the magnitude. On the other hand, Hoshiba et al. (2010) indicated that the maximum value of acceleration amplitude tends to appear earlier than that of displacement amplitude, thus the maximum magnitude may be estimated earlier by acceleration amplitude than by displacement. In this study, we examined a method to estimate the magnitude from the amplitude of vertical acceleration in order to improve rapidness of its estimation. 10342 K-NET waveform data of 190 earthquakes (M<3.9, focal depth <150km) were used for the analysis. First, we grouped seismic waveform data according to hypocentral distances and magnitudes, then we averaged time histories of vertical acceleration of each group to examine their features. As the result, we found that the amplitude of the very initial phase (about 0.5 sec after the arrival of P-wave) mainly depends not on magnitude, but on hypocentral distances. So as to reduce the effect of hypocentral distance, we divided the high-frequency (10-20 Hz) vertical acceleration time history by the amplitude value at 0.5 sec after the arrival of P-wave, and examined statistical relationship between the normalized value and the magnitude. It was found out that correlation between the normalized value and the magnitude is significantly high. For example, the relational expression between the magnitude and the normalized value at 1.5 sec after the arrival of P-wave is A = 0.0212 * e ^ (0.9075 * M) where A and M denote the normalized value and the magnitude. To validate the accuracy of this method, we calculate differences (RMS) between the magnitude published by JMA and the magnitude estimated from the relationship obtained above. In this case, estimation error is found to be 0.6. It is obvious that high-frequency acceleration waveform is superposition of various waves radiated from fracture surface, and growth in the amplitude of observed acceleration corresponds to spreading of the fault area of rupture front. That is, it is thought that the magnitude estimated by this method using high-frequency acceleration is equivalent to the magnitude obtained by the conventional technique using low-frequency seismic data. Therefore, it would be possible to estimate the growth of the magnitude earlier by using acceleration data characterized by rapidness.

  9. P wave attenuation structure below the Tokyo Metropolitan area

    NASA Astrophysics Data System (ADS)

    Panayotopoulos, Y.; Sakai, S.; Nakagawa, S.; Kasahara, K.; Hirata, N.; Aketagawa, T.; Kimura, H.; Lee, C.

    2010-12-01

    The material properties of the complex subduction zone beneath the Tokyo Metropolitan can be estimated by the seismic attenuation Q-1 of seismic waves observed at local seismic stations. The attenuation of seismic waves is represented by the t* attenuation operator that can be estimated by fitting the observed P wave amplitude spectrum to a theoretical spectrum using an ω2 source model. The waveform data used in this study are recorded at the dense seismic array of the Metropolitan Seismic Observation network (MeSO-net). The station network is distributed on five lines with an average spacing of 3 km and in an area with a spacing of 5 km in the central part of Kanto plane. The MeSO-net stations are equipped with a three-component accelerometer at a bottom of a 20-m-deep borehole, signals from which are digitized at a sampling rate of 200 Hz with a dynamic range of 135 dB.The waveforms of 141 earthquakes observed at 226 stations were selected from the Japan Meteorological Agency (JMA) unified earthquake list from January 1st 2010 to August 4th 2010. Only high-quality amplitude spectra of earthquakes with M > 3 were used for the estimation of reliable attenuation parameters. The acceleration waveforms were integrated twice to yield the corresponding displacement vectors, applying a high pass filter to remove the effect of the low-frequency background noise. Taking into account that the majority of the events occurred at depth greater than 30 km a search window of 5 sec starting 1 sec before the P wave arrival was implemented for the creation of the dataset. The t* values were estimated from the amplitude spectra of approximately 33800 P wave waveforms conducting a fast Fourier transform analysis. The Q values for the Tokyo Metropolitan area estimate by this study range from 100 to 500 in the upper 30 km of the crust. A site effect on the attenuation near stations inside a densely populated area is also a possible reason for the large Q variations observed.

  10. Landing together: How flocks arrive at a coherent action in time and space in the presence of perturbations

    NASA Astrophysics Data System (ADS)

    Ferdinandy, B.; Bhattacharya, K.; Ábel, D.; Vicsek, T.

    2012-02-01

    Collective motion is abundant in nature, producing a vast amount of phenomena which have been studied in recent years, including the landing of flocks of birds. We investigate the collective decision making scenario where a flock of birds decides the optimal time of landing in the absence of a global leader. We introduce a simple phenomenological model in the spirit of the statistical mechanics-based self-propelled particles (SPPs) approach to interpret this process. We expect that our model is applicable to a larger class of spatiotemporal decision making situations than just the landing of flocks (which process is used as a paradigmatic case). In the model birds are only influenced by observable variables, like position and velocity. Heterogeneity is introduced in the flock in terms of a depletion time after which a bird feels increasing bias to move towards the ground. Our model demonstrates a possible mechanism by which animals in a large group can arrive at an egalitarian decision about the time of switching from one activity to another in the absence of a leader. In particular, we show the existence of a paradoxical effect where noise enhances the coherence of the landing process.

  11. One dimensional P wave velocity structure of the crust beneath west Java and accurate hypocentre locations from local earthquake inversion

    SciTech Connect

    Supardiyono; Santosa, Bagus Jaya

    2012-06-20

    A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299 Degree-Sign were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquake locations and represents a further step toward more detailed seismotectonic studies in this area of West Java.

  12. Simulation-based validation and arrival-time correction for Patlak analyses of Perfusion-CT scans

    NASA Astrophysics Data System (ADS)

    Bredno, Jörg; Hom, Jason; Schneider, Thomas; Wintermark, Max

    2009-02-01

    Blood-brain-barrier (BBB) breakdown is a hypothesized mechanism for hemorrhagic transformation in acute stroke. The Patlak analysis of a Perfusion Computed Tomography (PCT) scan measures the BBB permeability, but the method yields higher estimates when applied to the first pass of the contrast bolus compared to a delayed phase. We present a numerical phantom that simulates vascular and parenchymal time-attenuation curves to determine the validity of permeability measurements obtained with different acquisition protocols. A network of tubes represents the major cerebral arteries ipsi- and contralateral to an ischemic event. These tubes branch off into smaller segments that represent capillary beds. Blood flow in the phantom is freely defined and simulated as non-Newtonian tubular flow. Diffusion of contrast in the vessels and permeation through vessel walls is part of the simulation. The phantom allows us to compare the results of a permeability measurement to the simulated vessel wall status. A Patlak analysis reliably detects areas with BBB breakdown for acquisitions of 240s duration, whereas results obtained from the first pass are biased in areas of reduced blood flow. Compensating for differences in contrast arrival times reduces this bias and gives good estimates of BBB permeability for PCT acquisitions of 90-150s duration.

  13. Analysis of time-of-arrival observations performed during ELF/VLF wave generation experiments at HAARP

    NASA Astrophysics Data System (ADS)

    Fujimaru, S.; Moore, R. C.

    2011-06-01

    Modulated high frequency (HF) heating of the lower ionosphere in the presence of auroral electrojet currents has become an important method for generating electromagnetic waves in the extremely-low frequency (ELF) and very-low frequency (VLF) bands. Recent research efforts focus on improving the efficiency of ELF/VLF wave generation. One method to do so involves the spatial mapping of modulated currents that result from HF heating for comparison with HF heating models. As a first step toward providing a spatial map of the modulated ionospheric currents, we introduce time-of-arrival (TOA) observations performed during a series of experimental research campaigns conducted at the High-frequency Active Auroral Research Program (HAARP) in Gakona, Alaska. The TOA method provides a measurement of the ELF/VLF amplitude and phase detected at a ground-based receiver as a function of time, and this information may be used to estimate the distribution of ELF/VLF source currents within the HF heated region. In an effort to test and improve the TOA method, the University of Florida conducted ELF/VLF wave generation experiments using the HAARP HF transmitter under varying ionospheric conditions and using various transmission formats. In this paper, we summarize our experimental results and compare observations with the predictions of a theoretical model.

  14. Anomalous delays of teleseismic P waves in Yellowstone National Park

    USGS Publications Warehouse

    Iyer, H.M.

    1975-01-01

    TELESEISMIC P waves recorded by a short-period seismic network, comprising 12 stations, in Yellowstone National Park, show anomalous delays of 1-2 s in their travel times in the central region of the park relative to the surrounding area. To explain this phenomenon, I propose that a substantial body of low velocity material is present beneath the park, with horizontal dimensions of several tens of kilometres; it may be the magma chamber associated with the volcanism of Yellowstone (ref. 1, and G. P. Eaton et al., unpublished). ?? 1975 Nature Publishing Group.

  15. Joint inversion of gravity and arrival time data from Parkfield: New constraints on structure and hypocenter locations near the SAFOD drill site

    USGS Publications Warehouse

    Roecker, S.; Thurber, C.; McPhee, D.

    2004-01-01

    Taking advantage of large datasets of both gravity and elastic wave arrival time observations available for the Parkfield, California region, we generated an image consistent with both types of data. Among a variety of strategies, the best result was obtained from a simultaneous inversion with a stability requirement that encouraged the perturbed model to remain close to a starting model consisting of a best fit to the arrival time data. The preferred model looks essentially the same as the best-fit arrival time model in areas where ray coverage is dense, with differences being greatest at shallow depths and near the edges of the model where ray paths are few. Earthquake locations change by no more than about 100 m, the general effect being migration of the seismic zone to the northeast, closer to the surface trace of the San Andreas Fault. Copyright 2004 by the American Geophysical Union.

  16. Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Pioneer Venus Orbiter, Compton Gamma-Ray Observatory, and ULYSSES

    NASA Astrophysics Data System (ADS)

    Laros, J. G.; Hurley, K. C.; Fenimore, E. E.; Klebesadel, R. W.; Briggs, M. S.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.; Cline, T. L.; Boer, M.; Niel, M.

    1998-10-01

    Between the Compton Gamma Ray Observatory (CGRO) launch in 1991 April and the Pioneer Venus Orbiter (PVO) demise in 1992 October, concurrent coverage by CGRO, PVO, and Ulysses was obtained for several hundred gamma-ray bursts (GRBs). Although most of these were below the PVO and Ulysses thresholds, 37 were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to ~2° accuracy by the CGRO Burst and Transient Source Experiment (BATSE), and three were also localized by COMPTEL. We computed arrival-time error boxes, whose larger dimensions range from about 2' to several degrees and whose smaller dimensions are in the arcminute range. Twelve have areas less than 10 arcmin2, and only four have areas greater than 1 deg2. The area of the smallest box is 0.44 arcmin2. We find that the overall BATSE localization accuracy for these events is consistent with the most recent stated uncertainties. This work indicates that the ROSAT soft X-ray source found within a preliminary IPN error box for GB920501 (Trig 1576) (Hurley et al.) is less likely to be the GRB counterpart than previously reported.

  17. The development of a general associative learning account of skill acquisition in a relative arrival-time judgment task.

    PubMed

    Loft, Shayne; Neal, Andrew; Humphreys, Michael S

    2007-08-01

    Current theory assumes that individuals only use information from the immediate environment to perform relative arrival-time judgment tasks. This article presents a theoretical analysis of the memory requirements of this task. The authors present an analysis of the inputs to the memory system and the processes that map those inputs onto outputs. The analysis generates a set of predictions regarding the specificity of transfer and the role of context during learning. In 3 experiments, participants decided whether pairs of aircraft would violate a minimum separation standard or pass each other safely. Participants were presented with pairs of aircraft in which properties of the pair varied along 3 structural and 3 surface dimensions. Contexts were defined by the co-occurrence of specific values along stimulus dimensions and the use of a neutral label. The results suggest that transfer was limited by the dimensions that were varied in training and the context in which those dimensions were varied. The discussion focuses on the problems that complex tasks like relative judgment pose for associative learning mechanisms and the development of precise models of cognition. PMID:17683239

  18. ARRIVAL TIME CALCULATION FOR INTERPLANETARY CORONAL MASS EJECTIONS WITH CIRCULAR FRONTS AND APPLICATION TO STEREO OBSERVATIONS OF THE 2009 FEBRUARY 13 ERUPTION

    SciTech Connect

    Moestl, C.; Rollett, T.; Temmer, M.; Veronig, A. M.; Biernat, H. K.; Lugaz, N.; Farrugia, C. J.; Galvin, A. B.; Davies, J. A.; Harrison, R. A.; Crothers, S.; Luhmann, J. G.; Zhang, T. L.; Baumjohann, W.

    2011-11-01

    One of the goals of the NASA Solar TErestrial RElations Observatory (STEREO) mission is to study the feasibility of forecasting the direction, arrival time, and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape [fixed-{Phi} (FP): a point and harmonic mean (HM): a circle]. These forecasting techniques use single-spacecraft imaging data and are based on the assumption of constant velocity and direction. We show that for the slow (350 km s{sup -1}) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hr than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 hr for the arrival time at Venus Express (MAG). We propose that the improvement is directly related to the ICME front shape being more accurately described by HM for an ICME with a low inclination of its symmetry axis to the ecliptic. In this case, the ICME has to be tracked to >30{sup 0} elongation to obtain arrival time errors < {+-} 5 hr. A newly derived formula for calculating arrival times with the HM method is also useful for a triangulation technique assuming the same geometry.

  19. Holographic p-wave superconductor with disorder

    NASA Astrophysics Data System (ADS)

    Areán, D.; Farahi, A.; Pando Zayas, L. A.; Salazar Landea, I.; Scardicchio, A.

    2015-07-01

    We implement the effects of disorder on a holographic p-wave superconductor by introducing a random chemical potential which defines the local energy of the charge carriers. Since there are various possibilities for the orientation of the vector order parameter, we explore the behavior of the condensate in the parallel and perpendicular directions to the introduced disorder. We clarify the nature of various branches representing competing solutions and construct the disordered phase diagram. We find that moderate disorder enhances superconductivity as determined by the value of the condensate. Though we mostly focus on uncorrelated noise, we also consider a disorder characterized by its spectral properties and study in detail its influence on the spectral properties of the condensate and charge density. We find fairly universal responses of the resulting power spectra characterized by linear functions of the disorder power spectrum.

  20. High-precision x-ray FEL pulse arrival time measurements at SACLA by a THz streak camera with Xe clusters.

    PubMed

    Jurani?, P N; Stepanov, A; Ischebeck, R; Schlott, V; Pradervand, C; Patthey, L; Radovi?, M; Gorgisyan, I; Rivkin, L; Hauri, C P; Monoszlai, B; Ivanov, R; Peier, P; Liu, J; Togashi, T; Owada, S; Ogawa, K; Katayama, T; Yabashi, M; Abela, R

    2014-12-01

    The accurate measurement of the arrival time of a hard X-ray free electron laser (FEL) pulse with respect to a laser is of utmost importance for pump-probe experiments proposed or carried out at FEL facilities around the world. This manuscript presents the latest device to meet this challenge, a THz streak camera using Xe gas clusters, capable of pulse arrival time measurements with an estimated accuracy of several femtoseconds. An experiment performed at SACLA demonstrates the performance of the device at photon energies between 5 and 10 keV with variable photon beam parameters. PMID:25606930

  1. Crustal structure of Nigeria and Southern Ghana, West Africa from P-wave receiver functions

    NASA Astrophysics Data System (ADS)

    Akpan, Ofonime; Nyblade, Andrew; Okereke, Chiedu; Oden, Michael; Emry, Erica; Julià, Jordi

    2016-04-01

    We report new estimates of crustal thickness (Moho depth), Poisson's ratio and shear-wave velocities for eleven broadband seismological stations in Nigeria and Ghana. Data used for this study came from teleseismic earthquakes recorded at epicentral distances between 30° and 95° and with moment magnitudes greater than or equal to 5.5. P-wave receiver functions were modeled using the Moho Ps arrival times, H-k stacking, and joint inversion of receiver functions and Rayleigh wave group velocities. The average crustal thickness of the stations in the Neoproterozoic basement complex of Nigeria is 36 km, and 23 km for the stations in the Cretaceous Benue Trough. The crustal structure of the Paleoproterozoic Birimian Terrain, and Neoproterozoic Dahomeyan Terrain and Togo Structural Unit in southern Ghana is similar, with an average Moho depth of 44 km. Poisson's ratios for all the stations range from 0.24 to 0.26, indicating a bulk felsic to intermediate crustal composition. The crustal structure of the basement complex in Nigeria is similar to the average crustal structure of Neoproterozoic terrains in other parts of Africa, but the two Neoproterozoic terrains in southern Ghana have a thicker crust with a thick mafic lower crust, ranging in thickness from 12 to 17 km. Both the thicker crust and thick mafic lower crustal section are consistent with many Precambrian suture zones, and thus we suggest that both features are relict from the collisional event during the formation of Gondwana.

  2. Reactivation and mantle dynamics of North China Craton: insight from P-wave anisotropy tomography

    NASA Astrophysics Data System (ADS)

    Tian, You; Zhao, Dapeng

    2013-12-01

    We determined the first 3-D P-wave anisotropic tomography beneath the North China Craton (NCC) using a large number of high-quality arrival-time data from local earthquakes and teleseismic events, which reveals depth-dependent azimuthal anisotropy in the crust and upper mantle down to 600 km depth. In the NCC western block, the fast velocity direction (FVD) varies from east-west in the southern part to northeast-southwest in the northern part, which may reflect either the interaction between the Yangtze block and NCC or fossil lithospheric fabrics in the craton. Under the NCC eastern block, a uniform northwest-southeast FVD is revealed in the lower part of the upper mantle (300-410 km depths) and the mantle transition zone (410-660 km depths), which may reflect horizontal and upwelling flows in the big mantle wedge (BMW) above the stagnant Pacific slab in the mantle transition zone. The NCC central block exhibits a northeast-southwest FVD, consistent with the surface tectonic orientation there, suggesting that the cold and thick (>300 km) cratonic root of the NCC western block may obstruct the northwest-southeast trending mantle flow induced by the Pacific Plate subduction, resulting in a northeast-southwest trending mantle flow under the central block. Our present results indicate that the corner flow in the BMW associated with the deep subduction of the Pacific Plate is the main cause of NCC reactivation and mantle dynamics under East China.

  3. Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences

    NASA Astrophysics Data System (ADS)

    Dahm, Torsten; Fischer, Tomas

    2014-02-01

    Crustal earthquake swarms are an expression of intensive cracking and rock damaging over periods of days, weeks or month in a small source region in the crust. They are caused by longer lasting stress changes in the source region. Often, the localized stressing of the crust is associated with fluid or gas migration, possibly in combination with pre-existing zones of weaknesses. However, verifying and quantifying localized fluid movement at depth remains difficult since the area affected is small and geophysical prospecting methods often cannot reach the required resolution. We apply a simple and robust method to estimate the velocity ratio between compressional (P) and shear (S) waves (vP/vS-ratio) in the source region of an earthquake swarm. The vP/vS-ratio may be unusual small if the swarm is related to gas in a porous or fractured rock. The method uses arrival time difference between P and S waves observed at surface seismic stations, and the associated double differences between pairs of earthquakes. An advantage is that earthquake locations are not required and the method seems lesser dependent on unknown velocity variations in the crust outside the source region. It is, thus, suited for monitoring purposes. Applications comprise three natural, mid-crustal (8-10 km) earthquake swarms between 1997 and 2008 from the NW-Bohemia swarm region. We resolve a strong temporal decrease of vP/vS before and during the main activity of the swarm, and a recovery of vP/vS to background levels at the end of the swarms. The anomalies are interpreted in terms of the Biot-Gassman equations, assuming the presence of oversaturated fluids degassing during the beginning phase of the swarm activity.

  4. Estimates of velocity structure and source depth using multiple P waves from aftershocks of the 1987 Elmore Ranch and Superstition Hills, California, earthquakes

    USGS Publications Warehouse

    Mori, J.

    1991-01-01

    Event record sections, which are constructed by plotting seismograms from many closely spaced earthquakes recorded on a few stations, show multiple free-surface reflections (PP, PPP, PPPP) of the P wave in the Imperial Valley. The relative timing of these arrivals is used to estimate the strength of the P-wave velocity gradient within the upper 5 km of the sediment layer. Consistent with previous studies, a velocity model with a value of 1.8 km/sec at the surface increasing linearly to 5.8 km/sec at a depth of 5.5 km fits the data well. The relative amplitudes of the P and PP arrivals are used to estimate the source depth for the aftershock distributions of the Elmore Ranch and Superstition Hills main shocks. Although the depth determination has large uncertainties, both the Elmore Ranch and Superstition Hills aftershock sequencs appear to have similar depth distribution in the range of 4 to 10 km. -Author

  5. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules § 301-11.10 Am I required to record...

  6. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules § 301-11.10 Am I required to record...

  7. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules § 301-11.10 Am I required to record...

  8. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules § 301-11.10 Am I required to record...

  9. 41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... departure/arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules § 301-11.10 Am I required to record...

  10. Comparison of P-Wave and S-Wave Reflection Surveying Effectiveness for Detection of Mine-Related Subsidence Activity Beneath a Heavily Traveled Roadway

    NASA Astrophysics Data System (ADS)

    Guy, E. D.; Daniels, J. J.

    2002-12-01

    We acquired high-resolution multicomponent seismic reflection data along an undermined 2200 ft (671 m) section of Interstate highway 70 (I-70) in eastern Ohio, in order to identify areas of active subsidence or soil piping into subsurface collapse features. This paper presents results from research conducted: 1) to investigate potential advantages and disadvantages associated with near-surface P- and S-wave reflection surveys, and 2) to determine the subsidence detection potential of common-mode P- and S-wave data components acquired in the study area. P-wave data have traditionally been acquired during shallow reflection surveys, however, the number of reports concerning shallow S-wave surveys is relatively small, and very few reports concerning the concurrent acquisition and analysis of P- and S-wave reflection data exist. Although S-wave reflections from the top-of-bedrock (located above the coal mine and targeted for subsidence detection purposes) were consistently observed in both XX component (inline-inline, SV-SV) and YY component (crossline-crossline, SH-SH) data, surface wave noise resulted in the optimum reflection window of XX data being relatively narrow. Stacks produced using YY data had a higher signal-to-noise ratio and better imaged the target horizon than those produced using XX data. Whereas S-waves were relatively insensitive to changes in overburden moisture content, P-wave reflections from the top-of-saturated-overburden (located above bedrock) were recorded in ZZ component (vertical-vertical, P-P) data. The arrival times of P-wave reflections and the characteristics of the recorded noise modes made it difficult to process and use P-wave reflections from this interface. P-wave events from deeper impedance contrasts were not observed in field data due to several factors: surface wave and air wave noise, a high P-wave reflection coefficient at the top-of-saturated-overburden, low P-wave reflection coefficients at deeper interfaces, and interference effects/resolution issues. Calculations suggest that the resolution of S-waves in the study area dry overburden is more than 1.7 times that of P-waves, and that the resolution of S-waves in the study area saturated overburden is more than 4.5 times that of P-waves. Given the study area subsurface conditions and acquired data characteristics, areas of the subsurface where subsidence processes have been active could be most accurately delineated through the processing and interpretation of YY (relative to XX and ZZ) data. Processed YY data indicate that the bedrock horizon is significantly disrupted due to mine-related subsidence processes at numerous locations along the roadway in the study area. Hence, these locations are regarded as having a relatively high risk for future mine-related surface failure.

  11. Eastern Edge of the Laurentian Cratonic Lithosphere Beneath Southern Quebec from Teleseismic P Waves

    NASA Astrophysics Data System (ADS)

    Menke, W. H.; Neitz, T.; Levin, V. L.; Darbyshire, F. A.; Bastow, I. D.

    2014-12-01

    The eastern margin of Laurentia was deformed by the late-Proterozoic Grenville orogeny, which metamorphosed the original Archean-age cratonic crust and added extensive intrusive rocks. The Laurentian crust clearly extends as far east as the Laurentian Highlands, just north of the St. Laurence River, where Grenville-deformed rocks outcrop. Small outliers of Grenville-deformed rocks amongst west-thrust Paleozoic sediments, 20-50 km east of the Appalachian Front in southern Quebec, suggest that the Laurentian crust extends beneath the shallow thrust sheets of this region, too. On the other hand, Laurentia does not extend east of the Norumbega fault in coastal Maine, for the crust there is derived from the Avalon micro-continent. We search for the eastern edge of Laurentia within this ~250 km wide interval using relative arrival times of teleseismic P waves which ascend sub-vertically through the lithosphere beneath the region. These times are expected to be most sensitive to upper mantle compressional velocity and so to be able to discriminate the cratonic lithosphere on the basis of its faster than average speed. We use signal-correlation techniques to measured delay times for all broadband seismic stations in the region, including the QMIII array, which is especially designed to have high station density near the Appalachian Front. As expected, we observe central Quebec to have anomalously early times and coastal Maine to have anomalously late times, by as much as ±1s, when compared to the predictions of the global AK135 traveltime model. The boundary between the two arrival time regimes is sharp and is collinear with the Appalachian Front, to within the ± 25 km spatial resolution of our study. We hypothesize that it represents the eastern edge of the Laurentian cratonic lithosphere. Tomographic inversion of the data indicates a 0.2 km/s (2.4%) drop in compressional velocity of the shallow (90 km deep) mantle from west to east across the boundary. This is a strong jump in mantle properties, as either a 400 deg C increase in temperature or a 11 decrease in Mg# (or some other as yet unidentified source of heterogeneity) is needed to explain it. Future work will use teleseismic shear waves to further characterize the lithosphere across this boundary.

  12. Chiral p-wave order in Sr2RuO4.

    PubMed

    Kallin, Catherine

    2012-04-01

    Shortly after the discovery in 1994 of superconductivity in Sr(2)RuO(4), it was proposed on theoretical grounds that the superconducting state may have chiral p-wave symmetry analogous to the A phase of superfluid (3)He. Substantial experimental evidence has since accumulated in favor of this pairing symmetry, including several interesting recent results related to broken time-reversal symmetry (BTRS) and vortices with half of the usual superconducting flux quantum. Great interest surrounds the possibility of chiral p-wave order in Sr(2)RuO(4), since this state may exhibit topological order analogous to that of a quantum Hall state, and can support such exotic physics as Majorana fermions and non-Abelian winding statistics, which have been proposed as one route to a quantum computer. However, serious discrepancies remain in trying to connect the experimental results to theoretical predictions for chiral p-wave order. In this paper, I review a broad range of experiments on Sr(2)RuO(4) that are sensitive to p-wave pairing, triplet superconductivity and time-reversal symmetry breaking and compare these experiments to each other and to theoretical predictions. In this context, the evidence for triplet pairing is strong, although some puzzles remain. The 'smoking gun' experimental results for chiral p-wave order, those which directly look for evidence of BTRS in the superconducting state of Sr(2)RuO(4), are most perplexing when the results are compared with each other and to theoretical predictions. Consequently, the case for chiral p-wave superconductivity in Sr(2)RuO(4) remains unresolved, suggesting the need to consider either significant modifications to the standard chiral p-wave models or possible alternative pairing symmetries. Recent ideas along these lines are discussed. PMID:22790504

  13. Finite Frequency P-Wave Tomography for French Polynesian Region

    NASA Astrophysics Data System (ADS)

    Obayashi, M.; Yoshimitsu, J.; Sugioka, H.; Ito, A.; Isse, T.; Shiobara, H.; Suetsugu, D.

    2014-12-01

    The French Polynesian region is characterized by positive topographic anomalies of 700 m, a concentration of hotspot chains. Many seismic tomography results show a broad low-velocity anomaly in the lower mantle continued from the base of the mantle. These observations suggest that a large-scale mantle flow rises from the bottom of the mantle beneath the region. Joint Japanese-French broadband seismological observations were performed from 2001 to 2005 with 10 island stations from the Polynesian PLUME project and 10 broadband ocean bottom seismometers (BBOBSs) from the Polynesian BBOBS project. A P-wave tomography using the data from these projects revealed that large-scale low-velocity anomalies (on the order of 1000 km in diameter) from the bottom of the mantle become smaller-scale low-velocity anomalies (on the order of 100 km in diameter) at the depth of about 1000 km. However the connection of the small-scale low-velocity anomalies to the surface hotspots was not unrevealed because of the poor resolution in the upper mantle. A new P-wave tomography with better resolution in the upper mantle was obtained by adding data from BBOSBSs around Society Islands deployed along the TIARES project during 2009 - 2010 and by taking the finite frequency effect into account for the frequency-depended differential travel times. The frequency-depended differential travel times were measured by multi-band cross correlating P waveforms. The new P-wave tomography shows strong low-velocity anomalies beneath the Society Islands and Pitcairn in the upper mantle although they do not extend to the 660-km discontinuity. This model also shows that small-scale low-velocity anomalies in the uppermost lower mantle. The low-velocity anomalies in the depth range about 550 - 900 km are smaller both in lateral area and amplitude than those in most of the upper mantle and the lower mantle. There is no correlation between velocity patterns in that depth range and those in the upper mantle or in the lower mantle, suggesting that the broad slow anomalies in the lower mantle do not connect to the surface directly.

  14. 3D P-wave velocity structure of the deep Galicia rifted margin: A first analysis of the Galicia 3D wide-angle seismic dataset

    NASA Astrophysics Data System (ADS)

    Bayrakci, Gaye; Minshull, Timothy A.; Davy, Richard G.; Karplus, Marianne S.; Kaeschen, Dirk; Papenberg, Cord; Krabbenhoeft, Anne; Sawyer, Dale; Reston, Timothy J.; Shillington, Donna J.; Ranero, César R.

    2014-05-01

    Galicia 3D, a reflection-refraction and long offset seismic experiment was carried out from May through September 2013, at the Galicia rifted margin (in the northeast Atlantic Ocean, west of Spain) as a collaboration between US, UK, German and Spanish groups. The 3D multichannel seismic acquisition conducted by R/V Marcus Langseth covered a 64 km by 20 km (1280 km2) zone where the main geological features are the Peridotite Ridge (PR), composed of serpentinized peridotite and thought be upper mantle exhumed to the seafloor during rifting, and the S reflector which has been interpreted to be a low angle detachment fault overlain by fault bounded, rotated, continental crustal blocks. In the 3D box, two airgun arrays of 3300 cu.in. were fired alternately (in flip-flop configuration) every 37.5 m. All shots are recorded by 44 short period four component ocean bottom seismometers (OBS) and 26 ocean bottom hydrophones (OBH) deployed and recovered by R/V Poseidon, as well as four 6 km hydrophone streamers with 12.5 m channel spacing towed by R/V Marcus Langseth. We present the preliminary results of the first arrival time tomography study which is carried out with a subset of the wide-angle dataset, in order to generate a 3D P-wave velocity volume for the entire depth sampled by the reflection data. After the relocation of OBSs and OBHs, an automatic first-arrival time picking approach is applied to a subset of the dataset, which comprises more than 5.5 million source-receiver pairs. Then, the first-arrival times are checked visually, in 3-dimensions. The a priori model used for the first-arrival time tomography is built up using information from previous seismic surveys carried out at the Galicia margin (e.g. ISE, 1997). The FAST algorithm of Zelt and Barton (1998) is used for the first-arrival time inversion. The 3D P-wave velocity volume can be used in interpreting the reflection dataset, as a starting point for migration, to quantify the thinning of the crustal layers, and to determine the degree of the serpentinization of the uppermost mantle.

  15. Real-time forecasting of ICME shock arrivals at L1 during the "April Fool’s Day" epoch: 28 March  21 April 2001

    NASA Astrophysics Data System (ADS)

    Sun, W.; Dryer, M.; Fry, C. D.; Deehr, C. S.; Smith, Z.; Akasofu, S.-I.; Kartalev, M. D.; Grigorov, K. G.

    2002-07-01

    The Sun was extremely active during the "April Fool’s Day" epoch of 2001. We chose this period between a solar flare on 28 March 2001 to a final shock arrival at Earth on 21 April 2001. The activity consisted of two presumed helmet-streamer blowouts, seven M-class flares, and nine X-class flares, the last of which was behind the west limb. We have been experimenting since February 1997 with real-time, end-to-end forecasting of interplanetary coronal mass ejection (ICME) shock arrival times. Since August 1998, these forecasts have been distributed in real-time by e-mail to a list of interested scientists and operational USAF and NOAA forecasters. They are made using three different solar wind models. We describe here the solar events observed during the April Fool’s 2001 epoch, along with the predicted and actual shock arrival times, and the ex post facto correction to the real-time coronal shock speed observations. It appears that the initial estimates of coronal shock speeds from Type II radio burst observations and coronal mass ejections were too high by as much as 30%. We conclude that a 3-dimensional coronal density model should be developed for application to observations of solar flares and their Type II radio burst observations.

  16. Typical CME-IP shock events during the ascending phase of Solar Cycle 24 and their arrival time predictions at Earth

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Feng, X.

    2013-12-01

    Predicting arrival times of interplanetary (IP) shocks at the near Earth space is an important ingredient of space weather forecasting because the passage of an IP shock at Earth will compress the magnetosphere and produce corresponding space weather effects. We have developed a new shock arrival time prediction model, called SPM2, based on 551 solar disturbance events during Solar Cycle 23. Here new shock events in Solar Cycle 24 will be used to check the predicting performance of SPM2. 35 typical CME-IP shock events during the ascending phase of Solar Cycle 24 (2009-2013) with near-simultaneous coronagraph observations of CMEs and metric type II radio bursts are adopted as the sample events. Comparisons between the initial shock speed calculated from the type II burst drifting rate and the CME speed derived from coronagraph observations are investigated. It is found that the multi-spacecraft coronagraph observations combined with appropriate CME leading edge fitting model can give a more reliable CME radial speed than the type II burst shock speed. Then, SPM2 and an empirical model, which input the type II shock speed and CME speed respectively, are used to give the arrival time prediction of the associated IP shocks at the Earth orbit. The predicting precision of the empirical model would become better if the CME is tracked to a larger helio-distance. The prediction of SPM2 gives a similar predicting accuracy even its input parameters contain larger uncertainties. On this sense, the potential capability of the SPM2 model is also discussed in terms of real-time shock arrival time forecasts.

  17. Arrival time distributions of electrons in air showers with primary energies above 10 (18)eV observed at 900m above sea level

    NASA Technical Reports Server (NTRS)

    Kakimoto, F.; Tsuchimoto, I.; Enoki, T.; Suga, K.; Nishi, K.

    1985-01-01

    Detection of air showers with primary energies above 10 to the 19th power eV with sufficient statistics is extremely important in an astrophysical aspect related to the Greisen cut off and the origin of such high energy cosmic rays. Recently, a method is proposed to observe such giant air showers by measuring the arrival time distributions of air-shower particles at large core distances with a mini array. Experiments to measure the arrival time distributions of muons were started in 1981 and those of electrons in early 1983 in the Akeno air-shower array (930 gcm cm squared atmospheric depth, 900m above sea level). During the time of observation, the detection area of the Akeno array was expanded from 1 sq km to sq km in 1982 and to 20 sq km in 1984. Now the arrival time distribution of electrons and muons can be measured for showers with primary energies above 1019eV at large core distances.

  18. Evaluation of the cone-shaped pickup performance for low charge sub-10 fs arrival-time measurements at free electron laser facilities

    NASA Astrophysics Data System (ADS)

    Angelovski, Aleksandar; Kuntzsch, Michael; Czwalinna, Marie Kristin; Penirschke, Andreas; Hansli, Matthias; Sydlo, Cezary; Arsov, Vladimir; Hunziker, Stephan; Schlarb, Holger; Gensch, Michael; Schlott, Volker; Weiland, Thomas; Jakoby, Rolf

    2015-01-01

    An evaluation of the cone-shaped pickup performance as a part of the high bandwidth bunch arrival-time monitors (BAMs) for a low charge sub-10 fs arrival-time measurements is presented. Three sets of pickups are installed at the free electron laser FLASH at Deutsches Elektronen-Synchrotron, the quasi-cw SRF accelerator ELBE at the Helmholtz-Zentrum Dresden-Rossendorf and the SwissFEL injector test facility at Paul Scherrer Institute. Measurements and simulations are in good agreement and the pickups fulfill the design specifications. Utilizing the high bandwidth BAM with the cone-shaped pickups, an improvement of the signal slope by a factor of 10 is demonstrated at ELBE compared to the BAM with a low bandwidth.

  19. Computer program modifications of Open-file report 82-1065; a comprehensive system for interpreting seismic-refraction and arrival-time data using interactive computer methods

    USGS Publications Warehouse

    Ackermann, Hans D.; Pankratz, Leroy W.; Dansereau, Danny A.

    1983-01-01

    The computer programs published in Open-File Report 82-1065, A comprehensive system for interpreting seismic-refraction arrival-time data using interactive computer methods (Ackermann, Pankratz, and Dansereau, 1982), have been modified to run on a mini-computer. The new version uses approximately 1/10 of the memory of the initial version, is more efficient and gives the same results.

  20. P-wave tomography of the western United States: Insight into the Yellowstone hotspot and the Juan de Fuca slab

    NASA Astrophysics Data System (ADS)

    Tian, You; Zhao, Dapeng

    2012-06-01

    We used 190,947 high-quality P-wave arrival times from 8421 local earthquakes and 1,098,022 precise travel-time residuals from 6470 teleseismic events recorded by the EarthScope/USArray transportable array to determine a detailed three-dimensional P-wave velocity model of the crust and mantle down to 1000 km depth under the western United States (US). Our tomography revealed strong heterogeneities in the crust and upper mantle under the western US. Prominent high-velocity anomalies are imaged beneath Idaho Batholith, central Colorado Plateau, Cascadian subduction zone, stable North American Craton, Transverse Ranges, and Southern Sierra Nevada. Prominent low-velocity anomalies are imaged at depths of 0-200 km beneath Snake River Plain, which may represent a small-scale convection beneath the western US. The low-velocity structure deviates variably from a narrow vertical plume conduit extending down to ˜1000 km depth, suggesting that the Yellowstone hotspot may have a lower-mantle origin. The Juan de Fuca slab is imaged as a dipping high-velocity anomaly under the western US. The slab geometry and its subducted depth vary in the north-south direction. In the southern parts the slab may have subducted down to >600 km depth. A "slab hole" is revealed beneath Oregon, which shows up as a low-velocity anomaly at depths of ˜100 to 300 km. The formation of the slab hole may be related to the Newberry magmatism. The removal of flat subducted Farallon slab may have triggered the vigorous magmatism in the Basin and Range and southern part of Rocky Mountains and also resulted in the uplift of the Colorado Plateau and Rocky Mountains.

  1. Investigation of inhomogeneities and anisotropy in the crust and upper mantle of central Europe by means of teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Wylegalla, K.; Bormann, P.; Baumbach, M.

    1988-06-01

    Travel-time residuals from global samples as well as azimuth and slowness deviations of teleseismic P-wave arrivals have been analysed both at the individual seismic stations BRG, CLL, MOX, and PRU, and using the G.D.R. station network. The main results of the analysis are as follows. (1) Azimuth and incidence-angle deviations of short-period P waves have been observed at individual stations by means of three-component measurements. Their transformations into the slowness space reveal a mislocation pattern at all stations, which suggests the superimposition of regional and strong local effects on wave propagation. (2) The mean station residuals, as well as the azimuth dependence of the residuals with a period of 2π, indicate a rising of the upper mantle discontinuities to the north of central Europe to the east European platform. (3) This general trend is confirmed by the mislocation patterns observed at various subnetworks of the telemetric system of seismic stations of the G.D.R. The refined model assumes a dipping of flat discontinuities or isotachs in the upper mantle down to the 20° discontinuity, with a dip angle of about 11° ± 2° north of the network centre and a zero dip south of it. The dip direction is 192° ± 5°. (4) Fourier analysis of the azimuth dependence of travel-time residuals revealed almost the same phase of the second azimuthal term at all individual stations. This fact could be interpreted in terms of an anisotropic layer of some 200 km thickness in the upper mantle assuming a coefficient of anisotropy of 6%. The azimuth of maximum velocity is 10° (+180°) and agrees well with the results derived by Bamford (1977) from Pn-wave measurements.

  2. Fast P-wave precursors in New Zealand: high velocity material associated with the subducted Hikurangi Plateau

    NASA Astrophysics Data System (ADS)

    Love, H.; LeGood, M.; Stuart, G.; Reyners, M.; Eberhart-Phillips, D. E.; Gubbins, D.

    2015-08-01

    Seismic tomography has revealed very high P-wave velocities, over 8.5 km s-1, at shallow depths, 30-100 km, beneath New Zealand. Here we study fast, high-frequency arrivals at North and South Island stations that contain additional information about the crust and mantle structure. These arrivals, which are from earthquakes within or close to the land mass, have a characteristic high-frequency precursor followed by a lower frequency, larger amplitude, main phase. Precursors were seen on at least one station from 262 of 306 candidate events; the best-recorded 76 events were analysed for wave speed, frequency content and polarization. Time-distance plots are consistent with two phases travelling at 8.38 ± 0.03 and 6.93 ± 0.05 km s-1. The precursor has typical frequencies 4-9 Hz, the second arrival 2-4 Hz. Polarizations are off-azimuth by 30° and steeper than predicted by ray tracing through a smooth 3-D tomographic model. These results are explained by propagation through a dipping layer of order 10 km thick with seismic velocity around 8.5 km s-1; it is too thin to propagate frequencies below 4 Hz and waves refract from it at a steep, out-of-plane angle, explaining the anomalous polarization. Ray paths cover a region coinciding with the subducted Hikurangi Plateau; the fast layer is interpreted as the lowest section of the plateau that has transformed to eclogite, which has the same fast seismic velocity that we observe. Unlike the fast, eclogitic layers identified in subduction zones such as the Kermadecs, this layer is shallower, at 30 km, than the eclogite transformation; we therefore propose that it formed at the base of the thick plateau prior to subduction.

  3. Robust Bayesian hypocentre and uncertainty region estimation: the effect of heavy-tailed distributions and prior information in cases with poor, inconsistent and insufficient arrival times

    NASA Astrophysics Data System (ADS)

    Martinsson, J.

    2013-03-01

    We propose methods for robust Bayesian inference of the hypocentre in presence of poor, inconsistent and insufficient phase arrival times. The objectives are to increase the robustness, the accuracy and the precision by introducing heavy-tailed distributions and an informative prior distribution of the seismicity. The effects of the proposed distributions are studied under real measurement conditions in two underground mine networks and validated using 53 blasts with known hypocentres. To increase the robustness against poor, inconsistent or insufficient arrivals, a Gaussian Mixture Model is used as a hypocentre prior distribution to describe the seismically active areas, where the parameters are estimated based on previously located events in the region. The prior is truncated to constrain the solution to valid geometries, for example below the ground surface, excluding known cavities, voids and fractured zones. To reduce the sensitivity to outliers, different heavy-tailed distributions are evaluated to model the likelihood distribution of the arrivals given the hypocentre and the origin time. Among these distributions, the multivariate t-distribution is shown to produce the overall best performance, where the tail-mass adapts to the observed data. Hypocentre and uncertainty region estimates are based on simulations from the posterior distribution using Markov Chain Monte Carlo techniques. Velocity graphs (equivalent to traveltime graphs) are estimated using blasts from known locations, and applied to reduce the main uncertainties and thereby the final estimation error. To focus on the behaviour and the performance of the proposed distributions, a basic single-event Bayesian procedure is considered in this study for clarity. Estimation results are shown with different distributions, with and without prior distribution of seismicity, with wrong prior distribution, with and without error compensation, with and without error description, with insufficient arrival times and in presence of significant outliers. A particular focus is on visual results and comparisons to give a better understanding of the Bayesian advantage and to show the effects of heavy-tailed distributions and informative prior information on real data.

  4. Analysis of the source scanning algorithm with a new P-wave picker

    NASA Astrophysics Data System (ADS)

    Zahradník, J.; Janský, J.; Plicka, V.

    2015-04-01

    We analyze the location of earthquakes in near regional networks using complete seismic records. The method is based on the source scanning algorithm (SSA) of Kao and Shan (2004), but similarly to Grigoli et al. (2013), seismograms are substituted by a P-wave picker trace. The picker traces in a network are repeatedly stacked using grid of trial source positions, and hypocenter is identified with the point providing the best stack (the largest brightness). The first innovation of this paper is a new picker, measuring the ratio of the summed absolute values of seismogram in the right and left part of a moving time window, the RPA/LPA picker. The brightness maps based on this picker are clearer than those based on the STA/LTA picker. The second innovation is a simple theoretical model of the brightness maps. It makes it easy to identify how individual stations contribute to form the brightness spot. It is shown on synthetic tests that the performance of the method depends on focal mechanism, progressively improving from normal to reverse and strike-slip events. The method is successfully applied to four events of different mechanisms and depths, recorded at different ranges of epicentral distance by either broad-band sensors or accelerographs. The events have been located close to previously published epicenters. The brightness maps provide an estimate of the relative uncertainty of the (non-linear) location problem. The uncertainty estimate is also applicable without measured arrival times, "without earthquakes", thus useful when designing or upgrading seismic networks for better location performance.

  5. Absolute timing with IBIS, SPI and JEM-X aboard INTEGRAL. Crab main-pulse arrival times in radio, X-rays and high-energy gamma -rays

    NASA Astrophysics Data System (ADS)

    Kuiper, L.; Hermsen, W.; Walter, R.; Foschini, L.

    2003-11-01

    We have verified the absolute timing capabilities of the high-energy instruments aboard INTEGRAL, i.e. the imager IBIS, the spectrometer SPI and the X-ray monitor JEM-X. Calibration observations of the Crab, contemporaneous with the Rossi X-ray Timing Explorer (RXTE), have been used to measure the absolute phase of the main pulse of the Crab pulse profile using the same Jodrell Bank radio ephemeris. The three INTEGRAL instruments and RXTE give within the statistical and systematic uncertainties consistent results: The X-ray main pulse is leading the radio pulse by 280+/-40 mus . Also the shapes of the X-ray pulse profiles as measured by the different instruments are fully consistent with each other. In addition, we present the first measurement of the absolute phase of the main pulse at gamma -ray energies above 30 MeV using data from the EGRET instrument aboard the Compton Gamma-Ray Observatory: The gamma -ray main pulse is leading the radio one by 241+/-29 mus , consistent with the value for the X-ray main pulse. Comparing absolute arrival times at multiple frequencies gives important constraints to models explaining the production of non-thermal emission in magnetospheres of rotation powered neutron stars. Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), Czech Republic and Poland, and with the participation of Russia and the USA.}

  6. P-wave tomography for 3-D radial and azimuthal anisotropy of Tohoku and Kyushu subduction zones

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Zhao, Dapeng

    2013-06-01

    We determined high-resolution P-wave tomography for 3-D radial and azimuthal anisotropy of the Tohoku and Kyushu subduction zones using a large number of high-quality arrival-time data of local earthquakes recorded by the dense seismic network on the Japan Islands. Trench-normal P-wave fast-velocity directions (FVDs) are revealed in the backarc mantle wedge in both Tohoku and Kyushu, which are consistent with the model of slab-driven corner flow. Trench-parallel FVDs with amplitude <4 per cent appear in the forearc mantle wedge under Tohoku and Kyushu, suggesting the existence of B-type olivine fabric there. Trench-parallel FVDs are also visible in the mantle wedge under the volcanic front in Tohoku but not in Kyushu, suggesting that 3-D flow may exist in the mantle wedge under Tohoku and the 3-D flow is affected by the subduction rate of the oceanic plate. Negative radial anisotropy (i.e. vertical velocity being faster than horizontal velocity) is revealed in the low-velocity zones in the mantle wedge under the arc volcanoes in Tohoku and Kyushu as well as in the low-velocity zones below the Philippine Sea slab under Kyushu, which may reflect hot upwelling flows and transitions of olivine fabrics with the presence of water in the upper mantle. Trench-parallel FVDs and positive radial anisotropy (i.e. horizontal velocity being faster than vertical velocity) are revealed in the subducting Pacific slab under Tohoku and the Philippine Sea slab under Kyushu, suggesting that the slabs keep their frozen-in anisotropy formed at the mid-ocean ridge or that the slab anisotropy is induced by the lattice-preferred orientation of the B-type olivine.

