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1

P-wave arrival times for the 1991 racha, Georgia earthquake sequence at stations of a test, sparse network  

Microsoft Academic Search

The following arrival information is a supplement to Myers and Schultz (2000). Myers and Schultz (2000) demonstrate the improvement in sparse-network location that can be achieved by using travel-time corrections determined with a Bayesian Kriging algorithm (Schultz et al., 1998). Precise, benchmark locations are provided by a local aftershock study of the 1991 Racha, Georgia earthquake sequence in the Caucasus

S C Myers; C A Schultz; F Ryall

2000-01-01

2

Seismic noise study for accurate P-wave arrival detection via MODWT  

NASA Astrophysics Data System (ADS)

The arrival timing of the onset of microseisms and weak events is difficult to be picked even manually. The proposed algorithm uses the maximal-overlap discrete wavelet transform (MODWT) to perform manual detection for such weak events. A seismic noise analysis was done to choose the best criteria for showing clear P-wave arrival. This algorithm is also used as an accurate automatic P-wave picking algorithm. The noise level at a seismic station does not affect the proposed picking algorithm because it adapts itself to the noise level in front of each earthquake. Local events recorded by the Egyptian National Seismic Network (ENSN) were used to test this proposed algorithm. The overall average error was found to be 0.02 s.

Hafez, Ali G.; Rabie, Mostafa; Kohda, T.

2013-04-01

3

Resolving P-wave travel-time anomalies using seismic array observations of oceanic storms  

E-print Network

Resolving P-wave travel-time anomalies using seismic array observations of oceanic storms Jian California reveals P-wave arrivals from distant storms in open oceans. In this case, the noise can results suggest using oceanic storms as additional seismic sources for resolving P-wave travel

Gerstoft, Peter

4

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)

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.

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

2015-04-01

5

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL  

E-print Network

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL REIMBURSEMENT obtain a Travel Advance for this trip? No Yes Was there any personal time during this trip? No Yes From.S. Citizen: Yes No City of Residence: Vendor I.D. # (if known): Purpose of Travel: Destination: Did you

Bigelow, Stephen

6

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL  

E-print Network

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL REIMBURSEMENT: ______________________ Date:_____________________ Non-UC travelers - your SSN # is required:_______________ U.S. Citizen: Yes): _______________________ Purpose of Travel: Destination: Did you obtain a Travel Advance for this trip? No Yes Was there any

Ahlers, Guenter

7

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

NASA Astrophysics Data System (ADS)

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.

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

2004-12-01

8

P-WAVE TIME-LAPSE SEISMIC DATA INTERPRETATION AT RULISON FIELD, PICEANCE BASIN, COLORADO  

E-print Network

: ______________________ Dr. Thomas L. Davis Thesis Advisor Golden, Colorado Date _____________ _______________________ Dr. Terence K. Young Professor and Head, Department of Geophysics #12;iii ABSTRACT Two dedicated P-wave time

9

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

PubMed

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

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

2015-12-01

10

Real-time event location of California arrival data using a 2-station subarray  

Microsoft Academic Search

A fundamental problem in seismology is earthquake location. It is especially important in real-time earthquake warning systems to locate a potentially hazardous earthquake as rapidly as possible in order to sound an alarm in the least amount of time. We have developed a method that uses only the two earliest p-wave arrival times in a seismic array. Assuming a simple

P. Rydelek; J. Pujol; S. Horiuchi

2005-01-01

11

The incorporation of fault zone head wave and direct wave secondary arrival times and arrival polarizations into seismic tomography: Application to the Parkfield, California area  

NASA Astrophysics Data System (ADS)

We present a 3D P-wave velocity (Vp) model of the Parkfield region that utilizes existing P-wave arrival time data, including fault zone head waves (FZHW), plus new data from direct wave secondary arrivals (DWSA). The first-arrival and DWSA travel times are obtained as the global and local minimum travel time paths, respectively. The inclusion of DWSA results in as much as a 10% increase in the across-fault velocity contrast for the Vp model at Parkfield relative to Thurber et al. (2006). Viewed along strike, three pronounced velocity contrast regions are observed: a pair of strong positive velocity contrasts (SW fast), one NW of the 1966 Parkfield hypocenter and the other SE of the 2004 Parkfield hypocenter, and a strong negative velocity contrast (NE fast) between the two hypocenters. The negative velocity contrast partially to entirely encompasses peak coseismic slip estimated in several slip models for the 2004 earthquake, suggesting that the negative velocity contrast played a part in defining the rupture patch of the 2004 Parkfield earthquake. We expand on this work by modifying our seismic tomography algorithm to incorporate arrival polarizations (azimuths). Synthetic tests will be presented to demonstrate the improvements in velocity structure when arrival polarizations are incorporated. These tests will compare the synthetic model recovered when FZHW/DWSA arrivals as well as existing P-wave arrival time data are inverted to that recovered with the same dataset with the inclusion of arrival polarizations. We plan to extend this work to carry out a full scale seismic tomography/relocation inversion at Parkfield, CA utilizing arrival polarizations from all first-P arrivals, and FZHW/DWSA arrivals as well as existing P-wave arrival time data. This effort requires the determination of polarization data for all P-waves and FZHW's at Parkfield. To this end, we use changes in the arrival azimuth from fault normal to source-receiver direction to identify FZHW and DWSA arrivals. We also use an eigenvalue decomposition to determine the direction of the incoming wave field, and to measure the arrival azimuths. This work is supported by the USGS Earthquake Hazards Program under grant numbers G11AP20027 and G11AP20028.

Bennington, N. L.; Thurber, C. H.; Peng, Z.; Zhao, P.

2012-12-01

12

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

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.

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

2007-07-06

13

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

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.

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

2007-06-06

14

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

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.

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

2007-07-06

15

Walk -Run Activity --An S and P Wave Travel Time ("S minus P" Earthquake Location Method)  

E-print Network

Walk - Run Activity --An S and P Wave Travel Time Simulation ("S minus P" Earthquake Location between distance and time of travel of seismic waves (a travel time-curve). To use the constructed time-travel pencils) Procedure: Part One: Constructing the Travel-Time Graph To model how earthquake waves travel

Smith-Konter, Bridget

16

DYNAMIC RESERVOIR CHARACTERIZATION USING P-WAVE SEISMIC TIME-LAPSE AT POSTLE FIELD,  

E-print Network

wells. In addition, an 8 square miles P-wave vintage survey was shot for Mobil Oil Company (herein, OKLAHOMA by Sony R Mohammad #12;#12;ABSTRACT Seismic time-lapse is a proven tool to monitor changes due to production and injection in reservoirs. Today, there are approximately 120 enhanced oil recovery projects

17

Earthquake Travel Times: Customized Listing of Recent Arrival Times  

NSDL National Science Digital Library

The US Geological Survey Earthquake Hazards Program Web site contains the Earthquake Travel Times Customized Listing of Recent Arrival Times online calculator. The tool allows visitors to generate a listing of the times that phases from recent earthquakes arrived at their particular seismic station. After inputting the latitude and longitude of their location, the distance and magnitude of earthquakes to consider, types of phases, and other parameters, the user gets a simple but informative readout. The data includes the date and time of the earthquake, phase codes, travel time in seconds, arrival time, direction of travel, and more. Any seismologist or other researchers in similar fields should thoroughly appreciate this simple and helpful resource.

18

Relativistic free-motion time-of-arrival  

E-print Network

Relativistic free-motion time-of-arrival theory for massive spin-1/2 particles is systematically developed. Contrary to the nonrelativistic time-of-arrival operator studied thoroughly in previous literatures, the relativistic time-of-arrival operator possesses self-adjoint extensions because of the particle-antiparticle symmetry. The nonrelativistic limit of our theory is in agreement with the nonrelativistic time-of-arrival theory. By comparing the time-of-arrival operator with the Hamiltonian operator of a free Dirac particle, one can show a duality between position space and momentum space.

Zhi-Yong Wang; Cai-Dong Xiong

2007-10-22

19

Confined quantum time of arrival for the vanishing potential  

SciTech Connect

We give full account of our recent report in E. A. Galapon, R. Caballar, and R. Bahague, Phys. Rev. Lett. 93, 180406 (2004), where it is shown that formulating the free quantum time of arrival problem in a segment of the real line suggests rephrasing the quantum time of arrival problem to finding a complete set of states that evolve to unitarily arrive at a given point at a definite time. For a spatially confined particle, here it is shown explicitly that the problem admits a solution in the form of an eigenvalue problem of a class of compact and self-adjoint time of arrival operators derived by a quantization of the classical time of arrival. The eigenfunctions of these operators are numerically demonstrated to unitarily arrive at the origin at their respective eigenvalues.