  7. P-wave tomography of the Calabrian Arc region (South Italy) using a new 'a priori

    NASA Astrophysics Data System (ADS)

    Orecchio, Barbara; Presti, Debora; Totaro, Cristina; Guerra, Ignazio; Neri, Giancarlo

    2010-05-01

    A recently published tomographic investigation of the Calabrian Arc, South Italy (Neri et al., SRL, 2009) has shown that the Ionian subducting slab appears in-depth continuous only beneath the central part of the Arc (southern Calabria), while it has already undergone detachment at the edges of the arcuate structure (northern Calabria and northeastern Sicily). Starting from this result we tried to better define the features of the slab by performing a new tomographic inversion of crust and upper lithosphere in the Calabrian Arc region. The starting velocity model was derived from the integration of a new crustal velocity model obtained applying the method proposed by Waldhauser et al. (GJI, 1998 and 2002) and a deep model used by Neri et al. (SRL, 2009). We merged these two models into an averaged regional one, ranging between the surface and 300km depth. Then we used it to perform a new P-wave tomographic inversion of shallow and deep earthquakes occurred between 1981 and 2008 in Southern Italy. We selected all the events with a minimum of 12P+S and 8 P+S readings for shallow and deep earthquakes respectively. The quality of the readings was, in the majority of cases, checked directly on the recordings. The final inversion dataset consists of 75141 P and 40118 S arrival times relative to 7050 earthquakes recorded at a total of 591 stations. All the data available from the national and local networks, including the CAT-SCAN and UniCal network, have been used for inversion. This new model reduced significantly the RMS parameter and allowed us to enlarge the inversion zone. The investigation, together with a detailed analysis of seismicity, allows us to propose an improved and more complete view of the subduction system with respect to the previous works, including Neri et al. (SRL, 2009).

  8. P wave crustal velocity structure in the greater Mount Rainier area from local earthquake tomography

    USGS Publications Warehouse

    Moran, S.C.; Lees, J.M.; Malone, S.D.

    1999-01-01

    We present results from a local earthquake tomographic imaging experiment in the greater Mount Rainier area. We inverted P wave arrival times from local earthquakes recorded at permanent and temporary Pacific Northwest Seismograph Network seismographs between 1980 and 1996. We used a method similar to that described by Lees and Crosson [1989], modified to incorporate the parameter separation method for decoupling the hypocenter and velocity problems. In the upper 7 km of the resulting model there is good correlation between velocity anomalies and surface geology. Many focal mechanisms within the St. Helens seismic zone have nodal planes parallel to the epicentral trend as well as to a north-south trending low-velocity trough, leading us to speculate that the trough represents a zone of structural weakness in which a moderate (M 6.5-7.0) earthquake could occur. In contrast, the western Rainier seismic zone does not correlate in any simple way with anomaly patterns or focal mechanism fault planes, leading us to infer that it is less likely to experience a moderate earthquake. A ???10 km-wide low-velocity anomaly occurs 5 to 18 km beneath the summit of Mount Rainier, which we interpret to be a signal of a region composed of hot, fractured rock with possible small amounts of melt or fluid. No systematic velocity pattern is observed in association with the southern Washington Cascades conductor. A midcrustal anomaly parallels the Olympic-Wallowa lineament as well as several other geophysical trends, indicating that it may play an important role in regional tectonics. Copyright 1999 by the American Geophysical Union.

  9. P wave crustal velocity structure in the greater Mount Rainier area from local earthquake tomography

    NASA Astrophysics Data System (ADS)

    Moran, Seth C.; Lees, Jonathan M.; Malone, Stephen D.

    1999-05-01

    We present results from a local earthquake tomographic imaging experiment in the greater Mount Rainier area. We inverted P wave arrival times from local earthquakes recorded at permanent and temporary Pacific Northwest Seismograph Network seismographs between 1980 and 1996. We used a method similar to that described by Lees and Crosson [1989], modified to incorporate the parameter separation method for decoupling the hypocenter and velocity problems. In the upper 7 km of the resulting model there is good correlation between velocity anomalies and surface geology. Many focal mechanisms within the St. Helens seismic zone have nodal planes parallel to the epicentral trend as well as to a north-south trending low-velocity trough, leading us to speculate that the trough represents a zone of structural weakness in which a moderate (M 6.5-7.0) earthquake could occur. In contrast, the western Rainier seismic zone does not correlate in any simple way with anomaly patterns or focal mechanism fault planes, leading us to infer that it is less likely to experience a moderate earthquake. A ˜10 km-wide low-velocity anomaly occurs 5 to 18 km beneath the summit of Mount Rainier, which we interpret to be a signal of a region composed of hot, fractured rock with possible small amounts of melt or fluid. No systematic velocity pattern is observed in association with the southern Washington Cascades conductor. A midcrustal anomaly parallels the Olympic-Wallowa lineament as well as several other geophysical trends, indicating that it may play an important role in regional tectonics.

  10. Stereoscopic study of the kinematic evolution of a coronal mass ejection and its driven shock from the sun to the earth and the prediction of their arrival times

    SciTech Connect

    Hess, Phillip; Zhang, Jie

    2014-09-01

    We present a detailed study of the complete evolution of a coronal mass ejection (CME). We have tracked the evolution of both the ejecta and its shock, and further fit the evolution of the fronts to a simple but physics-based analytical model. This study focuses on the CME initiated on the Sun on 2012 July 12 and arriving at the Earth on 2012 July 14. Shock and ejecta fronts were observed by white light images, as well as in situ by the Advanced Composition Explorer satellite. We find that the propagation of the two fronts is not completely dependent upon one another, but can each be modeled in the heliosphere with a drag model that assumes the dominant force of affecting CME evolution to be the aerodynamic drag force of the ambient solar wind. Results indicate that the CME ejecta front undergoes a more rapid deceleration than the shock front within 50 R {sub ☉} and therefore the propagation of the two fronts is not completely coupled in the heliosphere. Using the graduated cylindrical shell model, as well as data from time-elongation stack plots and in situ signatures, we show that the drag model can accurately describe the behavior of each front, but is more effective with the ejecta. We also show that without the in situ data, based on measurements out to 80 R {sub ☉} combined with the general values for drag model parameters, the arrival of both the shock and ejecta can be predicted within four hours of arrival.

  11. Black Hole Window into p-Wave Dark Matter Annihilation.

    PubMed

    Shelton, Jessie; Shapiro, Stuart L; Fields, Brian D

    2015-12-01

    We present a new method to measure or constrain p-wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes. We demonstrate that the high DM densities, together with the increased velocity dispersion, within such spikes combine to make thermal p-wave annihilation cross sections potentially visible in γ-ray observations of the Galactic center (GC). The resulting DM signal is a bright central point source with emission originating from DM annihilations in the absence of a detectable spatially extended signal from the halo. We define two simple reference theories of DM with a thermal p-wave annihilation cross section and establish new limits on the combined particle and astrophysical parameter space of these models, demonstrating that Fermi Large Area Telescope is currently sensitive to thermal p-wave DM over a wide range of possible scenarios for the DM distribution in the GC. PMID:26684108

  12. Black Hole Window into p -Wave Dark Matter Annihilation

    NASA Astrophysics Data System (ADS)

    Shelton, Jessie; Shapiro, Stuart L.; Fields, Brian D.

    2015-12-01

    We present a new method to measure or constrain p -wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes. We demonstrate that the high DM densities, together with the increased velocity dispersion, within such spikes combine to make thermal p -wave annihilation cross sections potentially visible in γ -ray observations of the Galactic center (GC). The resulting DM signal is a bright central point source with emission originating from DM annihilations in the absence of a detectable spatially extended signal from the halo. We define two simple reference theories of DM with a thermal p -wave annihilation cross section and establish new limits on the combined particle and astrophysical parameter space of these models, demonstrating that Fermi Large Area Telescope is currently sensitive to thermal p -wave DM over a wide range of possible scenarios for the DM distribution in the GC.

  13. Impact of patients' arrival time on the care and in-hospital mortality in patients with non-ST-elevation myocardial infarction.

    PubMed

    Kim, Sung Soo; Jeong, Myung Ho; Rhew, Shi Hyun; Jeong, Wook Young; Ahn, Young Keun; Cho, Jeong Gwan; Kim, Young Jo; Cho, Myeong Chan; Kim, Chong Jin

    2014-01-15

    Only a few studies have focused on the clinical characteristics and outcomes of non-ST-segment myocardial infarction (NSTEMI) during off-hours. The purpose of this study was to compare the impact of patients' arrival time on the care of NSTEMI and whether this pattern might affect hospital mortality. This study analyzed 4,736 NSTEMI patients included in the Korea Acute Myocardial Infarction Registry from November 2005 to January 2008. Patients' arrival time was classified into regular hours (weekdays, 9:00 a.m. to 6:00 p.m.) and off-hours (weekdays 18:01 p.m. to 8:59 a.m., weekends, and holidays). A subtotal of 2,225 (46.9%) patients was admitted during off hours, compared with 2,511 (53.1%) patients with regular-hour admission. A higher proportion of patients admitted during off-hours had a higher Killip class, had more frequent cardiopulmonary resuscitation, were less likely to receive percutaneous coronary intervention (PCI) (67.7% vs 72.7%, p <0.001), and had longer door-to-balloon times (28 hours, interquartile range: 11 to 63 vs 23 hours, interquartile range 4 to 67, p <0.001). Although unadjusted hospital mortality was associated with admission during off-hours (4.5% vs 3.3%, p = 0.023), after adjusting for all patients covariates, the difference in mortality was attenuated and was no longer statistically significant (odds ratio 0.94, 95% confidence interval 0.59 to 1.48, p = 0.793). In conclusion, despite receiving fewer PCIs and having substantially longer waiting times to PCI, patients admitted during off-hours may not be at risk for increased in-hospital mortality. If patients are treated within an appropriate reperfusion strategy according to their clinical risk, arrival time may not influence on mortality. PMID:24295548

  14. Environmental and lunar cues are predictive of the timing of river entry and spawning-site arrival in lake sturgeon Acipenser fulvescens.

    PubMed

    Forsythe, P S; Scribner, K T; Crossman, J A; Ragavendran, A; Baker, E A; Davis, C; Smith, K K

    2012-07-01

    The associations were quantified between daily and interannual variation in the timing of a closed population of lake sturgeon Acipenser fulvescens migration and arrival at spawning sites with stream environmental and lunar covariates. Spawning data were gathered from 1262 fish in Black Lake, Michigan 2001 to 2008 and by video monitoring 2000 to 2002. Sex-specific variation in responses to external cues was also tested. Results showed that a greater number of individuals initiated migration from lake to riverine habitats at dawn and dusk relative to other times of the day. Current and lagged effects of water temperature and river discharge, and periods in the lunar cycle were important variables in models quantifying movements into the river and timing of adult arrival at spawning sites. Different suites of covariates were predictive of A. fulverscens responses during different periods of the spawning season. The timing of initiation of migration and spawning, and the importance of covariates to the timing of these events, did not differ between sexes. Stream flow and temperature covaried with other variables including day length and the lunar cycle. Anthropogenic disruption of relationships among variables may mean that environmental cues may no longer reliably convey information for Acipenseriformes and other migratory fishes. PMID:22747803

  15. The effects of iron deficiency anemia on p wave duration and dispersion

    PubMed Central

    Simsek, Hakkı; Gunes, Yilmaz; Demir, Cengiz; Sahin, Musa; Gumrukcuoglu, Hasan Ali; Tuncer, Mustafa

    2010-01-01

    OBJECTIVES: The association between P wave dispersion and iron deficiency anemia has not been documented in the literature. In this study, we evaluated P wave dispersion in patients with iron deficiency anemia and the possible relationships between P wave dispersion and other echocardiographic parameters. INTRODUCTION: The iron status of an individual may play an important role in cardiovascular health. Anemia is an independent risk factor for adverse cardiovascular outcomes. P wave dispersion is a simple electrocardiographic marker that has a predictive value for the development of atrial fibrillation. Apart from cardiovascular diseases, several conditions, such as seasonal variation, alcohol intake and caffeine ingestion, have been demonstrated to affect P wave dispersion. METHODS: The study included 97 patients who had iron deficiency anemia and 50 healthy subjects. The cases were evaluated with a clinical examination and diagnostic tests that included 12‐lead electrocardiography and transthoracic echocardiography. RESULTS: Compared to the control group, patients with iron deficiency anemia showed significantly longer maximum P wave duration (Pmax) (91.1±18.0 vs. 85.8±6.7 msec, p = 0.054), P wave dispersion (PWD) (48.1±7.7 vs. 40.9±5.6 msec, p<0.001), mitral inflow deceleration time (DT) (197.5±27.9 vs. 178.8±8.9 msec, p<0.001) and isovolumetric relaxation time (IVRT) (93.3±9.2 vs. 77.4±8.2 msec, p<0.001); they also showed increased heart rate (85.7±16.1 vs. 69.0±4.4, p<0.001) and frequency of diastolic dysfunction (7 (7.2%) vs. 0). Correlation analysis revealed that PWD was significantly correlated with IVRT, DT, heart rate, the presence of anemia and hemoglobin level. CONCLUSIONS: Iron deficiency anemia may be associated with prolonged P wave duration and dispersion and impaired diastolic left ventricular filling. PMID:21243273

  16. Arrival Metering Precision Study

    NASA Technical Reports Server (NTRS)

    Prevot, Thomas; Mercer, Joey; Homola, Jeffrey; Hunt, Sarah; Gomez, Ashley; Bienert, Nancy; Omar, Faisal; Kraut, Joshua; Brasil, Connie; Wu, Minghong, G.

    2015-01-01

    This paper describes the background, method and results of the Arrival Metering Precision Study (AMPS) conducted in the Airspace Operations Laboratory at NASA Ames Research Center in May 2014. The simulation study measured delivery accuracy, flight efficiency, controller workload, and acceptability of time-based metering operations to a meter fix at the terminal area boundary for different resolution levels of metering delay times displayed to the air traffic controllers and different levels of airspeed information made available to the Time-Based Flow Management (TBFM) system computing the delay. The results show that the resolution of the delay countdown timer (DCT) on the controllers display has a significant impact on the delivery accuracy at the meter fix. Using the 10 seconds rounded and 1 minute rounded DCT resolutions resulted in more accurate delivery than 1 minute truncated and were preferred by the controllers. Using the speeds the controllers entered into the fourth line of the data tag to update the delay computation in TBFM in high and low altitude sectors increased air traffic control efficiency and reduced fuel burn for arriving aircraft during time based metering.

  17. Observations of high-frequency P wave earthquake and explosion spectra compared with ω-3, ω-2, and sharpe source models

    NASA Astrophysics Data System (ADS)

    Walter, William R.; Brune, James N.; Priestley, Keith F.; Fletcher, Jon

    1988-06-01

    Observations of 10-, 20-, and 30-Hz P wave spectral amplitudes from earthquakes and explosions are compared with the Archambeau [1968, 1972] earthquake model featuring a P wave falloff of ω-3 beyond the corner frequency, a modified Brune [1970, 1971] earthquake model with ω-2 falloff, and the Sharpe [1942] explosion model which has a ω-2 falloff. The Archambeau and Sharpe models have been, in part, the basis of a proposal by Evernden et al. [1986] that high-frequency (≈30 Hz) seismic energy could provide an effective solution to the problem of detection and identification of low-yield coupled and fully decoupled underground nuclear explosions. The observations of earthquakes show an increase in spectral amplitude with moment approximately in agreement with the ω-2 falloff model and, for larger moments, in disagreement with the ω-3 model. Comparison of theoretical and actual seismograms narrow-band filtered at 30 Hz shows that in part the increase in spectral amplitude of earthquakes is due to the complex and long duration of the rupture process and not because of an increase in an impulsive first arrival like that characteristic of an explosion. The 30-Hz amplitudes for explosions show much scatter, and many events have a spectral falloff greater than the ω-2 predicted by the Sharpe model. Whether this is due entirely to attenuation or is the actual source spectrum is not determined. High stress drop earthquakes are predicted to have larger spectral amplitudes than the Sharpe model. Thus any discrimination technique using high-frequency P wave spectra should probably take into account differences in pulse shape and amplitude in the time domain.

  18. Trends of some high quantiles of average and extremes inter-arrival times and rainfall depths at daily scale for an Italian Sub-Alpine area

    NASA Astrophysics Data System (ADS)

    Ferraris, Stefano; Agnese, Carmelo; Baiamonte, Giorgio; Canone, Davide; Previati, Maurizio; Cat Berro, Daniele; Mercalli, Luca

    2015-04-01

    Modeling of rainfall statistical structure represents an important research area in hydrology, meteorology, atmospheric physics and climatology, because of the several theoretical and practical implications. The statistical inference of the alternation of wet periods (WP) and dry periods (DP) in daily rainfall records can be achieved through the modelling of inter-arrival time-series (IT), defined as the succession of times elapsed from a rainy day and the one immediately preceding it. It has been shown previously that the statistical structure of IT can be well described by the 3-parameter Lerch distribution (Lch). In this work, Lch was successfully applied to IT data belonging to a sub-alpine area (Piemonte and Valle d'Aosta, NW Italy); furthermore the same statistical procedure was applied to daily rainfall records to ITs associated. The analysis has been carried out for 26 daily rainfall long-series (≈ 90 yr of observations). The main objective of this work was to detect temporal trends of some features describing the statistical structure of both inter-arrival time-series (IT) and associated rainfall depth (H). Each time-series was divided on subsets of five years long and for each of them the estimation of the Lch parameter was performed, so to extend the trend analysis to some high quantiles.

  19. [Evaluation of Sorafenib for Hepatocellular Carcinoma with Low α-Fetoprotein by Arrival Time Parametric Imaging Using Contrast-Enhanced Ultrasonography with Sonazoid].

    PubMed

    Shiozawa, Kazue; Watanabe, Manabu; Ikehara, Takashi; Matsukiyo, Yasushi; Kogame, Michio; Shinohara, Mie; Kikuchi, Yoshinori; Shinohara, Masao; Igarashi, Yoshinori; Sumino, Yasukiyo

    2016-02-01

    We aimed to determine the usefulness of arrival time parametric imaging (AtPI) using contrast-enhanced ultrasonography (CEUS)with Sonazoid in the evaluation of early response to sorafenib for hepatocellular carcinoma (HCC). Thirteen ad- vanced HCC patients with low a / -fetoprotein (AFP) level (≤35 ng/mL) who received sorafenib for at least 4 weeks were enrolled in this study. CEUS was performed before and after treatment (2 weeks), and the images of the target lesion in the arterial phase were analyzed by AtPI. In the color mapping images obtained by AtPI, the mean arrival time of the contrast agent in the target lesion from the starting point (mean time: MT) was calculated. In each patient, differences between MT before and MT 2 weeks after treatment were compared. MT (+) and MT(-) groups were designated as such if the difference was 0 or greater(blood flow velocity of the lesion was reduced)and less than 0 sec(blood flow velocity of the lesion was increased), respectively. The overall survival was evaluated between the 2 groups. In the MT (+) group (7 patients) and MT (-) group (6 patients), the median survival times were 307 and 208 days, respectively, which was statistically significant. We suggest AtPI is useful for evaluating early response to sorafenib in advanced HCC patients with low AFP level. PMID:27067685

  20. P-wave and S-wave traveltime residuals in Caledonian and adjacent units of Northern Europe and Greenland

    NASA Astrophysics Data System (ADS)

    Hejrani, Babak; Balling, Niels; Holm Jacobsen, Bo; Kind, Rainer; Tilmann, Frederik; England, Richard; Bom Nielsen, Søren

    2014-05-01

    This work combines P-wave and S-wave travel time residuals from in total 477 temporary and 56 permanent stations deployed across Caledonian and adjacent units in Northern Europe and Greenland (Tor, Gregersen et al. 2002; SVEKALAPKO, Sandoval et al., 2003; CALAS, Medhus et al, 2012a; MAGNUS, Weidle et al. 2010; SCANLIPS south, England & Ebbing 2012; SCANLIPS north, Hejrani et al. 2012; JULS Hejrani et al. 2013; plus permanent stations in the region). We picked data from 2002 to 2012 (1221 events) using a cross correlation technique on all waveforms recorded for each event. In this way we achieve maximum consistency of relative residuals over the whole region (Medhus et al. 2012b). On the European side 18362 P-wave travel time residuals was delivered. In East Greenland 1735 P-wave residuals were recovered at the Central Fjord array (13 stations) and 2294 residuals from the sparse GLISN-array (23 stations). Likewise, we picked a total of 6034 residuals of the SV phase (For the Tor and SVEKALAPKO projects we used data from Amaru et al. 2008). Relative residuals within the region are mainly due to sub-crustal uppermost mantle velocity anomalies. A dominant subvertical boundary was detected by Medhus et al. (2012), running along the Tornquist zone, east of the Oslo Graben and crossing under high topography of the southern Scandes. We delineated this boundary in more detail, tracking it towards the Atlantic margin north of Trondheim. Further north (Scanlips north), a similar subvertical upper mantle boundary seems to be present close to the coast, coinciding with the edge of the stretched crust. The North German Caledonides were probed by the new JULS (JUtland Lower Saxony) profile which closes the gap between Tor and CALAS arrays. Mantle structure found by the Tor project was confirmed, and modelling was extended to the eastern edge of the North Sea. References: Amaru, M. L., Spakman, W., Villaseñor, A., Sandoval, S., Kissling, E., 2008, A new absolute arrival time data set for Europe.Geophysical Journal International, 173, 465-472. England, R. W.; Ebbing, J., 2012, Crustal structure of central Norway and Sweden from integrated modelling of teleseismic receiver functions and the gravity anomaly.GEOPHYSICAL JOURNAL INTERNATIONAL, 191, 1-11. Gregersen S., Voss P., TOR Working Group, 2002. Summary of project TOR: delineation of a stepwise, sharp, deep lithosphere transition across Germany-Denmark-Sweden, Tectonophysics, 360, 61-73. Hejrani, B., Jacobsen, B. H., Balling,N. and England, R. W.. 2012, A seismic tomography study of lithospheric structure under the Norwegian Caledonides.Geophysical Research Abstracts, 14, 4334. Hejrani, B.; Jacobsen, B.H.; Balling, N.;Tilmann, F.; Kind, R., 2013, Upper-mantle velocity structure beneathJutland, Denmark and northern Germany:Preliminary results. Joint Assembly Gothenburg Abstract S401S2.01, Medhus, A. B., Balling, N., Jacobsen, B. H., Weidle, C., England, R. W., Kind, R., Thybo, H., Voss, P. (2012a): Upper-mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone revealed by P-wave traveltime tomography. Geophysical Journal International, 189, 3, 1315-1334. Medhus, Jacobsen, B. H.,A. B., Balling, N., 2012b, Bias Problems in Existing Teleseismic Travel Time Databases: Ignore or Repair? Seismological Research Letters, 83, 1030-1037. Sandoval, S., Kissling, E. &Ansorge, J., 2003.High-resolution body wave tomography beneath the SVEKALAPKO array: I. A priori three-dimensional crustal model and associated traveltime effects on teleseismic wave fronts, Geophys. J. Int., 153, 75-87. Weidle, C., Maupin, V., Ritter, J.,Kværna, T., Schweitzer J., Balling, N.,Thybo, H.,Faleide, J. I.,and,Wenzel, F., 2010, MAGNUS-A Seismological Broadband Experiment to Resolve Crustal and Upper Mantle Structure beneath the Southern Scandes Mountains in Norway. SEISMOLOGICAL RESEARCH LETTERS, 81, 76-84.

  1. Predicting interplanetary shock arrivals at Earth, Mars, and Venus: A real-time modeling experiment following the solar flares of 5-14 December 2006

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S. M. P.; Dryer, M.; Fry, C. D.; Smith, Z. K.; Intriligator, D. S.; Courtney, W. R.; Deehr, C. S.; Sun, W.; Kecskemety, K.; Kudela, K.; Balaz, J.; Barabash, S.; Futaana, Y.; Yamauchi, M.; Lundin, R.

    2008-06-01

    A 3-D, kinematic, solar wind model (Hakamada-Akasofu-Fry version 2 (HAFv.2)) is used to predict interplanetary shock arrivals at Venus, Earth, and Mars during a sequence of significant solar events that occurred in the interval 5-14 December 2006. Mars and Venus were on the opposite side of the Sun from Earth during this period. The shocks from the first two east limb events (5 and 6 December) were predicted to interact to form a single disturbance before reaching Earth and Venus. A single shock was indeed recorded at Earth only about 3 h earlier than had been predicted. The composite shock was predicted by HAFv.2 to arrive at Venus on 8 December at ˜0500 UT. Solar energetic particles (SEPs) were detected in Venus Express Analyzer of Space Plasmas and Energetic Atoms-4 data for some 3 d (from <0530 UT on 6 December), and an energetic storm particle (ESP) event signaled the arrival of a single shock wave at 0900 UT on 7 December. SEPs were correspondingly recorded at Mars. However, the eastern flank of the composite shock was predicted to decay to an MHD wave prior to reaching this location, and no shock signature was observed in the available data. The shocks generated in association with two flare events that occurred closer to the West Limb on 13 and 14 December were predicted by HAFv.2 to remain separate when they arrived at Earth but to combine thereafter before reaching Mars. Each was expected to decay to MHD waves before reaching Venus, which was at that time located behind the Sun. Separated shocks were observed to arrive at L1 (ACE) only 8 min earlier than and 5.3 h later than their predicted times. The western flank of the combined shocks was predicted to arrive at Mars early on 20 December 2006. An indication of the passage of this shock was provided by a signature of ion heating in Mars Express IMA (ion mass-resolving analyzer) data from <0424 UT on 20 December. The predictions of the HAFv.2 model for Earth were each well within the ±11 h. RMS error earlier found, on the basis of significant statistics, to apply at 1 AU during the rise and maximum phases of solar cycle 23. Overall, the model is demonstrated to be capable of predicting the effects produced by shocks and by the background solar wind at Venus, Earth, and Mars. It is suggested that the continuous presence of solar wind monitors (plasma and interplanetary magnetic field observations) at "benchmark planets" can constitute a necessary and valuable component of ongoing and future space weather programs for the validation of solar wind models such as HAFv.2.

  2. Fluctuation and strain effects in a chiral p -wave superconductor

    NASA Astrophysics Data System (ADS)

    Fischer, Mark H.; Berg, Erez

    2016-02-01

    For a tetragonal material, order parameters of px and py symmetry are related by rotation and hence have the same Tc at a mean-field level. This degeneracy can be lifted by a symmetry-breaking field, such as (uniaxial) in-plane strain, such that at Tc, the order parameter is only of px or py symmetry. Only at a lower temperature also the respective other order parameter condenses to form a chiral p -wave state. At the mean-field level, the derivative of Tc with strain is discontinuous at zero strain. We analyze the consequences of (thermal) fluctuations on the strain-temperature phase diagram within a Ginzburg-Landau approach. We find that the order-parameter fluctuations can drive the transition to be weakly first order, rounding off this discontinuity. We discuss the possibility of a second-order transition into a nonsuperconducting time-reversal-symmetry-breaking phase and consequences for the spin-triplet superconductor Sr2RuO4 .

  3. Comparison of the CME-associated shock arrival times at the earth using the WSA-ENLIL model with three cone models

    NASA Astrophysics Data System (ADS)

    Jang, S.; Moon, Y.; Na, H.

    2012-12-01

    We have made a comparison of CME-associated shock arrival times at the earth based on the WSA-ENLIL model with three cone models using 29 halo CMEs from 2001 to 2002. These halo CMEs have cone model parameters from Michalek et al. (2007) as well as their associated interplanetary (IP) shocks. For this study we consider three different cone models (an asymmetric cone model, an ice-cream cone model and an elliptical cone model) to determine CME cone parameters (radial velocity, angular width and source location), which are used for input parameters of the WSA-ENLIL model. The mean absolute error (MAE) of the arrival times for the elliptical cone model is 10 hours, which is about 2 hours smaller than those of the other models. However, this value is still larger than that (8.7 hours) of an empirical model by Kim et al. (2007). We are investigating several possibilities on relatively large errors of the WSA-ENLIL cone model, which may be caused by CME-CME interaction, background solar wind speed, and/or CME density enhancement.

  4. Detection of the electrocardiogram P-wave using wavelet analysis

    SciTech Connect

    Anant, K.S.; Rodrigue, G.H. |; Dowla, F.U.

    1994-01-01

    Since wavelet analysis is an effective tool for analyzing transient signals, we studied its feature extraction and representation properties for events in electrocardiogram (EKG) data. Significant features of the EKG include the P-wave, the QRS complex, and the T-wave. For this paper the feature that we chose to focus on was the P-wave. Wavelet analysis was used as a pre-processor for a backpropagation neural network with conjugate gradient learning. The inputs to the neural network were the wavelet transforms of EKGs at a particular scale. The desired output was the location of the P-wave. The results were compared to results obtained without using the wavelet transform as a pre-processor.

  5. Detection of the electrocardiogram P-wave using wavelet analysis

    NASA Astrophysics Data System (ADS)

    Anant, Kanwaldip S.; Dowla, Farid U.; Rodrigue, Garry H.

    1994-03-01

    Since wavelet analysis is an effective tool for analyzing transient signals, we studied its feature extraction and representation properties for events in electrocardiogram (EKG) data. Significant features of the EKG include the P-wave, the QRS complex, and the T-wave. For this paper the feature that we chose to focus on was the P-wave. Wavelet analysis was used as a preprocessor for a backpropagation neural network with conjugate gradient learning. The inputs to the neural network were the wavelet transforms of EKGs at a particular scale. The desired output was the location of the P-wave. The results were compared to results obtained without using the wavelet transform as a preprocessor.

  6. Effect of transcatheter aortic valve replacement on P-wave duration, P-wave dispersion and left atrial size

    PubMed Central

    Dursun, Huseyin; Tanriverdi, Zulkif; Colluoglu, Tugce; Kaya, Dayimi

    2015-01-01

    Background P-wave dispersion (PWD), a measure of heterogeneity of atrial refractoriness, is defined as the difference between the maximum and minimum P-wave duration. In patients with severe aortic stenosis (AS), P-wave duration and PWD were shown to be increased, indicating atrial electrical remodeling. However, the effect of transcatheter aortic valve replacement (TAVR) on P-wave morphology has not been established yet. The aim of this study is to assess the short and long-term effects of TAVR with two types of bioprosthetic valves on P-wave duration and PWD in association with left atrial (LA) size. Methods Fifty-two (36 female) eligible patients in sinus rhythm who underwent transfemoral TAVR between June 01, 2012 and July 31, 2014 with either a Medtronic CoreValve (MCV) (n = 32) or an Edwards SAPIEN XT Valve (n = 20) were enrolled. Standard 12-lead electrocardiogram and echocardiographic evaluations were performed pre-procedurally, post-TAVR day one and 6 months post-TAVR. P-wave duration and PWD were measured and correlation analyses with echocardiographic variables were performed. Results P-wave duration and PWD were significantly decreased on post-TAVR day one (P < 0.05). They continued to decrease during the six month follow-up period, but were not significantly different from short-term values (P > 0.05). The decrease of LA diameter was found significant at the sixth-months of follow-up (P < 0.05). These changes were independent from the types of bioprosthetic valves implanted (P > 0.05). A positive correlation was detected between minimum P-wave duration and maximum aortic valve gradients at post-TAVR day one (r = 0.297, P = 0.032). Conclusions P-wave duration and PWD were significantly reduced early after TAVR indicating early reverse atrial electrical remodeling. Moreover, structural reverse remodeling of atrium was detected at the 6-months of follow-up. The effects of two types of bioprosthetic valves on atrial remodeling were similar. PMID:26788037

  7. Embedded Fiber Optic Sensors for Measuring Transient Detonation/Shock Behavior;Time-of-Arrival Detection and Waveform Determination.

    SciTech Connect

    Chavez, Marcus Alexander; Willis, Michael David; Covert, Timothy T.

    2014-09-01

    The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.

  8. Estimating the value of containment strategies in delaying the arrival time of an influenza pandemic: A case study of travel restriction and patient isolation

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Zhang, Yan; Huang, Tianyi; Li, Xiang

    2012-09-01

    With a simple phenomenological metapopulation model, which characterizes the invasion process of an influenza pandemic from a source to a subpopulation at risk, we compare the efficiency of inter- and intrapopulation interventions in delaying the arrival of an influenza pandemic. We take travel restriction and patient isolation as examples, since in reality they are typical control measures implemented at the inter- and intrapopulation levels, respectively. We find that the intrapopulation interventions, e.g., patient isolation, perform better than the interpopulation strategies such as travel restriction if the response time is small. However, intrapopulation strategies are sensitive to the increase of the response time, which might be inevitable due to socioeconomic reasons in practice and will largely discount the efficiency.

  9. Analytical solution for the covariance and for the decorrelation time of the angle of arrival of a wave front corrugated by atmospheric turbulence.

    PubMed

    Conan, R; Borgnino, J; Ziad, A; Martin, F

    2000-10-01

    The two-dimensional (2D) spatial covariance of the angle-of-arrival (AA) fluctuations is often used to investigate the properties of wave fronts corrugated by the atmosphere for high-angular-resolution techniques. Theoretical series expansions of this covariance are presented. The fast convergence of these series reduces the calculation time of the covariance done by numerical integration. The 2D covariance is a nonradial function. A physical interpretation of this anisotropy is proposed. The spatiotemporal correlation of the AA is deduced from the covariance assuming the "frozen-flow" hypothesis. The impact of the anisotropy on the evaluation of the number of predominant turbulent layers and on the corresponding winds is investigated, and an analysis of temporal correlations is performed. A simple theoretical approximation of the decorrelation time of the AA is given, which is found to be in agreement with experimental results. PMID:11028529

  10. Longitudinal development of muons in large air showers studies from the arrival time distributions measured at 900m above sea level

    NASA Technical Reports Server (NTRS)

    Kakimoto, F.; Tsuchimoto, I.; Enoki, T.; Suga, K.; Nishi, K.

    1985-01-01

    The arrival time distributions of muons with energies above 1.0GeV and 0.5GeV have been measured in the Akeno air-shower array to study the longitudinal development of muons in air showers with primary energies in the range 10 to the 17th power to 10 to the 18th power ev. The average rise times of muons with energies above 1.0GeV at large core distances are consistent with those expected from very high multiplicity models and, on the contrary, with those expected from the low multiplicity models at small core distances. This implies that the longitudinal development at atmospheric depth smaller than 500 cm square is very fast and that at larger atmospheric depths is rather slow.

  11. Position surveillance using one active ranging satellite and time-of-arrival of a signal from an independent satellite

    NASA Technical Reports Server (NTRS)

    Anderson, R. E.; Frey, R. L.; Lewis, J. R.

    1981-01-01

    A satellite-aided mobile communication service was tested for position surveillance, with an automatic responder circuit connected between the vehicle receiver and transmitter, and a receiver coded for signals from another satellite. Using the ATS-6 and GOES satellites, a tone-code ranging transponder was connected between the receiver and transmitter, and a 468 MHz receiver was connected to the responder unit for passive reception of the 100 bit per second timing and data signal. Results showed lines of position derived from the active ranging through ATS-6 to be accurate to approximately 0.1 nautical mile, while the NOAA-GOES signals were accurate to about 1.6 miles. The active ranging bandwidth was 2.44 kHz, and the integration time was 0.1 second, while the limitation on accuracy was the 100 Hz bandwidth. This technique of position surveillance was concluded to be feasible and simple to operate, providing needed, good quality communications to the inland waterways industry.

  12. P wave {pi}{pi} amplitude from dispersion relations

    SciTech Connect

    Szczepaniak, Adam P.; Guo, Peng; Battaglieri, M.; De Vita, R.

    2010-08-01

    We solve the dispersion relation for the P-wave {pi}{pi} amplitude. We discuss the role of the left-hand cut vs the Castillejo-Dalitz-Dyson pole contribution and compare the solution with a generic quark model description. We review the generic properties of analytical partial wave scattering and production amplitudes and discuss their applicability and fits of experimental data.

  13. Basement configuration of on-land Kutch basin from seismic refraction studies and modeling of first arrival travel time skips

    NASA Astrophysics Data System (ADS)

    Prasad, B. Rajendra; Venkateswarlu, N.; Prasad, A. S. S. S. R. S.; Murthy, A. S. N.; Sateesh, T.

    2010-10-01

    The Kutch basin is one of the three (Narmada, Cambay and Kutch) major marginal rift basins that are close to each other in mid-western part of the Indian subcontinent. The seismic refraction and wide-angle reflection data were acquired and a first order velocity structure of the Kutch sedimentary basin along Jakhau-Mandvi, Mandvi-Mundra, Mundra-Adesar and Hamirpur-Halvad profiles is derived. The travel time skip phenomenon has been noticed in the travel time plots and record sections indicating presence of low velocity sediments. Derived two-dimensional velocity-depth models revealed a Mesozoic sedimentary sequence sandwiched between Trap and Limestone layers, in some of the profiles. Two thick low velocity layers (that corresponds early to late Mesozoic era) have been identified. These are dipping towards Mandvi along Jakhau-Mandvi profile. The early Mesozoic layer that is thinning towards southeast is completely missing in Mandvi-Mundra profile. It is also noticed that the early Mesozoic Bhuj formation exists in the northern parts of the Mundra-Adesar and Hamirpur-Halvad profiles, where it directly overlies the granitic basement. The derived velocity-depth model suggests that the basement is about 3 km deep near Jakhau and reaches a depth of about 6 km near Mandvi. The layered structure may correspond to the Tertiary, Trap, Late Mesozoic sediments and Mesozoic limestone. The velocity-depth model obtained in Kutch is very similar to earlier derived model for Jamnagar and Dwarka sub-basins of northwestern Saurashtra peninsula suggesting probable continuity/linkage between southern on-land Kutch and, across the Gulf of Kutch to Saurashtra peninunsula. We also conclude that the evolution of Kutch basin, as a peri-cratonic rift basin, is essentially controlled by the four (F1-F4) faults inferred from obvious abrupt changes in layer thickness/velocity along the seismic refraction profiles.

  14. The transient analysis of the queue-length distribution in the batch arrival system with N-policy, multiple vacations and setup times

    NASA Astrophysics Data System (ADS)

    Kempa, Wojciech M.

    2010-10-01

    A batch arrival queueing system of the MX/G/1 type with unlimited queue is considered. After each busy period the server begins a multiple vacation period, consisting of independent single vacations, when the service process is blocked. The server begins successive single vacations as far as at the end of one of them the number of customers waiting in the queue equals at least N. The service of the first customer after the vacation period is preceded by a setup time. The analysis of the queue-size distribution on the first vacation cycle is directed to the analysis of the same characteristic in the corresponding "usual" system with unremovable server on its first busy period. The renewal-theory approach is used to obtain results in the general case. As main result the explicit representation for the LT of queue-size distribution is derived for the original system.

  15. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks Using Tera-Scale Optical Core Devices

    DOE PAGESBeta

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot bemore » readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.« less

  16. 3D P-Wave Velocity Structure of the Deep Galicia Rifted Margin

    NASA Astrophysics Data System (ADS)

    Bayrakci, G.; Minshull, T. A.; Davy, R. G.; Sawyer, D. S.; Klaeschen, D.; Papenberg, C. A.; Reston, T. J.; Shillington, D. J.; Ranero, C. R.

    2014-12-01

    The combined wide-angle reflection-refraction and multi-channel seismic (MCS) experiment, Galicia 3D, was carried out in 2013 at the Galicia rifted margin in the northeast Atlantic Ocean, west of Spain. The main geological features within the 64 by 20 km (1280 km²) 3D box investigated by the survey are the peridotite ridge (PR), the fault bounded, rotated basement blocks and the S reflector, which has been interpreted to be a low angle detachment fault. 44 short period four-component ocean bottom seismometers and 28 ocean bottom hydrophones were deployed in the 3D box. 3D MCS profiles sampling the whole box were acquired with two airgun arrays of 3300 cu.in. fired alternately every 37.5 m. We present the results from 3D first-arrival time tomography that constrains the P-wave velocity in the 3D box, for the entire depth sampled by reflection data. Results are validated by synthetic tests and by the comparison with Galicia 3D MCS lines. The main outcomes are as follows: 1- The 3.5 km/s iso-velocity contour mimics the top of the acoustic basement observed on MCS profiles. Block bounding faults are imaged as velocity contrasts and basement blocks exhibit 3D topographic variations. 2- On the southern profiles, the top of the PR rises up to 5.5 km depth whereas, 20 km northward, its basement expression (at 6.5 km depth) nearly disappears. 3- The 6.5 km/s iso-velocity contour matches the topography of the S reflector where the latter is visible on MCS profiles. Within a depth interval of 0.6 km (in average), velocities beneath the S reflector increase from 6.5 km/s to 7 km/s, which would correspond to a decrease in the degree of serpentinization from ~45 % to ~30 % if these velocity variations are caused solely by variations in hydration. At the intersections between the block bounding normal faults and the S reflector, this decrease happens over a larger depth interval (> 1 km), suggesting that faults act as conduit for the water flow in the upper mantle.

  17. 3D P-Wave Velocity Structure of the Deep Galicia Rifted Margin

    NASA Astrophysics Data System (ADS)

    Bayrakci, Gaye; Minshull, Timothy; Davy, Richard; Sawyer, Dale; Klaeschen, Dirk; Papenberg, Cord; Reston, Timothy; Shillington, Donna; Ranero, Cesar

    2015-04-01

    The combined wide-angle reflection-refraction and multi-channel seismic (MCS) experiment, Galicia 3D, was carried out in 2013 at the Galicia rifted margin in the northeast Atlantic Ocean, west of Spain. The main geological features within the 64 by 20 km (1280 km²) 3D box investigated by the survey are the peridotite ridge (PR), the fault bounded, rotated basement blocks and the S reflector, which has been interpreted to be a low angle detachment fault. 44 short period four-component ocean bottom seismometers and 28 ocean bottom hydrophones were deployed in the 3D box. 3D MCS profiles sampling the whole box were acquired with two airgun arrays of 3300 cu.in. fired alternately every 37.5 m. We present the results from 3D first-arrival time tomography that constrains the P-wave velocity in the 3D box, for the entire depth sampled by reflection data. Results are validated by synthetic tests and by the comparison with Galicia 3D MCS lines. The main outcomes are as follows: 1- The 3.5 km/s iso-velocity contour mimics the top of the acoustic basement observed on MCS profiles. Block bounding faults are imaged as velocity contrasts and basement blocks exhibit 3D topographic variations. 2- On the southern profiles, the top of the PR rises up to 5.5 km depth whereas, 20 km northward, its basement expression (at 6.5 km depth) nearly disappears. 3- The 6.5 km/s iso-velocity contour matches the topography of the S reflector where the latter is visible on MCS profiles. Within a depth interval of 0.6 km (in average), velocities beneath the S reflector increase from 6.5 km/s to 7 km/s, which would correspond to a decrease in the degree of serpentinization from ~45 % to ~30 % if these velocity variations are caused solely by variations in hydration. At the intersections between the block bounding normal faults and the S reflector, this decrease happens over a larger depth interval (> 1 km), suggesting that faults act as conduit for the water flow in the upper mantle.

  18. P-wave velocity structure offshore central Sumatra: implications for compressional and strike-slip faulting

    NASA Astrophysics Data System (ADS)

    Karplus, M.; Henstock, T.; McNeill, L. C.; Vermeesch, P. M. T.; Barton, P. J.

    2014-12-01

    The Sunda subduction zone features significant along-strike structural variability including changes in accretionary prism and forearc morphology. Some of these changes have been linked to changes in megathrust faulting styles, and some have been linked to other thrust and strike-slip fault systems across this obliquely convergent margin (~54-58 mm/yr convergence rate, 40-45 mm/yr subduction rate). We examine these structural changes in detail across central Sumatra, from Siberut to Nias Island, offshore Indonesia. In this area the Investigator Fracture Zone and the Wharton Fossil Ridge, features with significant topography, are being subducted, which may affect sediment thickness variation and margin morphology. We present new seismic refraction P-wave velocity models using marine seismic data collected during Sonne cruise SO198 in 2008. The experiment geometry consisted of 57 ocean bottom seismometers, 23 land seismometers, and over 10,000 air gun shots recorded along ~1750 km of profiles. About 130,000 P-wave first arrival refractions were picked, and the picks were inverted using FAST (First Arrivals Refraction Tomography) 3-D to give a velocity model, best-resolved in the top 25 km. Moho depths, crustal composition, prism geometry, slab dip, and upper and lower plate structures provide insight into the past and present tectonic processes at this plate boundary. We specifically examine the relationships between velocity structure and faulting locations/ styles. These observations have implications for strain-partitioning along the boundary. The Mentawai Fault, located west of the forearc basin in parts of Central Sumatra, has been interpreted variably as a backthrust, strike-slip, and normal fault. We integrate existing data to evaluate these hypotheses. Regional megathrust earthquake ruptures indicate plate boundary segmentation in our study area. The offshore forearc west of Siberut is almost aseismic, reflecting the locked state of the plate interface, which last ruptured in 1797. The weakly-coupled Batu segment experiences sporadic clusters of events near the forearc slope break. The Nias segment in the north ruptured in the 2005 M8.7 earthquake. We compare P-wave velocity structure to the earthquake data to examine potential links between lithospheric structure and seismogenesis.

  19. Role of the P-wave high frequency energy and duration as noninvasive cardiovascular predictors of paroxysmal atrial fibrillation.