Galapon, Eric A. [Theoretical Physics Group, National Institute of Physics, University of the Philippines, Diliman, Quezon City, 1101 (Philippines); Theoretical Physics, University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain); Chemical Physics, University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain); Caballar, Roland F.; Bahague, Ricardo [Theoretical Physics Group, National Institute of Physics, University of the Philippines, Diliman, Quezon City, 1101 (Philippines)

2005-12-15

20

A case study: travel time inversion for P-wave velocity using OBS data of South China Sea  

NASA Astrophysics Data System (ADS)

It is very important for converting the seismic data from the time domain to the depth domain. Here we discuss the approaches of inverse modeling of travel times for determination of the P-wave velocity (Vp). The migration section of the single channel seismic data is used to define the model horizons and help to control their geometry. Wide angle hydrophone data of OBS are used to determine P-wave travel times. The picked travel times from various shots are inverted for P-wave interval velocities using RayInvr, which calculated theoretical travel times via ray tracing. Damped least squares optimization is performed to fine tune the fits between observed and calculated travel times. In the end, the Vp curve is achieved and the results are compared with that derived from the conventional hyperbolic curve velocity analysis method, the shape of the two curves are similar, and the velocity increases in the layer where gas hydrates are present.

Wang, Xiangchun; Minshull, Timothy A.; Xia, Changliang; Liu, Xuewei

2012-12-01

21

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

NASA Technical Reports Server (NTRS)

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.

Houston, Vincent E.; Barmore, Bryan

2009-01-01

22

Mantle P wave travel time tomography of Eastern and Southern Africa: New images of mantle upwellings  

NASA Astrophysics Data System (ADS)

Much of Eastern Africa, including Ethiopia, Kenya, and Tanzania, has undergone extensive tectonism, including rifting, uplift, and volcanism during the Cenozoic. The cause of this tectonism is often attributed to the presence of one or more mantle upwellings, including starting thermal plumes and superplumes. Previous regional seismic studies and global tomographic models show conflicting results regarding the spatial and thermal characteristics of these upwellings. Additionally, there are questions concerning the extent to which the Archean and Proterozoic lithosphere has been altered by possible thermal upwellings in the mantle. To further constrain the mantle structure beneath Southern and Eastern Africa and to investigate the origin of the tectonism in Eastern Africa, we present preliminary results of a large-scale P wave travel time tomographic study of the region. We invert travel time measurements from the EHB database with travel time measurements taken from regional PASSCAL datasets including the Ethiopia Broadband Seismic Experiment (2000-2002); Kenya Broadband Seismic Experiment (2000-2002); Southern Africa Seismic Experiment (1997- 1999); Tanzania Broadband Seismic Experiment (1995-1997), and the Saudi Arabia PASSCAL Experiment (1995-1997). The tomographic inversion uses 3-D sensitivity kernels to combine different datasets and is parameterized with an irregular grid so that high spatial resolution can be obtained in areas of dense data coverage. It uses an adaptive least-squares context using the LSQR method with norm and gradient damping.

Benoit, M. H.; Li, C.; van der Hilst, R.

2006-12-01

23

Time-of-arrival probabilities for general particle detectors  

E-print Network

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.

Charis Anastopoulos; Ntina Savvidou

2012-07-16

24

A ROBUST TIME DIFFERENCE OF ARRIVAL ESTIMATOR IN REVERBERANT ENVIRONMENTS  

Microsoft Academic Search

This paper proposes a robust generalized cross correlation (GCC)-based time difference of arrival (TDOA) estimator in reverberant and noisy environments. Under the assumption that the phase of cross channel power spectrum should be lin- ear in a normal single source environment, the effect of re- verberation to cross power spectrum is directly reduced by a recursive estimation method. An adaptive

Jae-Mo Yang; Chang-Heon Lee; Hong-Goo Kang

2009-01-01

25

Global-scale P wave tomography optimized for prediction of teleseismic and regional travel times for Middle East events: 2. Tomographic inversion  

NASA Astrophysics Data System (ADS)

We construct a model of three-dimensional P wave velocity structure in the crust and mantle that is global in extent, but with detailed upper mantle heterogeneities throughout the greater Middle East region. Fully three-dimensional ray tracing is employed to achieve accurate travel time predictions of P and Pn arrivals, requiring the characterization of irregular and discontinuous boundaries. Therefore, we explicitly represent undulating seismic discontinuities in the crust and upper mantle within a spherical tessellation modeling framework. The tessellation-based model architecture is hierarchical in that fine node sampling is achieved by recursively subdividing a base level tessellation. Determining the required node spacing to effectively model a given set of data is problematic, given the uneven sampling of seismic data and the differing wavelengths of actual seismic heterogeneity. To address this problem, we have developed an inversion process called Progressive Multilevel Tessellation Inversion (PMTI) that exploits the hierarchical nature of the tessellation-based design and allows the data to determine the level of model complexity. PMTI serves as an alternative to existing multiresolution approaches and robustly images regional trends while allowing localized details to emerge where resolution is sufficient. To demonstrate our complete modeling concept, we construct a velocity model based on teleseismic P travel time data for global events and regional Pn travel time data for events occurring throughout the Middle East. Input data are a product of the statistical procedure called Bayesloc that simultaneously models all components of a multievent system including event locations, origin times, and arrival times (described in the Myers et al. (2011) companion paper). The initial tomographic image provides a new glimpse of the complex upper mantle velocity anomalies associated with the convergence of the Arabian and Indian plates with Eurasia. More important for event monitoring, the model accurately predicts both teleseismic and regional travel times for events occurring within the Middle East region.

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

2011-04-01

26

Arrival time of satellite-broadened laser pulses  

NASA Technical Reports Server (NTRS)

A method for measuring the time of arrival of very narrow laser pulses which have been reflected and randomly broadened by a target is examined. It is known that these return pulses from the target have very small rise times. A threshold detection algorithm that detects the rising edge of the pulse is used for obtaining the pulse arrival times. The errors of the scheme are evaluated numerically for different pulse shapes, and a loose bound on the errors of detecting a typical pulse is obtained. A gamma-density model is used to characterize the random gain processes of the optical receiver, and the effect of such random gains on the errors of threshold detection is analyzed.

Iyer, R. S.

1976-01-01

27

Quantum arrival and dwell times via idealized clocks  

SciTech Connect

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.

Yearsley, J. M.; Downs, D. A.; Halliwell, J. J.; Hashagen, A. K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

2011-08-15

28

Response Time Analysis for Distributed Real-Time Systems with Bursty Job Arrivals  

E-print Network

Response Time Analysis for Distributed Real-Time Systems with Bursty Job Arrivals Chengzhi Li schedulability analysis methodology for distributed hard real-time systems with bursty job arrivals. If the job set in the system is static, design-time analysis validates that no tim- ing constraints

Bettati, Riccardo

29

Response Time Analysis for Distributed RealTime Systems with Bursty Job Arrivals  

E-print Network

Response Time Analysis for Distributed Real­Time Systems with Bursty Job Arrivals Chengzhi Li schedulability analysis methodology for distributed hard real­time systems with bursty job arrivals. If the job set in the system is static, design­time analysis validates that no tim­ ing constraints

Bettati, Riccardo

30

Quantum-classical comparison: arrival times and statistics  

NASA Astrophysics Data System (ADS)

Classical and quantum scattering of a non-Gaussian wave packet by a rectangular barrier is studied in terms of arrival times to a given detector location. A classical wave equation, proposed by N Rosen (1964 Am. J. Phys. 32 377), is used to study the corresponding classical dynamics. Mean arrival times are then computed and compared for different values of initial wave packet parameters and barrier width. The agreement is improved in the large mass limit as one expects. A short comment on the possibility of generalization of Rosen?s proposal to a two-body system is given. Differences in distributions of particles obeying different statistics are studied by considering a system composed of two free particles.

Mousavi, S. V.; Miret-Artés, S.

2015-02-01

31

Multi-mode Lamb wave tomography with arrival time sorting  

NASA Astrophysics Data System (ADS)

Lamb wave tomography has been shown to be an effective nondestructive evaluation technique for platelike structures. A series of pitch-catch measurements between ultrasonic transducers can be taken from different orientations across the sample to create a map of a particular feature of interest such as plate thickness. Most previous work has relied solely on the first arriving mode for the time-of-flight measurements and tomographic reconstructions. The work described here demonstrates the capability of the Lamb wave tomography system to generate accurate reconstructions from multiple modes. Because each mode has different through-thickness displacement values, each is sensitive to different types of flaws, and the information gained from a multi-mode analysis can improve understanding of the structural integrity of the inspected material. However, one of the problems with the extraction of multi-mode arrival times is that destructive interference between two modes may cause one of the modes to seemingly disappear in the signal. The goal of the sorting algorithm presented in this work is to try and counteract this problem by using multiple frequency scans-also known as frequency walking-to sort the arrival times into their correct mode series. .