    PubMed

    Alcaraz, Ral; Martnez, Arturo; Rieta, Jos J

    2015-04-01

    A normal cardiac activation starts in the sinoatrial node and then spreads throughout the atrial myocardium, thus defining the P-wave of the electrocardiogram. However, when the onset of paroxysmal atrial fibrillation (PAF) approximates, a highly disturbed electrical activity occurs within the atria, thus provoking fragmented and eventually longer P-waves. Although this altered atrial conduction has been successfully quantified just before PAF onset from the signal-averaged P-wave spectral analysis, its evolution during the hours preceding the arrhythmia has not been assessed yet. This work focuses on quantifying the P-wave spectral content variability over the 2h preceding PAF onset with the aim of anticipating as much as possible the arrhythmic episode envision. For that purpose, the time course of several metrics estimating absolute energy and ratios of high- to low-frequency power in different bands between 20 and 200Hz has been computed from the P-wave autoregressive spectral estimation. All the analyzed metrics showed an increasing variability trend as PAF onset approximated, providing the P-wave high-frequency energy (between 80 and 150Hz) a diagnostic accuracy around 80% to discern between healthy subjects, patients far from PAF and patients less than 1h close to a PAF episode. This discriminant power was similar to that provided by the most classical time-domain approach, i.e., the P-wave duration. Furthermore, the linear combination of both metrics improved the diagnostic accuracy up to 88.07%, thus constituting a reliable noninvasive harbinger of PAF onset with a reasonable anticipation. The information provided by this methodology could be very useful in clinical practice either to optimize the antiarrhythmic treatment in patients at high-risk of PAF onset and to limit drug administration in low risk patients. PMID:25758369

  20. P-wave residuals at stations in Nepal - Evidence for a high velocity region beneath the Karakorum

    NASA Technical Reports Server (NTRS)

    Pandey, M. R.; Roecker, Steven W.; Molnar, Peter

    1991-01-01

    P-wave residuals recorded at stations in Nepal from events to the northwest and closer than about 20 deg are consistently earlier than those from other directions by about 2.5 sec. These early arrivals are associated with paths confined to the upper 300 km of the earth and suggest that cold material occupies the uppermost mantle beneath the Karakorum, northwest Himalaya, and western Kunlun. Thus, these data suggest that convective downwelling occurs more vigorously in this region than beneath the rest of the Himalaya, Tibet, and their surroundings.

  1. Mantle Attenuation Estimated from Regional and Teleseismic P-waves of Deep Earthquakes and Surface Explosions

    NASA Astrophysics Data System (ADS)

    Ichinose, G.; Woods, M.; Dwyer, J.

    2014-03-01

    We estimated the network-averaged mantle attenuation t*(total) of 0.5 s beneath the North Korea test site (NKTS) by use of P-wave spectra and normalized spectral stacks from the 25 May 2009 declared nuclear test (mb 4.5; IDC). This value was checked using P-waves from seven deep (580-600 km) earthquakes (4.8 < M w < 5.5) in the Jilin-Heilongjiang, China region that borders with Russia and North Korea. These earthquakes are 200-300 km from the NKTS, within 200 km of the Global Seismic Network seismic station in Mudanjiang, China (MDJ) and the International Monitoring System primary arrays at Ussuriysk, Russia (USRK) and Wonju, Republic of Korea (KSRS). With the deep earthquakes, we split the t*(total) ray path into two segments: a t*(u), that represents the attenuation of the up-going ray from the deep hypocenters to the local-regional receivers, and t*(d), that represents the attenuation along the down-going ray to teleseismic receivers. The sum of t*(u) and t*(d) should be equal to t*(total), because they both share coincident ray paths. We estimated the upper-mantle attenuation t*(u) of 0.1 s at stations MDJ, USRK, and KSRS from individual and stacks of normalized P-wave spectra. We then estimated the average lower-mantle attenuation t*(d) of 0.4 s using stacked teleseismic P-wave spectra. We finally estimated a network average t*(total) of 0.5 s from the stacked teleseismic P-wave spectra from the 2009 nuclear test, which confirms the equality with the sum of t*(u) and t*(d). We included constraints on seismic moment, depth, and radiation pattern by using results from a moment tensor analysis and corner frequencies from modeling of P-wave spectra recorded at local distances. We also avoided finite-faulting effects by excluding earthquakes with complex source time functions. We assumed ω2 source models for earthquakes and explosions. The mantle attenuation beneath the NKTS is clearly different when compared with the network-averaged t* of 0.75 s for the western US and is similar to values of approximately 0.5 s for the Semipalatinsk test site within the 0.5-2 Hz range.

  2. Nontopological nature of the edge current in a chiral p -wave superconductor

    NASA Astrophysics Data System (ADS)

    Huang, Wen; Lederer, Samuel; Taylor, Edward; Kallin, Catherine

    2015-03-01

    The edges of time-reversal symmetry breaking topological superconductors support chiral Majorana bound states as well as spontaneous charge currents. The Majorana modes are a robust, topological property, but the charge currents are nontopological—and therefore sensitive to microscopic details—even if we neglect Meissner screening. We give insight into the nontopological nature of edge currents in chiral p -wave superconductors using a variety of theoretical techniques, including lattice Bogoliubov-de Gennes equations, the quasiclassical approximation, and the gradient expansion, and we describe those special cases in which edge currents do have a topological character. While edge currents are not quantized, they are generically large, but they can be substantially reduced for a sufficiently anisotropic gap function, a scenario of possible relevance for the putative chiral p -wave superconductor Sr2RuO4 .

  3. p -wave superfluid shells for trapped fermions with population imbalance

    NASA Astrophysics Data System (ADS)

    Kirmani, Ammar; Quader, Khandker; Dzero, Maxim

    We present the phase diagram for a p-wave fermionic superfluid with imbalanced populations in a potential trap. We find shells of various superfluid phases, whose realization is determined by the parameters of a trap. In order to compute the resulting phase diagram, we use weak-coupling BCS theory together with the local density approximation in which the effect of the trapping potential is accounted for by a spatially inhomogeneous chemical potential. We compare our phase diagram with the one found for the trapped population imbalanced s-wave fermionic superfluid [Lin, Yi & Duan, Phys. Rev. A 74, 031604R (2006)], and also point out key differences with results for the population imbalanced p-wave case in the absence of a trap [Liao, Popescu & Quader, Phys. Rev. B 88, 134507 (2013)]. NSF-DMR-1506547.

  4. Electrocardiographic P-wave characteristics in patients with psoriasis vulgaris

    PubMed Central

    Erdogan, Ercan; Tasal, Abdurrrahman; Vatankulu, Mehmet Akif; Kul, Seref; Sevgili, Emrah; Ertas, Gokhan; Dizman, Didem; Onsun, Nahide; Uysal, Omer

    2013-01-01

    Purpose Psoriasis vulgaris is one of the most common skin disorders. Patients with psoriasis carry an excessive risk of atrial fibrillation (AF). The differences between the maximum (Pmax) and the minimum (Pmin) P-wave duration on ECG are defined as P-wave dispersion (PWD). Prolongation of PWD is an independent risk factor for the development of AF. The aim of this the study was to investigate P-wave duration and PWD in patients with psoriasis. Methods Sixty-one adult patients with psoriasis vulgaris (group 1) and 58 age and sex-matched healthy individuals (group 2) were included in this study. ECG recordings were obtained, and the P-wave variables were calculated. Results were reported as mean standard deviation and percentages. Continuous variables were analysed using Student's t test. A value of P < 0.05 was considered statistically signi?cant. Results Pmax and PWD were significantly higher in group 1 than in group 2 (108.8 21.3 ms versus 93.3 13.0 ms, P < 0.001; 67.4 22.9 ms versus 45.0 19.6 ms, P < 0.001, respectively). Also, Pmin was significantly lower in group 1 (41.3 12.3 ms versus 48.3 14.3 ms, P = 0.04). The psoriasis disease activity score and hsCRP correlated with PWD (P < 0.01). Conclusions Atrial conduction of sinus impulses was impaired in patients with psoriasis vulgaris. It was more prominent in patients with severe disease. Physicians caring for patients with psoriasis vulgaris should screen them for AF development. PMID:23153368

  5. Observation and modelling of P-wave polarization for teleseismic events

    NASA Astrophysics Data System (ADS)

    Cristiano, Luigia; Minakov, Alexander; Meier, Thomas; Keers, Henk

    2014-05-01

    P-wave polarization may yield valuable information on lateral heterogeneity and anisotropy of the crust and uppermost mantle. Using 20 years of the Gräfenberg (GRF) array data we show that stable measurements of P-wave polarization attributes - azimuthal deviation and incidence angle - may be obtained by automated data processing. The P-wave polarization at the GRF array is frequency dependent and a function of backazimuth. By applying harmonic analysis, properties of the 180° and 360° periodicities of azimuthal deviation and incidence angle as a function of backazimuth are quantified. The observations point to the presence of azimuthal anisotropy and lateral heterogenetiy in the crust and uppermost mantle in the vicinity of the stations. The fast propagation direction of P-waves and lateral velocity gradients of P-wave velocity may be estimated based on results of the harmonic analysis. For the GRF array the fast direction of P-wave propagation is found to be about 20° in the frequency range from 0.03 to 0.1Hz that is mainly sensitive to the lower crust and the uppermost mantle. At higher frequencies from 0.1 to 0.5 Hz, mainly related to the upper crust, the variability is larger with a predominant direction of fast P-wave propagation of about 100°. In order to investigate the sensitivity of P-wave polarization to azimuthal anisotropy quantitatively, full waveform forward modellings are performed using 3D Elastic Ray-Born Modelling. Ray and ray-Born techniques have proven their importance in seismology as all travel time tomography is based on ray tracing and all finite frequency travel time and amplitude kernels are based on ray-Born theory. Moreover ray and ray-Born methods are relatively fast and specifically valid at high frequencies. Thus these methods complement the finite-difference and spectral-element full waveform modelling methods . The actual implementation is done using an isotropic background medium with an anisotropic medium perturbation characterized by the 3 Thomsen parameters (which were originally developed for use in hydrocarbon exploration). The ray tracing through the background model is done using 4th order Runge-Kutta and the background model maybe 1D or 3D. Kinematic ray tracing is used for the computation of the travel times and dynamic ray tracing is used for the computation of the amplitudes. In our numerical examples we use a velocity model with a horizontal size 2000 km and depth 1000 km. The background model is a smoothed version of PREM. The 3D anisotropic perturbation has a Gaussian shape and is placed 30 km below the receiver. The modelling is done for earthquakes located within an annulus around the receiver. The inner radius of the annulus is 1400 km and its outer radius is 1900 km. All three components of the seismograms have been computed and are shown. These seismograms are used to perform a synthetic polarization analysis of the P-phase. The effects of the strength, depth and horizontal location of the anisotropic perturbation are investigated. Finally, we compute and show sensitivity attributes for the polarization parameters.

  6. p-wave optical Feshbach resonances in {sup 171}Yb

    SciTech Connect

    Goyal, Krittika; Deutsch, Ivan; Reichenbach, Iris

    2010-12-15

    We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized {sup 171}Yb spin-1/2 fermions. A laser exciting two colliding atoms to the {sup 1}S{sub 0}+{sup 3}P{sub 1} channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schroedinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized {sup 171}Yb, where the three colors correspond to the three spatial orbitals of the first excited p band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.

  7. Observation of continuous microseismic P waves in Asia

    NASA Astrophysics Data System (ADS)

    Sheen, Dong-Hoon; Shin, Jin Soo

    2016-01-01

    We investigate the characteristics of spectral peaks at a frequency of around 0.2 Hz in the double-frequency microseismic band. During the Northern Hemisphere winter, these peaks are clearly and very persistently observed for several months at most seismic stations in Asia. Polarization analysis shows that this energy consistently propagates from a certain direction toward the Pacific Ocean. Using the rectilinearity and phase difference between the vertical and radial motions, we discriminate these peaks from typical Rayleigh wave microseisms that are locally generated and aperiodically continue for several days. A frequency-wave number (FK) analysis of the seismic array indicated that the peaks propagated with velocities typical of mantle phases, which implies that these peaks are microseismic P waves. Backprojection of the FK results and triangulation of back azimuths from individual seismic stations in Asia showed that these microseismic P waves were probably generated near the northern center of the Pacific, which accords well with previous observations. This suggests that microseismic P waves generated in the North Pacific can be identified easily even at individual seismic stations in interior continental Asia. Therefore, these stations will provide more information for characterizing global storm behavior.

  8. Detection of regular variations in the intensity and pulse time of arrival of the anomalous pulsar PSR B0943+10

    NASA Astrophysics Data System (ADS)

    Suleymanova, S. A.; Rodin, A. E.

    2014-11-01

    Timing of the anomalous pulsar PSR B0943+10 during 2007-2013 was carried out on the Large Phased Array radio telescope of the Pushchino Radio Astronomy Observatory at 112 MHz. The astrometric and rotational parameters for epoch MJD=56 500 have been determined. Considerable deviations of the pulse times of arrival from the precalculated values with a characteristic period of several years due to the presence of correlated low-frequency noise in the pulsar spin phase have been detected. These deviations can be explained in a planetary model by the presence of two companions of the pulsar, whose orbital parameters have been determined. A continuous increase in the longitude of the pulse maximum within the emission window, the pulse width, and the intensity have been detected after each switch to the burst mode. Together with the changes in pulse shape, degree of linear polarization of the pulse, and drift rate of individual pulses detected earlier, this indicates that all the main parameters of the radio emission in the B mode are unstable. This distinguishes PSR B0943+10 from all other modes-witching pulsars. The origin of the observed properties of this pulsar are probably associated with the interaction of its extended magnetosphere with the surrounding medium.

  9. INTEGRATING P-WAVE AND S-WAVE SEISMIC DATA TO IMPROVE CHARACTERIZATION OF OIL RESERVOIRS

    SciTech Connect

    Innocent J. Aluka

    2004-12-01

    The data used in this study were acquired by nine-component (9C) vertical seismic profile (VSP), using three orthogonal vector sources. The 9C vertical seismic profile is capable of generating P-wave mode and the fundamental S-wave mode (SH-SH and SV-SV) directly at the source station and permits the basic components of elastic wavefield (P, SH-SH and SV-SV) to be separated from one another for the purposes of imaging. Analysis and interpretations of data from the study area show that incident full-elastic seismic wavefield is capable of reflecting four different wave modes, P, SH , SV and C which can be utilized to fully understand the architecture and heterogeneities of geologic sequences. The conventional seismic stratigraphy utilizes only reflected P-wave modes. The notation SH mode is the same as SH-SH; SV mode means SV-SV and C mode which is a converted shear wave is a special SV mode and is the same as P-SV. These four wave modes image unique geologic stratigraphy and facies and at the same time reflect independent stratal surfaces because of the unique orientation of their particle-displacement vectors. As a result of the distinct orientation of individual mode.s particle-displacement vector, one mode may react to a critical subsurface sequence more than the other. It was also observed that P-wave and S-wave do not always reflect from the same stratal boundaries. At inline coordinate 2100 and crossline coordinates of 10,380, 10430, 10480 and 10,520 the P-wave stratigraphy shows coherency at time slice 796 m/s and C-wave stratigraphy shows coherency at time slice 1964 m/s at the same inline coordinate and crossline coordinates of 10,400 to 10470. At inline coordinate 2800 and crossline coordinate 10,650, P-wave stratigraphy shows coherency at time slice 792 m/s and C-wave stratigraphy shows coherency at time slice 1968 m/s. The utilization of full-elastic seismic wavefield needs to be maximized in oil and gas explorations in order to optimize the search for hydrocarbons.

  10. P-wave attenuation tomography of Mount St. Helens: preliminary results from coda-normalized spectra

    NASA Astrophysics Data System (ADS)

    de Siena, L.; Hicks, S.; Waite, G. P.; Moran, S. C.

    2010-12-01

    The P-wave velocity structure of Mount St. Helens has been recently imaged with local earthquake tomography, using the data recorded since its eruption in 1980. Part of this dataset has been processed to obtain a preliminary frequency dependent Qp image of the crust below the volcanic cone. We extended the so-called coda-normalization method, usually applied to S-waves, to the measurement of path-dependent P-wave attenuation. A scattering model has been developed in order to select the best time-window to measure the P-wave spectral amplitude on each trace. The objective is to average the effect of the source radiation pattern with the properties of early coda. The weighting matrix in the final inversion is dependent on the source radiation pattern and the spectral amplitude of noise. The Discrete Picard Condition and the Discrepancy Principle have been applied to investigate the maximum resolution available in each part of the medium. Truncated Singular Value Decomposition as well as Zeroth-, first- and second-order Tikhonov regularization techniques have been investigated by using the multi-resolution inversion code (MuReATA). The interpretation of the preliminary results is carried out by using cluster analysis on velocity and attenuation measurements.

  11. Molecular phylogeny of Larrea and its allies (Zygophyllaceae): reticulate evolution and the probable time of creosote bush arrival to North America.

    PubMed

    Lia, V V; Confalonieri, V A; Comas, C I; Hunziker, J H

    2001-11-01

    Nucleotide sequences of Rubisco Large Subunit (rbcL) and the internal transcribed spacers (ITS) of nrDNA were obtained for the five species of Larrea and one species each of Bulnesia (ITS only) and Plectrocarpa (rbcL only). Parsimony analyses were conducted, including sequences from seven genera of Zygophyllaceae reported by other authors-Kallstroemia, Zygophyllum, Augea, Fagonia, Pintoa, Guaiacum, and Porlieria. The main conclusions of the present study are (1) the Argentine endemic Plectrocarpa tetracantha belongs to the subfamily Larreoideae (New World Clade); (2) all three phylogenies obtained from rbcL, ITS, and combined data sets show a close relationship between the tetraploid L. cuneifolia (sect. Bifolium) and the diploid multifoliolate pair L. nitida-L. ameghinoi (sect. Larrea), which could result from a possible intersectional hybrid origin of the tetraploid; (3) L. divaricata (sect. Bifolium) and L. tridentata (sect. Bifolium) form a highly supported monophyletic group, which agrees with previous cytogenetic and molecular evidence; and (4) the rate of nucleotide substitution of rbcL was estimated based on geological and fossil records. Under the molecular clock hypothesis, nucleotide sequence divergence between L. divaricata and L. tridentata suggests a Late Neogene (8.4 to 4.2 mybp) time of arrival of the diploid ancestors of L. tridentata to North American deserts. PMID:11697924

  12. Memory of the Lake Rotorua catchment - time lag of the water in the catchment and delayed arrival of contaminants from past land use activities

    NASA Astrophysics Data System (ADS)

    Morgenstern, Uwe; Daughney, Christopher J.; Stewart, Michael K.; McDonnell, Jeffrey J.

    2013-04-01

    The transit time distribution of streamflow is a fundamental descriptor of the flowpaths of water through a catchment and the storage of water within it, controlling its response to landuse change, pollution, ecological degradation, and climate change. Significant time lags (catchment memory) in the responses of streams to these stressors and their amelioration or restoration have been observed. Lag time can be quantified via water transit time of the catchment discharge. Mean transit times can be in the order of years and decades (Stewart et al 2012, Morgenstern et al., 2010). If the water passes through large groundwater reservoirs, it is difficult to quantify and predict the lag time. A pulse shaped tracer that moves with the water can allow quantification of the mean transit time. Environmental tritium is the ideal tracer of the water cycle. Tritium is part of the water molecule, is not affected by chemical reactions in the aquifer, and the bomb tritium from the atmospheric nuclear weapons testing represents a pulse shaped tracer input that allows for very accurate measurement of the age distribution parameters of the water in the catchment discharge. Tritium time series data from all catchment discharges (streams and springs) into Lake Rotorua, New Zealand, allow for accurate determination of the age distribution parameters. The Lake Rotorua catchment tritium data from streams and springs are unique, with high-quality tritium data available over more than four decades, encompassing the time when the bomb-tritium moved through the groundwater system, and from a very high number of streams and springs. Together with the well-defined tritium input into the Rotorua catchment, this data set allows for the best understanding of the water dynamics through a large scale catchment, including validation of complicated water mixing models. Mean transit times of the main streams into the lake range between 27 and 170 years. With such old water discharging into the lake, most of the water inflows into the lake are not yet fully representing the nitrate loading in their sub-catchments from current land use practises. These water inflows are still 'diluted' by pristine old water, but over time, the full amount of nitrate load will arrive at the lake. With the age distribution parameters, it is possible to predict the increase in nitrate load to the lake via the groundwater discharges. All sub-catchments have different mean transit times. The mean transit times are not necessarily correlated with observable hydrogeologic properties like hydraulic conductivity and catchment size. Without such age tracer data, it is therefore difficult to predict mean transit times (lag times, memory) of water transfer through catchments. References: Stewart, M.K., Morgenstern, U., McDonnell, J.J., Pfister, L. (2012). The 'hidden streamflow' challenge in catchment hydrology: A call to action for streamwater transit time analysis. Hydrol. Process. 26,2061-2066, Invited commentary. DOI: 10.1002/hyp.9262 Morgenstern, U., Stewart, M.K., and Stenger, R. (2010) Dating of streamwater using tritium in a post nuclear bomb pulse world: continuous variation of mean transit time with streamflow, Hydrol. Earth Syst. Sci, 14, 2289-2301

  13. Regional P wave velocity structure of the Northern Cascadia Subduction Zone

    USGS Publications Warehouse

    Ramachandran, K.; Hyndman, R.D.; Brocher, T.M.

    2006-01-01

    This paper presents the first regional three-dimensional, P wave velocity model for the Northern Cascadia Subduction. Zone (SW British Columbia and NW Washington State) constructed through tomographic inversion of first-arrival traveltime data from active source experiments together with earthquake traveltime data recorded at permanent stations. The velocity model images the structure of the subducting Juan de Fuca plate, megathrust, and the fore-arc crust and upper mantle. Beneath southern Vancouver Island the megathrust above the Juan de Fuca plate is characterized by a broad zone (25-35 km depth) having relatively low velocities of 6.4-6.6 km/s. This relative low velocity zone coincides with the location of most of the episodic tremors recently mapped beneath Vancouver Island, and its low velocity may also partially reflect the presence of trapped fluids and sheared lower crustal rocks. The rocks of the Olympic Subduction Complex are inferred to deform aseismically as evidenced by the lack of earthquakes withi the low-velocity rocks. The fore-arc upper mantle beneath the Strait of Georgia and Puget Sound is characterized by velocities of 7.2-7.6 km/s. Such low velocities represent regional serpentinization of the upper fore-arc mantle and provide evidence for slab dewatering and densification. Tertiary sedimentary basins in the Strait of Georgia and Puget Lowland imaged by the velocity model lie above the inferred region of slab dewatering and densification and may therefore partly result from a higher rate of slab sinking. In contrast, sedimentary basins in the Strait of Juan de Fuca lie in a synclinal depression in the Crescent Terrane. The correlation of in-slab earthquake hypocenters M>4 with P wave velocities greater than 7.8 km/s at the hypocenters suggests that they originate near the oceanic Moho of the subducting Juan de Fuca plate. Copyright 2006 by the American Geophysical Union.

  14. Hydrodynamic modes of a holographic p-wave superfluid

    NASA Astrophysics Data System (ADS)

    Arias, Raúl E.; Landea, Ignacio Salazar

    2014-11-01

    In this work we analyze the hydrodynamics of a p- wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.

  15. Deuteron P wave in elastic backward proton-deuteron scattering

    NASA Astrophysics Data System (ADS)

    Illarionov, A. Yu.; Lykasov, G. I.

    2001-10-01

    The elastic backward proton-deuteron scattering is analyzed within a covariant approach based on the invariant expansion of the reaction amplitude. The relativistic invariant equations for all the polarization observables are presented. Within the impulse approximation the relation of the tensor analyzing power T20 and the polarization transfer ?0 to the P-wave components of the deuteron wave function is found. Comparison of the theoretical calculations with the experimental data is presented. Experimental verification of the reaction mechanism by constructing some combinations of different observables is suggested.

  16. Impact of Phase Transitions on P Wave Velocities

    SciTech Connect

    D Weidner; L Li

    2011-12-31

    In regions where a high pressure phase is in equilibrium with a low pressure phase, the bulk modulus defined by the P-V relationship is greatly reduced. Here we evaluate the effect of such transitions on the P wave velocity. A model, where cation diffusion is the rate limiting factor, is used to project laboratory data to the conditions of a seismic wave propagating in the two-phase region. We demonstrate that for the minimum expected effect there is a significant reduction of the seismic velocity, as large as 10% over a narrow depth range.

  17. Electron-H P-Wave Elastic Scattering

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.

    2004-01-01

    In previous papers [Bhatia and Temkin, Phys. Rev. A 64, 032709-1 (2001), Phys. Rev. A 66, 064702 (2002)], electron-hydrogen and electron-He(+) S-wave scattering phase shifts were calculated using the optical potential approach. This method is now extended to the singlet and triplet electron-H P-wave scattering in the elastic region. Phase shifts are calculated using Hylleraas-type correlation functions with up to 220 terms. Results are rigorous lower bounds to the exact phase shifts and they are compared to phase shifts obtained from previous calculations.

  18. p-Wave Cold Collisions in an Optical Lattice Clock

    SciTech Connect

    Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Ludlow, A. D.; Stecher, J. von; Rey, A. M.

    2011-09-02

    We study ultracold collisions in fermionic ytterbium by precisely measuring the energy shifts they impart on the atoms' internal clock states. Exploiting Fermi statistics, we uncover p-wave collisions, in both weakly and strongly interacting regimes. With the higher density afforded by two-dimensional lattice confinement, we demonstrate that strong interactions can lead to a novel suppression of this collision shift. In addition to reducing the systematic errors of lattice clocks, this work has application to quantum information and quantum simulation with alkaline-earth atoms.

  19. P Wave Indices: Current Status and Future Directions in Epidemiology, Clinical and Research Applications

    PubMed Central

    Magnani, Jared W.; Williamson, MaryAnn; Ellinor, Patrick T.; Monahan, Kevin M.; Benjamin, Emelia J.

    2009-01-01

    Indices of P wave duration and dispersion are accessible from the surface electrocardiogram. Their prolongation reflects inhomogeneous atrial depolarization secondary to insults such as chronically elevated atrial pressure, ischemia, or metabolic stress. In turn, these insults promote atrial structural remodeling and provide a substrate for atrial fibrillation (AF). P wave indices have been examined in cardiac and non-cardiac disease states. Prolonged P wave indices have been associated with hypertension, obesity and diabetes, all of which are risk factors for AF. Similarly, prolonged P wave duration and dispersion have been associated with AF recurrence in patients with paroxysmal AF and following cardioversion, and with incident AF following cardiothoracic surgeries. Our review describes the current field of P wave indices. We report the methodology for determining P wave indices. We also describe the strengths and limitations of the current literature on the clinical correlates and prognosis of P wave indices. We suggest future clinical and research directions for P wave indices. PMID:19808445

  20. P Wave Amplitudes in the 3d Earth

    NASA Astrophysics Data System (ADS)

    Michaelson, C.; Nolet, G.; Koulakov, I.; Tibuleac, I. M.

    2001-05-01

    The information contained in the amplitudes of seismic phases has so far largely been neglected in the construction of global models for P velocity. While it is generally acknowledged that the effects of focusing/defocusing make amplitudes very sensitive to velocity heterogeneities along the raypath (the ray amplitudes focus with the second derivative of the velocity perpendicular to the path), amplitudes are considered too noisy or too complicated to interpret. As a result, global models differ appriciably in their prediction of P wave amplitude variations.\\With the advent of well calibrated stations of the GSN it seems appropriate to reconsider the question of use of amplitudes in seismological studies of the mantle structure. We report on a pilot study in which we took several measures of the amplitude variations observable in broad-band teleseismic P wave displacement pulses s(t) from deep earthquakes: (1) the zero-to-peak, (2) peak-to-peak, (3) the integral ∫ s(t) dt, and (4) the rms amplitude [ ∫ s(t)2 dt ]1/2. Of these, the latter two appear to to be the most stable. We compare these observed amplitudes with predicted amplitudes for several global 3D models, as well as for a spherically symmetric earth.

  1. Induced p-wave superconductivity without spin-orbit interactions

    NASA Astrophysics Data System (ADS)

    Deus, Fernanda; Continentino, Mucio A.; Caldas, Heron

    2015-11-01

    The study of Majorana fermions is of great importance for the implementation of a quantum computer. These modes are topologically protected and very stable. It is now well known that a p-wave superconducting wire can sustain, in its topological non-trivial phase, Majorana quasi-particles at its ends. Since this type of superconductor is not found in nature, many methods have been devised to implement it. Most of them rely on the spin-orbit interaction. In this paper we study the superconducting properties of a two-band system in the presence of antisymmetric hybridization. We consider inter-band attractive interactions and also an attractive interaction in one of the bands. We show that superconducting fluctuations with p-wave character are induced in the non-interacting band due to the combined effects of inter-band coupling and hybridization. In the case of a wire, this type of induced superconductivity gives rise to four Majorana modes at its ends. The long range correlation between the different charge states of these modes offers new possibilities for the implementation of protected q-bits.

  2. High-frequency P wave spectra from explosions and earthquakes

    NASA Astrophysics Data System (ADS)

    Walter, W. R.; Priestley, K. F.

    1991-08-01

    Two explosion P wave spectral models and two earthquake P wave spectral models are reviewed to assess their implications for high frequency (greater than 1 Hz) seismic discrimination between earthquakes and explosions. The importance of the corner frequency scaling, particularly for models with the same high frequency spectral decay rate, is demonstrated by calculating source spectral ratios (a potentially important regional discriminant) for these models. We compare North American events and a limited data set of Central Asian events with these spectral models. We find North American earthquakes are consistent with a constant stress drop modified Brune model between 10 and 30 Hz. Shallow (less than 700 m depth) Pahute Mesa explosions at the Nevada Test Site have a high frequency spectral decay between 10 and 30 Hz greater than the omega (exp -2) predicted by the explosion models. Near regional recordings of the Soviet Joint Verification Experiment (JVE) explosion show a higher corner frequency and lower 1 to 4 Hz spectral ratios than predicted by either explosion model. The higher corner frequency of the Soviet JVE appears not to be due to attenuation, or receiver effects, and may represent a need for different corner frequency scaling, or result from source complications such as spall and tectonic release. A regional recording of the Soviet JVE (NEIC m sub b equals 6.1) is shown to have a lower 1 to 4 Hz spectral ratio than a smaller earthquake (NEIC m sub b equals 4.6) recorded on a nearly reciprocal path.

  3. Application of scattering theory to P-wave amplitude fluctuations in the crust

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Kazuo; Takemura, Shunsuke; Kobayashi, Manabu

    2015-12-01

    The amplitudes of high-frequency seismic waves generated by local and/or regional earthquakes vary from site to site, even at similar hypocentral distances. It had been suggested that, in addition to local site effects (e.g., variable attenuation and amplification in surficial layers), complex wave propagation in inhomogeneous crustal media is responsible for this observation. To quantitatively investigate this effect, we performed observational, theoretical, and numerical studies on the characteristics of seismic amplitude fluctuations in inhomogeneous crust. Our observations of P-wave amplitude for small to moderately sized crustal earthquakes revealed that fluctuations in P-wave amplitude increase with increasing frequency and hypocentral distance, with large fluctuations showing up to ten-times difference between the largest and the smallest P-wave amplitudes. Based on our theoretical investigation, we developed an equation to evaluate the amplitude fluctuations of time-harmonic waves that radiated isotropically from a point source and propagated spherically in acoustic von Kármán-type random media. Our equation predicted relationships between amplitude fluctuations and observational parameters (e.g., wave frequency and hypocentral distance). Our numerical investigation, which was based on the finite difference method, enabled us to investigate the characteristics of wave propagation in both acoustic and elastic random inhomogeneous media using a variety of source time functions. The numerical simulations indicate that amplitude fluctuation characteristics differ a little between medium types (i.e., acoustic or elastic) or source time function durations. These results confirm the applicability of our analytical equation to practical seismic data analysis.

  4. Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs

    NASA Astrophysics Data System (ADS)

    Abers, Geoffrey A.

    1994-03-01

    Free-air gravity highs over forearcs represent a large fraction of the power in the Earth's anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivals for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25-0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m-3)/(km s-1), when a 50-km-thick slab is included with a density of 0.055±0.005 Mg m-3. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed. The inclusion of upper-plate velocity anomalies predicts the correct width of the anomaly, 100-150 km, where the anomaly is most positive. Because the forearc gravity high is continuous along the entire Aleutian arc and is found in most arcs globally, high upper-plate forearc velocities are suspected to be a common feature of the upper plate of most subduction zones. The forearc mass excesses appear to be sustained by upward regional flexure of the upper plate that partly balances the depression of the lower plate at the trench, thus elevating high-density and high-velocity material. Thus a part of the downward flexure of the subducting plate is regionally compensated by shallow positive mass anomalies in the upper plate, and the strength of the upper plate helps generate the forearc gravity highs.

  5. Association of hematological variables and castration status at the time of arrival at a research facility with the risk of bovine respiratory disease in beef calves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to analyze the association between hematological parameters (CBC) and gender at stocker receiving facility arrival and the risk of subsequent clinical bovine respiratory disease (BRD) diagnosis, and (2) to determine and evaluate the accuracy of CBC parameter threshold...

  6. Time-of-Arrival Measurements of X-ray Emission Associated with Dart-Stepped Leader Steps in Natural and Rocket-and-Wire Triggered Lightning

    NASA Astrophysics Data System (ADS)

    Jordan, D. M.; Hill, J. D.; Uman, M. A.; Dwyer, J. R.; Rassoul, H. K.

    2012-12-01

    Time-of-arrival (TOA) techniques were used to determine the three-dimensional locations and emission times of x-ray and dE/dt sources measured at ground level in association with dart-stepped leader steps in natural and rocket-and-wire triggered lightning discharges recorded during summer 2011 at Camp Blanding, FL. The measurement network consisted of ten flat plate dE/dt antennas approximately co-located with eight plastic and two Lanthanum Bromide scintillation detectors arrayed around the launching facility over an area of about 0.25 square kilometers. For two triggered lightning dart-stepped leaders, x-ray sources were emitted from locations separated by average distances of 22.7 m and 29 m, respectively, from the locations of the associated dE/dt pulse peaks. The x-ray sources occurred beneath the dE/dt sources in 88% of the cases. X-rays were emitted from 20 ns to 2.16 μs following the dE/dt pulse peaks, with average temporal separations of 150 ns and 290 ns, respectively, for the two triggered lightning events. For one natural lightning dart-stepped leader, x-ray sources were emitted an average total distance of 39.2 m from the associated dE/dt pulse peak, and occurred beneath the location of the dE/dt source in 86% of the cases. The x-rays were emitted from 10 ns to 1.76 μs following the dE/dt pulse peak with an average temporal separation of 280 ns. In each of the three events, the altitude displacement between the dE/dt and x-ray sources dominated the total separation, accounting for 90%, 63%, and 72%, respectively, of the total separation. X-ray sources were distributed randomly in the lateral directions about the lightning channel in each event. For the triggered lightning events, x-rays were located from 2.5-83.5 μs prior to the return stroke at altitudes ranging from 24-336 m. For the natural lightning event, x-rays were located from 40.4-222.3 μs prior to the return stroke at altitudes ranging from 99-394 m. Cumulatively, 67% of the located x-ray sources occurred between 60-280 m in altitude. Inferences on the properties of the propagating dart-stepped leaders are given based on the TOA analyses and observations of the x-ray emission at ground level as a function of the leader-tip altitude are discussed.

  7. Majorana zero modes in the hopping-modulated one-dimensional p-wave superconducting model

    PubMed Central

    Gao, Yi; Zhou, Tao; Huang, Huaixiang; Huang, Ran

    2015-01-01

    We investigate the one-dimensional p-wave superconducting model with periodically modulated hopping and show that under time-reversal symmetry, the number of the Majorana zero modes (MZMs) strongly depends on the modulation period. If the modulation period is odd, there can be at most one MZM. However if the period is even, the number of the MZMs can be zero, one and two. In addition, the MZMs will disappear as the chemical potential varies. We derive the condition for the existence of the MZMs and show that the topological properties in this model are dramatically different from the one with periodically modulated potential. PMID:26586205

  8. Majorana zero modes in the hopping-modulated one-dimensional p-wave superconducting model

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhou, Tao; Huang, Huaixiang; Huang, Ran

    2015-11-01

    We investigate the one-dimensional p-wave superconducting model with periodically modulated hopping and show that under time-reversal symmetry, the number of the Majorana zero modes (MZMs) strongly depends on the modulation period. If the modulation period is odd, there can be at most one MZM. However if the period is even, the number of the MZMs can be zero, one and two. In addition, the MZMs will disappear as the chemical potential varies. We derive the condition for the existence of the MZMs and show that the topological properties in this model are dramatically different from the one with periodically modulated potential.

  9. Majorana zero modes in the hopping-modulated one-dimensional p-wave superconducting model.

    PubMed

    Gao, Yi; Zhou, Tao; Huang, Huaixiang; Huang, Ran

    2015-01-01

    We investigate the one-dimensional p-wave superconducting model with periodically modulated hopping and show that under time-reversal symmetry, the number of the Majorana zero modes (MZMs) strongly depends on the modulation period. If the modulation period is odd, there can be at most one MZM. However if the period is even, the number of the MZMs can be zero, one and two. In addition, the MZMs will disappear as the chemical potential varies. We derive the condition for the existence of the MZMs and show that the topological properties in this model are dramatically different from the one with periodically modulated potential. PMID:26586205

  10. High-frequency P wave spectra from explosions and earthquakes

    NASA Astrophysics Data System (ADS)

    Walter, William R.; Priestley, Keith F.

    Two explosion P wave spectral models [Sharpe, 1942; Mueller-Murphy, 1971] and two earthquake P wave spectral models [Archambeau, 1968, 1972; modified Brune 1970, 1971] are reviewed to assess their implications for high-frequency (>1 Hz) seismic discrimination between earthquakes and explosions. The importance of the corner frequency scaling, particularly for models with the same high-frequency spectral decay rate, is demonstrated by calculating source spectral ratios (a potentially important regional discriminant) for these models. We compare North American events and a limited data set of Central Asian events with these spectral models. We find North American earthquakes are consistent with a constant stress drop modified Brune model between 10 and 30 Hz. Shallow (<700 m depth) Pahute Mesa explosions at the Nevada Test Site have a high-frequency spectral decay between 10 and 30 Hz greater than the ω-2 predicted by the explosion models. Near regional recordings of the Soviet Joint Verification Experiment (JVE) explosion show a higher corner frequency and lower 1 to 4 Hz spectral ratios than predicted by either explosion model. The higher corner frequency of the Soviet JVE appears not to be due to attenuation, or receiver effects, and may represent a need for different corner frequency scaling, or result from source complications such as spall and tectonic release. A regional recording of the Soviet JVE (NEIC mb = 6.1) is shown to have a lower 1 to 4 Hz spectral ratio than a smaller earthquake (NEIC mb = 4.6) recorded on a nearly reciprocal path.

  11. Relationship between macro-fracture density, P-wave velocity, and permeability of coal

    NASA Astrophysics Data System (ADS)

    Wang, Haichao; Pan, Jienan; Wang, Sen; Zhu, Haitao

    2015-06-01

    This study was undertaken to determine the quantitative relationship between macro-fracture density, P-wave velocity, porosity and permeability of different coal rank samples from mining areas in North China. The coal sample permeability shows an exponential growth with increasing fracture density. The relation between P-wave velocity and porosity is power function and P-wave velocity decreases with the increasing porosity. P-wave velocity linearly or nonlinearly decreases with the increase of fracture density in the selected coal samples (0.73-3.59% Ro). However, the overall trend is that P-wave velocity decreases with an increase in macro-fracture density. The permeability of coal samples linearly decreases with the increase of P-wave velocity. The quantitative relationship between P-wave velocity and permeability could provide reference for the further study of permeability predicting.

  12. The influence of speed, cyclists' age, pedaling frequency, and observer age on observers' time to arrival judgments of approaching bicycles and e-bikes.

    PubMed

    Schleinitz, Katja; Petzoldt, Tibor; Krems, Josef F; Gehlert, Tina

    2016-07-01

    Given their potential to reach higher speed levels than conventional bicycles, the growing market share of e-bikes has been the reason for increased concerns regarding road safety. Previous studies have shown a clear relationship between object approach speed and an observers' judgment of when the object would reach a predefined position (i.e., time to arrival, TTA), with higher speed resulting in longer TTA estimates. Since TTA estimates have been linked to road users' decisions of whether or not to cross or turn in front of approaching vehicles, the higher potential speeds of e-bikes might result in an increased risk for traffic conflicts. The goal of the two experiments presented in this paper was to examine the influence of speed and a variety of other factors on TTA estimation for conventional bicycles and for e-bikes. In both experiments, participants from two age groups (20-45 years old and 65 years or older) watched video sequences of bicycles approaching at different speeds (15-25km/h) and were asked to judge the TTA at the moment the video was stopped. The results of both experiments showed that an increase in bicycle approach speed resulted in longer TTA estimates (measured as the proportion of estimated TTA relative to actual TTA) for both bicycle types (ηp(2)Exp.1=.489, ηp(2)Exp.2=.705). Compared to younger observers, older observers provided shorter estimates throughout (Exp. I: MDiff=0.35, CI [0.197, 0.509], ηp(2)=.332, Exp. II: MDiff=0.50, CI [.317, 0.682], ηp(2)=.420). In Experiment I, TTA estimates for the conventional bicycle were significantly shorter than for the e-bike (MDiff=0.03, CI [.007, 0.044], ηp(2)=.154), as were the estimates for the elder cyclist compared to the younger one (MDiff=0.05, CI [.025, 0.066], ηp(2)=.323). We hypothesized that the cause for this effect might lie in the seemingly reduced pedaling effort for the e-bike as a result of the motor assistance it provides. Experiment II was able to show that a high pedaling frequency indeed resulted in shorter TTA estimates compared to a low one (MDiff=0.07, CI [0.044, 0.092], ηp(2)=.438). Our findings suggest that both the e-bikes' potential to reach higher speeds and the fact that they reduce the perceived cycling effort increase the risk of TTA misjudgments by other road users. PMID:27058264

  13. Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion Data in the Wavelet Domain Constrained by Sparsity Regularization

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Fang, H.; Yao, H.; Maceira, M.; van der Hilst, R. D.

    2014-12-01

    Recently, Zhang et al. (2014, Pure and Appiled Geophysics) have developed a joint inversion code incorporating body-wave arrival times and surface-wave dispersion data. The joint inversion code was based on the regional-scale version of the double-difference tomography algorithm tomoDD. The surface-wave inversion part uses the propagator matrix solver in the algorithm DISPER80 (Saito, 1988) for forward calculation of dispersion curves from layered velocity models and the related sensitivities. The application of the joint inversion code to the SAFOD site in central California shows that the fault structure is better imaged in the new model, which is able to fit both the body-wave and surface-wave observations adequately. Here we present a new joint inversion method that solves the model in the wavelet domain constrained by sparsity regularization. Compared to the previous method, it has the following advantages: (1) The method is both data- and model-adaptive. For the velocity model, it can be represented by different wavelet coefficients at different scales, which are generally sparse. By constraining the model wavelet coefficients to be sparse, the inversion in the wavelet domain can inherently adapt to the data distribution so that the model has higher spatial resolution in the good data coverage zone. Fang and Zhang (2014, Geophysical Journal International) have showed the superior performance of the wavelet-based double-difference seismic tomography method compared to the conventional method. (2) For the surface wave inversion, the joint inversion code takes advantage of the recent development of direct inversion of surface wave dispersion data for 3-D variations of shear wave velocity without the intermediate step of phase or group velocity maps (Fang et al., 2014, Geophysical Journal International). A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. We will test the new joint inversion code at the SAFOD site to compare its performance over the previous code. We will also select another fault zone such as the San Jacinto Fault Zone to better image its structure.

  14. Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion Data for Three-Dimensional Seismic Velocity Structure Around SAFOD

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Thurber, C. H.; Maceira, M.; Roux, P.

    2013-12-01

    The crust around the San Andreas Fault Observatory at depth (SAFOD) has been the subject of many geophysical studies aimed at characterizing in detail the fault zone structure and elucidating the lithologies and physical properties of the surrounding rocks. Seismic methods in particular have revealed the complex two-dimensional (2D) and three-dimensional (3D) structure of the crustal volume around SAFOD and the strong velocity reduction in the fault damage zone. In this study we conduct a joint inversion using body-wave arrival times and surface-wave dispersion data to image the P-and S-wave velocity structure of the upper crust surrounding SAFOD. The two data types have complementary strengths - the body-wave data have good resolution at depth, albeit only where there are crossing rays between sources and receivers, whereas the surface waves have very good near-surface resolution and are not dependent on the earthquake source distribution because they are derived from ambient noise. The body-wave data are from local earthquakes and explosions, comprising the dataset analyzed by Zhang et al. (2009). The surface-wave data are for Love waves from ambient noise correlations, and are from Roux et al. (2011). The joint inversion code is based on the regional-scale version of the double-difference (DD) tomography algorithm tomoDD. The surface-wave inversion code that is integrated into the joint inversion algorithm is from Maceira and Ammon (2009). The propagator matrix solver in the algorithm DISPER80 (Saito, 1988) is used for the forward calculation of dispersion curves from layered velocity models. We examined how the structural models vary as we vary the relative weighting of the fit to the two data sets and in comparison to the previous separate inversion results. The joint inversion with the 'optimal' weighting shows more clearly the U-shaped local structure from the Buzzard Canyon Fault on the west side of SAF to the Gold Hill Fault on the east side.

  15. Further evidence for P-wave complexity in regions with slow slip events

    NASA Astrophysics Data System (ADS)

    Dougherty, S. L.; Zhan, Z.; Helmberger, D. V.; Chu, R.; Chen, T.; Clayton, R. W.; Kanamori, H.

    2009-12-01

    A recent study on subduction beneath Central America indicates that there is a relationship between slow slip events (SSE’s) and the complexity of P-waves. Simple P waveforms indicate normal slab conditions with no occurrences of SSE’s whereas complex P waveforms imply the presence of a thin ultra-slow velocity layer (USL) and SSE’s. Here, we further test this hypothesis in two regions that have SSE’s and have a dense set of local stations; southwest Japan and southern Mexico. The former has the Hi-net array (2D) while the latter has a dense line across Mexico, from Veracruz to Oaxaca, consisting of 47 stations. Both regions display some complex P waveforms on local stations and teleseismically on individual broadband seismographs and on short period monitoring arrays. We use forward modeling of the 2D structure of the subducted plate in each region using a finite-difference algorithm in order to provide constraints on the thickness, velocity, and spatial extent of the possible USL. Unfortunately, both regions have abrupt changes in slab dip which apparently complicates the analysis and requires refinement of both slab geometry and source parameters. Nevertheless, complexity at the top of the slab is needed to explain the strong secondary arrivals observed.