Leonard, Kevin R.; Hinders, Mark K.

2005-04-01

32

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

33

Quantum time of arrival distribution in a simple lattice model  

NASA Astrophysics Data System (ADS)

Imagine an experiment where a quantum particle inside a box is released at some time in some initial state. A detector is placed at a fixed location inside the box and its clicking signifies arrival of the particle at the detector. What is the time of arrival (TOA) of the particle at the detector ? Within the paradigm of the measurement postulate of quantum mechanics, one can use the idea of projective measurements to define the TOA. We consider a setup where a detector keeps making instantaneous measurements at regular finite time intervals until it detects the particle at time t, which is defined as the TOA. This is a stochastic variable and, for a simple lattice model of a free particle in a one-dimensional box, we find interesting features such as power-law tails in its distribution and in the probability of survival (non-detection). We propose a perturbative calculational approach which yields results that compare very well with exact numerics.

Dhar, Shrabanti; Dasgupta, Subinay; Dhar, Abhishek

2015-03-01

34

Quantum time of arrival distribution in a simple lattice model  

E-print Network

Imagine an experiment where a quantum particle inside a box is released at some time in some initial state. A detector is placed at a fixed location inside the box and its clicking signifies arrival of the particle at the detector. What is the \\emph{time of arrival} (TOA) of the particle at the detector ? Within the paradigm of the measurement postulate of quantum mechanics, one can use the idea of projective measurements to define the TOA. We consider the setup where a detector keeps making instantaneous measurements at regular finite time intervals {\\emph{till}} it detects the particle at some time $t$, which is defined as the TOA. This is a stochastic variable and, for a simple lattice model of a free particle in a one-dimensional box, we find interesting features such as power-law tails in its distribution and in the probability of survival (non-detection). We propose a perturbative calculational approach which yields results that compare very well with exact numerics.

Shrabanti Dhar; Subinay Dasgupta; Abhishek Dhar

2015-03-02

35

Rounding of Arrival and Departure Times in Travel Surveys: An Interpretation in Terms of Scheduled Activities  

Microsoft Academic Search

In travel surveys most respondents apply rounding of departure and arrival times to multiples of 5, 15 and 30 minutes: in the annual Dutch travel survey about 85-95 percent of all reported times are 'round' ones. We estimate rounding models for departure and arrival times. The model allows one to compute the probability that a reported arrival time m (say

Piet Rietveld

2001-01-01

36

ConcepTest: P Wave Arrival  

NSDL National Science Digital Library

Examine the seismogram below that shows a 26-minute long record of the seismic waves from the 1906 San Francisco earthquake as it was received by a seismograph station in Germany, over 14,000 km away. Which letter ...

37

Walk - Run Activity: An S and P Wave Travel Time Simulation  

NSDL National Science Digital Library

In this activity, the process of finding the epicenter of an earthquake with a travel time graph is simulated. During the course of this activity students will model how earthquake waves travel through the Earth at different speeds, construct and utilize a graph to characterize the relationship between distance and time of travel of seismic waves (a travel time-curve), and use the constructed time-travel graphs to locate the epicenter of a simulated earthquake by triangulation. The site contains detailed instructions and all of the charts and graphs required. Sample data is also included.

Larry Braile

38

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

PubMed Central

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

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

2014-01-01

39

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

40

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

PubMed

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

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

2014-01-01

41

Upper mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone - results from teleseismic P-wave travel time tomography  

Microsoft Academic Search

Structure and dynamics of the upper mantle is important in understanding timing and mechanisms shaping prensent day topography and near surface geology. Debate persists regarding the geological age of the Scandes Mountains. We contribute by imaging upper mantle structure beneath southern Scandinavia using teleseismic P-wave travel time tomography (P-tomography). We include data from mobile stations deployed in projects CALAS, CENMOVE,

Anna Bondo Medhus; Niels Balling; Bo Holm Jacobsen; Richard W. England; Rainer Kind; Zaher Hossein Shomali; Christian Weidle; Søren Gregersen; Peter Voss; Hans Thybo

2010-01-01

42

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

43

Theoretical P-Wave Travel Times, Magnitude 6.7 Island of Hawaii, Hawaii, Sunday, October 15, 2006 at 17:07:49 UTC  

NSDL National Science Digital Library

This page from the USGS displays the predicted travel times of the P-Waves originating from the 6.7 magnitude earthquake that struck near Puako, HI on October 15th, 2006. There is a table of data as well as the map visualization.

Earthquake Hazards Program

44

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

45

Uppermost mantle P wave velocities beneath Turkey and Iran  

SciTech Connect

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.

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

1980-01-01

46

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

SciTech Connect

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.

RUTLEDGE, JAMES T. [Los Alamos National Laboratory; JONES, ROB H. [Los Alamos National Laboratory

2007-01-05

47

Grid travel{time tracing: second{order method for the rst arrivals in smooth media *  

E-print Network

Grid travel{time tracing: second{order method for the #12;rst arrivals in smooth media * Lud#20;ek the #12;rst{arrival travel times on a rectangular grid of points is proposed. Whereas the former "#12;nite is of the second{order accu- racy. It means that the relative propagation{velocity error of calculated travel time

Cerveny, Vlastislav

48

Grid travel{time tracing: second{order method for the rst arrivals in smooth media  

E-print Network

Grid travel{time tracing: second{order method for the #12;rst arrivals in smooth media Lud#20;ek{arrival travel times on a rectan- gular grid of points is proposed. The new proposed method is of second{order accuracy. This means that the error of the calculated travel time is proportional to the second power

Cerveny, Vlastislav

49

The prediction of bus arrival time using Automatic Vehicle Location Systems data  

E-print Network

Prediction Models ...............................................................6 1.3.7 Identify the Prediction Interval of the Bus Arrival Time...................7 1.3.8 Identify the Probability of a Bus Being on Time... ...................................................................................................191 7.1 SUMMARY.................................................................................................191 7.2 Bus Arrival Time Prediction Models...........................................................191 7...

Jeong, Ran Hee

2005-02-17

50

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

ERIC Educational Resources Information Center

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…

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

2008-01-01

51

Arrival timing in subadult and adult Black Redstart males: competition-dependent behaviour?  

Microsoft Academic Search

The different arrival times of 1-year-old and older males is a widely recognised phenomenon in most migrating passerines. The converse pattern, i.e. the yearlings arriving at the breeding grounds at the same time as adults, has been reported only exceptionally. Two hypotheses have been formulated to explain the delayed arrival of yearling males: investment reduction, and energetic constraint hypotheses, respectively.

L. Schwarzová; P. Štros; D. Frynta; R. Fuchs

2010-01-01

52

Transition from discrete to continuous time-of-arrival distribution for a quantum particle  

SciTech Connect

We show that the Kijowski distribution for time of arrivals in the entire real line is the limiting distribution of the time-of-arrival distribution in a confining box as its length increases to infinity. The dynamics of the confined time-of-arrival eigenfunctions is also numerically investigated and demonstrated that the eigenfunctions evolve to have point supports at the arrival point at their respective eigenvalues in the limit of arbitrarily large confining lengths, giving insight into the ideal physical content of the Kijowsky distribution.

Galapon, Eric A. [Theoretical Physics Group, National Institute of Physics, University of the Philippines, Diliman, Quezon City, 1101 (Philippines); Departamento de Quimica Fisica, UPV-EHU, Apdo. 644, 48080 Bilbao (Spain); Theoretical Physics, The University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain); Delgado, F.; Muga, J. Gonzalo [Departamento de Quimica Fisica, UPV-EHU, Apdo. 644, 48080 Bilbao (Spain); Egusquiza, Inigo [Theoretical Physics, University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain)

2005-10-15

53

Distortions of Experimental Muon Arrival Time Distributions of Extensive Air Showers by the Observation Conditions  

E-print Network

Event-by-event measured arrival time distributions of Extensive Air Shower (EAS) muons are affected and distorted by various interrelated effects which originate from the time resolution of the timing detectors, from fluctuations of the reference time and the number (multiplicity) of detected muons spanning the arrival time distribution of the individual EAS events. The origin of these effects is discussed, and different correction procedures, which involve detailed simulations, are proposed and illustrated. The discussed distortions are relevant for relatively small observation distances (R < 200 m) from the EAS core. Their significance decreases with increasing observation distance and increasing primary energies. Local arrival time distributions which refer to the observed arrival time of the first local muon prove to be less sensitive to the mass of the primary. This feature points to the necessity of arrival time measurements with additional information on the curvature of the EAS disk.