  16. Improved P-wave Tomography of the Lowermost Mantle and Consequences for Mantle and Core Dynamics

    NASA Astrophysics Data System (ADS)

    Tkalcic, H.; Young, M. K.; Muir, J. B.

    2014-12-01

    The core mantle boundary (CMB) separates the liquid iron core from the slowly-convecting solid mantle. The ~300 km thick barrier above the boundary has proven to be far more than a simple dividing layer; rather it is a complex region with a range of proposed phenomena such as thermal and compositional heterogeneity, partial melting and anisotropy. Characterizing the heterogeneity in the lowermost mantle through seismic tomography will prove crucial to accurately understanding key geodynamical processes within our planet, not just in the mantle above, but also a possible "mapping" onto the inner core boundary (ICB) through a thermochemical convection in the outer core, which in turn might control the growth of the inner core (e.g. Aubert et al., 2008; Gubbins et al., 2011). Here we obtain high-resolution compressional wave (P-wave) velocity images and uncertainty estimates for the lowermost mantle using travel time data collected by waveform cross-correlation. Strikingly, independent datasets of seismic phases that "see" the lowermost mantle in a different way yield similar P-wave velocity distributions at lower harmonic degrees. We also consider the effect of CMB topography. The images obtained are void of explicit model parameterization and regularization (through transdimensional Bayesian tomography) and contain features on multiple spatial scales. Subsequent spectral analyses reveal a power of heterogeneity three times larger than previous estimates. The P-wave tomograms of the lowermost mantle contain the harmonic degree 2-structure, similar to tomographic images derived from S-wave data (e.g. Ritsema et al. 2011), but with additional higher harmonic degrees (notably, 3-7). In other words, the heterogeneity size is uniformly distributed between about 500 and 6000 km. Inter alia, the resulting heterogeneity spectrum provides a bridge between the long-wavelength features of most global models and the very short-scale dimensions of scatterers mapped in independent studies. We argue that the new images of P-wave velocity in the lowermost mantle, void of explicit parameterization and damping, improve the imaging resolution and provide realistic boundary conditions at the CMB (due to a high sensitivity to heat flux) with important consequences for Earth dynamics.

  17. Crustal structure of Deception Island volcano from P wave seismic tomography: Tectonic and volcanic implications

    NASA Astrophysics Data System (ADS)

    Zandomeneghi, Daria; Barclay, Andrew; Almendros, Javier; IbañEz Godoy, Jesús M.; Wilcock, William S. D.; Ben-Zvi, Tami

    2009-06-01

    Deception Island (62°59'S, 60°41'W) is an active volcano located in the Bransfield Strait between the Antarctic Peninsula and the South Shetland Islands. The island is composed of rocks that date from <0.75 Ma to historical eruptions (1842, 1967, 1969, and 1970), and nowadays most of its activity is represented by vigorous hydrothermal circulation, slight resurgence of the inner bay floor, and intense seismicity, with frequent volcano-tectonic and long-period events. In January 2005 an extensive seismic survey took place in and around the island to collect high-quality data for a high-resolution P wave velocity tomography study. A total of 95 land and 14 ocean bottom seismometers were deployed, and more than 6600 air gun shots were fired. As a result of this experiment, more than 70,000 travel time data were used to obtain the velocity model, which resolves strong P wave velocity contrasts down to 5 km depth. The joint interpretation of the Vp distribution together with the results of geological, geochemical, and other geophysical (magnetic and gravimetric) measurements allows us to map and interpret several volcanic features of the island and surroundings. The most striking feature is the low P wave velocity beneath the caldera floor which represents the seismic image of an extensive region of magma beneath a sediment-filled basin. Another low-velocity zone to the east of Deception Island corresponds to seafloor sedimentary deposits, while high velocities to the northwest are interpreted as the crystalline basement of the South Shetland Islands platform. In general, in the tomographic image we observe NE-SW and NW-SE distributions of velocity contrasts that are compatible with the regional tectonic directions and suggest that the volcanic evolution of Deception Island is strongly conditioned by the Bransfield Basin geodynamics.

  18. GPS/Loran-C interoperability for time and frequency applications: A survey of the times of arrival of Loran-C transmissions via GPS common mode/common view satellite observations

    NASA Technical Reports Server (NTRS)

    Penrod, Bruce; Funderburk, Richard; Dana, Peter

    1990-01-01

    The results from this survey clearly indicate that the Global Positioning System (GPS) time transfer capability is superior to that of the Loran-C system for absolute timing accuracy, and that even with the most careful calibration of the Loran-C receiver delay and propagation path, inexplicable time of arrival (TOA) biases remain which are larger than the variations across all of the transmitters. Much more data covering years would be needed to show that these biases were stable enough to be removed with a one time site calibration. The synchronization of the transmissions is excellent, all showing low parts in 10(exp 13) offsets versus the United States Naval Observatory (USNO) master clock. With the exception of the Searchlight transmitter, all of the transmissions exhibit timing stabilities over the entire period of less than 300 ns RMS which is at the observed levels of GPS under selective availability (SA). The Loran-C phase instabilities take place over a much greater time interval than those being forced onto the GPS signals under SA, providing for better medium to short term frequency stability. Data show that all but the most distant transmitters offer better than three parts in 10(exp 11) stability at this averaging time. It is in the frequency control area where GPS/Loran-C interoperation will offer some synergistic advantages over GPS alone under SA.

  19. Derivation of site-specific relationships between hydraulic parameters and p-wave velocities based on hydraulic and seismic tomography

    SciTech Connect

    Brauchler, R.; Doetsch, J.; Dietrich, P.; Sauter, M.

    2012-01-10

    In this study, hydraulic and seismic tomographic measurements were used to derive a site-specific relationship between the geophysical parameter p-wave velocity and the hydraulic parameters, diffusivity and specific storage. Our field study includes diffusivity tomograms derived from hydraulic travel time tomography, specific storage tomograms, derived from hydraulic attenuation tomography, and p-wave velocity tomograms, derived from seismic tomography. The tomographic inversion was performed in all three cases with the SIRT (Simultaneous Iterative Reconstruction Technique) algorithm, using a ray tracing technique with curved trajectories. The experimental set-up was designed such that the p-wave velocity tomogram overlaps the hydraulic tomograms by half. The experiments were performed at a wellcharacterized sand and gravel aquifer, located in the Leine River valley near Göttingen, Germany. Access to the shallow subsurface was provided by direct-push technology. The high spatial resolution of hydraulic and seismic tomography was exploited to derive representative site-specific relationships between the hydraulic and geophysical parameters, based on the area where geophysical and hydraulic tests were performed. The transformation of the p-wave velocities into hydraulic properties was undertaken using a k-means cluster analysis. Results demonstrate that the combination of hydraulic and geophysical tomographic data is a promising approach to improve hydrogeophysical site characterization.

  20. Predicting the macroseismic intensity from early radiated P wave energy for on-site earthquake early warning in Italy

    NASA Astrophysics Data System (ADS)

    Brondi, P.; Picozzi, M.; Emolo, A.; Zollo, A.; Mucciarelli, M.

    2015-10-01

    Earthquake Early Warning Systems (EEWS) are potentially effective tools for risk mitigation in active seismic regions. The present study explores the possibility of predicting the macroseismic intensity within EEW timeframes using the squared velocity integral (IV2) measured on the early P wave signals, a proxy for the P wave radiated energy of earthquakes. This study shows that IV2 correlates better than the peak displacement measured on P waves with both the peak ground velocity and the Housner Intensity, with the latter being recognized by engineers as a reliable proxy for damage assessment. Therefore, using the strong motion recordings of the Italian Accelerometric Archive, a novel relationship between the parameter IV2 and the macroseismic intensity (IM) has been derived. The validity of this relationship has been assessed using the strong motion recordings of the Istituto Nazionale di Geofisica e Vulcanologia Strong Motion Data and Osservatorio Sismico delle Strutture databases, as well as, in the case of the MW 6, 29 May 2012 Emilia earthquake (Italy), comparing the predicted intensities with the ones observed after a macroseismic survey. Our results indicate that P wave IV2 can become a key parameter for the design of on-site EEWS, capable of proving real-time predictions of the IM at target sites.

  1. Rupture history of the 1997 Cariaco, Venezuela, earthquake from teleseismic P waves

    USGS Publications Warehouse

    Mendoza, C.

    2000-01-01

    A two-step finite-fault waveform inversion scheme is applied to the broadband teleseismic P waves recorded for the strike-slip, Cariaco, Venezuela, earthquake of 9 July 1997 to recover the distribution of mainshock slip. The earthquake is first analyzed using a long narrow fault with a maximum rise time of 20 sec. This line-source analysis indicates that slip propagated to the west with a constant rupture velocity and a relatively short rise time. The results are then used to constrain a second inversion of the P waveforms using a 60-km by 20-km two-dimensional fault. The rupture shows a zone of large slip (1.3-m peak) near the hypocenter and a second, broader source extending updip and to the west at depths shallower than 5 km. The second source has a peak slip of 2.1 meters and accounts for most of the moment of 1.1 × 1026 dyne-cm (6.6 Mww) estimated from the P waves. The inferred rupture pattern is consistent with macroseismic effects observed in the epicentral area.

  2. Prediction of maintenance of sinus rhythm after cardioversion of atrial fibrillation by analysis of serial signal-averaged P waves.

    PubMed

    Stafford, P J; Kamalvand, K; Tan, K; Vincent, R; Sulke, N

    1998-07-01

    After cardioversion from atrial fibrillation (AF) many patients develop early recurrence of the arrhythmia. While these patients may be appropriate for immediate prophylaxis against AF recurrence their identification at the time of cardioversion is not possible. Since the signal-averaged P wave (SAPW) is abnormal in individuals with atrial arrhythmia, we assessed its utility for predicting early AF recurrence after cardioversion. Seventy-five cardioversions in 31 patients were evaluated. The mean age was 59 (range 28-79) years; 26 were male. Fifty-eight cardioversions were internal using low energy biphasic DC shocks delivered via electrodes placed in the right atrial appendage and coronary sinus. P wave specific signal averaging was performed at 3 and 24 hours after each cardioversion to estimate filtered P wave duration and energy from 20, 40, and 60 to 150 Hz. Follow-up was by regular clinic visits and transtelephonic ECG monitoring. Early recurrence of AF (prospectively defined as sinus rhythm duration < 1 week) occurred after 30 cardioversions. No differences were found in any P wave variable measured at 3 hours between these cardioversions and those that resulted in a longer duration of sinus rhythm. Paired 3- and 24-hour signal-averaged data were available in 47 cardioversions. There were significant falls in P wave energy from 3 to 24 hours after 31 cardioversions that resulted in sinus rhythm for > 1 week, (P40: 3 hours 11.2 [+/- 1.5] micro V2.s, 24 hours 8.6 [+/- 1.2] micro V2.s, P < 0.001), but not following the 16 after which AF returned within 1 week (P40: 3 hours 9.0 [+/- 1.2] micro V2.s, 24 hours 8.5 [+/- 1.2 micro V2.s, P = NS). A fall in P40 of > 25% had a positive predictive accuracy for maintenance of sinus rhythm of 87%; negative predictive accuracy was only 37%. Similar falls in P wave energy occurred after cardioversions that resulted in longer term (> 4 weeks) sinus rhythm, but not in those that did not. However, the predictive accuracy of a fall in P40 was less (positive predictive accuracy 38%, negative predictive accuracy 62%). Patients with relapsing permanent AF who remain in sinus rhythm for at least 1 week after cardioversion show a fall in P wave energy within the first 24 hours. However, in these patients the technique does not predict recurrent AF within 1 week nor sinus rhythm > 4 weeks. These observations suggest persistent disordered atrial activation as a mechanism for early recurrence of AF after cardioversion. PMID:9670182

  3. Seismic modelling study of P-wave attenuation and velocity dispersion in patchy-saturated porous media

    NASA Astrophysics Data System (ADS)

    Li, Xiaobo; Dong, Liangguo; Zhao, Qun

    2014-12-01

    Seismic wave propagation in patchy-saturated porous media is studied by numerical simulation in time domain at the seismic frequency band (1-1000 Hz). The models consist of hundreds of representative elementary volumes (REVs), where the REV is partially saturated with water and gas pockets. Seismic modelling experiments are implemented in a traditional way, with ‘periodic’ boundary conditions applied to get rid of undrained boundary conditions at the outer edges of the REVs. The characteristics of confining pressure, induced pore pressure, solid particle velocities and Darcy filtration velocities are analysed. The snapshots show that strong pore pressure gradients are generated across the interface between gas and water phases, and significant fluid flow occurs. The conversion of a fast P-wave into a dissipating slow P-wave takes place at seismic frequencies, and the converted slow P-wave diffuses strongly in both gas- and water-saturated phases. These numerical results can help us to understand the loss mechanism at seismic frequencies. Then, P-wave attenuation and velocity dispersion of a heterogeneous REV are calculated during traditional seismic modelling at seismic frequencies. The numerical results show good agreement with theoretical predictions obtained from patchy saturation theory. Furthermore, the effects of different fluid distributions on P-wave attenuation and velocity dispersion are analysed numerically. A series of experiments are implemented by considering large, small and random gas-patchy inclusions. The decrease of gas pocket size makes the peak frequency move towards high frequencies. Random distribution of gas patches may affect both the peak attenuation and peak frequencies. Seismic attenuation caused by Biot global flow, elastic scattering and wave-induced fluid flow (WIFF) associated with patchy saturation are computed numerically. The results show that the contribution of Biot’s global flow and scattering to the overall attenuation are negligible. Mesoscopic WIFF may dominate the loss mechanism in patchy-saturated media at seismic frequencies (1-1000 Hz).

  4. Non-topological nature of the edge current in a chiral p-wave superconductor

    NASA Astrophysics Data System (ADS)

    Taylor, Edward; Huang, Wen; Lederer, Samuel; Kallin, Catherine

    2015-03-01

    The edges of time reversal symmetry breaking topological superconductors support chiral Majorana bound states as well as spontaneous charge currents. The Majorana modes are a robust, topological property, but the charge currents are non-topological-and therefore sensitive to microscopic details-even if we neglect Meissner screening. We give insight into the non-topological nature of edge currents in chiral p-wave superconductors using a variety of theoretical techniques, including lattice Bogoliubov-de Gennes equations, the quasiclassical approximation, and the gradient expansion, and describe those special cases where edge currents do have a topological character. While edge currents are not quantized, they are generically large, but can be substantially reduced for a sufficiently anisotropic gap function, a scenario of possible relevance for the putative chiral p-wave superconductor Sr2RuO4 . Supported by NSERC and CIFAR at McMaster and by the Canada Research Chair and Canada Council Killam programs and NSF Grant No. NSF PHY11-25915 (CK). SL is supported by the DOE Office of Basic Energy Sciences, contract DEAC02-76SF00515

  5. Effective p -wave interaction and topological superfluids in s -wave quantum gases

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Zheng, Zhen; Pu, Han; Zou, Xubo; Guo, Guangcan

    2016-03-01

    p -wave interaction in cold atoms may give rise to exotic topological superfluids. However, the realization of p -wave interaction in a cold atom system is experimentally challenging. Here we propose a simple scheme to synthesize effective p -wave interaction in conventional s -wave interacting quantum gases. The key idea is to load atoms into a spin-dependent optical lattice potential. Using two concrete examples involving spin-1/2 fermions, we show how the original system can be mapped into a model describing spinless fermions with nearest-neighbor p -wave interaction, whose ground state can be a topological superfluid that supports Majorana fermions under proper conditions. Our proposal has the advantage that it does not require spin-orbit coupling or loading atoms onto higher orbitals, which is the key in earlier proposals to synthesize effective p -wave interaction in s -wave quantum gases, and may provide a completely new route for realizing p -wave topological superfluids.

  6. The P-wave boundary of the Large-Low Shear Velocity Province beneath the Pacific

    NASA Astrophysics Data System (ADS)

    Frost, Daniel A.; Rost, Sebastian

    2014-10-01

    The Large Low Shear Velocity Provinces (LLSVPs) in the lower mantle represent volumetrically significant thermal or chemical or thermo-chemical heterogeneities. Their structure and boundaries have been widely studied, mainly using S-waves, but much less is known about their signature in the P-wavefield. We use an extensive dataset recorded at USArray to create, for the first time, a high-resolution map of the location, shape, sharpness, and extent of the boundary of the Pacific LLSVP using P(Pdiff)-waves. We find that the northern edge of the Pacific LLSVP is shallow dipping (26° relative to the horizontal) and diffuse (∼120 km wide transition zone) whereas the eastern edge is steeper dipping (70°) and apparently sharp (∼40 km wide). We trace the LLSVP boundary up to ∼500 km above the CMB in most areas, and 700 km between 120° and 90°W at the eastern extent of the boundary. Apparent P-wave velocity drops are ∼1-3% relative to PREM, indicating a strong influence of LLSVPs on P-wave velocity, at least in the high-frequency wavefield, in contrast to previous studies. A localised patch with a greater velocity drop of ∼15-25% is detected, defined by large magnitude gradients of the travel-time residuals. We identify this as a likely location of an Ultra-Low Velocity Zone (ULVZ), matching the location of a previously detected ULVZ in this area. The boundary of a separate low velocity anomaly, of a similar height to the LLSVP, is detected in the north-west Pacific, matching tomographic images. This outlier appears to be connected to the main LLSVP through a narrow channel close to the CMB and may be in the process of joining or splitting from the main LLSVP. We also see strong velocity increases in the lower mantle to the east of the LLSVP, likely detecting subducted material beneath central America. The LLSVP P-wave boundary is similar to that determined in high-resolution S-wave studies and follows the -0.4% ΔVS iso-velocity contour in the S40RTS tomography model. Additionally, the LLSVP boundary roughly matches the shape of the -0.4% ΔVP iso-velocity contour of the P-wave model GyPSuM but defines an area more similar to that defined by the 0.0% VP iso-velocity contour. High resolution P-wave velocity determination allows for estimation of the ratio of P- and S-wave velocity anomalies (RS,P) which can be used to indicate dominantly thermal or chemical control of seismic velocities. Although the RS,P is found here to be approximately 2.4, which is indicative of a thermo-chemical anomaly. However, this result contains a large amount of uncertainty and the implications for the origin of LLSVPs likely remain inconclusive. Nonetheless, other observations of the Pacific LLSVP are consistent with a thermo-chemical anomaly whose shape and boundary sharpness are controlled by proximity to active and past subduction.

  7. P-wave [cs][cs] tetraquark state: Y(4260) or Y(4660)?

    SciTech Connect

    Zhang Jianrong; Huang Mingqiu

    2011-02-01

    The mass of a P-wave cs-scalar-diquark cs-scalar-antidiquark state is computed in the framework of QCD sum rules. The result 4.69{+-}0.36 GeV is in good agreement with the experimental value of Y(4660) but higher than Y(4260)'s, which supports the P-wave [cs][cs] configuration for Y(4660) while disfavors the interpretation of Y(4260) as the P-wave [cs][cs] state. In the same picture, the mass of P-wave [bs][bs] is predicted to be 11.19{+-}0.49 GeV.

  8. Applications of detailed 3D P-wave velocity crustal model in Poland for local, regional and global seismic tomography

    NASA Astrophysics Data System (ADS)

    Polkowski, Marcin; Grad, Marek

    2015-04-01

    The 3D P-wave seismic velocity model was obtained by combining data from multiple studies during past 50 years. Data sources included refraction seismology, reflection seismology, geological boreholes, vertical seismic profiling, magnetotellurics and gravimetry. Use of many data sources allowed creation of detailed 3D P-wave velocity model that reaches to depth of 60 km and includes 6-layers of sediments and 3-layers of the crust. Purpose of this study is to analyze how 3D model influences local (accuracy of location and source time estimation for local events), regional (identification of wide-angle seismic phases) and global (teleseismic tomography) seismic travel times. Additionally we compare results of forward seismic wave propagation with signals observed on short period and broadband stations. National Science Centre Poland provided financial support for this work by NCN grant DEC-2011/02/A/ST10/00284.

  9. P wave Velocity Structure in the Crust and Upper Mantle Beneath Northeastern South China Sea and Surrounding Regions

    NASA Astrophysics Data System (ADS)

    LI, Zhiwei; XU, Yi; HAO, Tianyao; XU, Ya; LIU, Jingsong

    With the local and teleseismic P wave arrival times from Chinese and International Seismological Centre (ISC) stations, the tomographic inversion was conducted for the three-dimensional velocity structure of the crust and upper mantle beneath the northeastern South China Sea (SCS) and surrounding regions. The tectonic discrepancies and deep geodynamic characters were analyzed based on the tomographic image. High-velocity anomalies at the uppermost mantle beneath the northeastern SCS reveal the extension of the lithospheric mantle from the South China continent to the marginal sea. The cold, thick lithosphere beneath the northeastern SCS inferred from high-velocity anomalies suggests that no magma was intruded from the upper mantle. Therefore, it can be inferred that the rifting of South China continent may only occur inside the crust rather than extend down to the upper mantle. The continental margin of SCS indicates the tectonic nature of passive non-volcanic continental margin. Low-velocity anomalies at the central sub-basin suggest the upwelling of hot materials from the mantle. The high-velocity anomalies in the South China continent and Taiwan region and the low-velocity anomalies at Okinawa Trough delineate the different tectonics of the crust. The former ones belong to the normal crust of Eurasia continents or the thickened crust induced by the collision between the Philippine Sea plate and Eurasian plate, whereas the latter one belongs to the thinned crust induced by back-arc spreading. The Binhai Fault belt represents the suture zone of South China continent and SCS, which separates the high velocities located in its two sides. The low velocities at the upper mantle beneath the marine of South China continent reveal the deep-driven magmatism. Velocity anomalies at Luzon, Manila Trench and eastern Lunzon Trench are all related to their tectonic natures. Low velocities at the upper mantle from southern Taiwan to northern Luzon depict two volcanic chains: western volcanic chain and eastern volcanic chain, whereas the high velocity belt near the north Luzon ridge suggests the subducted continental slab.

  10. The correlations between the saturated and dry P-wave velocity of rocks.

    PubMed

    Kahraman, S

    2007-11-01

    Sometimes engineers need to estimate the wet-rock P-wave velocity from the dry-rock P-wave velocity. An estimation equation embracing all rock classes will be useful for the rock engineers. To investigate the predictability of wet-rock P-wave velocity from the dry-rock P-wave velocity, P-wave velocity measurements were performed on 41 different rock types, 11 of which were igneous, 15 of which were sedimentary and 15 of which was metamorphic. In addition to the dry- and wet-rock P-wave velocity measurements, the P-wave velocity changing as a function of saturation degree was studied. Moreover, dry-rock S-wave velocity measurements were conducted. The test results were modeled using Gassmann's and Wood's theory and it was seen that the measured data did not fit the theories. The unconformity is due to the fact that the theories are valid for high-porosity unconsolidated sediments at low frequencies. Gassmann's equation was modified for the rocks except high-porosity unconsolidated sediments. The dry- and wet-rock P-wave velocity values were evaluated using regression analysis. A strong linear correlation between the dry- and wet-rock P-wave velocities was found. Regression analyses were repeated for the rock classes and it was shown that correlation coefficients were increased. Concluding remark is that the derived equations can be used for the prediction of wet-rock P-wave velocity from the dry-rock P-wave velocity. PMID:17624388

  11. Estimation of Electro-Magnetic Signals Generated by Stress Changes before the Arrival of Seismic Waves

    NASA Astrophysics Data System (ADS)

    Yamazaki, K.

    2014-12-01

    This work aims to increase the efficiency of earthquake early warning (EEW) systems. Conventional EEW systems detect occurrence of earthquakes by means of detecting seismic P-waves; thus, they cannot make alert before P-waves reach the ground surface in principle. If we desires to break this limitation, we must observe other physical quantities including the electromagnetic (EM) and gravitational fields, variations of which propagate faster than elastic waves. The present study focuses on changes in the magnetic field generated by co-seismic stress changes in the Earth's crust. When magnetic minerals in the Earth's crust are subjected to mechanical forces, increments or decrements of magnetization appear. This is called the piezomagnetic effect. Significant changes in values of the geomagnetic field has frequently observed between before and after major earthquakes or volcanic ground deformation, which is considered to be generated by the piezomagnetic effect. The problem is, however, whether or not co-seismic changes in the stress field generates earlier signals, that is, changes in the magnetic field at observation sites which occur before arrival of seismic waves. To answer the question, a set of equations governing elastodynamics, electromagnetics, and the piezomagnetic effect, are solved for a whole space stuffed with a uniform physical properties. An impulsive double couple is assumed to represent the earthquake source mechanism. A set of solutions is derived in time-domain, and its features are investigated for several sets of parameters including electrical conductivity and seismic velocities. We can confirm that there are certain amount of changes in the EM field, even before arrival of seismic waves. EM signals before arrival of seismic waves (i.e. earlier EM signals) are relatively large in the case that the Earth's crust is conductive (> 0.01 S/m). However, the appearance of relatively large EM signal is not simultaneous to the rupture; instead, it is only after seismic waves approach the observation site. This result means detection of earthquakes by means of observing piezomagnetic signals is not easy at present in general, although it will be possible if sensitivity of EM sensors improves.

  12. P-wave velocity anomalies of the plume beneath the French Polynesia

    NASA Astrophysics Data System (ADS)

    Obayashi, Masayuki; Yoshimitsu, Junko; Sugioka, Hiroko; Ito, Aki; Isse, Takehi; Shiobara, Hajime; Suetsugu, Daisuke

    2015-04-01

    The French Polynesian region is characterized by positive topographic anomalies of 700 m, a concentration of hotspot chains. Many seismic tomography results show a broad low-velocity anomaly in the lower mantle continued from the base of the mantle. These observations suggest that a large-scale mantle flow rises from the bottom of the mantle beneath the region. Joint Japanese-French broadband seismological observations were performed from 2001 to 2005 with 10 island stations from the Polynesian PLUME project (Barruol et al. 2002) and 10 broadband ocean bottom seismometers (BBOBSs) from the Polynesian BBOBS project (Suetsugu et al. 2005). A P-wave tomography using the data from these projects revealed that large-scale low-velocity anomalies (on the order of 1000 km in diameter) from the bottom of the mantle become smaller-scale low-velocity anomalies (on the order of 100 km in diameter) at the depth of about 1000 km. However the connection of the small-scale low-velocity anomalies to the surface hotspots was not unrevealed because of the poor resolution in the upper mantle. A new P-wave tomography with better resolution in the upper mantle was obtained by adding data from BBOSBSs around Society Islands deployed along the TIARES project during 2009 - 2010 (Suetsugu et al. 2012) and by taking the finite frequency effect into account for the frequency-depended differential travel times. The frequency-depended differential travel times were measured by multi-band cross correlating P waveforms. The new P-wave tomography shows strong low-velocity anomalies beneath the Society Islands and Pitcairn in the upper mantle although they do not extend to the 660-km discontinuity. This model also shows that small-scale low-velocity anomalies in the uppermost lower mantle. The low-velocity anomalies in the depth range about 550 - 900 km are smaller both in lateral area and amplitude than those in most of the upper mantle and the lower mantle. The velocity patterns are well correlated each other in the depth range but are not correlated with the patterns above and below, indicating the mantle beneath the French polynesia can be divided into 3 layers in terns of radial correlation.

  13. Medically treated anorexia nervosa is associated with normal P wave parameters.

    PubMed

    Nussinovitch, Moshe; Gur, Eitan; Nussinovitch, Naomi; Kaminer, Keren; Volovitz, Benjamin; Nussinovitch, Udi

    2012-07-30

    Anorexia nervosa (AN) is an increasingly common medical condition. Some studies have demonstrated an increased prevalence of atrial premature contractions and anatomical changes in AN patients. Our aim was to investigate P wave parameters and P wave dispersion, an electrocardiographic marker for supraventricular arrhythmias, and its effect on AN. The study group included 48 patients with AN, most hospitalized for a few weeks, and a matched control group. All participants underwent 12-lead electrocardiography (ECG) under strict standards. P wave length and P wave dispersion in each patient were computed from a randomly selected beat and an averaged beat, constructed from 7 to 12 beats, included in a 10-s ECG. There were no statistically significant differences found between the groups for minimal, maximal, average P wave duration and P wave dispersion, calculated either from a random beat or averaged beats. In conclusion, medically treated AN patients who have gained weight have normal P wave parameters, and therefore do not appear to have an increased electrocardiographic risk for atrial fibrillation compared with healthy controls. Further studies are required to evaluate the influence of different disease stages, electrolyte imbalance and other medical complications on P wave parameters and risk for supraventricular arrhythmias in AN patients. PMID:22421068

  14. P-wave seismic imaging through dipping transversely isotropic media

    NASA Astrophysics Data System (ADS)

    Leslie, Jennifer Meryl

    2000-10-01

    P-wave seismic anisotropy is of growing concern to the exploration industry. The transmissional effects through dipping anisotropic strata, such as shales, cause substantial depth and lateral positioning errors when imaging subsurface targets. Using anisotropic physical models the limitations of conventional isotropic migration routines were determined to be significant. In addition, these models were used to validate both anisotropic depth migration routines and an anisotropic, numerical raytracer. In order to include anisotropy in these processes, one must be able to quantify the anisotropy using two parameters, epsilon and delta. These parameters were determined from headwave velocity measurements on anisotropic strata, in the parallel-, perpendicular- and 45-to-bedding directions. This new method was developed using refraction seismic techniques to measure the necessary velocities in the Wapiabi Formation shales, the Brazeau Group interbedded sandstones and shales, the Cardium Formation sandstones and the Palliser Formation limestones. The Wapiabi Formation and Brazeau Group rocks were determined to be anisotropic with epsilon = 0.23 +/- 0.05, delta = --0.05 +/- 0.07 and epsilon = 0.11 +/- 0.04, delta = 0.42 +/- 0.06, respectively. The sandstones and limestones of the Cardium and Palliser formations were both determined to be isotropic, in these studies. In a complementary experiment, a new procedure using vertical seismic profiling (VSP) techniques was developed to measure the anisotropic headwave velocities. Using a multi-offset source configuration on an appropriately dipping, uniform panel of anisotropic strata, the required velocities were measured directly and modelled. In this study, the geologic model was modelled using an anisotropic raytracer, developed for the experiment. The anisotropy was successfully modelled using anisotropic parameters based on the refraction seismic results. With a firm idea of the anisotropic parameters from the aforementioned studies, these parameters were then used in the anisotropic depth migration of a real dataset from the Alberta Foothills. The final anisotropic section demonstrated several improvements over the isotropic section. This anisotropic section is considered to be more accurate, in terms of depth and lateral position of reflectors, and thus a more complete solution than the isotropic result. In conclusion, seismic velocity anisotropy can seriously affect the imaging of subsurface play targets and every effort should be made to take these effects into account using anisotropic processing routines.

  15. Chiral p -wave superconductivity in Sb(111) thin films close to Van Hove singularities

    NASA Astrophysics Data System (ADS)

    Huang, Jin-Qin; Hsu, Chuang-Han; Lin, Hsin; Yao, Dao-Xin; Tsai, Wei-Feng

    2016-04-01

    We theoretically investigate the development of unconventional superconductivity in the Sb(111) thin film when its Fermi level is tuned to near type-II Van Hove singularities (VHS), which locate at non-time-reversal invariant momenta. Via patch renormalization group analysis, we show that the leading instability is a chiral p +i p -wave superconducting order. The origin of such pairing relies on the hexagonal structure of the VHS and strong spin-orbit coupling, resulting in the anisotropy of the electron-electron scattering to provide an attractive channel. Our study hence suggests that superconducting Sb thin films originated from VHS physics may host Majorana zero modes in the magnetic vortices and provides another application perspective to such material.

  16. Magnetic-field effects on p-wave phase transition in Gauss-Bonnet gravity

    NASA Astrophysics Data System (ADS)

    Wu, Ya-Bo; Lu, Jun-Wang; Jin, Yong-Yi; Lu, Jian-Bo; Zhang, Xue; Wu, Si-Yu; Wang, Cui

    2014-07-01

    In the probe limit, we study the holographic p-wave phase transition in the Gauss-Bonnet gravity via numerical and analytical methods. Concretely, we study the influences of the external magnetic field on the Maxwell complex vector model in the five-dimensional Gauss-Bonnet-AdS black hole and soliton backgrounds, respectively. For the two backgrounds, the results show that the magnetic field enhances the superconductor phase transition in the case of the lowest Landau level, while the increasing Gauss-Bonnet parameter always hinders the vector condensate. Moreover, the Maxwell complex vector model is a generalization of the SU(2) Yang-Mills model all the time. In addition, the analytical results backup the numerical results. Furthermore, this model might provide a holographic realization for the QCD vacuum instability.

  17. Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

    NASA Astrophysics Data System (ADS)

    Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

    2015-08-01

    We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications.

  18. Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

    PubMed Central

    Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

    2015-01-01

    We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications. PMID:26244284

  19. Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave.

    PubMed

    Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

    2015-01-01

    We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell's law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications. PMID:26244284

  20. Global P-wave Tomography Using Finite-Frequency Modeling and Finite-Frequency Data

    NASA Astrophysics Data System (ADS)

    Sigloch, K.; Nolet, G.

    2007-12-01

    We use our matched-filtering measurements of finite-frequency, teleseismic body-wave traveltimes and amplitudes as input data for global-scale "banana-doughnut" tomography. We present a new mantle model of Vp anomalies obtained from joint inversion of P-wave traveltimes and amplitudes. A Qs model is also obtained since amplitudes are inverted simultaneously for focusing and attenuation. In accordance with their definition in the Born approximation, traveltimes and amplitudes were measured by cross-correlating observed and predicted seismograms. Observables are consistent across frequency bands since for any source-receiver path, finite-frequency measurements are derived by filtering a single broadband seismogram into distinct sub-bands. Our bandpass filters have central frequencies between 0.03 and 1~Hz. In this range, predicted waveforms depend heavily on accurate estimates of source time functions, a challenge explicitly addressed by our method. Frechet kernels are computed using the exact frequency responses of the bandpass filters used. Our data set comprises teleseismic P-wave data from 1999-2007, available from IRIS DMC. We have processed all events for which mb ≥ 6.0, and most events for which 5.7 ≤ mb < 6.0, for a total of >1,500 earthquakes. We have thus far concentrated on the inversion of teleseismic P-wave data observed in North America. The obtained models predict traveltime dispersion due to diffraction effects on the order of 0.1-0.5 sec, consistent with what we observe in the data. Amplitude dispersion is on the order of 20%. Our models explain roughly half of the variance associated with the amplitude data. For North America, we observe a close correspondence of upper mantle Vp patterns with known surface tectonics. Thanks to the excellent USArray data, features on the order of 200~km can be resolved in large parts of the upper mantle under the Western U.S. Deeper down and further east, the presumed fragments of the subducting Farallon plate are clearly visible. We expect to include the full data set with global source-receiver coverage and to present preliminary results for a global inversion in addition to the North American tomography.

  1. Finite-fault source inversion using teleseismic P waves: Simple parameterization and rapid analysis

    USGS Publications Warehouse

    Mendoza, C.; Hartzell, S.

    2013-01-01

    We examine the ability of teleseismic P waves to provide a timely image of the rupture history for large earthquakes using a simple, 2D finite‐fault source parameterization. We analyze the broadband displacement waveforms recorded for the 2010 Mw∼7 Darfield (New Zealand) and El Mayor‐Cucapah (Baja California) earthquakes using a single planar fault with a fixed rake. Both of these earthquakes were observed to have complicated fault geometries following detailed source studies conducted by other investigators using various data types. Our kinematic, finite‐fault analysis of the events yields rupture models that similarly identify the principal areas of large coseismic slip along the fault. The results also indicate that the amount of stabilization required to spatially smooth the slip across the fault and minimize the seismic moment is related to the amplitudes of the observed P waveforms and can be estimated from the absolute values of the elements of the coefficient matrix. This empirical relationship persists for earthquakes of different magnitudes and is consistent with the stabilization constraint obtained from the L‐curve in Tikhonov regularization. We use the relation to estimate the smoothing parameters for the 2011 Mw 7.1 East Turkey, 2012 Mw 8.6 Northern Sumatra, and 2011 Mw 9.0 Tohoku, Japan, earthquakes and invert the teleseismic P waves in a single step to recover timely, preliminary slip models that identify the principal source features observed in finite‐fault solutions obtained by the U.S. Geological Survey National Earthquake Information Center (USGS/NEIC) from the analysis of body‐ and surface‐wave data. These results indicate that smoothing constraints can be estimated a priori to derive a preliminary, first‐order image of the coseismic slip using teleseismic records.

  2. Frequency and distance changes in the apparent P-wave radiation pattern: effects of seismic wave scattering in the crust inferred from dense seismic observations and numerical simulations

    NASA Astrophysics Data System (ADS)

    Kobayashi, Manabu; Takemura, Shunsuke; Yoshimoto, Kazuo

    2015-09-01

    Frequency and distance changes in the apparent P-wave radiation pattern (0.75-12 Hz) are investigated using velocity seismograms of shallow strike-slip earthquakes occurring in Chugoku region, southwestern Japan. Data from a dense seismic monitoring network revealed that the four-lobe apparent P-wave radiation pattern was gradually distorted with increasing frequency and propagation distance. Observed features suggest that seismic wave scattering due to small-scale velocity heterogeneity in the crust may be a major cause of this distortion. The effects of seismic wave scattering on apparent P-wave radiation pattern were investigated via 3-D finite difference simulation of seismic wave propagation. Our simulations demonstrated that the scattering of seismic waves modified the apparent P-wave radiation pattern from the original four-lobe shape, and that the small-scale velocity heterogeneity, characterized by the von Kármán-type power spectral density function with correlation distance of 1 km, root-mean-square value of 0.03 and decay rate parameter of 0.5, might be adequate for modelling crustal heterogeneity in the target region. It was also found that the scattering attenuation of P wave expected from this heterogeneity is significantly smaller than the apparent P-wave attenuation and S-wave scattering attenuation reported by Multiple Lapse Time Window Analysis of previous studies in Japan. These results might imply that scattering attenuation is not the dominant mechanism of P-wave attenuation in the crust of Chugoku region.

  3. Seismic characterization of fracture orientation in the Austin Chalk using azimuthal P-wave AVO

    NASA Astrophysics Data System (ADS)

    Al-Shuhail, Abdullatif Adulrahman

    The Austin Chalk is a naturally fractured reservoir. Horizontal drilling, to intersect more fractures, is the most efficient method to develop this reservoir. Information about the predominant fracture orientation in the subsurface is essential before horizontal drilling. This information may be provided by cores, well logs, outcrop, or seismic data. In this study, I apply the azimuthal P-wave AVO method suggested by Ruger and Tsvankin (1997) on 2-D P-wave seismic data in Gonzales County, Texas, in order to determine the fracture azimuth in the Austin Chalk. The data also include oil production from horizontal wells and various types of well logs from vertical wells in the study area. The raw seismic data was imaged through a processing sequence that preserved the relative changes of amplitudes with offset. The stacked sections of some seismic lines showed that the top of the Austin Chalk reflector is laterally inconsistent. This is interpreted as an indication of fractured zones in the subsurface. This interpretation was strengthened by well logs that indicated fracturing in nearby wells. The AVO gradient of every CDP in a seismic line was determined. The median AVO gradient of all the CDPs in a seismic line was chosen to represent the whole line. The median AVO gradients of the lines and their corresponding line azimuths were used repeatedly to solve the azimuthal AVO equation, of Ruger and Tsvankin (1997), for the fracture azimuth using a combination of three different lines every time. The resultant fracture-azimuth solutions clustered about two, nearly perpendicular, azimuths: N58E and S31E. To resolve the inherently ambiguous solutions, the results from the production and well log data were used. Since the production and well log data indicated the presence of NE-trending fractures, I chose the N58E direction as the fracture azimuth. This result agreed with the results of other studies in surrounding areas, using different methods, about the fracture azimuth in the Austin Chalk.

  4. Complex seismic amplitude inversion for P-wave and S-wave quality factors

    NASA Astrophysics Data System (ADS)

    Zong, Zhaoyun; Yin, Xingyao; Wu, Guochen

    2015-07-01

    Stratum quality factors (P-wave and S-wave quality factors, Qp and Qs) have gradually been utilized in the study of physical state of crust and uppermost mantle, tectonic evolution, hydrogeololgy, gas hydrates, petroleum exploration, etc. Different opinions of the seismic attenuation mechanism result in various approaches to estimate the P-wave and S-wave quality factors. Considering the viscoelasticity of the underground medium, the constitutive matrix of the Earth medium is written as the superposition of homogeneous background medium, elastic perturbation medium and viscoelastic perturbation medium. Under the hypothesis of Born integral and stationary phase approximation, the seismic reflectivity is initially raised in terms of P-wave and S-wave moduli, density, P-wave and S-wave quality factors. Furthermore, incorporating the complex seismic traces with the seismic wavelets at different offsets, a two-step inversion approach is proposed to estimate the P-wave and S-wave quality factors. The AVO/AVA Bayesian inversion approach is suggested to estimate the P-wave modulus and S-wave modulus with the real component of the pre-stack seismic data initially. Taking the estimated P-wave and S-wave moduli as prior information, the P-wave and S-wave quality factors are further estimated with the imaginary component of the complex pre-stack seismic data, which is the quadrature of the original data. Finally, synthetic examples demonstrate that the proposed approach is able to estimate P-wave and S-wave quality factors stably and properly, and two field data examples demonstrate that the proposed approach may work as an efficient approach to fluid identification.

  5. Automatic identification of fault zone head waves and direct P waves and its application in the Parkfield section of the San Andreas Fault, California

    NASA Astrophysics Data System (ADS)

    Li, Zefeng; Peng, Zhigang

    2016-03-01

    Fault zone head waves (FZHWs) are observed along major strike-slip faults, and can provide high-resolution imaging of fault interface properties at seismogenic depth. In this paper we present a new method to automatically detect FZHWs and pick direct P waves secondary arrivals (DWSAs). The algorithm identifies FZHWs by computing the amplitude ratios between the potential FZHWs and DSWAs. The polarities, polarizations and characteristic periods of FZHWs and DSWAs are then used to refine the picks or evaluate the pick quality. We apply the method to the Parkfield section of the San Andreas Fault where FZHWs have been identified before by manual picks. We compare results from automatically and manually picked arrivals and find general agreement between them. The obtained velocity contrast at Parkfield is generally 5%-10% near Middle Mountain while it decreases below 5% near Gold Hill. We also find many FZHWs recorded by the stations within 1 km of the background seismicity (i.e., the Southwest Fracture Zone) that have not been reported before. These FZHWs could be generated within a relatively wide low velocity zone sandwiched between the fast Salinian block on the southwest side and the slow Franciscan Mélange on the northeast side. Station FROB on the southwest (fast) side also recorded a small portion of weak precursory signals before sharp P waves. However, the polarities of weak signals are consistent with the right-lateral strike-slip mechanisms, suggesting that they are unlikely genuine FZHW signals.

  6. P-wave tomography of eastern North America: Evidence for mantle evolution from Archean to Phanerozoic, and modification during subsequent hot spot tectonism

    NASA Astrophysics Data System (ADS)

    Villemaire, M.; Darbyshire, F. A.; Bastow, I. D.

    2012-12-01

    The unique physical and chemical properties of cratonic lithosphere are thought to be key to its long-term survival and its resistance to pervasive modification by tectonic processes. Study of mantle structure in southeast Canada and the northeast US offers an excellent opportunity to address this issue because the region spans 3 billion years of Earth history, including Archean formation of the Superior craton and younger accretion of terranes to eastern Laurentia during the Proterozoic Grenville and Phanerozoic Appalachian orogenies. Trending NW-SE through each of these terranes is the track of the Great Meteor hot spot, which affected the region during the Mesozoic. Here we study mantle seismic velocity structure beneath this region of eastern North America using tomographic inversion of teleseismic P-wave relative arrival-times recorded by a large-aperture seismograph network. There are no large-scale systematic differences between Superior and Grenville mantle wave speed structure, which may suggest that tectonic stabilization of cratons occurred in a similar fashion during the Archean and Proterozoic. Cratonic lithosphere is largely thought to be resistant to modification by hot spot processes, in contrast to younger terranes where lithospheric erosion and significant magmatism are expected. Low velocities beneath the regions affected by the Great Meteor hot spot are broadest beneath the Paleozoic Appalachian terranes, indicating pervasive modification of the lithosphere during magmatism. The zone of modification narrows considerably into the Proterozoic Grenville province before disappearing completely in the Archean Superior craton, where the surface signature of Mesozoic magmatism is limited to kimberlite eruptions.

  7. Evidence for back scattering of near-podal seismic P'P' waves from the 150-220 km zone in Earth's upper mantle

    SciTech Connect

    Tkalcic, H; Flanagan, M P; Cormier, V F

    2005-07-15

    The deepest and most inaccessible parts of Earth's interior--the core and core-mantle boundary regions can be studied from compressional waves that turn in the core and are routinely observed following large earthquakes at epicentral distances between 145{sup o} and 180{sup o} (also called P', PKIKP or PKP waves). P'P' (PKPPKP) are P' waves that travel from a hypocenter through the Earth's core, reflect from the free surface and travel back through the core to a recording station on the surface. P'P' waves are sometimes accompanied by precursors, which were reported first in the 1960s as small-amplitude arrivals on seismograms at epicentral distances of about 50{sup o}-70{sup o}. Most prominent of these observed precursors were explained by P'P' waves generated by earthquakes or explosions that did not reach the Earth's surface but were reflected from the underside of first order velocity discontinuities at 410 and 660 km in the upper mantle mantle. Here we report the discovery of hitherto unobserved near-podal P'P' waves (at epicentral distance less than 10{sup o}) and very prominent precursors preceding the main energy by as much as 55 seconds. We interpret these precursors as a back scattered energy from undocumented structure in the upper mantle, in a zone between 150 and 220 km depth beneath Earth's surface. From these observations, we identify a frequency dependence of Q (attenuation quality factor) in the lithosphere that can be modeled by a flat relaxation spectrum below about 0.05-0.1 Hz and increasing with as the first power of frequency above this value, confirming pioneering work by B. Gutenberg.

  8. Induced p-wave Superfluidity in Imbalanced Fermi Gases in a Synthetic Gauge Field

    NASA Astrophysics Data System (ADS)

    Caldas, Heron; Continentino, Mucio

    2015-03-01

    We study pairing formation and the appearance of induced spin-triplet p-wave superfluidity in dilute three-dimensional imbalanced Fermi gases in the presence of a uniform non-Abelian gauge field. This gauge field generates a synthetic Rashba-type spin-orbit interaction which has remarkable consequences in the induced p-wave pairing gaps. Without the synthetic gauge field, the p-wave pairing occurs in one of the components due to the induced (second-order) interaction via an exchange of density fluctuations in the other component. We show that this p-wave superfluid gap induced by density fluctuations is greatly enhanced due to the Rashba-type spin-orbit coupling. This work was partially supported by CAPES, CNPq, FAPERJ, and FAPEMIG (Brazilian Agencies).

  9. Finite Frequency Measurements of Conventional and Core-diffracted P-waves (P and Pdiff)

    NASA Astrophysics Data System (ADS)

    Hosseini, K.; Sigloch, K.; Stähler, S. C.

    2014-12-01

    Core-diffracted waves are body waves that dive deep enough to sense the core, and by interaction with this wave guide become dispersive. They sample the core-mantle boundary and the lower third of the mantle extensively. In ray theoretical modeling, the deepest part of the ray starts to graze the core at around 97 degrees distance, but ray theory is a very poor approximation to propagation of core-diffracted waves. In reality, finite-frequency waves with their spatially extend sensitivity regions start to sense the core at significantly smaller distances already. The actual, non-ray-like sensitivities have been difficult to model, as have been the associated synthetic seismograms. Core-diffracted waves have therefore not been used in tomography, despite abundant observations of these phases on modern broadband seismograms. Hence current global body-wave tomographies illuminate the lower third of the mantle much less well than the upper and especially the middle third. This study aims for broadband, global waveform tomography that seamlessly incorporates core-diffracted phases alongside conventional, teleseismic waves as well as regional body-waves. Here, we investigate the properties of P-diffracted waves in terms of waveform characteristics and travel-time measurements as compared to teleseismic P-wave measured by the same methods. Travel time anomalies, the primary data for tomography, are measured by waveform cross-correlation of data with synthetics, where the synthetics are calculated from fully numerical wave propagation in a spherically symmetric background model. These same numerical tools will be used to calculate the associated sensitivity kernels for tomography (figure, top). Demonstrating the extent to which waveform modeling can fit real data, we assemble and discuss a global data set of 851,905 Pdiff and 2,368,452 P-wave multi-frequency cross-correlation travel times. Findings are summarized in the Pdiff travel time map (figure, bottom) in which most major structures found in previous studies are detectable, plus several new velocity anomalies.

  10. Eternal inflation with arrival terminals

    NASA Astrophysics Data System (ADS)

    Stoltenberg, Henry; Albrecht, Andreas

    2015-01-01

    We analyze the cosmological role of terminal vacua in the string theory landscape, and point out that existing work on this topic makes very strong assumptions about the properties of the terminal vacua. We explore the implications of relaxing these assumptions (by including "arrival" as well as "departure" terminals) and demonstrate that the results in earlier work are highly sensitive to their assumption of no arrival terminals. We use our discussion to make some general points about tuning and initial conditions in cosmology.

  11. P-Wave Velocity Tomography from Local Earthquakes in Western Mexico

    NASA Astrophysics Data System (ADS)

    Ochoa-Chávez, Juan A.; Escudero, Christian R.; Núñez-Cornú, Francisco J.; Bandy, William L.

    2015-11-01

    In western Mexico, the subduction of the Rivera and Cocos plates beneath the North America plate has deformed and fragmented the overriding plate, forming several structural rifts and crustal blocks. To obtain a reliable subsurface image of the continental crust and uppermost mantle in this complex area, we used P-wave arrivals of local earthquakes along with the Fast Marching Method tomography technique. We followed an inversion scheme consisting of (1) the use of a high-quality earthquake catalog and corrected phase picks, (2) the selection of earthquakes using a maximum location error threshold, (3) the estimation of an improved 1-D reference velocity model, and (4) the use of checkerboard testing to determine the optimum configuration of the velocity nodes and inversion parameters. Surprisingly, the tomography results show a very simple δVp distribution that can be described as being controlled by geologic structures formed during two stages of the separation of the Rivera and Cocos plates. The earlier period represents the initial stages of the separation of the Rivera and Cocos plates beneath western Mexico; the later period represents the more advanced stage of rifting where the Rivera and Cocos plates had separated sufficiently to allow melt to accumulate below the Colima Volcanic complex. During the earlier period (14 or 10-1.6 Ma), NE-SW-oriented structures/lineaments (such as the Southern Colima Rift) were formed as the two plates separated. During the second period (1.6 Ma to the present), the deformation is attributed to magma, generated within and above the tear zone between the Rivera and Cocos plates, rising beneath the region of the Colima Volcanic Complex. The rising magma fractured the overlying crust, forming a classic triple-rift junction geometry. This triple-rift system is confined to the mid- to lower crust perhaps indicating that this rifting process is still in an early stage. This fracturing, along with fluid circulation and associated heat advection within the fractures, can easily explain the observed distribution of δVp, as well as many of the results of previous seismological studies. Also surprisingly, we find no evidence at deep crustal depths to support either a trenchward migration of the volcanic arc or toroidal asthenospheric flow through the slab tears bounding the Jalisco Block to the NW and SE.

  12. Increased P-wave dispersion a risk for atrial fibrillation in adolescents with anorexia nervosa.

    PubMed

    Ertuğrul, İlker; Akgül, Sinem; Derman, Orhan; Karagöz, Tevfik; Kanbur, Nuray

    2016-01-01

    Studies have shown that a prolonged P-wave dispersion is a risk factor for the development of atrial fibrillation. The aim of this study was to evaluate P-wave dispersion in adolescents with anorexia nervosa at diagnosis. We evaluated electrocardiographic findings, particularly the P-wave dispersion, at initial assessment in 47 adolescents with anorexia nervosa. Comparison of P-wave dispersion between adolescents with anorexia nervosa and controls showed a statistically significant higher P-wave dispersion in patients with anorexia nervosa (72 ± 16.3 msec) when compared to the control group (43.8 ± 9.5 msec). Percent of body weight lost, lower body mass index, and higher weight loss rate in the patients with anorexia nervosa had no effect on P-wave dispersion. Due to the fact that anorexia nervosa has a high mortality rate we believe that cardiac pathologies such as atrial fibrillation must also be considered in the medical evaluation. PMID:25985103

  13. Strongly interacting one-dimensional quantum gas mixtures with weak p -wave interactions

    NASA Astrophysics Data System (ADS)

    Hu, Haiping; Pan, Lei; Chen, Shu

    2016-03-01

    We study one-dimensional strongly interacting quantum gas mixtures, including both the Bose-Fermi and spin-1 /2 Fermi-Fermi mixtures, with weak p -wave interaction between intracomponent fermions, and demonstrate that the weak p -wave interaction cannot be omitted in the strong interaction region where the strength of p -wave interaction is comparable with the inverse of the strength of strongly repulsive s -wave interaction. While the total density distribution is not sensitive to the weak p -wave interaction, we find that the p -wave interaction plays an important role in determining the species-dependent (or spin-dependent) density distributions and produces significant physical effects on the low-energy spin dynamics. We also derive effective spin-exchange models for strongly interacting quantum gas mixtures with weak p -wave interaction, which indicate that a quantum phase transition from an antiferromagnetic state to a ferromagnetic state can be induced by tuning the relative strengths of intracomponent and intercomponent interactions.

  14. Mariscope: Observing P Waves (and much more) Everywhere in the Oceans

    NASA Astrophysics Data System (ADS)

    Nolet, G.; Hello, Y.; Bonnieux, S.; Sukhovich, A.; Simons, F. J.

    2014-12-01

    The lack of stations on islands or the ocean bottom deprives seismic tomographers of almost 2/3 of the information potentially available for global seismic tomography. The "Mermaid", developed at Geoazur, is an underwater seismograph, based on a TWR Apex float. P wave signals are automatically identified and transmitted using the detection algorithm from Sukhovich et al. (GRL, 2011), GPS is used to locate the sensor at the time of transmission. We have studied the performance of Mermaids under different noise conditions in the Mediterranean, Indian Ocean and most recently near the Galapagos islands and will show a selection of observations. In the Mediterranean, we regularly detect P waves at teleseismic distances of earthquakes with magnitude 6, occasionally below that. Local and regional earthquakes of much lower magnitude, such as a M 4.9 earthquake near Barcelonette (figure), yield seismograms with a high signal to noise ratio.In the much noisier environment of the Indian Ocean the threshold for useful seismograms is close to magnitude 6.5. Yet we were also able to record 235 low magnitude events when a Mermaid was close to a swarm near the Indian Ocean triple junction, with the lowest magnitude estimated to be 2.1; this sequence also enabled us to put an upper limit of about 250 m to the error in sensor location at the time of recording. Preliminary data from the Galapagos indicate low noise conditions similar to those in the Mediterranean, with good recordings of events in the magnitude 5 range.A new prototype of a spherical "MultiMermaid" is currently being tested. It allows for multidisciplinary observations (seismic and kHz acoustics, magnetic field, temperature, bathymetry) and will function about five years with lithium batteries. A global deployment of such instruments in a five-year program is affordable: project MariScope aims for at least 300 floating seismometers in the world's oceans. At the time of writing of this abstract, a proposal is being prepared that involves geophysicists and biologists from France, Germany, Italy and Greece and should result in a first installment of MariScope. We shall discuss the possibility of a local rapid response network in which the instruments locate themselves while under water.

  15. Electric car arrives - again

    SciTech Connect

    Dunn, S.

    1997-03-01

    The first mass-produced electric cars in modern times are here, although they are expensive, limited in capability and unfamiliar to most prospective consumers. This article presents a brief history of the reintroduction of the modern electric car as well as discussions of the limitations of development, alternative routes to both producing and selling electric cars or some modified version of electric cars, economic incentives and governmental policies, and finally a snapshot description of the future for electric cars. 6 refs., 1 tab.

  16. A statistical study of the performance of the Hakamada-Akasofu-Fry version 2 numerical model in predicting solar shock arrival times at Earth during different phases of solar cycle 23

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S. M. P.; Fry, C. D.; Dryer, M.; Heynderickx, D.; Kecskemety, K.; Kudela, K.; Balaz, J.

    2012-02-01

    The performance of the Hakamada Akasofu-Fry, version 2 (HAFv.2) numerical model, which provides predictions of solar shock arrival times at Earth, was subjected to a statistical study to investigate those solar/interplanetary circumstances under which the model performed well/poorly during key phases (rise/maximum/decay) of solar cycle 23. In addition to analyzing elements of the overall data set (584 selected events) associated with particular cycle phases, subsets were formed such that those events making up a particular sub-set showed common characteristics. The statistical significance of the results obtained using the various sets/subsets was generally very low and these results were not significant as compared with the hit by chance rate (50%). This implies a low level of confidence in the predictions of the model with no compelling result encouraging its use. However, the data suggested that the success rates of HAFv.2 were higher when the background solar wind speed at the time of shock initiation was relatively fast. Thus, in scenarios where the background solar wind speed is elevated and the calculated success rate significantly exceeds the rate by chance, the forecasts could provide potential value to the customer. With the composite statistics available for solar cycle 23, the calculated success rate at high solar wind speed, although clearly above 50%, was indicative rather than conclusive. The RMS error estimated for shock arrival times for every cycle phase and for the composite sample was in each case significantly better than would be expected for a random data set. Also, the parameter "Probability of Detection, yes" (PODy) which presents the Proportion of Yes observations that were correctly forecast (i.e. the ratio between the shocks correctly predicted and all the shocks observed), yielded values for the rise/maximum/decay phases of the cycle and using the composite sample of 0.85, 0.64, 0.79 and 0.77, respectively. The statistical results obtained through detailed analysis of the available data provided insights into how changing circumstances on the Sun and in interplanetary space can affect the performance of the model. Since shock arrival predictions are widely utilized in making commercially significant decisions re. protecting space assets, the present detailed archival studies can be useful in future operational decision making during solar cycle 24. It would be of added value in this context to use Briggs-Rupert methodology to estimate the cost to an operator of acting on an incorrect forecast.

  17. Fluid pressure arrival time tomography: Estimation and assessment in the presence of inequality constraints, with an application to a producing gas field at Krechba, Algeria

    SciTech Connect

    Rucci, A.; Vasco, D.W.; Novali, F.

    2010-04-01

    Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based upon these changes we estimate diffusive travel times associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage an approach based upon travel times, as opposed to one based upon the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. We apply the formulation to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is approximately 0.5 cm, overlying the eastern margin of the anticlinal structure defining the gas field. Using data from 15 irregularly-spaced images of range change, we calculate the diffusive travel times associated with the startup of a gas production well. The inequality constraints are incorporated into the estimates of model parameter resolution and covariance, improving the resolution by roughly 30 to 40%.

  18. Knowledge-based scheduling of arrival aircraft

    NASA Technical Reports Server (NTRS)

    Krzeczowski, K.; Davis, T.; Erzberger, H.; Lev-Ram, I.; Bergh, C.

    1995-01-01

    A knowledge-based method for scheduling arrival aircraft in the terminal area has been implemented and tested in real-time simulation. The scheduling system automatically sequences, assigns landing times, and assigns runways to arrival aircraft by utilizing continuous updates of aircraft radar data and controller inputs. The scheduling algorithms is driven by a knowledge base which was obtained in over two thousand hours of controller-in-the-loop real-time simulation. The knowledge base contains a series of hierarchical 'rules' and decision logic that examines both performance criteria, such as delay reduction, as well as workload reduction criteria, such as conflict avoidance. The objective of the algorithms is to devise an efficient plan to land the aircraft in a manner acceptable to the air traffic controllers. This paper will describe the scheduling algorithms, give examples of their use, and present data regarding their potential benefits to the air traffic system.

  19. Comparison of interplanetary CME arrival times and solar wind parameters based on the WSA-ENLIL model with three cone types and observations

    NASA Astrophysics Data System (ADS)

    Jang, Soojeong; Moon, Y.-J.; Lee, Jae-Ok; Na, Hyeonock

    2014-09-01

    We have made a comparison between coronal mass ejection (CME)-associated shock propagations based on the Wang-Sheeley-Arge (WSA)-ENLIL model using three cone types and in situ observations. For this we use 28 full-halo CMEs, whose cone parameters are determined and their corresponding interplanetary shocks were observed at the Earth, from 2001 to 2002. We consider three different cone types (an asymmetric cone model, an ice cream cone model, and an elliptical cone model) to determine 3-D CME cone parameters (radial velocity, angular width, and source location), which are the input values of the WSA-ENLIL model. The mean absolute error of the CME-associated shock travel times for the WSA-ENLIL model using the ice-cream cone model is 9.9 h, which is about 1 h smaller than those of the other models. We compare the peak values and profiles of solar wind parameters (speed and density) with in situ observations. We find that the root-mean-square errors of solar wind peak speed and density for the ice cream and asymmetric cone model are about 190 km/s and 24/cm3, respectively. We estimate the cross correlations between the models and observations within the time lag of ± 2 days from the shock travel time. The correlation coefficients between the solar wind speeds from the WSA-ENLIL model using three cone types and in situ observations are approximately 0.7, which is larger than those of solar wind density (cc ˜0.6). Our preliminary investigations show that the ice cream cone model seems to be better than the other cone models in terms of the input parameters of the WSA-ENLIL model.

  20. A Powerful Twin Arrives

    NASA Astrophysics Data System (ADS)

    1999-11-01

    First Images from FORS2 at VLT KUEYEN on Paranal The first, major astronomical instrument to be installed at the ESO Very Large Telescope (VLT) was FORS1 ( FO cal R educer and S pectrograph) in September 1998. Immediately after being attached to the Cassegrain focus of the first 8.2-m Unit Telescope, ANTU , it produced a series of spectacular images, cf. ESO PR 14/98. Many important observations have since been made with this outstanding facility. Now FORS2 , its powerful twin, has been installed at the second VLT Unit Telescope, KUEYEN . It is the fourth major instrument at the VLT after FORS1 , ISAAC and UVES.. The FORS2 Commissioning Team that is busy installing and testing this large and complex instrument reports that "First Light" was successfully achieved already on October 29, 1999, only two days after FORS2 was first mounted at the Cassegrain focus. Since then, various observation modes have been carefully tested, including normal and high-resolution imaging, echelle and multi-object spectroscopy, as well as fast photometry with millisecond time resolution. A number of fine images were obtained during this work, some of which are made available with the present Press Release. The FORS instruments ESO PR Photo 40a/99 ESO PR Photo 40a/99 [Preview - JPEG: 400 x 345 pix - 203k] [Normal - JPEG: 800 x 689 pix - 563kb] [Full-Res - JPEG: 1280 x 1103 pix - 666kb] Caption to PR Photo 40a/99: This digital photo shows the twin instruments, FORS2 at KUEYEN (in the foreground) and FORS1 at ANTU, seen in the background through the open ventilation doors in the two telescope enclosures. Although they look alike, the two instruments have specific functions, as described in the text. FORS1 and FORS2 are the products of one of the most thorough and advanced technological studies ever made of a ground-based astronomical instrument. They have been specifically designed to investigate the faintest and most remote objects in the universe. They are "multi-mode instruments" that may be used in several different observation modes. FORS2 is largely identical to FORS1 , but there are a number of important differences. For example, it contains a Mask Exchange Unit (MXU) for laser-cut star-plates [1] that may be inserted at the focus, allowing a large number of spectra of different objects, in practice up to about 70, to be taken simultaneously. Highly sophisticated software assigns slits to individual objects in an optimal way, ensuring a great degree of observing efficiency. Instead of the polarimetry optics found in FORS1 , FORS2 has new grisms that allow the use of higher spectral resolutions. The FORS project was carried out under ESO contract by a consortium of three German astronomical institutes, the Heidelberg State Observatory and the University Observatories of Göttingen and Munich. The participating institutes have invested a total of about 180 man-years of work in this unique programme. The photos below demonstrate some of the impressive possibilities with this new instrument. They are based on observations with the FORS2 standard resolution collimator (field size 6.8 x 6.8 armin = 2048 x 2048 pixels; 1 pixel = 0.20 arcsec). In addition, observations of the Crab pulsar demonstrate a new observing mode, high-speed photometry. Protostar HH-34 in Orion ESO PR Photo 40b/99 ESO PR Photo 40b/99 [Preview - JPEG: 400 x 444 pix - 220kb] [Normal - JPEG: 800 x 887 pix - 806kb] [Full-Res - JPEG: 2000 x 2217 pix - 3.6Mb] The Area around HH-34 in Orion ESO PR Photo 40c/99 ESO PR Photo 40c/99 [Preview - JPEG: 400 x 494 pix - 262kb] [Full-Res - JPEG: 802 x 991 pix - 760 kb] The HH-34 Superjet in Orion (centre) PR Photo 40b/99 shows a three-colour composite of the young object Herbig-Haro 34 (HH-34) , now in the protostar stage of evolution. It is based on CCD frames obtained with the FORS2 instrument in imaging mode, on November 2 and 6, 1999. This object has a remarkable, very complicated appearance that includes two opposite jets that ram into the surrounding interstellar matter. This structure is produced by a machine-gun-like blast of "bullets" of dense gas ejected from the star at high velocities (approaching 250 km/sec). This seems to indicate that the star experiences episodic "outbursts" when large chunks of material fall onto it from a surrounding disk. HH-34 is located at a distance of approx. 1,500 light-years, near the famous Orion Nebula , one of the most productive star birth regions. Note also the enigmatic "waterfall" to the upper left, a feature that is still unexplained. PR Photo 40c/99 is an enlargement of a smaller area around the central object. Technical information : Photo 40b/99 is based on a composite of three images taken through three different filters: B (wavelength 429 nm; Full-Width-Half-Maximum (FWHM) 88 nm; exposure time 10 min; here rendered as blue), H-alpha (centered on the hydrogen emission line at wavelength 656 nm; FWHM 6 nm; 30 min; green) and S II (centrered at the emission lines of inonized sulphur at wavelength 673 nm; FWHM 6 nm; 30 min; red) during a period of 0.8 arcsec seeing. The field shown measures 6.8 x 6.8 arcmin and the images were recorded in frames of 2048 x 2048 pixels, each measuring 0.2 arcsec. The Full Resolution version shows the original pixels. North is up; East is left. N 70 Nebula in the Large Magellanic Cloud ESO PR Photo 40d/99 ESO PR Photo 40d/99 [Preview - JPEG: 400 x 444 pix - 360kb] [Normal - JPEG: 800 x 887 pix - 1.0Mb] [Full-Res - JPEG: 1997 x 2213 pix - 3.4Mb] The N 70 Nebula in the LMC ESO PR Photo 40e/99 ESO PR Photo 40e/99 [Preview - JPEG: 400 x 485 pix - 346kb] [Full-Res - JPEG: 986 x 1196 pix - 1.2Mb] The N70 Nebula in the LMC (detail) PR Photo 40d/99 shows a three-colour composite of the N 70 nebula. It is a "Super Bubble" in the Large Magellanic Cloud (LMC) , a satellite galaxy to the Milky Way system, located in the southern sky at a distance of about 160,000 light-years. This photo is based on CCD frames obtained with the FORS2 instrument in imaging mode in the morning of November 5, 1999. N 70 is a luminous bubble of interstellar gas, measuring about 300 light-years in diameter. It was created by winds from hot, massive stars and supernova explosions and the interior is filled with tenuous, hot expanding gas. An object like N70 provides astronomers with an excellent opportunity to explore the connection between the lifecycles of stars and the evolution of galaxies. Very massive stars profoundly affect their environment. They stir and mix the interstellar clouds of gas and dust, and they leave their mark in the compositions and locations of future generations of stars and star systems. PR Photo 40e/99 is an enlargement of a smaller area of this nebula. Technical information : Photos 40d/99 is based on a composite of three images taken through three different filters: B (429 nm; FWHM 88 nm; 3 min; here rendered as blue), V (554 nm; FWHM 111 nm; 3 min; green) and H-alpha (656 nm; FWHM 6 nm; 3 min; red) during a period of 1.0 arcsec seeing. The field shown measures 6.8 x 6.8 arcmin and the images were recorded in frames of 2048 x 2048 pixels, each measuring 0.2 arcsec. The Full Resolution version shows the original pixels. North is up; East is left. The Crab Nebula in Taurus ESO PR Photo 40f/99 ESO PR Photo 40f/99 [Preview - JPEG: 400 x 446 pix - 262k] [Normal - JPEG: 800 x 892 pix - 839 kb] [Full-Res - JPEG: 2036 x 2269 pix - 3.6Mb] The Crab Nebula in Taurus ESO PR Photo 40g/99 ESO PR Photo 40g/99 [Preview - JPEG: 400 x 444 pix - 215kb] [Full-Res - JPEG: 817 x 907 pix - 485 kb] The Crab Nebula in Taurus (detail) PR Photo 40f/99 shows a three colour composite of the well-known Crab Nebula (also known as "Messier 1" ), as observed with the FORS2 instrument in imaging mode in the morning of November 10, 1999. It is the remnant of a supernova explosion at a distance of about 6,000 light-years, observed almost 1000 years ago, in the year 1054. It contains a neutron star near its center that spins 30 times per second around its axis (see below). PR Photo 40g/99 is an enlargement of a smaller area. More information on the Crab Nebula and its pulsar is available on the web, e.g. at a dedicated website for Messier objects. In this picture, the green light is predominantly produced by hydrogen emission from material ejected by the star that exploded. The blue light is predominantly emitted by very high-energy ("relativistic") electrons that spiral in a large-scale magnetic field (so-called syncrotron emission ). It is believed that these electrons are continuously accelerated and ejected by the rapidly spinning neutron star at the centre of the nebula and which is the remnant core of the exploded star. This pulsar has been identified with the lower/right of the two close stars near the geometric center of the nebula, immediately left of the small arc-like feature, best seen in PR Photo 40g/99 . Technical information : Photo 40f/99 is based on a composite of three images taken through three different optical filters: B (429 nm; FWHM 88 nm; 5 min; here rendered as blue), R (657 nm; FWHM 150 nm; 1 min; green) and S II (673 nm; FWHM 6 nm; 5 min; red) during periods of 0.65 arcsec (R, S II) and 0.80 (B) seeing, respectively. The field shown measures 6.8 x 6.8 arcmin and the images were recorded in frames of 2048 x 2048 pixels, each measuring 0.2 arcsec. The Full Resolution version shows the original pixels. North is up; East is left. The High Time Resolution mode (HIT) of FORS2 ESO PR Photo 40h/99 ESO PR Photo 40h/99 [Preview - JPEG: 400 x 304 pix - 90kb] [Normal - JPEG: 707 x 538 pix - 217kb] Time Sequence of the Pulsar in the Crab Nebula ESO PR Photo 40i/99 ESO PR Photo 40i/99 [Preview - JPEG: 400 x 324 pix - 42kb] [Normal - JPEG: 800 x 647 pix - 87kb] Lightcurve of the Pulsar in the Crab Nebula In combination with the large light collecting power of the VLT Unit Telescopes, the high time resolution (25 nsec = 0.000000025 sec) of the ESO-developed FIERA CCD-detector controller opens a new observing window for celestial objects that undergo light intensity variations on very short time scales. A first implementation of this type of observing mode was tested with FORS2 during the first commissioning phase, by means of one of the most fascinating astronomical objects, the rapidly spinning neutron star in the Crab Nebula . It is also known as the Crab pulsar and is an exceedingly dense object that represents an extreme state of matter - it weighs as much as the Sun, but measures only about 30 km across. The result presented here was obtained in the so-called trailing mode , during which one of the rectangular openings of the Multi-Object Spectroscopy (MOS) assembly within FORS2 is placed in front of the lower end of the field. In this way, the entire surface of the CCD is covered, except the opening in which the object under investigation is positioned. By rotating this opening, some neighbouring objects (e.g. stars for alignment) may be observed simultaneously. As soon as the shutter is opened, the charges on the chip are progressively shifted upwards, one pixel at a time, until those first collected in the bottom row behind the opening have reached the top row. Then the entire CCD is read out and the digital data with the full image is stored in the computer. In this way, successive images (or spectra) of the object are recorded in the same frame, displaying the intensity variation with time during the exposure. For this observation, the total exposure lasted 2.5 seconds. During this time interval the image of the pulsar (and those of some neighbouring stars) were shifted 2048 times over the 2048 rows of the CCD. Each individual exposure therefore lasted exactly 1.2 msec (0.0012 sec), corresponding to a nominal time-resolution of 2.4 msec (2 pixels). Faster or slower time resolutions are possible by increasing or decreasing the shift and read-out rate [2]. In ESO PR Photo 40h/99 , the continuous lines in the top and bottom half are produced by normal stars of constant brightness, while the series of dots represents the individual pulses of the Crab pulsar, one every 33 milliseconds (i.e. the neutron star rotates around its axis 30 times per second). It is also obvious that these dots are alternatively brighter and fainter: they mirror the double-peaked profile of the light pulses, as shown in ESO PR Photo 40i/99 . In this diagramme, the time increases along the abscissa axis (1 pixel = 1.2 msec) and the momentary intensity (uncalibrated) is along the ordinate axis. One full revolution of the neutron star corresponds to the distance from one high peak to the next, and the diagramme therefore covers six consecutive revolutions (about 200 milliseconds). Following thorough testing, this new observing mode will allow to investigate the brightness variations of this and many other objects in great detail in order to gain new and fundamental insights in the physical mechanisms that produce the radiation pulses. In addition, it is foreseen to do high time resolution spectroscopy of rapidly varying phenomena. Pushing it to the limits with an 8.2-m telescope like KUEYEN will be a real challenge to the observers that will most certainly lead to great and exciting research projects in various fields of modern astrophysics. Technical information : The frame shown in Photo 40h/99 was obtained during a total exposure time of 2.5 sec without any optical filtre. During this time, the charges on the CCD were shifted over 2048 rows; each row was therefore exposed during 1.2 msec. The bright continuous line comes from the star next to the pulsar; the orientation was such that the "observation slit" was placed over two neighbouring stars. Preliminary data reduction: 11 pixels were added across the pulsar image to increase the signal-to-noise ratio and the background light from the Crab Nebula was subtracted for the same reason. Division by a brighter star (also background-subtracted, but not shown in the image) helped to reduce the influence of the Earth's atmosphere. Notes [1] The masks are produced by the Mask Manufacturing Unit (MMU) built by the VIRMOS Consortium for the VIMOS and NIRMOS instruments that will be installed at the VLT MELIPAL and YEPUN telescopes, respectively. [2] The time resolution achieved during the present test was limited by the maximum charge transfer rate of this particular CCD chip; in the future, FORS2 may be equipped with a new chip with a rate that is up to 20 times faster. How to obtain ESO Press Information ESO Press Information is made available on the World-Wide Web (URL: http://www.eso.org../ ). ESO Press Photos may be reproduced, if credit is given to the European Southern Observatory.

  1. Universal High-Momentum Asymptote and Thermodynamic Relations in a Spinless Fermi Gas with a Resonant p-Wave Interaction.

    PubMed

    Yoshida, Shuhei M; Ueda, Masahito

    2015-09-25

    We investigate universal relations in a spinless Fermi gas near a p-wave Feshbach resonance, and show that the momentum distribution n_{k} has an asymptote proportional to k^{-2} with the proportionality constant-the p-wave contact-scaling with the number of closed-channel molecules. We prove the adiabatic sweep theorem for a p-wave resonance which reveals the thermodynamic implication of the p-wave contact. In contrast to the unitary Fermi gas in which Tan's contact is universal, the p-wave contact depends on the short-range details of the interaction. PMID:26451563

  2. Model input and output files for the simulation of time of arrival of landfill leachate at the water table, Municipal Solid Waste Landfill Facility, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso County, Texas

    USGS Publications Warehouse

    Abeyta, Cynthia G.; Frenzel, Peter F.

    1999-01-01

    This report contains listings of model input and output files for the simulation of the time of arrival of landfill leachate at the water table from the Municipal Solid Waste Landfill Facility (MSWLF), about 10 miles northeast of downtown El Paso, Texas. This simulation was done by the U.S. Geological Survey in cooperation with the U.S. Department of the Army, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas. The U.S. Environmental Protection Agency-developed Hydrologic Evaluation of Landfill Performance (HELP) and Multimedia Exposure Assessment (MULTIMED) computer models were used to simulate the production of leachate by a landfill and transport of landfill leachate to the water table. Model input data files used with and output files generated by the HELP and MULTIMED models are provided in ASCII format on a 3.5-inch 1.44-megabyte IBM-PC compatible floppy disk.

  3. Evaluation of the P Wave Axis in Patients With Systemic Lupus Erythematosus

    PubMed Central

    Acar, Rezzan Deniz; Bulut, Mustafa; Acar, Şencan; Izci, Servet; Fidan, Serdar; Yesin, Mahmut; Efe, Suleyman Cagan

    2015-01-01

    Introduction: P wave axis is one of the most practical clinical tool for evaluation of cardiovascular disease. The aim of our study was to evaluate the P wave axis in electrocardiogram (ECG), left atrial function and association between the disease activity score in patients with systemic lupus erythematosus (SLE). Methods: Standard 12-lead surface ECGs were recorded by at a paper speed of 25 m/s and an amplifier gain of 10 mm/mV. The heart rate (HR), the duration of PR, QRS, QTd (dispersion), the axis of P wave were measured by ECG machine automatically. Results: The P wave axis was significantly increased in patients with SLE (49 ± 20 vs. 40 ± 18, P = 0.037) and the disease activity score was found positively correlated with P wave axis (r: 0.382, P = 0.011). The LA volume and the peak systolic strain of the left atrium (LA) were statistically different between the groups (P = 0.024 and P = 0.000). The parameters of the diastolic function; E/A and E/e’ were better in the control group than the patients with SLE (1.1 ± 0.3 vs. 1.3 ± 0.3, P = 0.041 and 6.6 ± 2.8 vs. 5.4 ± 1.4, P = 0.036, respectively). Conclusion: P wave axis was found significantly increased in patients with SLE and positively correlated with SELENA-SLEDAI score. As the risk score increases in patients with SLE, P wave axis changes which may predict the risk of all-cause and cardiovascular mortality. PMID:26702344

  4. Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks using Tera-scale Optical-Core Devices

    SciTech Connect

    Imam, Neena; Barhen, Jacob

    2009-01-01

    For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.

  5. Fracture density estimates in glaciogenic deposits from P-wave velocity reductions

    SciTech Connect

    Karaman, A.; Carpenter, P.J.

    1997-01-01

    Subsidence-induced fracturing of glaciogenic deposits over coal mines in the southern Illinois basis alters hydraulic properties of drift aquifers and exposes these aquifers to surface contaminants. In this study, refraction tomography surveys were used in conjunction with a generalized form of a seismic fracture density model to estimate the vertical and lateral extent of fracturing in a 12-m thick overburden of loess, clay, glacial till, and outwash above a longwall coal mine at 90 m depth. This generalized model accurately predicted fracture trends and densities from azimuthal P-wave velocity variations over unsaturated single- and dual-parallel fractures exposed at the surface. These fractures extended at least 6 m and exhibited 10--15 cm apertures at the surface. The pre- and postsubsidence velocity ratios were converted into fracture densities that exhibited qualitative agreement with the observed surface and inferred subsurface fracture distribution. Velocity reductions as large as 25% were imaged over the static tension zone of the mine where fracturing may extend to depths of 10--15 m. Finally, the seismically derived fracture density estimates were plotted as a function of subsidence-induced drawdown across the panel to estimate the average specific storage of the sand and gravel lower drift aquifer. This value was at least 20 times higher than the presubsidence (unfractured) specific storage for the same aquifer.

  6. Investigation of Semileptonic {ital B} Meson Decays to {ital p} -Wave Charm Mesons

    SciTech Connect

    Anastassov, A.; Duboscq, J.E.; Fujino, D.; Gan, K.K.; Hart, T.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.; Spencer, M.B.; Sung, M.; Undrus, A.; Wanke, R.; Wolf, A.; Zoeller, M.M.; Nemati, B.; Richichi, S.J.; Ross, W.R.; Skubic, P.; Bishai, M.; Fast, J.; Hinson, J.W.; Menon, N.; Miller, D.H.; Shibata, E.I.; Shipsey, I.P.; Yurko, M.; Glenn, S.; Johnson, S.D.; Kwon, Y.; Roberts, S.; Thorndike, E.H.; Jessop, C.P.; Lingel, K.; Marsiske, H.; Perl, M.L.; Savinov, V.; Ugolini, D.; Wang, R.; Zhou, X.; Coan, T.E.; Fadeyev, V.; Korolkov, I.; Maravin, Y.; Narsky, I.; Shelkov, V.; Staeck, J.; Stroynowski, R.; Volobouev, I.; Ye, J.; Artuso, M.; Efimov, A.; Goldberg, M.; He, D.; Kopp, S.; Moneti, G.C.; Mountain, R.; Schuh, S.; Skwarnicki, T.; Stone, S.; Viehhauser, G.; Xing, X.; Bartelt, J.; Csorna, S.E.; Jain, V.; McLean, K.W.; Marka, S.; Godang, R.; Kinoshita, K.; Lai, I.C.; Pomianowski, P.; Schrenk, S.; Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L.P.; Zhou, G.J.; Barish, B.; Chadha, M.; Chan, S.; Eigen, G.; Miller, J.S.; OGrady, C.; Schmidtler, M.; Urheim, J.; Weinstein, A.J.; Wuerthwein, F.; Bliss, D.W.; Masek, G.; Paar, H.P.; Prell, S.; Sharma, V. and others

    1998-05-01

    We have studied semileptonic B meson decays with a p -wave charm meson in the final state using 3.29{times}10{sup 6} B{ovr B} events collected with the CLEOII detector at the Cornell Electron-Positron Storage Ring. We find a value for the exclusive semileptonic product branching fraction B(B{sup {minus}}{r_arrow}D{sup 0}{sub 1} {ell}{sup {minus}}{ovr {nu}}{sub {ell}}) B(D{sup 0}{sub 1}{r_arrow}D{sup {asterisk}+} {pi}{sup {minus}})=(0.373{plus_minus}0.085{plus_minus} 0.052{plus_minus}0.024){percent} and an upper limit for B(B{sup {minus}}{r_arrow}D{sup {asterisk}0}{sub 2} {ell}{sup {minus}}{ovr {nu}}{sub {ell}}) B(D{sup {asterisk}0}{sub 2}{r_arrow}D{sup {asterisk}+ }{pi}{sup {minus}}){lt}0.16{percent} (90{percent} C.L.). Furthermore, we present the first measurement of the q{sup 2} spectrum for B{sup {minus}}{r_arrow}D{sup 0}{sub 1}{ell}{sup {minus}} {ovr {nu}}{sub {ell}} . {copyright} {ital 1998} {ital The American Physical Society}

  7. Imaging the Juan de Fuca plate beneath southern Oregon using teleseismic P wave residuals

    USGS Publications Warehouse

    Harris, R.A.; Iyer, H.M.; Dawson, P.B.

    1991-01-01

    Images the Juan de Fuca plate in southern Oregon using seismic tomography. P wave travel time residuals from a 366-km-long seismic array operated in southern Oregon in 1982 are inverted. The southeast striking array extended from the Coast ranges to the Modoc Plateau and crossed the High Cascades at Crater Lake, Oregon. Three features under the array were imaged: one high-velocity zone and two low-velocity zones. The high-velocity zone is 3-4% faster than the surrounding upper mantle. It dips steeply at 65?? to the east beneath the Cascade Range and extends down to at least 200 km. It is proposed that this high-velocity feature is subducted Juan de Fuca plate. Two low-velocity zones were also imaged, both of which are 3-4% slower than the surrounding earth structure. The southeastern low-velocity zone may be caused by partially molten crust underlying the Crater Lake volcano region. -from Authors

  8. A P wave-based, on-site method for earthquake early warning

    NASA Astrophysics Data System (ADS)

    Colombelli, S.; Caruso, A.; Zollo, A.; Festa, G.; Kanamori, H.

    2015-03-01

    A new strategy for a P wave-based, on-site earthquake early warning system has been developed and tested on Japanese strong motion data. The key elements are the real-time, continuous measurement of three peak amplitude parameters and their empirical combination to predict the ensuing peak ground velocity. The observed parameters are compared to threshold values and converted into a single, dimensionless variable. A local alert level is issued as soon as the empirical combination exceeds a given threshold. The performance of the method has been evaluated by applying the approach to the catalog of Japanese earthquake records and counting the relative percentage of successful, missed, and false alarms. We show that the joint use of three peak amplitude parameters improves the performance of the system as compared to the use of a single parameter, with a relative increase of successful alarms of about 35%. The proposed methodology provides a more reliable prediction of the expected ground shaking and improves the robustness of a single-station, threshold-based earthquake early warning system.

  9. Upper mantle and crustal P-wave attenuation beneath the North Korea region

    NASA Astrophysics Data System (ADS)

    Cleveland, M.; Randall, G. E.; Patton, H. J.; Phillips, W. S.

    2014-12-01

    Accurate estimation of the magnitude of crustal seismic sources is dependent upon a strong understanding of the anelastic P-wave attenuation in the crust and upper mantle. In this study, we estimate the crustal/upper mantle average attenuation (t*) for the region around North Korea by expanding upon methods described by Ichinose et al. [2013]. We estimate t* by modeling the observed spectra and spectral ratio of regional and teleseismic P- and pP-phases of large, deep (> 500 km) earthquakes rupturing beneath the North Korea region. We use seismograms, acquired from the IRIS data archive, from operational stations at the time of each earthquake. Because of a trade-off between the variables, we use multi-variable optimization to estimate the best-fitting corner frequency (fc) and t* for each spectrum. In addition to using a more quantitative and global approach than earlier studies, we introduce new measurement approaches enabling a better understanding of the uncertainty in the measured t* value and its trade-off with fc.

  10. What Do s- and p-Wave Neutron Average Radiative Widths Reveal

    SciTech Connect

    Mughabghab, S.F.

    2010-04-30

    A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

  11. P wave dispersion is prolonged in patients with Wilson’s disease

    PubMed Central

    Arat, Nurcan; Kacar, Sabite; Golbasi, Zehra; Akdogan, Meral; Sokmen, Yeliz; Kuran, Sedef; Idilman, Ramazan

    2008-01-01

    AIM: To investigate the P wave dispersion as a non-invasive marker of intra-atrial conduction disturbances in patients with Wilson’s disease. METHODS: We compared Wilson’s disease patients (n = 18) with age matched healthy subjects (n = 15) as controls. The diagnosis was based on clinical symptoms, laboratory tests (ceruloplasmin, urinary and hepatic copper concentrations). P wave dispersion, a measurement of the heterogeneity of atrial depolarization, was measured as the difference between the duration of the longest and the shortest P-waves in 12 lead electrocardiography. RESULTS: All the patients were asymptomatic on cardiological examination and have sinusal rhythm in electrocardiography. Left ventricular and left atrial diameters, left ventricular ejection fraction and left ventricular mass index were similar in both groups. The Wilson’s disease patients had a significantly higher P wave dispersion compared with the controls (44.7 ± 5.8 vs 25.7 ± 2.5, P < 0.01). CONCLUSION: There was an increase in P wave dispersion in cardiologically asymptomatic Wilson’s disease patients which probably represents an early stage of cardiac involvement. PMID:18300353

  12. The Effect of Wavefront Healing on Estimates of S-Wave and P-Wave Heterogeneity in D"

    NASA Astrophysics Data System (ADS)

    Ritsema, J.; Deuss, A. F.; Koelemeijer, P.

    2014-12-01

    Large Low-Shear Velocity Provinces (LLSVPs) form the dominant degree-2 heterogeneity in the lower mantle and cause the largest perturbations of teleseismic body-wave traveltimes and normal-mode frequencies. The ratio R = dlnVS/dlnVP of perturbations in the S-wave velocity and P-wave velocity has been estimated to be higher than 2-3 for LLSVPs. This and other observations support the hypothesis that LLSVPs represent compositionally distinct piles in the lower mantle. R in the lowermost mantle is primarily estimated using diffracted P waves (Pd) and diffracted S waves (Sd). These long-period body waves have different Fresnel zones. Our preliminary analysis of Pd and Sd traveltimes using spectral-element method synthetics for long-wavelength models of wave speed heterogeneity in D" indicate that ray-theoretical interpretations of Pd and Sd delay times may bias estimates of R. We discuss the effect of wave front healing on Pd and Sd delay times, compare our simulations with 15,000 Pd and Sd delay times and the splitting of Stoneley modes with peak sensitivity in D", and evaluate the purely thermal and thermo-chemical interpretations of LLSVPs.

  13. Universal Relations for a Fermi Gas Close to a p -Wave Interaction Resonance

    NASA Astrophysics Data System (ADS)

    Yu, Zhenhua; Thywissen, Joseph H.; Zhang, Shizhong

    2015-09-01

    We investigate the properties of a spinless Fermi gas close to a p -wave interaction resonance. We show that the effects of interaction near a p -wave resonance are captured by two contacts, which are related to the variation of energy with the p -wave scattering volume v and with the effective range R in two adiabatic theorems. Exact pressure and virial relations are derived. We show how the two contacts determine the leading and subleading asymptotic behavior of the momentum distribution (˜1 /k2 and ˜1 /k4) and how they can be measured experimentally by radio-frequency and photoassociation spectroscopies. Finally, we evaluate the two contacts at high temperature with a virial expansion.

  14. Vanishing edge currents and orbital angular momentum in non- p-wave topological chiral superconductors

    NASA Astrophysics Data System (ADS)

    Huang, Wen; Taylor, Edward; Kallin, Catherine

    2015-03-01

    The edge currents of two dimensional topological chiral superconductors with nonzero Cooper pair angular momentum-e.g., chiral p-, d-, and f-wave superconductivity-are studied. Bogoliubov-de Gennes and Ginzburg-Landau calculations are used to show that in the continuum limit, only chiral p-wave states have a nonzero edge current and orbital angular momentum. Outside this limit, when lattice effects become important, edge currents in non- p-wave superconductors are comparatively smaller, but can be nonzero. Using Ginzburg-Landau theory, a simple criterion is derived for when edge currents vanish for non- p-wave chiral superconductivity on a lattice. The implications of our results for putative chiral superconductors such as Sr2RuO4 and UPt3 are discussed. Work supported by NSERC, CIFAR, Canada Council Killam programs (CK) and the National Science Foundation (CK).