R. Haeusler; A. F. Badea; H. Rebel; I. M. Brancus; J. Oehlschlaeger

2001-10-17

54

Localization of a noisy broadband surface target using time differences of multipath arrivals.  

PubMed

Previous studies [Tiemann et al., J. Acoust. Soc. Am. 120, 2355-2365 (2006)] have reported the localization of marine mammals in 3-D from their clicks using multipath arrivals. Bathymetric variations were advantageously used to predict multipath arrival times with a raytracer. These arrivals are directly discernible from the time series for impulsive sources, such as whale clicks, but extension of the method to continuous broadband sources presents additional complications. By pulse compressing noise emitted from a small boat using two hydrophones, the hyperbolic direct-arrival ambiguity can be refined in both range and bearing. Acoustic-derived results are validated with target GPS measurements. PMID:23862911

Gebbie, John; Siderius, Martin; McCargar, Reid; Allen, John S; Pusey, Grant

2013-07-01

55

Passive source localization employing intersecting spherical surfaces from time-of-arrival differences  

Microsoft Academic Search

Problems associated with the use of intersecting hyperboloids for passive source localization from time-of-arrival difference signals are discussed. A closed-form solution for source location is presented given time-of-arrival difference measurements when the distance from the source to any arbitrary reference is unknown.

H. C. SCHAU; A. Z. ROBINSON

1987-01-01

56

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

NASA Technical Reports Server (NTRS)

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.

Cassandras, Christos G.; Pan, Jie

1991-01-01

57

Stabilizing Performance in a Single-Server Queue with Time-Varying Arrival Rate  

E-print Network

is provided in order of arrival. It has been shown how server staffing (choosing a time-varying number, such as hospital surgery rooms and airport security inspection lines. In the short run, there may be a fixed number

Whitt, Ward

58

Arrival-time fluctuations of coherent reflections from surface gravity water waves.  

PubMed

Arrival time fluctuations of coherent reflections from surface gravity waves are examined. A two-dimensional ray model with an evolving rough sea surface is used to explain the mechanism and formation of the deterministic striation patterns due to the surface reflection. Arrival time predictions from the ray model match qualitatively well with the measurements from bidirectional acoustic transmissions in a water depth of 100?m. PMID:24815293

Badiey, Mohsen; Eickmeier, Justin; Song, Aijun

2014-05-01

59

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

60

A Global-scale P-wave Tomography Model for Regional and Teleseismic Event Monitoring  

Microsoft Academic Search

We construct a global-scale P-wave tomography model of the crust and mantle that depicts both large-scale tectonic\\/dynamic features, as well as detailed upper mantle heterogeneities. Fully three-dimensional ray tracing is employed to achieve accurate travel time predictions of P and Pn arrivals, necessitating the characterization of irregular and discontinuous boundaries. Therefore, we explicitly represent undulating seismic discontinuities in the crust

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

2010-01-01

61

Mapping P-wave crustal structure using deformable-layer tomography in Southern California  

Microsoft Academic Search

P-wave first arrival time data from earthquakes and surface seismic data have been used to map the crustal velocity structure in southern California. The combined data result in a dense and highly non-uniform ray-path distribution in the study area. Moho depths obtained from previous published studies have been used in the tomographic inversions to improve the lower crust portion of

Li Li

2007-01-01

62

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

SciTech Connect

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.

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

2008-02-04

63

P-wave tomography, anisotropy and seismotectonics in the eastern margin of Japan Sea  

NASA Astrophysics Data System (ADS)

To understand the seismotectonics in the eastern margin of the Japan Sea, we determined the first high-resolution 3-D P-wave velocity structure and azimuthal anisotropy under the Japan Sea off Northeast Japan using 175,425 high-precision P-wave arrival times from 2833 local earthquakes recorded by 330 seismograph stations. P-wave arrival times from 145 suboceanic earthquakes relocated with sP depth phase are crucial to determine the structure of the crust and uppermost mantle under the Japan Sea. Our results show that strong velocity variations exist in the crust and uppermost mantle under the eastern margin of the Japan Sea. Many large crustal earthquakes occurred in or around low-velocity zones which may represent weak sections of the seismogenic crust. The P-wave azimuthal anisotropy is complex under the Japan Sea, which may also indicate the complex crustal structures there. In the eastern margin of the Japan Sea, the strong heterogeneities in the crust and upper mantle revealed by seismic tomography may reflect the complicated geologic structures such as the alternate rift zones, ridges, basins, horsts, grabens, volcanics, and continental fragments which were produced during the back-arc spreading, opening of the Japan Sea and the present compressional stage of the Honshu arc.