  15. Flutrer-like P waves in a case of atrioventricular reciprocating tachycardia.

    PubMed

    Cheng, Kai-Hung; Chu, Chih-Sheng; Lee, Kun-Tai; Lee, Shuo-Psan; Su, Ho-Ming; Lin, Tsung-Hsien; Sheu, Sheng-Hsiung; Lai, Wen-Ter

    2005-08-01

    Typical atrial flutter is characterized by its sawtooth flutter wave in leads II, III, aVF, and V1. Atrioventricular reciprocating tachycardia is characterized by its small retrograde P wave after completion of QRS complex, where sawtooth flutter-like P waves are rarely seen in the electrocardiogram during atrioventricular reciprocating tachycardia. We report on a 62-year-old patient who presented the characteristic sawtooth flutter-like P waves in the electrocardiogram during attack of supraventricular tachycardia. By electrophysiologic study, the mechanism of his supraventricular tachycardia was atrioventricular reciprocating tachycardia using the left posterior lateral concealed accessory pathway for retrograde conduction. The accessory pathway was successfully ablated by radiofrequency ablation therapy. PMID:16158881

  16. Universal Relations for a Fermi Gas Close to a p-Wave Interaction Resonance.

    PubMed

    Yu, Zhenhua; Thywissen, Joseph H; Zhang, Shizhong

    2015-09-25

    We investigate the properties of a spinless Fermi gas close to a p-wave interaction resonance. We show that the effects of interaction near a p-wave resonance are captured by two contacts, which are related to the variation of energy with the p-wave scattering volume v and with the effective range R in two adiabatic theorems. Exact pressure and virial relations are derived. We show how the two contacts determine the leading and subleading asymptotic behavior of the momentum distribution (∼1/k^{2} and ∼1/k^{4}) and how they can be measured experimentally by radio-frequency and photoassociation spectroscopies. Finally, we evaluate the two contacts at high temperature with a virial expansion. PMID:26451564

  17. Behavioral cardiology --has its time finally arrived?

    PubMed

    Pickering, Thomas; Clemow, Lynn; Davidson, Karina; Gerin, William

    2003-03-01

    Traditional cardiology has taken a mechanistic approach to heart disease. But the new discipline of behavioral cardiology takes a broader view, concluding that heart disease is not inevitable, but develops largely from unhealthy lifestyles, such as smoking, overeating and physical inactivity, and from psychosocial stress. Physical inactivity and excessive caloric intake are also responsible for the epidemic of obesity, which is associated with a dramatic increase in the prevalence of diabetes. This increase in the incidence of diabetes may, in turn, reverse the recent decline of cardiovascular deaths in the US. A variety of psychosocial stressors have been implicated in the development of cardiovascular disease. These include occupational stress, anxiety, social isolation, hostility, anger, and type A behavior. There is clearly some overlap between these stressors, all of which may affect the heart adversely. Both the lifestyle and psychosocial factors can be altered by behavioral treatment, in which the patient and the practitioner work together. Unfortunately, various barriers can impair the successful implementation of behavioral treatment. These barriers include poor compliance by the patient, lack of skill in providing effective interventions by the health care provider, and lack of incentives within the health care system, particularly reimbursement. PMID:12634902

  18. Factors Influencing Intracavitary Electrocardiographic P-Wave Changes during Central Venous Catheter Placement.

    PubMed

    Wang, Guorong; Guo, Ling; Jiang, Bin; Huang, Min; Zhang, Jian; Qin, Ying

    2015-01-01

    Amplitude changes in the P-wave of intracavitary electrocardiography have been used to assess the tip placement of central venous catheters. The research assessed the sensitivity and specificity of this sign in comparison with standard radiographic techniques for tip location, focusing on factors influencing its clinical utility. Both intracavitary electrocardiography guided tip location and X-ray positioning were used to verify catheter tip locations in patients undergoing central venous catheter insertion. Intracavitary electrocardiograms from 1119 patients (of a total 1160 subjects) showed specific amplitude changes in the P-wave. As the results show, compared with X-ray positioning, the sensitivity of electrocardiography-guided tip location was 97.3%, with false negative rate of 2.7%; the specificity was 1, with false positive rate of zero. Univariate analyses indicated that features including age, gender, height, body weight, and heart rate have no statistically significant influence on P-wave amplitude changes (P > 0.05). Multivariate logistic regression revealed that catheter insertion routes (OR = 2.280, P = 0.003) and basal P-wave amplitude (OR = 0.553, P = 0.003) have statistically significant impacts on P-wave amplitude changes. As a reliable indicator of tip location, amplitude change in the P-wave has proved of good sensitivity and excellent specificity, and the minor, zero, false positive rate supports the clinical utility of this technique in early recognition of malpositioned tips. A better sensitivity was achieved in placement of centrally inserted central catheters (CICCs) than that of peripherally inserted central catheters (PICCs). In clinical practice, a combination of intracavitary electrocardiography, ultrasonic inspection and the anthropometric measurement method would further improve the accuracy. PMID:25915758

  19. Teleseismic P wave spectra from USArray and implications for upper mantle attenuation and scattering

    NASA Astrophysics Data System (ADS)

    Cafferky, Samantha; Schmandt, Brandon

    2015-10-01

    Teleseismic P wave amplitude spectra from deep earthquakes recorded by USArray are inverted for maps of upper mantle ?t* for multiple frequency bands within 0.08-2 Hz. All frequency bands show high ?t* regions in the southwestern U.S., southern Rocky Mountains, and Appalachian margin. Low ?t* is more common across the cratonic interior. Inversions with narrower frequency bands yield similar patterns, but greater ?t* magnitudes. Even the two standard deviation ?t* magnitude for the widest band is 2-7 times greater than predicted by global QS tomography or an anelastic olivine thermal model, suggesting that much of the ?t* signal is nonthermal in origin. Nonthermal contributions are further indicated by only a moderate correlation between ?t* and P travel times. Some geographic variations, such as high ?t* in parts of the cratonic interior with high mantle velocities and low heat flow, demonstrate that the influence of temperature is regionally overwhelmed. Transverse spectra are used to investigate the importance of scattering because they would receive no P energy in the absence of 3-D heterogeneity or anisotropy. Transverse to vertical (T/Z) spectral ratios for stations with high ?t* are higher and exhibit steeper increases with frequency compared to T/Z spectra for low ?t* stations. The large magnitude of ?t* estimates and the T/Z spectra are consistent with major contributions to ?t* from scattering. A weak positive correlation between intrinsic attenuation and apparent attenuation due to scattering may contribute to ?t* magnitude and the moderate correlation of ?t* with travel times.

  20. Finite-momentum superfluidity and phase transitions in a p-wave resonant Bose gas

    SciTech Connect

    Choi, Sungsoo; Radzihovsky, Leo

    2011-10-15

    We study a degenerate two-species gas of bosonic atoms interacting through a p-wave Feshbach resonance as, for example, realized in a {sup 85}Rb-{sup 87}Rb mixture. We show that, in addition to a conventional atomic and a p-wave molecular spinor-1 superfluidity at large positive and negative detunings, respectively, the system generically exhibits a finite-momentum atomic-molecular superfluidity at intermediate detuning around the unitary point. We analyze the detailed nature of the corresponding phases and the associated quantum and thermal phase transitions.

  1. Flame Arrival Measurement By Instrumented Spark Plug or Head Gasket

    Energy Science and Technology Software Center (ESTSC)

    1995-04-10

    PLUGBIN was developed to support Sandia technologies involving instrumented head gaskets and spark plugs for engine research and development. It acquires and processes measurements of flame arrival and pressure from a spark ignition. Flame arrival is determined from analog ionization-probe or visible-emission signals, and/or digitial signals from a dedicated flame arrival measurement processor. The pressure measurements are analyzed to determine the time of peak pressure and the time to burn 10 and 90 percent ofmore » the charge. Histograms are then calculated and displayed for each measurement.« less

  2. Effect of a low-velocity sedimentary cover on the 3-D velocity models derived from inversion of local arrival times. An example from the New Madrid seismic zone.

    NASA Astrophysics Data System (ADS)

    Pujol, J. M.; Chiu, J. M.

    2014-12-01

    When applying seismic tomography to local arrival times from an area with a low-velocity sedimentary cover, the effect of the sediments on travel times should be taken into account. If that is not done, the resulting velocity model(s) cannot be assumed to be correct. This fairly obvious statement has been challenged recently by Powell et al. (JGR, 2010), who claimed that the sediments that cover the New Madrid seismic zone (NMSZ, central United States) can be ignored. This claim is examined here and shown to be incorrect. The NMSZ is covered by low-velocity, poorly consolidated sediments (Vp=1.8 km/s, Vs=3), which are underlain by Paleozoic rocks of much higher velocity. In the central NMSZ the sediment thickness varies between about 0.1 and 0.7 km. The JHD analysis of the data collected in that area by a portable network (PANDA) showed that the P- and S-wave station corrections spanned large ranges (0.35 and 0.63 s, respectively, Pujol et al., Eng. Geol., 1997). This study also showed that a Vp/Vs of 3 for the sediments would be too high if the lateral velocity variations were confined to the sedimentary cover. Here we generate synthetic traveltimes for a model with a sedimentary cover having variable depth (as determined from boreholes) underlain by the high-velocity layers in the 1-D model used for the JHD analysis. The synthetic data were generated for the station and event distributions corresponding to the Panda data. The tomographic inversion of the synthetic times produces spurious anomalies in Vp, Vs, and Vp/Vs, from the surface to a depth of 10 km. In addition, the events are mislocated in depth, with errors between 0 and 1 km for most of them. These results should dispel the notion that the effect of the unconsolidated sediments can be ignored. On the other hand, the inversion of the actual Panda data results in velocity anomalies similar to the synthetic anomalies, although larger, which is consistent with the conclusions of Pujol et al. (1997). Unfortunately, extricating the effects of the sediments from those of deeper velocity anomalies will not be possible with seismic tomography unless in-situ determinations of Vp/Vs for the sediments in the network area become available. Alternatively, analysis techniques that make use of more than just P- and S-wave arrivals (such as S-to-P converted waves) may have to be designed.

  3. Subduction in the southern Caribbean: Images from finite-frequency P wave tomography

    NASA Astrophysics Data System (ADS)

    Bezada, M. J.; Levander, A.; Schmandt, B.

    2010-12-01

    The eastern boundary of the Caribbean plate is marked by subduction of the Atlantic under the Lesser Antilles. The southeastern plate boundary is characterized by a strike-slip margin, while different configurations of subduction of the southwest Caribbean under South America have been proposed. We investigate the slab geometry in the upper mantle using multiple-frequency, teleseismic P wave tomography. Waveforms from P and PKPdf phases from 285 (Mb > 5.0) events occurring at epicentral distances from 30° to 90° and greater than 150° were bandpass filtered and cross-correlated to obtain up to three sets of delay times for each event. The delay times were inverted using approximate first Fresnel zone sensitivity kernels. Our results show the subducting Atlantic slab, as well as a second slab in the west of the study area that we interpret as a subducting fragment of the Caribbean plate. Both slabs have steep dips where imaged and can be traced to depths greater than 600 km. These results are consistent with transition zone boundary topography as determined by receiver function analysis. The Atlantic slab extends continent-ward south of the plate bounding strike-slip margin. We interpret this extension as continental margin lithospheric mantle that is detaching from beneath South America and subducting along with the oceanic Atlantic slab. The steep subduction of the Caribbean occurs ˜500 km landward from the trench, implying an initial stage of shallow subduction as far to the east as the Lake Maracaibo-Mérida Andes region, as has been inferred from intermediate depth seismicity.

  4. Geohydrology of the unsaturated zone and simulated time of arrival of landfill leachate at the water table, municipal solid waste landfill facility, US Army Air Defense Artillery Center and Fort Bliss, El Paso County, Texas

    USGS Publications Warehouse

    Frenzel, Peter F.; Abeyta, Cynthia G.

    1999-01-01

    The U.S. Air Defense Artillery Center and Fort Bliss Municipal Solid Waste Landfill Facility (MSWLF) is located about 10 miles northeast of downtown El Paso, Texas. The landfill is built on the Hueco Bolson, a deposit that yields water to five public-supply wells within 1.1 miles of the landfill boundary on all sides. The bolson deposits consist of lenses and mixtures of sand, clay, silt, gravel, and caliche. The unsaturated zone at the landfill is about 300 feet thick. The Hydrologic Evaluation of Landfill Performance (HELP) and the Multimedia Exposure Assessment Model for Evaluating the Land Disposal of Wastes (MULTIMED) computer models were used to simulate the time of first arrival of landfill leachate at the water table. Site-specific data were collected for model input. At five sites on the landfill cover, hydraulic conductivity was measured by an in situ method; in addition, laboratory values were obtained for porosity, moisture content at field capacity, and moisture content at wilting point. Twenty-seven sediment samples were collected from two adjacent boreholes drilled near the southwest corner of the landfill. Of these, 23 samples were assumed to represent the unsaturated zone beneath the landfill. The core samples were analyzed in the laboratory for various characteristics required for the HELP and MULTIMED models: initial moisture content, dry bulk density, porosity, saturated hydraulic conductivity, moisture retention percentages at various suction values, total organic carbon, and pH. Parameters were calculated for the van Genuchten and Brooks-Corey equations that relate hydraulic conductivity to saturation. A reported recharge value of 0.008 inch per year was estimated on the basis of soil- water chloride concentration. The HELP model was implemented using input values that were based mostly on site-specific data or assumed in a conservative manner. Exceptions were the default values used for waste characteristics. Flow through the landfill was assumed to be at steady state. The HELP-estimated landfill leakage rate was 101.6 millimeters per year, approximately 500 times the estimated recharge rate for the area near the landfill. The MULTIMED model was implemented using input values that were based mainly on site-specific data and some conservatively assumed values. Landfill leakage was assumed to begin when the landfill was established and to continue at a steady-state rate of 101.6 millimeters per year as estimated by the HELP model. By using an assumed solute concentration in the leachate of 1 milligram per liter and assuming no delay or decay of solute, the solute serves as a tracer to indicate the first arrival of landfill leachate. The simulated first arrival of leachate at the water table was 204 to 210 years after the establishment of the landfill.

  5. P-wave holographic superconductor/insulator phase transitions affected by dark matter sector

    NASA Astrophysics Data System (ADS)

    Rogatko, Marek; Wysokinski, Karol I.

    2016-03-01

    The holographic approach to building the p-wave superconductors results in three different models: the Maxwell-vector, the SU(2) Yang-Mills and the helical. In the probe limit approximation, we analytically examine the properties of the first two models in the theory with dark matter sector. It turns out that the effect of dark matter on the Maxwell-vector p-wave model is the same as on the s-wave superconductor studied earlier. For the non-Abelian model we study the phase transitions between p-wave holographic insulator/superconductor and metal/superconductor. Studies of marginally stable modes in the theory under consideration allow us to determine features of p-wave holographic droplet in a constant magnetic field. The dependence of the superconducting transition temperature on the coupling constant α to the dark matter sector is affected by the dark matter density ρD . For ρ D > ρ the transition temperature is a decreasing function of α. The critical chemical potential μ c for the quantum phase transition between insulator and metal depends on the chemical potential of dark matter μ D and for μ D = 0 is a decreasing function of α.

  6. Rupture imaging of the Mw 7.9 12 May 2008 Wenchuan earthquake from back projection of teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Koper, Keith D.; Sufri, Oner; Zhu, Lupei; Hutko, Alexander R.

    2009-04-01

    The Mw 7.9 Wenchuan earthquake of 12 May 2008 was the most destructive Chinese earthquake since the 1976 Tangshan event. Tens of thousands of people were killed, hundreds of thousands were injured, and millions were left homeless. Here we infer the detailed rupture process of the Wenchuan earthquake by back-projecting teleseismic P energy from several arrays of seismometers. This technique has only recently become feasible and is potentially faster than traditional finite-fault inversion of teleseismic body waves; therefore, it may reduce the notification time to emergency response agencies. Using the IRIS DMC, we collected 255 vertical component broadband P waves at 30-95° from the epicenter. We found that at periods of 5 s and greater, nearly all of these P waves were coherent enough to be used in a global array. We applied a simple down-sampling heuristic to define a global subarray of 70 stations that reduced the asymmetry and sidelobes of the array response function (ARF). We also considered three regional subarrays of seismometers in Alaska, Australia, and Europe that had apertures less than 30° and P waves that were coherent to periods as short as 1 s. Individual ARFs for these subarrays were skewed toward the subarrays; however, the linear sum of the regional subarray beams at 1 s produced a symmetric ARF, similar to that of the groomed global subarray at 5 s. For both configurations we obtained the same rupture direction, rupture length, and rupture time. We found that the Wenchuan earthquake had three distinct pulses of high beam power at 0, 23, and 57 s after the origin time, with the pulse at 23 s being highest, and that it ruptured unilaterally to the northeast for about 300 km and 110 s, with an average speed of 2.8 km/s. It is possible that similar results can be determined for future large dip-slip earthquakes within 20-30 min of the origin time using relatively sparse global networks of seismometers such as those the USGS uses to locate earthquakes in near-real time.

  7. Rupture imaging of the Mw 7.9 12 May 2008 Wenchuan earthquake from back projection of teleseismic P waves

    USGS Publications Warehouse

    Xu, Y.; Koper, K.D.; Sufri, O.; Zhu, L.; Hutko, Alexander R.

    2009-01-01

    [1] The Mw 7.9 Wenchuan earthquake of 12 May 2008 was the most destructive Chinese earthquake since the 1976 Tangshan event. Tens of thousands of people were killed, hundreds of thousands were injured, and millions were left homeless. Here we infer the detailed rupture process of the Wenchuan earthquake by back-projecting teleseismic P energy from several arrays of seismometers. This technique has only recently become feasible and is potentially faster than traditional finite-fault inversion of teleseismic body waves; therefore, it may reduce the notification time to emergency response agencies. Using the IRIS DMC, we collected 255 vertical component broadband P waves at 30-95?? from the epicenter. We found that at periods of 5 s and greater, nearly all of these P waves were coherent enough to be used in a global array. We applied a simple down-sampling heuristic to define a global subarray of 70 stations that reduced the asymmetry and sidelobes of the array response function (ARF). We also considered three regional subarrays of seismometers in Alaska, Australia, and Europe that had apertures less than 30?? and P waves that were coherent to periods as short as 1 s. Individual ARFs for these subarrays were skewed toward the subarrays; however, the linear sum of the regional subarray beams at 1 s produced a symmetric ARF, similar to that of the groomed global subarray at 5 s. For both configurations we obtained the same rupture direction, rupture length, and rupture time. We found that the Wenchuan earthquake had three distinct pulses of high beam power at 0, 23, and 57 s after the origin time, with the pulse at 23 s being highest, and that it ruptured unilaterally to the northeast for about 300 km and 110 s, with an average speed of 2.8 km/s. It is possible that similar results can be determined for future large dip-slip earthquakes within 20-30 min of the origin time using relatively sparse global networks of seismometers such as those the USGS uses to locate earthquakes in near-real time. Copyright 2009 by the American Geophysical Union.

  8. Queues with Dropping Functions and General Arrival Processes.

    PubMed

    Chydzinski, Andrzej; Mrozowski, Pawel

    2016-01-01

    In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process-the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions. PMID:26943171

  9. Queues with Dropping Functions and General Arrival Processes

    PubMed Central

    Chydzinski, Andrzej; Mrozowski, Pawel

    2016-01-01

    In a queueing system with the dropping function the arriving customer can be denied service (dropped) with the probability that is a function of the queue length at the time of arrival of this customer. The potential applicability of such mechanism is very wide due to the fact that by choosing the shape of this function one can easily manipulate several performance characteristics of the queueing system. In this paper we carry out analysis of the queueing system with the dropping function and a very general model of arrival process—the model which includes batch arrivals and the interarrival time autocorrelation, and allows for fitting the actual shape of the interarrival time distribution and its moments. For such a system we obtain formulas for the distribution of the queue length and the overall customer loss ratio. The analytical results are accompanied with numerical examples computed for several dropping functions. PMID:26943171

  10. Scheduling and Separating Departures Crossing Arrival Flows in Shared Airspace

    NASA Technical Reports Server (NTRS)

    Chevalley, Eric; Parke, Bonny K.; Lee, Paul; Omar, Faisal; Lee, Hwasoo; Beinert, Nancy; Kraut, Joshua M.; Palmer, Everett

    2013-01-01

    Flight efficiency and reduction of flight delays are among the primary goals of NextGen. In this paper, we propose a concept of shared airspace where departures fly across arrival flows, provided gaps are available in these flows. We have explored solutions to separate departures temporally from arrival traffic and pre-arranged procedures to support controllers' decisions. We conducted a Human-in-the-Loop simulation and assessed the efficiency and safety of 96 departures from the San Jose airport (SJC) climbing across the arrival airspace of the Oakland and San Francisco arrival flows. In our simulation, the SJC tower had a tool to schedule departures to fly across predicted gaps in the arrival flow. When departures were mistimed and separation could not be ensured, a safe but less efficient route was provided to the departures to fly under the arrival flows. A coordination using a point-out procedure allowed the arrival controller to control the SJC departures right after takeoff. We manipulated the accuracy of departure time (accurate vs. inaccurate) as well as which sector took control of the departures after takeoff (departure vs. arrival sector) in a 2x2 full factorial plan. Results show that coordination time decreased and climb efficiency increased when the arrival sector controlled the aircraft right after takeoff. Also, climb efficiency increased when the departure times were more accurate. Coordination was shown to be a critical component of tactical operations in shared airspace. Although workload, coordination, and safety were judged by controllers as acceptable in the simulation, it appears that in the field, controllers would need improved tools and coordination procedures to support this procedure.

  11. P-wave Local Earthquake Tomography in the Central Alborz Mountains, Iran

    NASA Astrophysics Data System (ADS)

    Mostafanejad, A.; Hosein Shomali, Z.

    2010-12-01

    The Alborz Mountain ranges in the southern margin of the Caspian Sea, as a part of the Alpine- Himalayan orogenic belt is an arc of parallel synclines and anticlines. Among the major tectonic and geological features of the Alborz Mountains are the Damavand quaternary volcano, and active and seismic faults like the Mosha, and North Tehran faults. In this study, the first 3D P-wave velocity model of the upper crust in the Central Alborz Mountains is obtained using a local travel-time earthquake tomography method. A data set of 895 earthquakes recorded on a local 19 station short-period network between 1996 and 2006 provided by the Iranian Seismological Centre (ISC) is used in this inversion. The result of tomography shows considerable velocity anomalies in this region. These anomalies show remarkable features in the vicinity of the Mosha and North Tehran faults, as well as in the Damavand volcanic area. In depth of 15 kilometer a low velocity region is observed parallel to the above two mentioned faults. This can be caused by the crushed rocks along these two faults. In the place of splitting North Tehran fault from the Mosha fault, a very noticeable low velocity anomaly represents intense fracturing in rocks. In the Damavand volcanic area and in the northern side of the summit an anomalous high velocity body found to the depth of 20 kilometer. According to its considerable correlation with the position of the old Damavand cone, it is related to the older and crystallized magma chamber of the Damavand volcano. A low velocity anomaly exactly beneath the present cone to the depth of seven kilometer, with another low velocity anomaly in depth of 10 to 20 kilometer constitutes the present magma chamber of the Damavand volcano.

  12. Anisotropic changes in P-wave velocity and attenuation during deformation and fluid infiltration of granite

    USGS Publications Warehouse

    Stanchits, S.A.; Lockner, D.A.; Ponomarev, A.V.

    2003-01-01

    Fluid infiltration and pore fluid pressure changes are known to have a significant effect on the occurrence of earthquakes. Yet, for most damaging earthquakes, with nucleation zones below a few kilometers depth, direct measurements of fluid pressure variations are not available. Instead, pore fluid pressures are inferred primarily from seismic-wave propagation characteristics such as Vp/Vs ratio, attenuation, and reflectivity contacts. We present laboratory measurements of changes in P-wave velocity and attenuation during the injection of water into a granite sample as it was loaded to failure. A cylindrical sample of Westerly granite was deformed at constant confining and pore pressures of 50 and 1 MPa, respectively. Axial load was increased in discrete steps by controlling axial displacement. Anisotropic P-wave velocity and attenuation fields were determined during the experiment using an array of 13 piezoelectric transducers. At the final loading steps (86% and 95% of peak stress), both spatial and temporal changes in P-wave velocity and peak-to-peak amplitudes of P and S waves were observed. P-wave velocity anisotropy reached a maximum of 26%. Transient increases in attenuation of up to 483 dB/m were also observed and were associated with diffusion of water into the sample. We show that velocity and attenuation of P waves are sensitive to the process of opening of microcracks and the subsequent resaturation of these cracks as water diffuses in from the surrounding region. Symmetry of the orientation of newly formed microcracks results in anisotropic velocity and attenuation fields that systematically evolve in response to changes in stress and influx of water. With proper scaling, these measurements provide constraints on the magnitude and duration of velocity and attenuation transients that can be expected to accompany the nucleation of earthquakes in the Earth's crust.

  13. Type 2 Diabetes Induces Prolonged P-wave Duration without Left Atrial Enlargement.

    PubMed

    Li, Bin; Pan, Yilong; Li, Xiaodong

    2016-04-01

    Prolonged P-wave duration has been observed in diabetes. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the possible mechanisms. A rat model of type 2 diabetes mellitus (T2DM) was used. P-wave durations were obtained using surface electrocardiography and sizes of the left atrium were determined using echocardiography. Cardiac inward rectifier K(+) currents (Ik1), Na(+) currents (INa), and action potentials were recorded from isolated left atrial myocytes using patch clamp techniques. Left atrial tissue specimens were analyzed for total connexin-40 (Cx40) and connexin-43 (Cx43) expression levels on western-blots. Specimens were also analyzed for Cx40 and Cx43 distribution and interstitial fibrosis by immunofluorescent and Masson trichrome staining, respectively. The mean P-wave duration was longer in T2DM rats than in controls; however, the mean left atrial sizes of each group of rats were similar. The densities of Ik1 and INa were unchanged in T2DM rats compared to controls. The action potential duration was longer in T2DM rats, but there was no significant difference in resting membrane potential or action potential amplitude compared to controls. The expression level of Cx40 protein was significantly lower, but Cx43 was unaltered in T2DM rats. However, immunofluorescent labeling of Cx43 showed a significantly enhanced lateralization. Staining showed interstitial fibrosis was greater in T2DM atrial tissue. Prolonged P-wave duration is not dependent on the left atrial size in rats with T2DM. Dysregulation of Cx40 and Cx43 protein expression, as well as fibrosis, might partly account for the prolongation of P-wave duration in T2DM. PMID:27051235

  14. Type 2 Diabetes Induces Prolonged P-wave Duration without Left Atrial Enlargement

    PubMed Central

    2016-01-01

    Prolonged P-wave duration has been observed in diabetes. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the possible mechanisms. A rat model of type 2 diabetes mellitus (T2DM) was used. P-wave durations were obtained using surface electrocardiography and sizes of the left atrium were determined using echocardiography. Cardiac inward rectifier K+ currents (Ik1), Na+ currents (INa), and action potentials were recorded from isolated left atrial myocytes using patch clamp techniques. Left atrial tissue specimens were analyzed for total connexin-40 (Cx40) and connexin-43 (Cx43) expression levels on western-blots. Specimens were also analyzed for Cx40 and Cx43 distribution and interstitial fibrosis by immunofluorescent and Masson trichrome staining, respectively. The mean P-wave duration was longer in T2DM rats than in controls; however, the mean left atrial sizes of each group of rats were similar. The densities of Ik1 and INa were unchanged in T2DM rats compared to controls. The action potential duration was longer in T2DM rats, but there was no significant difference in resting membrane potential or action potential amplitude compared to controls. The expression level of Cx40 protein was significantly lower, but Cx43 was unaltered in T2DM rats. However, immunofluorescent labeling of Cx43 showed a significantly enhanced lateralization. Staining showed interstitial fibrosis was greater in T2DM atrial tissue. Prolonged P-wave duration is not dependent on the left atrial size in rats with T2DM. Dysregulation of Cx40 and Cx43 protein expression, as well as fibrosis, might partly account for the prolongation of P-wave duration in T2DM. PMID:27051235

  15. Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by {ital Pioneer} {ital V}{ital enus} {ital Orbiter}, {ital Compton} {ital Gamma}-{ital Ray} {ital Observatory}, and {ital Ulysses}

    SciTech Connect

    Laros, J.G.; Hurley, K.C.; Fenimore, E.E.; Klebesadel, R.W.; Briggs, M.S.; Kouveliotou, C.; McCollough, M.L.

    1998-10-01

    Between the {ital Compton} {ital Gamma} {ital Ray} {ital Observatory} ({ital CGRO}) launch in 1991 April and the {ital Pioneer} {ital V}{ital enus} {ital Orbiter} ({ital PVO}) demise in 1992 October, concurrent coverage by {ital CGRO}, {ital PVO}, and {ital Ulysses} was obtained for several hundred gamma-ray bursts (GRBs). Although most of these were below the {ital PVO} and {ital Ulysses} thresholds, 37 were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to {approximately}2{degree} accuracy by the {ital CGRO} Burst and Transient Source Experiment (BATSE), and three were also localized by COMPTEL. We computed arrival-time error boxes, whose larger dimensions range from about 2{prime} to several degrees and whose smaller dimensions are in the arcminute range. Twelve have areas less than 10 arcmin{sup 2}, and only four have areas greater than 1 deg{sup 2}. The area of the smallest box is 0.44 arcmin{sup 2}. We find that the overall BATSE localization accuracy for these events is consistent with the most recent stated uncertainties. This work indicates that the {ital ROSAT} soft X-ray source found within a preliminary IPN error box for GB920501 (Trig 1576) (Hurley et al.) is less likely to be the GRB counterpart than previously reported. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

  16. Collaborative Arrival Planning: Data Sharing and User Preference Tools

    NASA Technical Reports Server (NTRS)

    Zelenka, Richard E.; Edwards, Thomas A. (Technical Monitor)

    1998-01-01

    Air traffic growth and air carrier economic pressures have motivated efforts to increase the flexibility of the air traffic management process and change the relationship between the air traffic control service provider and the system user. One of the most visible of these efforts is the U.S. government/industry "free flight" initiative, in which the service provider concentrates on safety and cross-airline fairness, and the user on their business objectives and operating preferences, including selecting their own path and speed in real-time. In the terminal arrival phase of flight, severe restrictions and rigid control are currently placed on system users, typically without regard for individual user operational preferences. Airborne delays applied to arriving aircraft into capacity constrained airports are imposed on a first-come, first-serve basis, and thus do not allow the system user to plan for or prioritize late arrivals, or to economically optimize their arrival sequence. A central tenant of the free-flight operating paradigm is collaboration between service providers and users in reaching air traffic management decisions. Such collaboration would be particularly beneficial to an airline's "hub" operation, where off-schedule arrival aircraft are a consistent problem, as they cause serious air-port ramp difficulties, rippling airline scheduling effects, and result in large economic inefficiencies. Greater collaboration can also lead to increased airport capacity and decrease the severity of over-capacity rush periods. In the NASA Collaborative Arrival Planning (CAP) project, both independent exchange of real-time data between the service provider and system user and collaborative decision support tools are addressed. Data exchange of real-time arrival scheduling, airspace management, and air carrier fleet data between the FAA service provider and an air carrier is being conducted and evaluated. Collaborative arrival decision support tools to allow intra-airline arrival preferences are being developed and simulated. The CAP project is part of and leveraged from the NASA/FAA Center TRACON Automation System (CTAS), a fielded set of decision support tools that provide computer generated advisories for both enroute and terminal area controllers to manage and control arrival traffic more efficiently. In this paper, the NASA Collaborative Arrival Planning project is outlined and recent results detailed, including the real-time use of CTAS arrival scheduling data by a major air carrier and simulations of tactical and strategic user preference decision support tools.

  17. Three-dimensional modeling of the Nevada Test Site and vicinity from teleseismic P-wave residuals

    USGS Publications Warehouse

    Monfort, Mary E.; Evans, John R.

    1982-01-01

    A teleseismic P-wave travel-time residual study is described which reveals the regional compressional-velocity structure of southern Nevada and neighboring parts of California to a depth of 280 km. During 1980, 98 teleseismic events were recorded at as many as 53 sites in this area. P-wave residuals were calculated relative to a network-wide average residual for each event and are displayed on maps of the stations for each of four event-azimuth quadrants. Fluctuations in these map-patterns of residuals with approach azimuth combined with results of linear, three-dimensional inversions of some 2887 residuals indicate the following characteristics of the velocity structure of the southern Nevada region: 1) a low-velocity body exists in the upper crust 50 km northeast of Beatty, Nevada, near the Miocene Timber Mountain-Silent Canyon caldera complex. Another highly-localized low-velocity anomaly occurs near the southwest corner of the Nevada Test Site (NTS). These two anomalies seem to be part of a low-velocity trough extending from Death Valley, California, to about 50 km north of NTS. 2) There is a high-velocity body in the mantle between 81 and 131 km deep centered about i0 km north of the edge of the Timber Mountain caldera, 3) a broad low-velocity body is delineated between 81 and 131 km deep centered about 30 km north of Las Vegas, 4) there is a monotonic increase in travel-time delays from west to east across the region, probably indicating an eastward decrease in velocity, and lower than average velocities in southeastern Nevada below 31 km, and 5) considerable complexity in three-dimensional velocity structure exists in this part of the southern Great Basin. Inversions of teleseismic P-wave travel-time residuals were also performed on data from 12 seismometers in the immediate vicinity of the Nevada Test Site to make good use of the closer station spacing i in that area. Results of these inversions show more details of the velocity structure but generally the same features as those found in the regional study.

  18. Enhancement to detection performance of regional arrivals at NOA

    NASA Astrophysics Data System (ADS)

    Jia, Y.; Coyne, J.; Tajan

    2009-04-01

    The International Monitoring System (IMS) station NOA at the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) has 7 subnets with an exceptional large aperture (ca 58 km). This station was initially designed to detect teleseismic signals. However, regional signals can be well observed at this station. Due to the incoherence of regional arrivals between the different subnets (caused by large distances between the subnets), many regional arrivals were not detected by the automated system at the International Data Centre (IDC). These missed arrivals had to be manually added by analysts during the interactive processing. To enhance the detection performance of regional arrivals at NOA and reduce the work load of analysts, configurations and software of Detection Feature Exactions (DFX) were modified to allow only using the data at the subnet NB2 for detecting and measuring the features of regional arrivals. Studies for designing the detection beam recipes of regional arrivals based on the coverage of array response for 3 dB energy loss, and for selecting an optimized filter band and a reasonable SNR threshold, will be presented. To validate the modifications made by this study, regional arrivals in a period of fifteen days were carefully reviewed by analysts in the Seismic Specialist Group at IDC. Testing results for this reviewed data set and the results on run-time system both showed significant improvements.

  19. Evaluation of QT and P Wave Dispersion and Mean Platelet Volume among Inflammatory Bowel Disease Patients

    PubMed Central

    DOGAN, Yuksel; SOYLU, Aliye; EREN, Gulay A.; POTUROGLU, Sule; DOLAPCIOGLU, Can; SONMEZ, Kenan; DUMAN, Habibe; SEVINDIR, Isa

    2011-01-01

    Background: In inflammatory bowel disease (IBD) number of thromboembolic events are increased due to hypercoagulupathy and platelet activation. Increases in mean platelet volume (MPV) can lead to platelet activation, this leads to thromboembolic events and can cause acute coronary syndromes. In IBD patients, QT-dispersion and P-wave dispersion are predictors of ventricular arrhythmias and atrial fibrilation; MPV is accepted as a risk factor for acute coronary syndromes, we aimed at evaluating the correlations of these with the duration of disease, its localization and activity. Methods: The study group consisted of 69 IBD (Ulcerative colitis n: 54, Crohn's Disease n:15) patients and the control group included 38 healthy individuals. Disease activity was evaluated both endoscopically and clinically. Patients with existing cardiac conditions, those using QT prolonging medications and having systemic diseases, anemia and electrolyte imbalances were excluded from the study. QT-dispersion, P-wave dispersion and MPV values of both groups were compared with disease activity, its localization, duration of disease and the antibiotics used. Results: The P-wave dispersion values of the study group were significantly higher than those of the control group. Duration of the disease was not associated with QT-dispersion, and MPV levels. QT-dispersion, P-wave dispersion, MPV and platelet count levels were similar between the active and in mild ulcerative colitis patients. QT-dispersion levels were similar between IBD patients and the control group. No difference was observed between P-wave dispersion, QT-dispersion and MPV values; with regards to disease duration, disease activity, and localization in the study group (p>0.05). Conclusions: P-wave dispersion which is accepted as a risk factor for the development of atrial fibirilation was found to be high in our IBD patients. This demonstrates us that the risk of developing atrial fibrillation may be high in patients with IBD. No significant difference was found in the QT-dispersion, and in the MPV values when compared to the control group. PMID:21960745

  20. Estimating Controller Intervention Probabilities for Optimized Profile Descent Arrivals

    NASA Technical Reports Server (NTRS)

    Meyn, Larry A.; Erzberger, Heinz; Huynh, Phu V.

    2011-01-01

    Simulations of arrival traffic at Dallas/Fort-Worth and Denver airports were conducted to evaluate incorporating scheduling and separation constraints into advisories that define continuous descent approaches. The goal was to reduce the number of controller interventions required to ensure flights maintain minimum separation distances of 5 nmi horizontally and 1000 ft vertically. It was shown that simply incorporating arrival meter fix crossing-time constraints into the advisory generation could eliminate over half of the all predicted separation violations and more than 80% of the predicted violations between two arrival flights. Predicted separation violations between arrivals and non-arrivals were 32% of all predicted separation violations at Denver and 41% at Dallas/Fort-Worth. A probabilistic analysis of meter fix crossing-time errors is included which shows that some controller interventions will still be required even when the predicted crossing-times of the advisories are set to add a 1 or 2 nmi buffer above the minimum in-trail separation of 5 nmi. The 2 nmi buffer was shown to increase average flight delays by up to 30 sec when compared to the 1 nmi buffer, but it only resulted in a maximum decrease in average arrival throughput of one flight per hour.

  1. Coupled ππ, KK¯ scattering in P-wave and the ρ resonance from lattice QCD

    DOE PAGESBeta

    Wilson, David J.; Briceño, Raúl A.; Dudek, Jozef J.; Edwards, Robert G.; Thomas, Christopher E.

    2015-11-02

    In this study, we determine elastic and coupled-channel amplitudes for isospin-1 meson-meson scattering inmore » $P$-wave, by calculating correlation functions using lattice QCD with light quark masses such that $$m_\\pi = 236$$ MeV in a cubic volume of $$\\sim (4 \\,\\mathrm{fm})^3$$. Variational analyses of large matrices of correlation functions computed using operator constructions resembling $$\\pi\\pi$$, $$K\\overline{K}$$ and $$q\\bar{q}$$, in several moving frames and several lattice irreducible representations, leads to discrete energy spectra from which scattering amplitudes are extracted. In the elastic $$\\pi\\pi$$ scattering region we obtain a detailed energy-dependence for the phase-shift, corresponding to a $$\\rho$$ resonance, and we extend the analysis into the coupled-channel $$K\\overline{K}$$ region for the first time, finding a small coupling between the channels.« less

  2. The rupture process and asperity distribution of three great earthquakes from long-period diffracted P-waves

    NASA Technical Reports Server (NTRS)

    Ruff, L.; Kanamori, H.

    1983-01-01

    The variation of maximum earthquake size along the subduction zones has been interpreted as a variation in the seismic coupling ostensibly related to the mechanical conditions of the fault zone. Great differences are noted between the seismographs of the three great earthquakes whose rupture processes are presently considered: in the Kurile Islands (1963), The Rat Islands (1965) and Alaska (1964). On-scale long period P waves were recorded in all cases. Source time functions are deconvolved from the observed periods. It is concluded that maximum earthquake size is related to the asperity distribution on the fault. The subduction zones with the largest earthquakes have very large asperities, as in the Alaskan case, while the zones with the smaller great earthquakes, such as the Kurile Islands, have smaller scattered asperities.

  3. Properties of skyrmions and multi-quanta vortices in chiral p-wave superconductors

    PubMed Central

    Garaud, Julien; Babaev, Egor

    2015-01-01

    Chiral p-wave superconducting state supports a rich spectrum of topological excitations different from those in conventional superconducting states. Besides domain walls separating different chiral states, chiral p-wave state supports both singular and coreless vortices also interpreted as skyrmions. Here, we present a numerical study of the energetic properties of isolated singular and coreless vortex states as functions of anisotropy and magnetic field penetration length. In a given chiral state, single quantum vortices with opposite winding have different energies and thus only one kind is energetically favoured. We find that with the appropriate sign of the phase winding, two-quanta (coreless) vortices are always energetically preferred over two isolated single quanta (singular) vortices. We also report solutions carrying more flux quanta. However those are typically more energetically expensive/metastable as compared to those carrying two flux quanta. PMID:26631985

  4. Properties of skyrmions and multi-quanta vortices in chiral p-wave superconductors

    NASA Astrophysics Data System (ADS)

    Garaud, Julien; Babaev, Egor

    2015-12-01

    Chiral p-wave superconducting state supports a rich spectrum of topological excitations different from those in conventional superconducting states. Besides domain walls separating different chiral states, chiral p-wave state supports both singular and coreless vortices also interpreted as skyrmions. Here, we present a numerical study of the energetic properties of isolated singular and coreless vortex states as functions of anisotropy and magnetic field penetration length. In a given chiral state, single quantum vortices with opposite winding have different energies and thus only one kind is energetically favoured. We find that with the appropriate sign of the phase winding, two-quanta (coreless) vortices are always energetically preferred over two isolated single quanta (singular) vortices. We also report solutions carrying more flux quanta. However those are typically more energetically expensive/metastable as compared to those carrying two flux quanta.

  5. The influence of rock anisotropy on elliptical-polarization state of inhomogenously refracted P-wave

    NASA Astrophysics Data System (ADS)

    Fa, Lin; Zhao, Jie; Han, YongLan; Li, GuoHui; Ding, PengFei; Zhao, MeiShan

    2016-04-01

    This paper discusses the influence of the anisotropy parameters on elliptical-polarization of the inhomogenously refracted P-wave induced at VTI-media interface. For this refracted P-wave, we have derived, the equations of the elliptical-polarization trajectory. Following the elliptical-polarization trajectory, we calculated the effects of the rock anisotropic-parameters on the polarization state, with a Poincaré-sphere-like representation, for several varying media parameters. It is noted that the size, shape and initial phase angle of the elliptical-polarization trajectory are all depending the anisotropy media, as well as on the incident-angle. We expect that the findings from this paper would be applied to practical applications of seismic exploration.

  6. Perturbative QCD fragmentation functions for production of [ital P]-wave charm and bottom mesons

    SciTech Connect

    Yuan, T.C. )

    1994-11-01

    We calculate the leading order QCD fragmentation functions for the production of [ital P]-wave charmed [ital b] mesons. Long-distance effects are factored into two nonperturbative parameters: the derivative of the radial wave function at the origin and a second parameter related to the probability for a ([ital [bar b]c]) heavy quark pair that is produced in a color-octet [ital S]-wave state to form a color-singlet [ital P]-wave bound state. The four 2[ital P] states and those 3[ital P] states which lie below the [ital BD] flavor threshold eventually all decay into the 1[ital S] ground state [ital B][sub [ital c

  7. HFER duration and displacement amplitudes from regional P waves as a possible tsunami earthquake discriminant

    NASA Astrophysics Data System (ADS)

    Hara, T.

    2014-12-01

    Hara (2007) showed that tsunami earthquakes could be characterized by long high frequency energy radiation (HFER) durations and small displacement amplitudes of P-waves in his analysis of tele-seismic data and suggested the possibility to discriminate tsunami earthquakes by measurements of HFER durations and displacement amplitudes. In this study, we investigated this possibility using waveform data recorded in a regional distance range (up to 30 degrees). We used a dataset compiled to develop a formula of Mhdd (Hara, 2013) for regional distance range (Hara, 2014, submitted). It consists of BHZ channel waveform data retrieved from the IRIS Data Management Center for 93 large shallow earthquakes that occurred between 1994 and July, 2013. Two tsunami earthquakes, the July 17, 2006 Java and October 25, 2010 Mentawai, were included. The distance correction for P wave displacements was done simply by a common logarithm of epicentral distance, although a slight different correction is adopted in the Mhdd formula. As was observed in the analysis of tele-seismic data, the tsunami earthquakes were characterized by long HFER durations and small displacement amplitudes measured from P waves. This suggests that it is possible to discriminate tsunami earthquakes by simple measurements of HFER durations and displacement amplitudes from regional P waves more rapidly than those from tele-seismic data. Since some strike slip events have the similar characteristics as tsunami earthquakes in terms of these measurements, rapid focal mechanism determination such as W phase source inversion would be helpful to distinguish tsunami earthquakes from these strike slip events.

  8. Input-output characterization of fiber reinforced composites by P waves

    NASA Technical Reports Server (NTRS)

    Renneisen, John D.; Williams, James H., Jr.

    1990-01-01

    Input-output characterization of fiber composites is studied theoretically by tracing P waves in the media. A new path motion to aid in the tracing of P and the reflection generated SV wave paths in the continuum plate is developed. A theoretical output voltage from the receiving transducer is calculated for a tone burst. The study enhances the quantitative and qualitative understanding of the nondestructive evaluation of fiber composites which can be modeled as transversely isotropic media.

  9. Spectral modulation effect in teleseismic P-waves from DPRK nuclear tests recorded at different azimuths

    NASA Astrophysics Data System (ADS)

    Gitterman, Yefim; Kim, So Gu; Hofstetter, Abraham

    2014-05-01

    Two underground nuclear explosions conducted by North Korea in 2009 and 2013 were recorded by the Israel Seismic Network. Pronounced coherent minima (spectral nulls) at 1.2-1.3 Hz were revealed in the spectra of teleseismic P-waves. For a ground-truth explosion with a shallow source depth (relatively to an earthquake), this phenomenon can be interpreted in terms of the interference between the down-going P-wave and the pP phase reflected from the Earth's surface. A similar effect was observed at ISN stations for the Pakistan nuclear explosion at a different frequency 1.7 Hz indicating a source and not site-effect. Similar spectral minima with about the same frequency were observed in teleseismic P-waves of all three North Korea explosions (including the 2006 test) recorded at network stations and arrays in Kazakhstan (KURK), Norway (NORESS, ARCESS), Australia (Alice Springs, Warramunga) and Canada (Yellowknife), covering a broad azimuthal range. Data of the 2013 test at Warramunga array showed harmonic spectral modulation with several minima, evidencing a clear interference effect. These observations support the above-mentioned interpretation. Based on the null frequency dependency on the near-surface acoustic velocity and the source depth, the depth of the North Korea tests was estimated as ~2 km (different from the value ~1 km reported by USGS for the third test). This unusual depth estimation needs an additional validation based on more stations and verification by other methods.

  10. P-wave velocity structure of the uppermost mantle beneath Hawaii from traveltime tomography

    USGS Publications Warehouse

    Tilmann, F.J.; Benz, H.M.; Priestley, K.F.; Okubo, P.G.

    2001-01-01

    We examine the P-wave velocity structure beneath the island of Hawaii using P-wave residuals from teleseismic earthquakes recorded by the Hawaiian Volcano Observatory seismic network. The station geometry and distribution of events makes it possible to image the velocity structure between ~ 40 and 100 km depth with a lateral resolution of ~ 15 km and a vertical resolution of ~ 30 km. For depths between 40 and 80 km, P-wave velocities are up to 5 per cent slower in a broad elongated region trending SE-NW that underlies the island between the two lines defined by the volcanic loci. No direct correlation between the magnitude of the lithospheric anomaly and the current level of volcanic activity is apparent, but the slow region is broadened at ~ 19.8??N and narrow beneath Kilauea. In the case of the occanic lithosphere beneath Hawaii, slow seismic velocities are likely to be related to magma transport from the top of the melting zone at the base of the lithosphere to the surface. Thermal modelling shows that the broad elongated low-velocity zone cannot be explained in terms of conductive heating by one primary conduit per volcano but that more complicated melt pathways must exist.

  11. Majorana modes and p-wave superfluids for fermionic atoms in optical lattices.

    PubMed

    Bhler, A; Lang, N; Kraus, C V; Mller, G; Huber, S D; Bchler, H P

    2014-01-01

    The quest for realization of non-Abelian phases of matter, driven by their possible use in fault-tolerant topological quantum computing, has been spearheaded by recent developments in p-wave superconductors. The chiral p(x)+ip(y)-wave superconductor in two-dimensions exhibiting Majorana modes provides the simplest phase supporting non-Abelian quasiparticles and can be seen as the blueprint of fractional topological order. Alternatively, Kitaev's Majorana wire has emerged as an ideal toy model to understand Majorana modes. Here we present a way to make the transition from Kitaev's Majorana wires to two-dimensional p-wave superconductors in a system with cold atomic gases in an optical lattice. The main idea is based on an approach to generate p-wave interactions by coupling orbital degrees of freedom with strong s-wave interactions. We demonstrate how this design can induce Majorana modes at edge dislocations in the optical lattice, and we provide an experimentally feasible protocol for the observation of the non-Abelian statistics. PMID:25060143

  12. Three-dimensional P wave azimuthal anisotropy in the lithosphere beneath China

    NASA Astrophysics Data System (ADS)

    Huang, Zhouchuan; Wang, Pan; Zhao, Dapeng; Wang, Liangshu; Xu, Mingjie

    2014-07-01

    Seismic anisotropy in the upper mantle beneath East Asia has been studied extensively using shear wave (SKS) splitting measurements, which have provided important information on mantle dynamics in this region. However, SKS measurements have poor vertical resolution, and so their interpretations are usually not unique. In this work we use a large number of traveltime data from 34,036 local earthquakes recorded by 1563 seismic stations to determine the first model of 3-D P wave azimuthal anisotropy in the lithosphere beneath China. Our results show that the fast velocity directions (FVDs) are generally correlated with the surface geologic features, such as the strikes of the orogens, active faults, and tectonic boundaries. The FVDs in the upper crust are normal to the maximal horizontal stress (?H) in regions with extensive compression such as the Tibetan Plateau, whereas they are subparallel to ?H in strike-slip shear zones such as the western and eastern Himalayan syntax. The comparison of the FVDs of P wave anisotropy with SKS splitting measurements indicates that beneath the Tibetan Plateau the seismic anisotropy in the lithosphere contributes significantly to the SKS splitting observations. In contrast, in east China the P wave FVDs in the lithosphere are different from the SKS splitting measurements, suggesting that the SKS splitting is mainly caused by the anisotropy in the deeper mantle such as the asthenosphere and the mantle transition zone under east China. These novel results provide important new information on the lithospheric deformation and mantle dynamics in East Asia.

  13. Effect of low dose sotalol on the signal averaged P wave in patients with paroxysmal atrial fibrillation.

    PubMed Central

    Stafford, P. J.; Cooper, J.; de Bono, D. P.; Vincent, R.; Garratt, C. J.

    1995-01-01

    OBJECTIVE--To investigate the effects of low dose sotalol on the signal averaged surface P wave in patients with paroxysmal atrial fibrillation. DESIGN--A longitudinal within patient crossover study. SETTING--Cardiac departments of a regional cardiothoracic centre and a district general hospital. PATIENTS--Sixteen patients with documented paroxysmal atrial fibrillation. The median (range) age of the patients was 65.5 (36-70) years; 11 were men. MAIN OUTCOME MEASURES--Analysis of the signal averaged P wave recorded from patients not receiving antiarrhythmic medication and after 4-6 weeks' treatment with sotalol. P wave limits were defined automatically by a computer algorithm. Filtered P wave duration and energies contained in frequency bands from 20, 30, 40, 60, and 80 to 150 Hz of the P wave spectrum expressed as absolute values (P20, P30, etc) and as ratios of high to low frequency energy (PR20, PR30, etc) were measured. RESULTS--No difference in P wave duration was observed between the groups studied (mean (SEM) 149 (4) without medication and 152 (3) ms with sotalol). Significant decreases in high frequency P wave energy (for example P60: 4.3 (0.4) v 3.3 (0.3) microV2.s, P = 0.003) and energy ratio (PR60: 5.6 (0.5) v 4.7 (0.6), P = 0.03) were observed during sotalol treatment. These changes were independent of heart rate. CONCLUSIONS--Treatment with low dose sotalol reduces high frequency P wave energy but does not change P wave duration. These results are consistent with the class III effect of the drug and suggest that signal averaging of the surface P wave may be a useful non-invasive measure of drug induced changes in atrial electrophysiology. PMID:8541169

  14. STS-93: Chandra Crew Arrival

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The primary objective of the STS-93 mission was to deploy the Advanced X-ray Astrophysical Facility, which had been renamed the Chandra X-ray Observatory in honor of the late Indian-American Nobel Laureate Subrahmanyan Chandrasekhar. The mission was launched at 12:31 on July 23, 1999 onboard the space shuttle Columbia. The mission was led by Commander Eileen Collins. The crew was Pilot Jeff Ashby and Mission Specialists Cady Coleman, Steve Hawley and Michel Tognini from the Centre National d'Etudes Spatiales (CNES). This videotape shows the astronauts arrival at Kennedy Space Center a week before the launch. Each of the astronauts gives brief remarks, beginning with Eileen Collins, the first woman to command a space mission.

  15. Multifrequency measurements of core-diffracted P waves (Pdiff) for global waveform tomography

    NASA Astrophysics Data System (ADS)

    Hosseini, Kasra; Sigloch, Karin

    2015-10-01

    The lower third of the mantle is sampled extensively by body waves that diffract around the earth's core (Pdiff and Sdiff phases), which could deliver highly resolved tomographic images of this poorly understood region. But core-diffracted waves-especially Pdiff waves-are not often used in tomography because they are difficult to model adequately. Our aim is to make core-diffracted body waves usable for global waveform tomography, across their entire frequency range. Here we present the data processing part of this effort. A method is demonstrated that routinely calculates finite-frequency traveltimes of Pdiff waves by cross-correlating large quantities of waveform data with synthetic seismograms, in frequency passbands ranging from 30.0 to 2.7 s dominant period. Green's functions for 1857 earthquakes, typically comprising thousands of seismograms, are calculated by theoretically exact wave propagation through a spherically symmetric earth model, up to 1 Hz dominant period. Out of 418 226 candidates, 165 651 (39.6 per cent) source-receiver pairs yielded at least one successful passband measurement of a Pdiff traveltime anomaly, for a total of 479 559 traveltimes in the eight passbands considered. Measurements of teleseismic P waves yielded 448 178 usable source-receiver paths from 613 057 candidates (73.1 per cent success rate), for a total of 2 306 755 usable teleseismic dT in eight passbands. Observed and predicted characteristics of Pdiff traveltimes are discussed and compared to teleseismic P for this very large data set. Pdiff measurements are noise-limited due to severe wave attenuation with epicentral distance and frequency. Measurement success drops from 40-60 per cent at 80° distance, to 5-10 per cent at 140°. Frequency has a 2-3 times stronger influence on measurement success for Pdiff than for P. The fewest usable dT measurements are obtained in the microseismic noise band, whereas the fewest usable teleseismic P measurements occur at the highest frequencies. dT anomalies are larger for Pdiff than for P, and frequency dependence of dT due to 3-D heterogeneity (rather than just diffraction) is larger for Pdiff as well. Projecting the Pdiff traveltime anomalies on their core-grazing segments, we retrieve well-known, large-scale structural heterogeneities of the lowermost mantle, such as the two Large Low Shear Velocity Provinces, an Ultra-Low Velocity Zone west of Hawaii, and subducted slab accumulations under East Asia and Central America.

  16. Finite difference modelling to evaluate seismic P wave and shear wave field data

    NASA Astrophysics Data System (ADS)

    Burschil, T.; Beilecke, T.; Krawczyk, C. M.

    2014-08-01

    High-resolution reflection seismic methods are an established non-destructive tool for engineering tasks. In the near surface, shear wave reflection seismic measurements usually offer a higher spatial resolution in the same effective signal frequency spectrum than P wave data, but data quality varies more strongly. To discuss the causes of these differences, we investigated a P wave and a SH wave reflection seismic profile measured at the same location on Föhr island, and applied reflection seismic processing to the field data as well as finite difference modelling of the seismic wavefield (SOFI FD-code). The simulations calculated were adapted to the acquisition field geometry, comprising 2 m receiver distance and 4 m shot distance along the 1.5 km long P wave and 800 m long SH wave profiles. A Ricker-Wavelet and the use of absorbing frames were first order model parameters. The petrophysical parameters to populate the structural models down to 400 m depth are taken from borehole data, VSP measurements and cross-plot relations. The first simulation of the P wave wavefield was based on a simplified hydrogeological model of the survey location containing six lithostratigraphic units. Single shot data were compared and seismic sections created. Major features like direct wave, refracted waves and reflections are imaged, but the reflectors describing a prominent till layer at ca. 80 m depth was missing. Therefore, the P wave input model was refined and 16 units assigned. These define a laterally more variable velocity model (vP = 1600-2300 m s-1) leading to a much better reproduction of the field data. The SH wave model was adapted accordingly but only led to minor correlation with the field data and produced a higher signal-to-noise ratio. Therefore, we suggest to consider for future simulations additional features like intrinsic damping, thin layering, or a near surface weathering layer. These may lead to a better understanding of key parameters determining the data quality of near-surface seismic measurements.

  17. Finite-difference modelling to evaluate seismic P-wave and shear-wave field data

    NASA Astrophysics Data System (ADS)

    Burschil, T.; Beilecke, T.; Krawczyk, C. M.

    2015-01-01

    High-resolution reflection seismic methods are an established non-destructive tool for engineering tasks. In the near surface, shear-wave reflection seismic measurements usually offer a higher spatial resolution in the same effective signal frequency spectrum than P-wave data, but data quality varies more strongly. To discuss the causes of these differences, we investigated a P-wave and a SH-wave seismic reflection profile measured at the same location on the island of Föhr, Germany and applied seismic reflection processing to the field data as well as finite-difference modelling of the seismic wave field. The simulations calculated were adapted to the acquisition field geometry, comprising 2 m receiver distance (1 m for SH wave) and 4 m shot distance along the 1.5 km long P-wave and 800 m long SH-wave profiles. A Ricker wavelet and the use of absorbing frames were first-order model parameters. The petrophysical parameters to populate the structural models down to 400 m depth were taken from borehole data, VSP (vertical seismic profile) measurements and cross-plot relations. The simulation of the P-wave wave-field was based on interpretation of the P-wave depth section that included a priori information from boreholes and airborne electromagnetics. Velocities for 14 layers in the model were derived from the analysis of five nearby VSPs (vP =1600-2300 m s-1). Synthetic shot data were compared with the field data and seismic sections were created. Major features like direct wave and reflections are imaged. We reproduce the mayor reflectors in the depth section of the field data, e.g. a prominent till layer and several deep reflectors. The SH-wave model was adapted accordingly but only led to minor correlation with the field data and produced a higher signal-to-noise ratio. Therefore, we suggest to consider for future simulations additional features like intrinsic damping, thin layering, or a near-surface weathering layer. These may lead to a better understanding of key parameters determining the data quality of near-surface shear-wave seismic measurements.

  18. Anisotropic characteristics of mesoscale fractures and applications to wide azimuth 3D P-wave seismic data

    NASA Astrophysics Data System (ADS)

    Wang, Yaojun; Chen, Shuangquan; Li, Xiang-Yang

    2015-06-01

    Mesoscale fractures of length on the order of centimeters to meters play a crucial role in fluid flow and hydrocarbon production in fractured reservoirs, and are of great interest to reservoir engineers. Therefore, we need to find a method for obtaining information on mesoscale fractures. Most information on fractures comes from seismic data, specifically through the study of fracture-induced azimuthal anisotropic attributes, such as velocity variation with azimuth (VVAZ), amplitude variation with azimuth (AVAZ) and Q (quality factor for attenuation) variation with azimuth (QVAZ). Using these anisotropic attributes to characterize fracture orientations and densities has been performed for a long time. However, it has not been reported whether these methods can be used to detect mesoscale fractures. In this study, through analysis of the anisotropic response to different lengths of fractures based on a mesoscale fracture model, we find that azimuthal anisotropic attenuation is only sensitive to mesoscale fractures, while the anisotropic velocity represents the response for overall scale fractures. Two models, containing mesoscale fractures of length 1 m and microscale fractures of length 0.01 m, are used to calculate synthetic seismograms. Through analysis of the azimuthal anisotropic attributes (VVAZ, AVAZ and QVAZ) from the synthetic seismograms, the identification ability for microscale and mesoscale fractures is compared. It is observed that QVAZ can be used to invert mesoscale fractures while VVAZ and AVAZ cannot. Finally, the QVAZ method is applied in a wide azimuth 3D P-wave seismic dataset to detect mesoscale fractures and the results are confirmed by imaging loggings. Thus, synthetic seismograms, rock physics analysis and field seismic application demonstrates that anisotropic attenuation is the most effective method to detect mesoscale fractures in wide azimuth 3D P-wave seismic data.

  19. The Evolution of P-wave Velocity in Fault Gouge: Initial Results for Samples from the SAFOD Volume.

    NASA Astrophysics Data System (ADS)

    Knuth, M. W.; Tobin, H. J.; Marone, C.

    2008-12-01

    We present initial results from a new technique for observing the evolution of elastic properties in sheared fault zone materials via acoustic wave velocity. The relationship between the mechanical strength of fault gouge and acoustic velocity during active deformation has important implications not only for a physical understanding of elasticity in deforming granular media, but also for the interpretation of the seismic velocity at the field scale. Experiments are conducted at atmospheric temperature and saturation state in a double-direct-shear testing apparatus, with normal stress stepped from 1 to 19 MPa to interrogate behavior during compaction, and sheared at a rate of 10 microns/second to observe changes in velocity with increasing strain. Tests are divided between those involving continuous shear to a displacement of 22.5 mm, and those with intervals of 3.75 mm shear separated by unloading and reloading sequences in normal stress. Velocity is measured by time-of-flight between two piezoelectric P-wave transducers set into the sample configuration on either side of the shearing layers. Samples tested include common laboratory standards for simulated fault gouge and field samples taken from representative localities in the 3D rock volume containing the San Andreas Fault Observatory at Depth experiment in Parkfield, California. The velocities of sand and clay end-member gouges are observed to behave differently under shear, and mixtures of quartz sand and montmorillonite behave differently from both end-member materials. Initial results suggest that particle sorting exerts a strong influence on both the absolute velocity and the evolution of velocity in response to increasing shear strain where the elastic properties of the grains are similar. We also observe a first-order relationship between the coefficient of friction and P-wave velocity that appears to be related to grain reorganization at the onset of shear following initial compaction.

  20. Investigation on relationship between epicentral distance and growth curve of initial P-wave propagating in local heterogeneous media for earthquake early warning system

    NASA Astrophysics Data System (ADS)

    Okamoto, Kyosuke; Tsuno, Seiji

    2015-10-01

    In the earthquake early warning (EEW) system, the epicenter location and magnitude of earthquakes are estimated using the amplitude growth rate of initial P-waves. It has been empirically pointed out that the growth rate becomes smaller as epicentral distance becomes far regardless of the magnitude of earthquakes. So, the epicentral distance can be estimated from the growth rate using this empirical relationship. However, the growth rates calculated from different earthquakes at the same epicentral distance mark considerably different values from each other. Sometimes the growth rates of earthquakes having the same epicentral distance vary by 104 times. Qualitatively, it has been considered that the gap in the growth rates is due to differences in the local heterogeneities that the P-waves propagate through. In this study, we demonstrate theoretically how local heterogeneities in the subsurface disturb the relationship between the growth rate and the epicentral distance. Firstly, we calculate seismic scattered waves in a heterogeneous medium. First-ordered PP, PS, SP, and SS scatterings are considered. The correlation distance of the heterogeneities and fractional fluctuation of elastic parameters control the heterogeneous conditions for the calculation. From the synthesized waves, the growth rate of the initial P-wave is obtained. As a result, we find that a parameter (in this study, correlation distance) controlling heterogeneities plays a key role in the magnitude of the fluctuation of the growth rate. Then, we calculate the regional correlation distances in Japan that can account for the fluctuation of the growth rate of real earthquakes from 1997 to 2011 observed by K-NET and KiK-net. As a result, the spatial distribution of the correlation distance shows locality. So, it is revealed that the growth rates fluctuate according to the locality. When this local fluctuation is taken into account, the accuracy of the estimation of epicentral distances from initial P-waves can improve, which will in turn improve the accuracy of the EEW system.

  1. BCVEGPY2.0: An upgraded version of the generator BCVEGPY with the addition of hadroproduction of the P-wave B states

    NASA Astrophysics Data System (ADS)

    Chang, Chao-Hsi; Wang, Jian-Xiong; Wu, Xing-Gang

    2006-02-01

    The generator BCVEGPY is upgraded by improving some of its features and by adding the hadroproduction of the P-wave excited B states (denoted by BcJ,L=1∗ or by hB_c and χB_c). In order to make the generator more efficient, we manipulate the amplitude as compact as possible with special effort. The correctness of the program is tested by various checks. We denote it as BCVEGPY2.0. As for the added part of the P-wave production, only the dominant gluon-gluon fusion mechanism ( gg→BcJ,L=1∗+c¯+b) is taken into account. Moreover, in the program, not only the ability to compute the contributions from the color-singlet components ( to the P-wave production but also the ability to compute the contributions from the color-octet components ( are available. With BCVEGPY2.0 the contributions from the two 'color components' to the production of each of the P-wave states may be computed separately by an option, furthermore, besides individually the event samples of the S-wave and P-wave ( cb¯)-heavy-quarkonium in various correct (realistic) mixtures can be generated by relevant options too. Program summaryTitle of program: BCVEGPY Version: 2.0 (December, 2004) Catalogue identifier: ADWQ Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADWQ Program obtained from: CPC Program Library, Queen's University of Belfast, N. Ireland Reference to original program: ADTJ (BCVEGPY1.0) Reference in CPC: Comput. Phys. Comm. 159 (2004) 192 Does the new version supersede the old program: yes Computer: Any computer with FORTRAN 77 or 90 compiler. The program has been tested on HP-SC45 Sigma-X parallel computer, Linux PCs and Windows PCs with Visual Fortran Operating systems: UNIX, Linux and Windows Programming language used: FORTRAN 77/90 Memory required to execute with typical data: About 2.0 MB No. of lines in distributed program, including test data, etc.: 124 297 No. of bytes in distributed program, including test data, etc.: 1 137 177 Distribution format: tar.g2 Nature of physical problem: Hadronic production of B meson itself and its excited states. Method of solution: The code with option can generate weighted and unweighted events. For jet hadronization, an interface to PYTHIA is provided. Reason for the new version: There are two reasons. One is to provide additional codes for the hadronic production of P-wave excited B states: the four via color-singlet P-wave state directly and the two via color-octet S-wave state accordingly. The other one is to decompose the color-flow factor for the amplitude by an approximate way, that is adopted in PYTHIA. Summary of Revisions: (1) The integration efficiency over the momentum fractions of the initial partons x and x are improved; (2) The amplitudes for the hadronic production of the color-singlet components corresponding to the four P-wave states, BcJ,L=1∗ or P1 and P3 ( J=0,1,2), are included; (3) The amplitudes for P-wave production via the two color-octet components |((S1)g> and |((S3)g> are included; (4) For comparison, the S-wave ( S1 and S3) hadronic production via the light quark-antiquark annihilation mechanism is also included; (5) For convenience, 24 data files to record the information of the generated events in one run are added; (6) An additional file, parameter.for, is added to set the initial values of the parameters; (7) Two new parameters 'IMIX' (IMIX = 0 or 1) and 'IMIXTYPE' (IMIXTYPE = 1, = 2 or = 3) are added to meet the needs of generating the events for simulating 'mixing' or 'separate' event samples for various B and its excited states correctly; (8) One switch, 'IVEGGRADE', is added to determine whether to use the existed importance sampling function to generate a more precise importance sampling function or not; (9) Two parameters, 'IOUTPDF' and 'IPDFNUM', are added to determine which type of PDFs to use; (10) The color-flow decomposition for the amplitudes is rewritten by an approximate way, that is adopted in PYTHIA. Restrictions on the complexity of the problem: The hadronic production of (cb¯)-quarkonium in S-wave and P-wave states via the mechanism of gluon-gluon fusion are given by the 'complete calculation' approach of the leading order QCD. The contributions from the other mechanisms for P-wave production which are small comparatively are not included. Typical running time: Generally speaking, it depends on which option is used to drive PYTHIA when generating the B events. Typically, for the hadronic production of the S-wave (cb¯)-quarkonium, if the PYTHIA parameter IDWTUP = 1, then it takes about 20 hours on a 1.8 GHz Intel P4-processor machine to generate 1000 events; however if IDWTUP = 3, to generate 10 6 events, it takes only about 40 minutes. For the hadronic production of the P-wave (cb¯)-quarkonium, the necessary time will be almost two times longer than the S-wave quarkonium production.

  2. Detection of Mantle and Core P- Arrivals, and Analysis of T-waves, Recorded on Ocean Sound-Channel Hydrophones Along the Mid-Atlantic Ridge (10°-35°N)

    NASA Astrophysics Data System (ADS)

    Dziak, R.; Haxel, J.; Matsumoto, H.; Fowler, M.; Fox, C.; Smith, D.; Bohnenstiehl, D.; Tolstoy, M.

    2002-12-01

    In February 1999, a consortium of U.S. investigators (NSF and NOAA) began long-term monitoring of Mid-Atlantic Ridge (MAR) seismicity between 15°N and 35°N. The experiment uses six NOAA/PMEL autonomous hydrophones moored within the SOFAR channel on the MAR flanks. The hydrophones record the hydroacoustic tertiary phase or T-wave of oceanic earthquakes from throughout the Atlantic basin. The low attenuation properties of the SOFAR channel allow for a reduction in the detection threshold (cutoff Magnitude) of MAR earthquakes from Mc=4.7 of the land-based seismic networks to Mc=3.0 with the hydrophones (Bohnenstiehl et al., 2002). The improved detection capability of the hydrophones allows for a better view of the overall spatio-temporal patterns in MAR earthquakes (Smith et al., 2002). To assess the waveform analysis capability of the hydrophones we present a preliminary examination of P- and T-wave arrivals recorded from 84 regional MAR and teleseismic earthquakes. The hydrophones (8 bit resolution) detect upper mantle Pn arrivals from regional MAR earthquakes at epicentral distances of 374-1771 km and from events as small as mb=3.6. The T-waves of regional MAR events are also clearly recorded although the signals are significantly clipped when earthquakes are <400 km distant or mb>5. A surprising result of the waveform analysis was the identification of P- arrivals from earthquakes outside the Atlantic Ocean basin. The hydrophones detected P-waves from global earthquakes with magnitudes from 5.8 to 8.3 at epicentral distances ranging from 29.6° to 167.2°. Examination of travel times suggests these teleseismic P-waves comprise the entire suite of body-wave arrivals from direct mantle P- to outer and inner core reflected/refracted phases. These global P- amplitudes also exhibit the typical solid-earth wavefield phenomena of a P- shadow zone and caustic at a Δ=142°. There is an apparent 2-second delay in expected {\\ P-} arrival times at the hydrophones consistent with acoustic conversion of seismic phases at the seafloor interface and propagation through the water-column. One goal of this study is to use the regional P- arrivals to estimate Pn velocity along the Mid-Atlantic Ridge between 10° and 35°N. The hydrophone arrays provide a unique opportunity to measure Pn velocities in the Atlantic Ocean upper mantle due to the difficulty in placing seismometers on the seafloor for an extended period of time. At this time, a preliminary MAR Pn velocity of 7.9 +/- 0.1 km/sec has been estimated from only 17 Pn arrival times. It is anticipated that with more arrival data we will be able to quantify variations in Pn velocity along the east and west sides of the MAR and southward along the MAR from the Azore hotspot.

  3. A Split of Direction of Propagation and Attenuation of P Waves in the Po Valley

    NASA Astrophysics Data System (ADS)

    Daminelli, R.; Tento, A.; Marcellini, A.

    2013-12-01

    On July 17, 2011 a ML 4.8 earthquake occurred in the PO valley at a 48 km epicentral distance from a seismic station located at Palazzo Te (Mantova). The station is situated on deep quaternary sediments: the uppermost layers are mainly composed of clay and silty clay with interbedded sands; the Robertson index is 1.4P wave particle motion, that appears rather difficult to explain if we assume the homogeneity of the P waves (that means attenuation is scalar). Note that the degree of nonlinearity is very low given that the maximum strain can be roughly estimated as 10-5 on the basis of maximum ground velocity of the P wave train considered and the Vp. On the contrary we show that P wave particle motion can be fully (and easily) described by a Homogeneous Isotropic Linear Viscoelastic model (HILV). HILV, as in the 2009 Borcherdt formulation adopted here, allows two different directions of propagation and attenuation; in other words attenuation becomes a vector that is not necessarily parallel to the propagation vector. The results evidence that the incidence angle and the inhomogeneity angle (it is the angle between propagation and attenuation vectors and it is closely related to Q factor) are in good agreement with the geological conditions of the site. Finally, we observed that these results are very similar to the ones obtained when we analyzed two explosions recorded by a seismic station in Milano, also situated in the Po valley at some 140 km from Mantova (Marcellini & Tento, 2011). Borcherdt, R.D. (2009) 'Viscoelastic Waves in Layered Media', Cambridge University Press, Cambridge, United Kingdom, 305 pp. Marcellini, A. and A. Tento (2011) ' Explosive Sources Prove the Validity of Homogeneous Isotropic Linear Viscoelastic Models', BSSA, Vol. 101, No. 4, pp. 1576-1583.

  4. P wave morphology in guiding the ablation strategy of focal atrial tachycardias and atrial flutter.

    PubMed

    Lee, Justin M S; Fynn, Simon P

    2015-01-01

    Focal atrial tachycardias arise preferentially from specific locations within the atria. Careful analysis of the P wave can provide useful information about the chamber and likely site of origin within that chamber. Macro-reentrant atrial flutter also tends to occur over a limited number of potential circuits. In this case, the ECG usually gives a guide to the chamber of origin, but unless it shows a specific morphology it is less useful in delineating the circuit involved. Nonetheless, prior knowledge of the likely chamber of origin helps to plan the ablation strategy. PMID:25308814

  5. P Wave Morphology in Guiding the Ablation Strategy of Focal Atrial Tachycardias and Atrial Flutter

    PubMed Central

    Lee, Justin M. S; Fynn, Simon P

    2015-01-01

    Focal atrial tachycardias arise preferentially from specific locations within the atria. Careful analysis of the P wave can provide useful information about the chamber and likely site of origin within that chamber. Macro-reentrant atrial flutter also tends to occur over a limited number of potential circuits. In this case, the ECG usually gives a guide to the chamber of origin, but unless it shows a specific morphology it is less useful in delineating the circuit involved. Nonetheless, prior knowledge of the likely chamber of origin helps to plan the ablation strategy. PMID:25308814

  6. Mission Specialist Scott Parazynski arrives at KSC

    NASA Technical Reports Server (NTRS)

    1998-01-01

    STS-95 Mission Specialist Scott E. Parazynski notes the time on his watch upon his late arrival aboard a T-38 jet at the Shuttle Landing Facility. Parazynski's first plane experienced problems at the stop at Tyndall AFB and he had to wait for another jet and pilot to finish the flight to KSC. He joined other crewmembers Mission Commander Curtis L. Brown Jr., Pilot Steven W. Lindsey, Mission Specialist Stephen K. Robinson, Payload Specialist John H. Glenn Jr., senator from Ohio, Mission Specialist Pedro Duque, with the European Space Agency (ESA), and Payload Specialist Chiaki Mukai, with the National Space Development Agency of Japan (NASDA), for final pre-launch preparations. STS-95 is expected to launch at 2 p.m. EST on Oct. 29, last 8 days, 21 hours and 49 minutes, and land at 11:49 a.m. EST on Nov. 7.

  7. Preliminary Results for Crustal Structure in Southeastern Africa from P-wave Receiver Functions

    NASA Astrophysics Data System (ADS)

    Kachingwe, M.; Nyblade, A.; Mulibo, G. D.; Mulowezi, A.; Kunkuta, E.; De Magalhes, V.; Wiens, D. A.; Wysession, M. E.; Julia, J.

    2013-12-01

    The crustal structure of southeastern Africa is investigated by modeling P-wave receiver functions using H-k stacking and joint inversion methods. P-wave receiver functions are analyzed for 29 broadband seismic stations in Zambia, Malawi and Mozambique. Estimates for the Moho depth and Poisson's ratio are determined from H-k stacking, and estimates for the shear wave velocity are determined by the joint inversion of receiver functions and surface wave dispersion. Preliminary results show that Moho depths beneath southeastern Africa range from 32 km to 51 km. Thicker crust is found in Proterozoic terrains, such as the Irumide Belt, while thinner crust is found in reworked Archean terrains, such as the Bangweulu Block. These results are consistent with previous studies and global averages for Precambrian terrains. The preliminary results also show a range of Poisson's ratios from 0.2 to 0.3. These new results for southeastern Africa are being combined with similar results from elsewhere in eastern and southern Africa to improve our understanding of African crustal structure.

  8. Preliminary Results for Crustal Structure in Southeastern Africa from P-wave Receiver Functions

    NASA Astrophysics Data System (ADS)

    Kachingwe, M.; Nyblade, A.; Mulibo, G.; Mulowezi, A.; Kunkuta, E.; De Magalhes, V.; Wysession, M. E.; Wiens, D. A.; Julia, J.

    2012-12-01

    The crustal structure of southeastern Africa is investigated by modeling P-wave receiver functions using H-k stacking and joint inversion methods. P-wave receiver functions are analyzed for 29 broadband seismic stations in Zambia, Malawi and Mozambique. Estimates for the Moho depth and Poisson's ratio are determined from H-k stacking, and estimates for the shear wave velocity are determined by the joint inversion of receiver functions and surface wave dispersion. Preliminary results show that Moho depths beneath southeastern Africa range from 32 km to 51 km. Thicker crust is found in Proterozoic terrains, such as the Irumide Belt, while thinner crust is found in reworked Archean terrains, such as the Bangweulu Block. These results are consistent with previous studies and global averages for Precambrian terrains. The preliminary results also show a range of Poisson's ratios from 0.2 to 0.3. These new results for southeastern Africa are being combined with similar results from elsewhere in eastern and southern Africa to improve our understanding of African crustal structure.

  9. P-Wave to Rayleigh-wave conversion coefficients for wedge corners; model experiments

    USGS Publications Warehouse

    Gangi, A.F.; Wesson, R.L.

    1978-01-01

    An analytic solution is not available for the diffraction of elastic waves by wedges; however, numerical solutions of finite-difference type are available for selected wedge angles. The P- to Rayleigh-wave conversion coefficients at wedge tips have been measured on two-dimensional seismic models for stress-free wedges with wedge angles, ??0, of 10, 30, 60, 90 and 120??. The conversion coefficients show two broad peaks and a minimum as a function of the angle between the wedge face and the direction of the incident P-wave. The minimum occurs for the P wave incident parallel to the wedge face and one maximum is near an incidence angle of 90?? to the wedge face. The amplitude of this maximum, relative to the other, decreases as the wedge angle increases. The asymmetry of the conversion coefficients, CPR(??; ??0), relative to parallel incidence (?? = 0) increases as the wedge angle increases. The locations of the maxima and the minimum as well as the asymmetry can be explained qualitatively. The conversion coefficients are measured with an accuracy of ??5% in those regions where there are no interfering waves. A comparison of the data for the 10?? wedge with the theoretical results for a half plane (0?? wedge) shows good correlation. ?? 1978.

  10. Collective modes of p-wave superfluid Fermi gases in BEC phase

    NASA Astrophysics Data System (ADS)

    Matera, Francesco; Wagner, Matthias F.

    2015-06-01

    The low-energy modes of a superfluid atomic Fermi gas at zero temperature are investigated. The Bose-Einstein-condensate (BEC) side of the superfluid phase is studied in detail. The atoms are assumed to be in only one internal state, so that for a sufficiently diluted gas the pairing of fermions can be considered effective in the l = 1 channel only. In agreement with previous works on p-wave superfluidity in Fermi systems, it is found that the p x + i p y phase represents the lowest energy state in both the Bardeen-Cooper-Schrieffer (BCS) and BEC sides. Our calculations show that at low energy three branches of collective modes can emerge, with different species of dispersion relations: a phonon-like mode, a single-particle-like mode and a gapped mode. A comparison with the Bogoliubov excitations of the corresponding spinor Bose condensate is made. They reproduce the dispersion relations of the excitation modes of the p-wave superfluid Fermi gas to a high accuracy.

  11. Detailed rupture imaging of the 25 April 2015 Nepal earthquake using teleseismic P waves

    NASA Astrophysics Data System (ADS)

    Fan, Wenyuan; Shearer, Peter M.

    2015-07-01

    We analyze the rupture process of the 25 April 2015 Nepal earthquake with globally recorded teleseismic P waves. The rupture propagated east-southeast from the hypocenter for about 160 km with a duration of ˜55 s. Backprojection of both high-frequency (HF, 0.2 to 3 Hz) and low-frequency (LF, 0.05 to 0.2 Hz) P waves suggest a multistage rupture process. From the low-frequency images, we resolve an initial slow downdip (northward) rupture near the nucleation area for the first 20 s (Stage 1), followed by two faster updip ruptures (20 to 40 s for Stage 2 and 40 to 55 s for Stage 3), which released most of the radiated energy northeast of Kathmandu. The centroid rupture power from LF backprojection agrees well with the Global Centroid Moment Tensor solution. The spatial resolution of the backprojection images is validated by applying similar analysis to nearby aftershocks. The overall rupture pattern agrees well with the aftershock distribution. A multiple-asperity model could explain the observed multistage rupture and aftershock distribution.

  12. Propagation and attenuation of P-waves in patchy saturated porous media

    NASA Astrophysics Data System (ADS)

    Zhang, Hui-Xing; He, Bing-Shou

    2015-09-01

    We establish a patchy saturation model and derive the seismic wave equations for patchy saturated porous media on the basis of Biot's equations and Johnson's bulk modulus. We solve the equations, obtain the attenuation coefficients, and analyze the characteristics of wave attenuation in the seismic frequency range. The results suggest that seismic waves show attenuation and dispersion in partially saturated rocks in the low frequency range. With frequency increasing, attenuation increases. The attenuation of P-waves of the second kind is more pronounced in agreement with Biot's theory. We also study the effect of porosity, saturation, and inner sphere radius on the attenuation of the P-waves of the first kind and find that attenuation increases with increasing frequency and porosity, and decreases with increasing frequency and degree of saturation. As for the inner sphere radius, wave attenuation is initially increasing with increasing frequency and inner sphere radius less than half the outer radius. Subsequently, wave attenuation decreases with increasing frequency and inner sphere radius is higher than half the outer sphere radius.

  13. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 8 Aliens and Nationality 1 2011-01-01 2011-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  14. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 8 Aliens and Nationality 1 2013-01-01 2013-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  15. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 8 Aliens and Nationality 1 2014-01-01 2014-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  16. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 8 Aliens and Nationality 1 2012-01-01 2012-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  17. 8 CFR 232.3 - Arriving aliens.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Arriving aliens. 232.3 Section 232.3 Aliens and Nationality DEPARTMENT OF HOMELAND SECURITY IMMIGRATION REGULATIONS DETENTION OF ALIENS FOR PHYSICAL AND MENTAL EXAMINATION § 232.3 Arriving aliens. When a district director has reasonable...

  18. The Galileo arrival date selection process

    NASA Technical Reports Server (NTRS)

    Ludwinski, Jan M.; Gershman, Robert

    1988-01-01

    The Galileo arrival date selection process has culminated in the selection of December 7,1995. This arrival date will provide excellent science opportunities at Jupiter as well as the first spacecraft reconnaissance ever of not one, but two asteroids during the cruise to Jupiter.

  19. STS-114: Discovery Crew Arrival

    NASA Technical Reports Server (NTRS)

    2005-01-01

    George Diller of NASA Public Affairs narrates the STS-114 Crew arrival at Kennedy Space Center aboard a Gulf Stream aircraft. They were greeted by Center Director Jim Kennedy. Commander Eileen Collins introduced each of her crew members and gave a brief description of their roles in the mission. Mission Specialist 3, Andrew Thomas will be the lead crew member on the inspection on flight day 2; he is the intravehicular (IV) crew member that will help and guide Mission Specialists Souichi Noguchi and Stephen Robinson during their spacewalks. Pilot James Kelly will be operating the shuttle systems in flying the Shuttle; he will be flying the space station robotic arm during the second extravehicular activity and he will be assisting Mission Specialist Wendy Lawrence during the other two extravehicular activities; he will be assisting on the rendezvous on flight day three, and landing of the shuttle. Commander Collins also mentioned Pilot Kelly's recent promotion to Colonel by the United States Air Force. Mission Specialist 1, Souichi Noguchi from JAXA (The Japanese Space Agency) will be flying on the flight deck for ascent; he will be doing three spacewalks on day 5, 7, and 9; He will be the photo/TV lead for the different types of cameras on board to document the flight and to send back the information to the ground for both technical and public affairs reasons. Mission Specialist 5, Charles Camada will be doing the inspection on flight day 2 with Mission Specialist Thomas and Pilot Kelly; he will be transferring the logistics off the shuttle and onto the space station and from the space station back to the shuttle; He will help set up eleven lap tops on board. Mission Specialist 4, Wendy Lawrence will lead the transfer of logistics to the space station; she is the space station arm operator during extravehicular activities 1 and 3; she will be carrying the 6,000 pounds of external storage platform from the shuttle payload bay over to the space station; she is also in charge of the shuttle storage. Mission Specialist 2, Stephen Robinson is the flight engineer of the shuttle; he will be doing spacewalks with Mission Specialist Noguchi; he will set up the 11 lap top computers on board. Each crew member gave a brief message to the press. Commander Eileen later gave her final message and the crew walked back to the Astronaut Corps.

  20. High-resolution 3-D P-wave tomographic imaging of the shallow magmatic system of Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Zandomeneghi, D.; Aster, R. C.; Barclay, A. H.; Chaput, J. A.; Kyle, P. R.

    2011-12-01

    Erebus volcano (Ross Island), the most active volcano in Antarctica, is characterized by a persistent phonolitic lava lake at its summit and a wide range of seismic signals associated with its underlying long-lived magmatic system. The magmatic structure in a 3 by 3 km area around the summit has been imaged using high-quality data from a seismic tomographic experiment carried out during the 2008-2009 austral field season (Zandomeneghi et al., 2010). An array of 78 short period, 14 broadband, and 4 permanent Mount Erebus Volcano Observatory seismic stations and a program of 12 shots were used to model the velocity structure in the uppermost kilometer over the volcano conduit. P-wave travel times were inverted for the 3-D velocity structure using the shortest-time ray tracing (50-m grid spacing) and LSQR inversion (100-m node spacing) of a tomography code (Toomey et al., 1994) that allows for the inclusion of topography. Regularization is controlled by damping and smoothing weights and smoothing lengths, and addresses complications that are inherent in a strongly heterogeneous medium featuring rough topography and a dense parameterization and distribution of receivers/sources. The tomography reveals a composite distribution of very high and low P-wave velocity anomalies (i.e., exceeding 20% in some regions), indicating a complex sub-lava-lake magmatic geometry immediately beneath the summit region and in surrounding areas, as well as the presence of significant high velocity shallow regions. The strongest and broadest low velocity zone is located W-NW of the crater rim, indicating the presence of an off-axis shallow magma body. This feature spatially corresponds to the inferred centroid source of VLP signals associated with Strombolian eruptions and lava lake refill (Aster et al., 2008). Other resolved structures correlate with the Side Crater and with lineaments of ice cave thermal anomalies extending NE and SW of the rim. High velocities in the summit area possibly constitute the seismic image of an older caldera, solidified intrusions or massive lava flows. REFERENCES: Aster et al., (2008) Moment tensor inversion of very long period seismic signals from Strombolian eruptions of Erebus volcano. J. Volcanol. Geotherm. Res., 177, 635-647. Toomey et al., (1994), Tomographic imaging of the shallow crustal structure of the East Pacific Rise at 9°30'N. J. Geophys. Res., 99 (B12), 24,135-24,157. Zandomeneghi et al., (2010), Seismic Tomography of Erebus Volcano, Antarctica, Eos, 91, 6, 53-55.

  1. Design Considerations for a New Terminal Area Arrival Scheduler

    NASA Technical Reports Server (NTRS)

    Thipphavong, Jane; Mulfinger, Daniel

    2010-01-01

    Design of a terminal area arrival scheduler depends on the interrelationship between throughput, delay and controller intervention. The main contribution of this paper is an analysis of the above interdependence for several stochastic behaviors of expected system performance distributions in the aircraft s time of arrival at the meter fix and runway. Results of this analysis serve to guide the scheduler design choices for key control variables. Two types of variables are analyzed, separation buffers and terminal delay margins. The choice for these decision variables was tested using sensitivity analysis. Analysis suggests that it is best to set the separation buffer at the meter fix to its minimum and adjust the runway buffer to attain the desired system performance. Delay margin was found to have the least effect. These results help characterize the variables most influential in the scheduling operations of terminal area arrivals.

  2. Effect of cracks on the pressure dependence of P wave velocities in crystalline rocks

    NASA Astrophysics Data System (ADS)

    Carlson, Richard L.; Gangi, Anthony F.

    1985-09-01

    To test the "bed of nails" model, we have made detailed measurements of P wave velocities in five low-porosity, crystalline rocks at effective pressures to 500 MPa and fit two equations based on the model to the laboratory data. The first equation, V(P) = V0(1 + P/ Pi)(1 - m)/2, applies at relatively low pressures because it assumes that the grain modulus is very much larger than the crack modulus. It can be fit to four of the five data sets. The fit to the data for a monomineralic epidote yields values for V0, Piand m of 8.02±0.02 km/s, 1.2±0.5 MPa, and 0.9845±0.0004, respectively, with a rms error of 6.28 m/s. The second equation, 1/V2 (P) = (1/Vc2 - Vg2)/(1 + P/Pi)1 - m + 1/Vg2 assigns a constant velocity to the grains and applies when the modulus of the cracks is of the order of the grain modulus at high pressures. This equation can be fit to three of the data sets; the fit to data for a diopside pyroxenite yields values of Vc, Vg, Pi, and m of 6.20±0.04 km/s, 8.28±0.02 km/s, 7±1 MPa, and 0.20±0.05, with a rms error of 17.9 m/s. For all seven fits to the laboratory data the rms errors range from 0.1 to 0.3% and are of the order of the limits of precision of the measurements. The "bed of nails" model explains the pressure dependence of P wave velocities in the samples remarkably well, as evidenced by the small rms errors. The variation with pressure of P wave velocities in these rocks clearly reflects the increasing stiffness of cracks. The fact that the first equation fits four of five data sets is one of several indications that cracks significantly affect the mechanical properties of the rocks even at 500 MPa. Finally, we note that different kinds of cracks have markedly different mechanical properties; the best fitting model parameters reflect the nature of the cracks which populate the samples.

  3. Anchorage Arrival Scheduling Under Off-Nominal Weather Conditions

    NASA Technical Reports Server (NTRS)

    Grabbe, Shon; Chan, William N.; Mukherjee, Avijit

    2012-01-01

    Weather can cause flight diversions, passenger delays, additional fuel consumption and schedule disruptions at any high volume airport. The impacts are particularly acute at the Ted Stevens Anchorage International Airport in Anchorage, Alaska due to its importance as a major international portal. To minimize the impacts due to weather, a multi-stage scheduling process is employed that is iteratively executed, as updated aircraft demand and/or airport capacity data become available. The strategic scheduling algorithm assigns speed adjustments for flights that originate outside of Anchorage Center to achieve the proper demand and capacity balance. Similarly, an internal departure-scheduling algorithm assigns ground holds for pre-departure flights that originate from within Anchorage Center. Tactical flight controls in the form of airborne holding are employed to reactively account for system uncertainties. Real-world scenarios that were derived from the January 16, 2012 Anchorage visibility observations and the January 12, 2012 Anchorage arrival schedule were used to test the initial implementation of the scheduling algorithm in fast-time simulation experiments. Although over 90% of the flights in the scenarios arrived at Anchorage without requiring any delay, pre-departure scheduling was the dominant form of control for Anchorage arrivals. Additionally, tactical scheduling was used extensively in conjunction with the pre-departure scheduling to reactively compensate for uncertainties in the arrival demand. For long-haul flights, the strategic scheduling algorithm performed best when the scheduling horizon was greater than 1,000 nmi. With these long scheduling horizons, it was possible to absorb between ten and 12 minutes of delay through speed control alone. Unfortunately, the use of tactical scheduling, which resulted in airborne holding, was found to increase as the strategic scheduling horizon increased because of the additional uncertainty in the arrival times of the aircraft. Findings from these initial experiments indicate that it is possible to schedule arrivals into Anchorage with minimal delays under low-visibility conditions with less disruption to high-cost, international flights.

  4. Doubly excited P-wave resonance states of H{sup ?} in Debye plasmas

    SciTech Connect

    Jiao, L. G.; Ho, Y. K.

    2013-08-15

    We investigate the doubly excited P-wave resonance states of H{sup ?} system in Debye plasmas modeled by static screened Coulomb potentials. The screening effects of the plasma environment on resonance parameters (energy and width) are investigated by employing the complex-scaling method with Hylleraas-type wave functions for both the shape and Feshbach resonances associated with the H(N = 2 to 6) thresholds. Under the screening conditions, the H(N) threshold states are no longer l degenerate, and all the H{sup ?} resonance energy levels are shifted away from their unscreened values toward the continuum. The influence of Debye plasmas on resonance widths has also been investigated. The shape resonance widths are broadened with increasing plasma screening strength, whereas the Feshbach resonance widths would generally decrease. Our results associated with the H(N = 2) and H(N = 3) thresholds are compared with others in the literature.

  5. Prediction of Building Limestone Physical and Mechanical Properties by Means of Ultrasonic P-Wave Velocity

    PubMed Central

    Concu, Giovanna; De Nicolo, Barbara; Valdes, Monica

    2014-01-01

    The aim of this study was to evaluate ultrasonic P-wave velocity as a feature for predicting some physical and mechanical properties that describe the behavior of local building limestone. To this end, both ultrasonic testing and compressive tests were carried out on several limestone specimens and statistical correlation between ultrasonic velocity and density, compressive strength, and modulus of elasticity was studied. The effectiveness of ultrasonic velocity was evaluated by regression, with the aim of observing the coefficient of determination r2 between ultrasonic velocity and the aforementioned parameters, and the mathematical expressions of the correlations were found and discussed. The strong relations that were established between ultrasonic velocity and limestone properties indicate that these parameters can be reasonably estimated by means of this nondestructive parameter. This may be of great value in a preliminary phase of the diagnosis and inspection of stone masonry conditions, especially when the possibility of sampling material cores is reduced. PMID:24511286

  6. Deformation-Driven p-Wave Halos at the Drip Line: Ne31

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Kobayashi, N.; Kondo, Y.; Satou, Y.; Tostevin, J. A.; Utsuno, Y.; Aoi, N.; Baba, H.; Fukuda, N.; Gibelin, J.; Inabe, N.; Ishihara, M.; Kameda, D.; Kubo, T.; Motobayashi, T.; Ohnishi, T.; Orr, N. A.; Otsu, H.; Otsuka, T.; Sakurai, H.; Sumikama, T.; Takeda, H.; Takeshita, E.; Takechi, M.; Takeuchi, S.; Togano, Y.; Yoneda, K.

    2014-04-01

    The halo structure of Ne31 is studied using 1n-removal reactions on C and Pb targets at 230 MeV /nucleon. A combined analysis of the cross sections of these nuclear and Coulomb dominated reactions that feed directly the Ne30 ground-state reveals Ne31 to have a small neutron separation energy, 0.15-0.10+0.16 MeV, and spin-parity 3/2-. Consistency of the data with reaction and large-scale shell-model calculations identifies Ne31 as deformed and having a significant p-wave halo component, suggesting that halos are more frequent occurrences at the neutron drip line.

  7. Spatial variations of P wave attenuation in the mantle beneath North America

    NASA Astrophysics Data System (ADS)

    Hwang, Yong Keun; Ritsema, Jeroen; Goes, Saskia

    2009-06-01

    We estimate the spatial variation of the seismic parameter t* using teleseismic (epicentral distance = 30°-85°) P wave spectra of about 200 deep (focal depths > 200 km) earthquakes recorded by 378 broadband seismometers in the United States and Canada. Relative P wave spectral ratios up to 1 Hz for about 63,000 station pairs with high signal-to-noise ratio and impulsive P waveforms are inverted for t*P by least squares inversion. The continental-scale t*P pattern correlates to the age of geological terrains and the seismic, heat flow, gravity, and magnetic variations across North America. Predominantly low values of t*P are obtained in stable central North America (SNA), and high t*P values are obtained for stations in the tectonically active western part of the continent (TNA). This variation is similar to that observed previously in short-period amplitude anomalies, spectral ratio variations, and ScS reverberations. On average, we resolve a contrast in t*P between SNA and TNA of about 0.2 s. We resolve regional variations in t*P, which correlate with tectonics. Relatively low t*P is associated with currently active subduction below Alaska. Relatively high t*P is found in SNA below the Appalachians and the Gulf Coast. The consistency between t*P and tectonics suggests that the observed variations in t*P are, on the scale of around 200-500 km, predominantly due to intrinsic attenuation. The similar patterns in t*P and predicted values for a recent global attenuation model confirm this further. The compatibility with the t*P computed for attenuation estimated via a thermal interpretation of shear wave velocity anomalies illustrates that variations in seismic velocity are predominantly due to physical effects with a strong attenuation signature, most likely temperature or a combination of temperature and water content.

  8. Crustal P-wave velocity structure from Altyn Tagh to Longmen mountains along the Taiwan-Altay geoscience transect

    USGS Publications Warehouse

    Wang, Y.-X.; Mooney, W.D.; Han, G.-H.; Yuan, X.-C.; Jiang, M.

    2005-01-01

    Based upon the seismic experiments along Geoscience Transect from the Altyn Tagh to the Longmen Mountains, the crustal P-wave velocity structure was derived to outline the characteristics of the crustal structure. The section shows a few significant features. The crustal thickness varies dramatically, and is consistent with tectonic settings. The Moho boundary abruptly drops to 73km depth beneath the southern Altyn Tagh from 50km below the Tarim basin, then rises again to about 58km depth beneath the Qaidam basin. Finally, the Moho drops again to about 70km underneath the Songpan-Garze Terrane and rises to 60km near the Longmen Mountains with a step-shape. Further southeast, the crust thins to 52km beneath the Sichuan basin in the southeast of the Longmen Mountains. In the north of the Kunlun fault, a low-velocity zone, which may be a layer of melted rocks due to high temperature and pressure at depth, exists in the the bottom of the middle crust. The two depressions of the Moho correlate with the Qilian and Songpan-Garze terranes, implying that these two mountains have thick roots. According to our results, it is deduced that the thick crust of the northeastern Tibetan Plateau probably is a result of east-west and northwest-southeast crustal shortening since Mesozoic time during the collision between the Asian and Indian plates.

  9. Dependence of P-wave dispersion on mean arterial pressure as an independent hemodynamic variable in school children

    PubMed Central

    González, Emilio F.; Llanes, María del Carmen; Llanes, Merlin Garí; García, Yosvany

    2013-01-01

    Introduction: The relationship between diastolic dysfunction and P-wave dispersion (PWD) in the electrocardiogram has been studied for some time. In this regard, echocardiography is emerging as a diagnostic tool to improve risk stratification for mild hypertension. Objective: To determine the dependence of PWD on the electrocardiogram and on echocardiographic variables in a pediatric population. Methods: 515 children from three elementary schools were studied from a total of 565 children. Those whose parents did not want them to take part in the study, as well as those with known congenital diseases, were excluded. Tests including 12-lead surface ECGs and 4 blood pressure (BP) measurements were performed. Maximum and minimum P-values were measured, and the PWD on the electrocardiogram was calculated. Echocardiography for structural measurements and the pulsed Doppler of mitral flow were also performed. Results: A significant correlation in statistical variables was found between PWD and mean BP for pre-hypertensive and hypertensive children, i.e., r = 0.32, p <0.01 and r = 0.33, p <0.01, respectively. There was a significant correlation found between PWD and the left atrial area (r = 0.45 and p <0.01). Conclusions: We highlight the dependency between PWD, the electrocardiogram and mean blood pressure. We also draw attention to the dependence of PWD on the duration of the mitral inflow A-wave. This result provides an explanation for earlier changes in atrial electrophysiological and hemodynamic characteristics in pediatric patients. PMID:24892616

  10. Effects of p-wave annihilation on the angular power spectrum of extragalactic gamma-rays from dark matter annihilation

    SciTech Connect

    Campbell, Sheldon; Dutta, Bhaskar

    2011-10-01

    We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with p-wave annihilation, for which the relative-velocity-weighted annihilation cross section is {sigma}v=a+bv{sup 2}. We determine that this significantly increases the gamma-ray power if b/a > or approx. 10{sup 6}. The effect of p-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given b/a is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong p-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly p-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong p wave were to be observed, it would likely indicate nonthermal production of dark matter in the early Universe.

  11. Using P-wave Triplications to Constrain the Mantle Transition Zone beneath Central Iranian Plateau and Surrounding Area

    NASA Astrophysics Data System (ADS)

    Chi, H. C.; Tseng, T. L.

    2014-12-01

    The Iranian Plateau is a tectonically complex region resulting from the continental collision between the African and Eurasian plates. The convergence of the two continents created the Zagros Mountains, the high topography southwest of Iran, and active seismicity along the Zagros-Bitlis suture. Tomographic studies in Iran reveal low seismic speeds and high attenuation of Sn wave in the uppermost mantle beneath the Iranian Plateau relative to adjacent regions. The deeper structure, however, remains curiously inconclusive. By contrast, a prominent fast seismic anomaly is found under central Tibet near depth of 600 km in the mantle transition zone (TZ), and it is speculated to be the remnant of lithosphere detached during the continental collision. We conduct a comparative study that utilizes triplicate arrivals of high-resolution P waveforms to investigate the velocity structure of mantle beneath the central Iranian Plateau and surroundings. Due to the abrupt increase in seismic wave speeds and density across the 410- and 660-km discontinuities, seismic waves at epicentral distances of 15-30 degrees would form multiple arrivals and the relative times and amplitudes between them are most sensitive to the variations in seismic speeds near the TZ. We combine several broadband arrays to construct 8 seismic profiles, each about 800 km long, that mainly sample the TZ under central Iranian Plateau, Turan shield and part of South Caspian basin. Move-outs between arrivals are clear in the profiles. Relative timings suggest a slightly smaller 660-km contrast under stable Turan shield. In the next stage, it is necessary to model waveforms after the source effect being removed properly. Our preliminary tests show that the F-K method can efficiently calculate the synthetic seismograms. We will determine the 1D velocity model for each sampled sector by minimizing the overall misfits between observed and predicted waveforms. The lateral variations may be further explored by comparing adjacent sectors. The results are important for understanding the lithosphere-mantle interaction during the process of continental collision.

  12. Application of P-wave Hybrid Theory to the Scattering of Electrons from He+ and Resonances in He and H ion

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.

    2012-01-01

    The P-wave hybrid theory of electron-hydrogen elastic scattering [Phys. Rev. A 85, 052708 (2012)] is applied to the P-wave scattering from He ion. In this method, both short-range and long-range correlations are included in the Schroedinger equation at the same time, by using a combination of a modified method of polarized orbitals and the optical potential formalism. The short-correlation functions are of Hylleraas type. It is found that the phase shifts are not significantly affected by the modification of the target function by a method similar to the method of polarized orbitals and they are close to the phase shifts calculated earlier by Bhatia [Phys. Rev. A 69, 032714 (2004)]. This indicates that the correlation function is general enough to include the target distortion (polarization) in the presence of the incident electron. The important fact is that in the present calculation, to obtain similar results only a 20-term correlation function is needed in the wave function compared to the 220- term wave function required in the above-mentioned calculation. Results for the phase shifts, obtained in the present hybrid formalism, are rigorous lower bounds to the exact phase shifts. The lowest P-wave resonances in He atom and hydrogen ion have been calculated and compared with the results obtained using the Feshbach projection operator formalism [Phys. Rev. A, 11, 2018 (1975)]. It is concluded that accurate resonance parameters can be obtained by the present method, which has the advantage of including corrections due to neighboring resonances, bound states and the continuum in which these resonance are embedded.

  13. Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

    2008-01-01

    This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.

  14. Pair bonds: arrival synchrony in migratory birds.

    PubMed

    Gunnarsson, T G; Gill, J A; Sigurbjörnsson, T; Sutherland, W J

    2004-10-01

    Synchronous arrival of pairs of migratory birds at their breeding grounds is important for maintaining pair bonds and is achieved by pairs that remain together all year round. Here we show that arrival is also synchronized in paired individuals of a migratory shorebird, the black-tailed godwit (Limosa limosa islandica), even though they winter hundreds of kilometres apart and do not migrate together. The mechanisms required to achieve this synchrony and prevent 'divorce' illustrate the complexity of migratory systems. PMID:15470417

  15. SERAPIS project - 3D imaging of the Campi Flegrei caldera (southern Italy) : high resolution P-wave velocity tomography

    NASA Astrophysics Data System (ADS)

    Judenherc, S.; Zollo, A.; Auger, E.; Boschi, L.; Satriano, C.; Serapis Working Group

    2003-04-01

    In September 2001, the SERAPIS project was carried out as an extended active seismic survey in the gulfs of Naples and Pozzuoli. A dense array of 60 three-component on-land stations and 72 sea bottom seismographs (OBS) have been deployed to record more than 5000 air gun shots at a spacing of about 125~m. As a preliminary analysis, the first P-arrival times of a the small offset data in the central part of the region has been inverted using the codes of H.M. Benz. The linearized iterative inversion of 38000 arrival times provided a >80% variance reduction with a node spacing of 250m. At the first order, our model shows a 2-layer structure : low velocity volcanic sediments (2.5-3.5km/s) lying on an inclined high velocity limestone platform (>6km/s). The caldera itself is very well identified, the rim is characterized by a 500-1000m upward shift of the velocity isolines. The whole dataset is expected to provide a wider image with the same resolution (250m). It includes the detailed shape of the refractor beneath the caldera as well as its irregularities out of the bay which have been observered in the seismic sections.

  16. Iterative direction-of-arrival estimation with wideband chirp signals

    NASA Astrophysics Data System (ADS)

    Wang, Genyuan; Xia, Xiang-Gen; Chen, Victor C.

    1999-11-01

    Amin et. al. recently developed a time-frequency MUSIC algorithm with narrow band models for the estimation of direction of arrival (DOA) when the source signals are chirps. In this research, we consider wideband models. The joint time-frequency analysis is first used to estimate the chirp rates of the source signals and then the DOA is estimated by the MUSIC algorithm with an iterative approach.

  17. The relationship between gas hydrate saturation and P-wave velocity of pressure cores obtained in the Eastern Nankai Trough

    NASA Astrophysics Data System (ADS)

    Konno, Y.; Yoneda, J.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Fujii, T.; Nagao, J.

    2014-12-01

    P-wave velocity is an important parameter to estimate gas hydrate saturation in sediments. In this study, the relationship between gas hydrate saturation and P-wave velocity have been analyzed using natural hydrate-bearing-sediments obtained in the Eastern Nankai Trough, Japan. The sediment samples were collected by the Hybrid Pressure Coring System developed by Japan Agency for Marine-Earth Science and Technology during June-July 2012, aboard the deep sea drilling vessel CHIKYU. P-wave velocity was measured on board by the Pressure Core Analysis and Transfer System developed by Geotek Ltd. The samples were maintained at a near in-situ pressure condition during coring and measurement. After the measurement, the samples were stored core storage chambers and transported to MHRC under pressure. The samples were manipulated and cut by the Pressure-core Non-destructive Analysis Tools or PNATs developed by MHRC. The cutting sections were determined on the basis of P-wave velocity and visual observations through an acrylic window equipped in the PNATs. The cut samples were depressurized to measure gas volume for saturation calculations. It was found that P-wave velocity correlates well with hydrate saturation and can be reproduced by the hydrate frame component model. Using pressure cores and pressure core analysis technology, nondestructive and near in-situ correlation between gas hydrate saturation and P-wave velocity can be obtained. This study was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan.

  18. 19 CFR 122.31 - Notice of arrival.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... advance notice of arrival in accordance with § 122.22 of this part. (ii) Aircraft arriving from Cuba. Aircraft arriving from Cuba must follow the advance notice of arrival procedures set forth in § 122.154 in... aircraft arriving from areas south of the United States (other than Cuba) must follow the advance notice...

  19. 19 CFR 122.31 - Notice of arrival.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... advance notice of arrival in accordance with § 122.22 of this part. (ii) Aircraft arriving from Cuba. Aircraft arriving from Cuba must follow the advance notice of arrival procedures set forth in § 122.154 in... aircraft arriving from areas south of the United States (other than Cuba) must follow the advance notice...

  20. 19 CFR 122.31 - Notice of arrival.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... advance notice of arrival in accordance with § 122.22 of this part. (ii) Aircraft arriving from Cuba. Aircraft arriving from Cuba must follow the advance notice of arrival procedures set forth in § 122.154 in... aircraft arriving from areas south of the United States (other than Cuba) must follow the advance notice...

  1. 19 CFR 122.31 - Notice of arrival.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... advance notice of arrival in accordance with § 122.22 of this part. (ii) Aircraft arriving from Cuba. Aircraft arriving from Cuba must follow the advance notice of arrival procedures set forth in § 122.154 in... aircraft arriving from areas south of the United States (other than Cuba) must follow the advance notice...

  2. 19 CFR 122.31 - Notice of arrival.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... advance notice of arrival in accordance with § 122.22 of this part. (ii) Aircraft arriving from Cuba. Aircraft arriving from Cuba must follow the advance notice of arrival procedures set forth in § 122.154 in... aircraft arriving from areas south of the United States (other than Cuba) must follow the advance notice...

  3. P-wave Tomographic Image Across the Central Transverse Ranges Region From Inversion of Local Earthquake and Active Source Data, Southern California

    NASA Astrophysics Data System (ADS)

    Li, L.; Zhou, H.

    2007-12-01

    The central Transverse Ranges region is considered as a place that has documented significant evidence of tectonic history of southern California. To investigate such a region associated with extensive Cenozoic tectonic activities, we apply a new deformable-layer tomography approach to determine layers of varying thickness as a direct product of tomographic imaging. 1,546 P-wave first arrival data from local earthquakes and 10,869 from active shots of Los Angles Regional Seismic Experiment (LARSE) I have been used together to invert the velocity structure along a northeastern trending 2-D profile across the Central Transverse Ranges region. The combined data result in highly dense ray path distribution, especially within the upper crust. In addition, Moho depths from previous study have been incorporated into the inversion to improve solving the model in the deep and sparsely sampled areas. The tomographic inversion procedure implemented in this study is as follows: first, a long wavelength model is constructed by inverting local earthquake arrivals only with sparse Moho constraints; second, this tomographic model is refined by adding surface seismic arrivals and introducing lateral velocity variations within layers. Along the profile, our tomographic image shows high resolution, detailed near-surface geological features besides those long-wavelength features resolved in the previous studies. The existence of the San Andreas Fault is clearly evidenced, which is characterized by a vertical low-velocity zone to at least 20-km depth. The sedimentary basin boundaries are observed unconformably lying above the high velocity basement. Near the northern edge of the Los Angeles Basin and southern foothills of the San Gabriel Mountains in the upper crust, the high velocity gradient units on two sides of this high velocity feature represent that the transition from sedimentary rocks to crystalline rocks is abrupt, which could be indicative of the major basin-bounding faults, such as the Whittier fault and the Sierra Madre fault zones. Our new tomographic image represented by both layers and cells has provided new insights across the Central Transverse Ranges region, and the resolution of the tomographic solution has been greatly improved by using local earthquake data and surface seismic data jointly.

  4. Does Pet Arrival Trigger Prosocial Behaviors in Individuals with Autism?

    PubMed Central

    Grandgeorge, Marine; Tordjman, Sylvie; Lazartigues, Alain; Lemonnier, Eric; Deleau, Michel; Hausberger, Martine

    2012-01-01

    Alteration of social interactions especially prosocial behaviors – an important aspect of development – is one of the characteristics of autistic disorders. Numerous strategies or therapies are used to improve communication skills or at least to reduce social impairments. Animal-assisted therapies are used widely but their relevant benefits have never been scientifically evaluated. In the present study, we evaluated the association between the presence or the arrival of pets in families with an individual with autism and the changes in his or her prosocial behaviors. Of 260 individuals with autism - on the basis of presence or absence of pets - two groups of 12 individuals and two groups of 8 individuals were assigned to: study 1 (pet arrival after age of 5 versus no pet) and study 2 (pet versus no pet), respectively. Evaluation of social impairment was assessed at two time periods using the 36-items ADI-R algorithm and a parental questionnaire about their child-pet relationships. The results showed that 2 of the 36 items changed positively between the age of 4 to 5 (t0) and time of assessment (t1) in the pet arrival group (study 1): “offering to share” and “offering comfort”. Interestingly, these two items reflect prosocial behaviors. There seemed to be no significant changes in any item for the three other groups. The interactions between individuals with autism and their pets were more – qualitatively and quantitatively - reported in the situation of pet arrival than pet presence since birth. These findings open further lines of research on the impact of pet’s presence or arrival in families with an individual with autism. Given the potential ability of individuals with autism to develop prosocial behaviors, related studies are needed to better understand the mechanisms involved in the development of such child-pet relationship. PMID:22870246

  5. Separation Assurance and Scheduling Coordination in the Arrival Environment

    NASA Technical Reports Server (NTRS)

    Aweiss, Arwa S.; Cone, Andrew C.; Holladay, Joshua J.; Munoz, Epifanio; Lewis, Timothy A.

    2016-01-01

    Separation assurance (SA) automation has been proposed as either a ground-based or airborne paradigm. The arrival environment is complex because aircraft are being sequenced and spaced to the arrival fix. This paper examines the effect of the allocation of the SA and scheduling functions on the performance of the system. Two coordination configurations between an SA and an arrival management system are tested using both ground and airborne implementations. All configurations have a conflict detection and resolution (CD&R) system and either an integrated or separated scheduler. Performance metrics are presented for the ground and airborne systems based on arrival traffic headed to Dallas/ Fort Worth International airport. The total delay, time-spacing conformance, and schedule conformance are used to measure efficiency. The goal of the analysis is to use the metrics to identify performance differences between the configurations that are based on different function allocations. A surveillance range limitation of 100 nmi and a time delay for sharing updated trajectory intent of 30 seconds were implemented for the airborne system. Overall, these results indicate that the surveillance range and the sharing of trajectories and aircraft schedules are important factors in determining the efficiency of an airborne arrival management system. These parameters are not relevant to the ground-based system as modeled for this study because it has instantaneous access to all aircraft trajectories and intent. Creating a schedule external to the CD&R and the scheduling conformance system was seen to reduce total delays for the airborne system, and had a minor effect on the ground-based system. The effect of an external scheduler on other metrics was mixed.

  6. Does pet arrival trigger prosocial behaviors in individuals with autism?

    PubMed

    Grandgeorge, Marine; Tordjman, Sylvie; Lazartigues, Alain; Lemonnier, Eric; Deleau, Michel; Hausberger, Martine

    2012-01-01

    Alteration of social interactions especially prosocial behaviors--an important aspect of development--is one of the characteristics of autistic disorders. Numerous strategies or therapies are used to improve communication skills or at least to reduce social impairments. Animal-assisted therapies are used widely but their relevant benefits have never been scientifically evaluated. In the present study, we evaluated the association between the presence or the arrival of pets in families with an individual with autism and the changes in his or her prosocial behaviors. Of 260 individuals with autism--on the basis of presence or absence of pets--two groups of 12 individuals and two groups of 8 individuals were assigned to: study 1 (pet arrival after age of 5 versus no pet) and study 2 (pet versus no pet), respectively. Evaluation of social impairment was assessed at two time periods using the 36-items ADI-R algorithm and a parental questionnaire about their child-pet relationships. The results showed that 2 of the 36 items changed positively between the age of 4 to 5 (t(0)) and time of assessment (t(1)) in the pet arrival group (study 1): "offering to share" and "offering comfort". Interestingly, these two items reflect prosocial behaviors. There seemed to be no significant changes in any item for the three other groups. The interactions between individuals with autism and their pets were more--qualitatively and quantitatively--reported in the situation of pet arrival than pet presence since birth. These findings open further lines of research on the impact of pet's presence or arrival in families with an individual with autism. Given the potential ability of individuals with autism to develop prosocial behaviors, related studies are needed to better understand the mechanisms involved in the development of such child-pet relationship. PMID:22870246

  7. Factors Associated with Early Hospital Arrival in Patients with Acute Ischemic Stroke

    PubMed Central

    Song, Dongbeom; Tanaka, Eijirou; Lee, Kijeong; Sato, Shoichiro; Koga, Masatoshi; Kim, Young Dae; Nagatsuka, Kazuyuki; Toyoda, Kazunori

    2015-01-01

    Background and Purpose Factors associated with early arrival may vary according to the characteristics of the hospital. We investigated the factors associated with early hospital arrival in two different stroke centers located in Korea and Japan. Methods Consecutive patients with ischemic stroke arrived hospital within 48 hours of onset between January 2011 and December 2012 were identified and the clinical and time variables were retrieved from the prospective stroke registries of Severance Hospital of Yonsei University Health System (YUHS; Seoul, Korea) and National Cerebral and Cardiovascular Center (NCVC; Osaka, Japan). Subjects were dichotomized into early (time from onset to arrival ≤4.5 hours) and late (>4.5 hours) arrival groups. Univariate and multivariate analyses were performed to evaluate factors associated with early hospital arrival. Results A total of 1,966 subjects (992 from YUHS; 974 from NCVC) were included in this study. The median time from onset to arrival was 6.1 hours [interquartile range, 1.7-17.8 hours]. In multivariate analysis, the factors associated with early arrival were atrial fibrillation (Odds ratio [OR], 1.505; 95% confidence interval [CI], [1.168-1.939]), higher initial National Institute of Health Stroke Scale scores (OR, 1.037; 95% CI [1.023-1.051]), onset during daytime (OR, 2.799; 95% CI [2.173-3.605]), and transport by an emergency medical service (OR, 2.127; 95% CI [1.700-2.661]). These factors were consistently associated with early arrival in both hospitals. Conclusions Despite differences between the hospitals, there were common factors related to early arrival. Efforts to identify and modify these factors may promote early hospital arrival and improve stroke outcome. PMID:26060803

  8. Dynamic and kinematic P wave tracing for a three-dimensional elastic inhomogeneous media by the asymptotic ray theory and application

    NASA Astrophysics Data System (ADS)

    Artsztein, Philippe Pascal

    1990-07-01

    This work deals with calculation of ray trajectories and P wave amplitudes in a three-dimensional medium characterized by variable velocity. The first chapter deals with the construction of a three-dimensional structure generator. A new method for creating complicated structures, such as those containing lenses or pinchouts is presented. The material interfaces are calculated by the pseudo polynomial spline interpolation method. The second chapter contains a review of the asymptotic ray theory. Simple algorithms for calculating the P wave trajectories in an inhomogeneous elastic medium, based on the solution of a system of six differential equations, are proposed. A method for calculating the directions of the reflected/transmitted rays is described. The third chapter deals with dynamic ray tracing. The propagating wave amplitudes are calculated by solving a system of 14 differential equations. This chapter also deals with the changes in amplitudes of the wave fronts upon crossing material dicontinuities. In the fourth chapter a scanning method for solving the two point ray tracing problem is presented. According to this method, a kinematic and dynamic ray tracing for common shot or normal incidence ray tracing is performed. At the end of the chapter, time-to-depth mappings are described by two methods: (A) ray tracing migration and (B) ray tracing inversion.

  9. Hybrid Theory of P-Wave Electron-Hydrogen Elastic Scattering

    NASA Technical Reports Server (NTRS)

    Bhatia, Anand

    2012-01-01

    We report on a study of electron-hydrogen scattering, using a combination of a modified method of polarized orbitals and the optical potential formalism. The calculation is restricted to P waves in the elastic region, where the correlation functions are of Hylleraas type. It is found that the phase shifts are not significantly affected by the modification of the target function by a method similar to the method of polarized orbitals and they are close to the phase shifts calculated earlier by Bhatia. This indicates that the correlation function is general enough to include the target distortion (polarization) in the presence of the incident electron. The important fact is that in the present calculation, to obtain similar results only 35-term correlation function is needed in the wave function compared to the 220-term wave function required in the above-mentioned previous calculation. Results for the phase shifts, obtained in the present hybrid formalism, are rigorous lower bounds to the exact phase shifts.

  10. Crustal Structure across the Appalachian Orogen in Pennsylvania from P-wave receiver functions

    NASA Astrophysics Data System (ADS)

    Arroyo, G.; Nyblade, A.; Homman, K.

    2014-12-01

    Crustal structure across the Appalachian Orogen from eastern Ohio to New Jersey is investigated using P-wave receiver functions to estimate Moho depths and crustal Vp/Vs ratios. Data for this study comes from the PASEIS and the USArray Transportable Array. The PASEIS seismic network includes 22 broadband seismic stations throughout Pennsylvania that were in installed in February 2013. Preliminary results from H-K stacking show that Moho depth varies greatly across the Appalachians, ranging from 53 km in northern Pennsylvania to only 32 km just west of the New Jersey border. The thickest crust can be found nearest to Lake Erie, and a relatively thick crust is maintained in northeastern Pennsylvania and along the Pennsylvania-Ohio border. Crustal thickness decreases to the southeast, and a rather sharp decrease can be seen well before the start of the Allegheny Front. Crustal thickness remains relatively uniform between 43 and 45km in the Appalachian Mountains, and decreases to 33-38km in the Piedmont province. Vp/Vs values range from 1.75 to 1.83, with no observable pattern to the variation.

  11. Improvement to Airport Throughput Using Intelligent Arrival Scheduling and an Expanded Planning Horizon

    NASA Technical Reports Server (NTRS)

    Glaab, Patricia C.

    2012-01-01

    The first phase of this study investigated the amount of time a flight can be delayed or expedited within the Terminal Airspace using only speed changes. The Arrival Capacity Calculator analysis tool was used to predict the time adjustment envelope for standard descent arrivals and then for CDA arrivals. Results ranged from 0.77 to 5.38 minutes. STAR routes were configured for the ACES simulation, and a validation of the ACC results was conducted comparing the maximum predicted time adjustments to those seen in ACES. The final phase investigated full runway-to-runway trajectories using ACES. The radial distance used by the arrival scheduler was incrementally increased from 50 to 150 nautical miles (nmi). The increased Planning Horizon radii allowed the arrival scheduler to arrange, path stretch, and speed-adjust flights to more fully load the arrival stream. The average throughput for the high volume portion of the day increased from 30 aircraft per runway for the 50 nmi radius to 40 aircraft per runway for the 150 nmi radius for a traffic set representative of high volume 2018. The recommended radius for the arrival scheduler s Planning Horizon was found to be 130 nmi, which allowed more than 95% loading of the arrival stream.

  12. Research Of Airborne Precision Spacing to Improve Airport Arrival Operations

    NASA Technical Reports Server (NTRS)

    Barmore, Bryan E.; Baxley, Brian T.; Murdoch, Jennifer L.

    2011-01-01

    In September 2004, the European Organization for the Safety of Air Navigation (EUROCONTROL) and the United States Federal Aviation Administration (FAA) signed a Memorandum of Cooperation to mutually develop, modify, test, and evaluate systems, procedures, facilities, and devices to meet the need for safe and efficient air navigation and air traffic control in the future. In the United States and Europe, these efforts are defined within the architectures of the Next Generation Air Transportation System (NextGen) Program and Single European Sky Air Traffic Management Research (SESAR) Program respectively. Both programs have identified Airborne Spacing as a critical component, with Automatic Dependent Surveillance Broadcast (ADS-B) as a key enabler. Increased interest in reducing airport community noise and the escalating cost of aviation fuel has led to the use of Continuous Descent Arrival (CDA) procedures to reduce noise, emissions, and fuel usage compared to current procedures. To provide these operational enhancements, arrival flight paths into terminal areas are planned around continuous vertical descents that are closer to an optimum trajectory than those in use today. The profiles are designed to be near-idle descents from cruise altitude to the Final Approach Fix (FAF) and are typically without any level segments. By staying higher and faster than conventional arrivals, CDAs also save flight time for the aircraft operator. The drawback is that the variation of optimized trajectories for different types and weights of aircraft requires the Air Traffic Controller to provide more airspace around an aircraft on a CDA than on a conventional arrival procedure. This additional space decreases the throughput rate of the destination airport. Airborne self-spacing concepts have been developed to increase the throughput at high-demand airports by managing the inter-arrival spacing to be more precise and consistent using on-board guidance. It has been proposed that the additional space needed around an aircraft performing a CDA could be reduced or eliminated when using airborne spacing techniques.

  13. High-temperature thermodynamics of strongly interacting s-wave and p-wave Fermi gases in a harmonic trap

    SciTech Connect

    Peng Shiguo; Li Shiqun; Drummond, Peter D.; Liu Xiaji

    2011-06-15

    We theoretically investigate the high-temperature thermodynamics of a strongly interacting trapped Fermi gas near either s-wave or p-wave Feshbach resonances, using a second-order quantum virial expansion. The second virial coefficient is calculated based on the energy spectrum of two interacting fermions in a harmonic trap. We consider both isotropic and anisotropic harmonic potentials. For the two-fermion interaction, either s-wave or p-wave, we use a pseudopotential parametrized by a scattering length and an effective range. This turns out to be the simplest way of encoding the energy dependence of the low-energy scattering amplitude or phase shift. This treatment of the pseudopotential can be easily generalized to higher partial-wave interactions. We discuss how the second virial coefficient and thermodynamics are affected by the existence of these finite-range interaction effects. The virial expansion result for a strongly interacting s-wave Fermi gas has already been proved very useful. In the case of p-wave interactions, our results for the high-temperature equation of state are applicable to future high-precision thermodynamic measurements for a spin-polarized Fermi gas near a p-wave Feshbach resonance.

  14. Evidence from P-wave receiver functions for lower mantle plumes and mantle transition zone water beneath West Antarctica

    NASA Astrophysics Data System (ADS)

    Nyblade, A.; Emry, E.; Juliá, J.; Anandakrishnan, S.; Aster, R. C.; Wiens, D. A.; Huerta, A. D.; Wilson, T. J.

    2014-12-01

    West Antarctica has experienced abundant Cenozoic volcanism, and it is suspected that the region is influenced by upwelling thermal plumes from the lower mantle; however this has not yet been verified, because seismic tomography results are not well resolved at mantle transition zone (MTZ) depths. We use P-wave receiver functions (PRFs) from the 2007-2013 Antarctic POLENET array to explore the characteristics of the MTZ throughout Marie Byrd Land and the West Antarctic Rift System. We obtained over 8000 high-quality PRFs for earthquakes occurring at 30-90° with Mb>5.5 using a time-domain iterative deconvolution method filtered with a Gaussian-width of 0.5 and 1.0, corresponding to frequencies less than ~0.24 Hz and ~0.48 Hz, respectively. We stack P receiver functions as single-station and by common conversion point and migrate them to depth using the ak135 1-d velocity model. Results suggest that the thickness of the MTZ varies throughout the region with thinning beneath the Ruppert Coast of Marie Byrd Land and beneath the Bentley Subglacial Trench and Whitmore Mountains. We identify the 520' discontinuity throughout much of West Antarctica; the discontinuity is most prominent beneath the Bentley Subglacial Trench and Whitmore Mountains. Additionally, prominent negative peaks are detected above the transition zone beneath much of West Antarctica and may be evidence for water-induced partial melt above the MTZ. We propose that the MTZ beneath West Antarctica is hotter than average in some regions, possibly due to material upwelling from the lower mantle. Furthermore, we propose that the transition zone is water-rich and that upward migration of hydrated material results in formation of a partial melt layer above the MTZ.

  15. Static and Dynamic Reservoir Characterization Using High Resolution P-Wave Velocity Data in Delhi Field, la

    NASA Astrophysics Data System (ADS)

    Hussain, S.; Davis, T.

    2012-12-01

    Static and dynamic reservoir characterization was done on high resolution P-wave seismic data in Delhi Field, LA to study the complex stratigraphy of the Holt-Bryant sands and to delineate the CO2 flow path. The field is undergoing CO2 injection for enhanced oil recovery. The seismic data was bandwidth extended by Geotrace to decrease the tuning thickness effect. Once the authenticity of the added frequencies in the data was determined, the interpretation helped map thin Tuscaloosa and Paluxy sands. Cross-equalization was done on the baseline and monitor surveys to remove the non-repeatable noise in the data. Acoustic impedance (AI) inversion was done on the baseline and monitor surveys to map the changes in AI with CO2 injection in the field. Figure 1 shows the AI percentage change at Base Paluxy. The analysis helped identify areas that were not being swept by CO2. Figure 2 shows the CO2 flow paths in Tuscaloosa formation. The percentage change of AI with CO2 injection and pressure increase corresponded with the fluid substitution modeling results. Time-lapse interpretation helped in delineating the channels, high permeability zones and the bypassed zones in the reservoir.; Figure 1: P-impedance percentage difference map with a 2 ms window centered at the base of Paluxy with the production data from June 2010 overlain; the black dashed line is the oil-water contact; notice the negative impedance change below the OWC. The lighter yellow color shows area where Paluxy is not being swept completely. ; Figure 2: P-impedance percentage difference map at TUSC 7 top; the white triangles are TUSC 7 injectors and the white circles are TUSC 7 producers; the black polygons show the flow paths of CO2.

  16. Feedlot Processing and Arrival Cattle Management.

    PubMed

    Noffsinger, Tom; Lukasiewicz, Kip; Hyder, LeeAnn

    2015-11-01

    Acclimating newly arrived cattle in a feedlot setting can increase cattle confidence, reduce stress, improve immune function, and increase cattle well-being. Understanding cattle instincts and using low-stress handling techniques teaches cattle to trust their caregivers and work efficiently for them throughout the feeding period. These techniques should be applied with newly arrived cattle when they are unloaded, moved from the holding pen to the home pen, and handled inside the home pen. Low-stress handling during processing and a sound processing protocol based on cattle history and proper risk assessment can improve cattle health from the start of the feeding period. PMID:26211440

  17. Analysis of sequencing and scheduling methods for arrival traffic

    NASA Technical Reports Server (NTRS)

    Neuman, Frank; Erzberger, Heinz

    1990-01-01

    The air traffic control subsystem that performs scheduling is discussed. The function of the scheduling algorithms is to plan automatically the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several important scheduling algorithms are described and the statistical performance of the scheduling algorithms is examined. Scheduling brings order to an arrival sequence for aircraft. First-come-first-served scheduling (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the traffic, gaps will remain in the scheduled sequence of aircraft. These gaps are filled, or partially filled, by time-advancing the leading aircraft after a gap while still preserving the FCFS order. Tightly scheduled groups of aircraft remain with a mix of heavy and large aircraft. Separation requirements differ for different types of aircraft trailing each other. Advantage is taken of this fact through mild reordering of the traffic, thus shortening the groups and reducing average delays. Actual delays for different samples with the same statistical parameters vary widely, especially for heavy traffic.

  18. Design Principles and Algorithms for Air Traffic Arrival Scheduling

    NASA Technical Reports Server (NTRS)

    Erzberger, Heinz; Itoh, Eri

    2014-01-01

    This report presents design principles and algorithms for building a real-time scheduler of arrival aircraft based on a first-come-first-served (FCFS) scheduling protocol. The algorithms provide the conceptual and computational foundation for the Traffic Management Advisor (TMA) of the Center/terminal radar approach control facilities (TRACON) automation system, which comprises a set of decision support tools for managing arrival traffic at major airports in the United States. The primary objective of the scheduler is to assign arrival aircraft to a favorable landing runway and schedule them to land at times that minimize delays. A further objective of the scheduler is to allocate delays between high-altitude airspace far away from the airport and low-altitude airspace near the airport. A method of delay allocation is described that minimizes the average operating cost in the presence of errors in controlling aircraft to a specified landing time. This report is a revision of an earlier paper first presented as part of an Advisory Group for Aerospace Research and Development (AGARD) lecture series in September 1995. The authors, during vigorous discussions over the details of this paper, felt it was important to the air-trafficmanagement (ATM) community to revise and extend the original 1995 paper, providing more detail and clarity and thereby allowing future researchers to understand this foundational work as the basis for the TMA's scheduling algorithms.

  19. Lithospheric structure beneath NW Iran using regional and teleseismic travel-time tomography

    NASA Astrophysics Data System (ADS)

    Bavali, K.; Motaghi, K.; Sobouti, F.; Ghods, A.; Abbasi, M.; Priestley, K.; Mortezanejad, G.; Rezaeian, M.

    2016-04-01

    We compute a 2-D tomogram using the P wave arrival time readings from a temporary seismic experiment to study the seismic structure of the crust and upper mantle in NW Iran. The study area includes the western margins of the South Caspian Basin (SCB), and the Sahand and Sabalan post-collisional volcanoes in NW Iran. We invert 2780 regional and teleseismic relative P wave arrival times recorded by 23 stations along the seismic profile extending from the western shoreline of the Caspian Sea to Lake Urumieh. Our tomographic results show a higher-velocity region beneath the SCB. The observed higher velocities strongly correlate with the observed positive gravity anomalies over the southwestern margins of the Caspian Sea, suggesting an oceanic like nature for the SCB lithosphere. The tomographic results also show several lower-velocity anomalies in the crust. The Sabalan volcano is underlain by a low-velocity zone in the lower crust, which is most likely thermal in nature. In the Sahand region, the lower velocities are considerably shallower in depth and might be controlled by shallow sedimentary structures, as well as an anomalously warm upper crust. The shallow low-velocity regions are connected with deeper low-velocity zones 60-100 km deep in the upper mantle. This pattern points to a possible mantle source of post-collisional volcanism in NW Iran, i.e. the melting of a subducted slab.

  20. P-wave and s-wave imaging from drill bit seismic data at SAFOD

    NASA Astrophysics Data System (ADS)

    Taylor, S. T.; Miller, D.; Haldorsen, J. B.; Coates, R.; Malin, P.; Shalev, E.

    2005-12-01

    We have used the drill bit seismic technique to develop preliminary images of fracture and shear zones associated with the San Andreas Fault at the SAFOD site, Parkfield, California. Our study included the interpretation of the USGS PSINE surface seismic profile and the drill bit seismic data recorded by three different geophone arrays. Three-component geophones were used in two of the arrays, one of which consisted of a 1.2 km string of geophones in the SAFOD Pilot Hole. The multi-component data allowed us to use both p-wave and s-wave imaging techniques for delineating subsurface structure after updating the velocity models for the site. Our interpretation of the locations and dips of linear features imaged in the migrated drill bit seismic data correlates very well with locations and dips of faults in the PSINE profile. Using the available seismic datasets, we interpret numerous faults to cut the Cenozoic sedimentary cover, the Salinian block, and an apparent wedge of metasediments at the SAFOD site. Based on the structural pattern of downward converging faults and fracture zones, we interpret the fault system to comprise a flower structure that is directly related to the tectonic regime of the San Andreas Fault. The interpretation of a flower structure at SAFOD, which is located 1.8 km SW of the SAF, fits well with the surface geological mapping that has been conducted at the site. This mapping and our data indicates that a pervasive system of fractures and faults trend subparallel to the SAF in a zone up to 3 km SW of the main trace of the fault.

  1. Source retrieval for mantle earthquakes by iterative deconvolution of long-period P-waves

    NASA Astrophysics Data System (ADS)

    Fukao, Yoshio; Kikuchi, Masayuki

    1987-12-01

    Long-period P-waves of eighteen deep and intermediate-depth earthquakes in a moment range 110 26-3 10 28 dyn cm are analysed by the method of Kikuchi and Fukao (this issue) to iteratively derive point dislocations on a plane. The fault plane is defined as the plane of point dislocations that gives the best fit between the synthetic and observed waveforms. For dip-slip type earthquakes the fault plane is found to dip more steeply than the auxiliary plane. In general, point dislocations tend to cluster into one or a few subevents. We characterize the largest subevent by its maximum moment rate ( M0) m and its half duration ? from which the associated stress drop ?? can be roughly estimated. For earthquakes shallower than 400 km, half duration ? is approximately constant, 5 s, so that stress drop ?? increases from < 100 to > 1000 bar as ( M0) m increases. The value of ? for the great Banda Sea earthquake of 1963 ( h = 100 km) is exceptionally large (?~10 s, for which ?? ~ 700 bar). For earthquakes deeper than 400 km, ? increases from 3 s to 9 s as ( M0) m increases so that ?? is approximately constant, 700 bar. Stress drop so obtained approximates to an overall stress drop with a possible exception of the several largest earthquakes. The distribution of point dislocations and the moment rate function indicate that rupture most often expands in a fan-shaped fault area and that a large part of the rupture front ceases propagation in a coherent manner. A sharp contrast in stress drop behavior across a depth of 400 km may be related to the olivine-spinel transition within the downgoing slab of lithosphere.

  2. Three-dimensional P wave velocity model for the San Francisco Bay region, California

    NASA Astrophysics Data System (ADS)

    Thurber, Clifford H.; Brocher, Thomas M.; Zhang, Haijiang; Langenheim, Victoria E.

    2007-07-01

    A new three-dimensional P wave velocity model for the greater San Francisco Bay region has been derived using the double-difference seismic tomography method, using data from about 5,500 chemical explosions or air gun blasts and approximately 6,000 earthquakes. The model region covers 140 km NE-SW by 240 km NW-SE, extending from 20 km south of Monterey to Santa Rosa and reaching from the Pacific coast to the edge of the Great Valley. Our model provides the first regional view of a number of basement highs that are imaged in the uppermost few kilometers of the model, and images a number of velocity anomaly lows associated with known Mesozoic and Cenozoic basins in the study area. High velocity (Vp > 6.5 km/s) features at ˜15-km depth beneath part of the edge of the Great Valley and along the San Francisco peninsula are interpreted as ophiolite bodies. The relocated earthquakes provide a clear picture of the geometry of the major faults in the region, illuminating fault dips that are generally consistent with previous studies. Ninety-five percent of the earthquakes have depths between 2.3 and 15.2 km, and the corresponding seismic velocities at the hypocenters range from 4.8 km/s (presumably corresponding to Franciscan basement or Mesozoic sedimentary rocks of the Great Valley Sequence) to 6.8 km/s. The top of the seismogenic zone is thus largely controlled by basement depth, but the base of the seismogenic zone is not restricted to seismic velocities of ≤6.3 km/s in this region, as had been previously proposed.

  3. Estimation of the Crustal Bulk Properties Beneath Mainland Portugal from P-Wave Teleseismic Receiver Functions

    NASA Astrophysics Data System (ADS)

    Dündar, Süleyman; Dias, Nuno A.; Silveira, Graça; Kind, Rainer; Vinnik, Lev; Matias, Luís; Bianchi, Marcelo

    2016-03-01

    In this work, we present results from teleseismic P-wave receiver functions (PRFs) obtained in Portugal, Western Iberia. A dense seismic station deployment conducted between 2010 and 2012, in the scope of the WILAS project and covering the entire country, allowed the most spatially extensive probing on the bulk crustal seismic properties of Portugal up to date. The application of the H-κ stacking algorithm to the PRFs enabled us to estimate the crustal thickness (H) and the average crustal ratio of the P- and S-waves velocities V p/V s (κ) for the region. Observations of Moho conversions indicate that this interface is relatively smooth with the crustal thickness ranging between 24 and 34 km, with an average of 30 km. The highest V p/V s values are found on the Mesozoic-Cenozoic crust beneath the western and southern coastal domain of Portugal, whereas the lowest values correspond to Palaeozoic crust underlying the remaining part of the subject area. An average V p/V s is found to be 1.72, ranging 1.63-1.86 across the study area, indicating a predominantly felsic composition. Overall, we systematically observe a decrease of V p/V s with increasing crustal thickness. Taken as a whole, our results indicate a clear distinction between the geological zones of the Variscan Iberian Massif in Portugal, the overall shape of the anomalies conditioned by the shape of the Ibero-Armorican Arc, and associated Late Paleozoic suture zones, and the Meso-Cenozoic basin associated with Atlantic rifting stages. Thickened crust (30-34 km) across the studied region may be inherited from continental collision during the Paleozoic Variscan orogeny. An anomalous crustal thinning to around 28 km is observed beneath the central part of the Central Iberian Zone and the eastern part of South Portuguese Zone.

  4. F-16: The Arrival of NASA 516

    NASA Technical Reports Server (NTRS)

    1991-01-01

    NASA 516, NASA Langley's F-16A Research Support Aircraft is shown on arrival at the center in late summer of 1991. Delivered from Eglin AFB, NASA 516 provided an advanced fighter capability for Langley research pilots in support of advanced Fighter Research Programs at the center.

  5. New Accessions Arriving at Field Records

    Materials arrive from across the country to be accessioned and processed at the Denver Library, Field Records Collection. Geologic Discipline scientists are encouraged to deposit their project materials and with the Field Records Collection. Materials in the collection are managed as Federal records...

  6. Wake Turbulence Mitigation for Arrivals (WTMA)

    NASA Technical Reports Server (NTRS)

    Williams, Daniel M.; Lohr, Gary W.; Trujillo, Anna C.

    2008-01-01

    The preliminary Wake Turbulence Mitigation for Arrivals (WTMA) concept of operations is described in this paper. The WTMA concept provides further detail to work initiated by the Wake Vortex Avoidance System Concept Evaluation Team and is an evolution of the Wake Turbulence Mitigation for Departure concept. Anticipated benefits about reducing wake turbulence separation standards in crosswind conditions, and candidate WTMA system considerations are discussed.