Huang, Zhouchuan; Zhao, Dapeng; Umino, Norihito; Wang, Liangshu; Matsuzawa, Toru; Hasegawa, Akira; Yoshida, Takeyoshi

2010-06-01

64

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

PubMed

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

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

2013-05-01

65

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

SciTech Connect

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.

Yan Qiurong; Sheng Lizhi [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences 710119, Xi'an (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao Baosheng; Liu Yong'an [State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences 710119, Xi'an (China)

2011-05-15

66

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

PubMed

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. PMID:21639490

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

2011-05-01

67

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

SciTech Connect

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.

Hinders, Mark K.; Hou Jidong; Leonard, Kevin R. [College of William and Mary in Virginia, Applied Science Dept., Williamsburg, VA 23187 (United States)

2005-04-09

68

Improvements of the shock arrival times at the Earth model STOA  

E-print Network

Prediction of the shocks' arrival times (SATs) at the Earth is very important for space weather forecast. There is a well-known SAT model, 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.

Liu, H -L

2015-01-01

69

Lithospheric structure of the Illinois Basin from teleseismic P-wave tomography  

NASA Astrophysics Data System (ADS)

We examine heterogeneity of the crust and upper mantle associated with a major intracratonic basin, using arrival time data from a regional EarthScope experiment extending across the western margin of the Illinois Basin. We measured 24,062 P-wave residuals associated with 399 teleseismic events recorded from January 2012 to March 2013 by 122 stations in the Illinois Basin region. We used data from the Ozark Illinois INdiana Kentucky (OIINK) Flexible Array, the permanent New Madrid Seismic Network, and a portion of the Earthscope Transportable Array. Precise relative arrival times were determined using array cross-correlation methods. We plotted the measured arrivals as residual maps to identify first order patterns of velocity heterogeneity and to fix outliers. These data were then inverted for P-wave velocity using non-linear tomography code developed by Steven Roecker. Our preliminary results indicate the upper 200 km of the mantle can be characterized by two blocks with a transition zone centered roughly parallel to the Ohio River boundary of Illinois and Kentucky. Estimated P-wave velocities are higher in Kentucky, located southeast of the transition zone compared to Missouri and Illinois, located northwest. We caution that at this stage our tomography model may be biased as we have not accounted for variations in crustal structure or applied corrections associated with the Illinois Basin. Parallel work with receiver functions by our group and the known geometry of the Illinois Basin will be used to calculate these corrections and modify the tomographic model accordingly.

Wilson, B.; Gilbert, H. J.; Hamburger, M. W.; Merrell, T.; Pavlis, G. L.; Sherrill, E.

2013-12-01

70

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

PubMed

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

Donnelly, Alison; Geyer, Heather; Yu, Rong

2015-01-01

71

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

PubMed Central

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

Geyer, Heather; Yu, Rong

2015-01-01

72

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

NASA Astrophysics Data System (ADS)

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.

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

73

Multichannel deconvolution of p waves at seismic arrays and three-component stations. Annual report, 1 October 1985-1 October 1986  

SciTech Connect

The results of a new multichannel method, applied to array recordings and three-component station networks for teleseismic P waves, are presented and interpreted in terms of possible surface reflections and other arrivals from the Nevada Test Site (NTS), Novaya Zemlya, and Eastern Kazakh Test Site (EKTS) nuclear explosions. The deconvolution method utilizes the well known fact that P-wave spectra can be decomposed into source and receiver spectral factors. The source functions obtained in the deconvolution process provide a better picture of the nature of explosion source time functions and, in particular, of the presence or lack of secondary arrivals following the P wave such as pP or spall. The presence of such secondary arrivals and their effects on the first cycle of the P wave are very important in yield estimation. For most events at the eastern part of EKTS the source time functions appear to contain a pP arrival but they also show later, unexplained arrivals and other complexities. At other test sites often there are no clearly identifiable pP phases in the deconvolved traces. Joint deconvolution of central EKTS data using all AWRE arrays indicated strong azimuthal asymmetries in the body-wave radiation. Deconvolutions of NTS events were considerably degraded by the limited signal bandwidth due to strong mantle attenuation under this test site. The site functions are also complex in most cases. Site and source effects contribute about equally to the energy observed in the P codas of the events analyzed.

Der, Z.A.; Lees, A.C.; Shumway, R.H.; McElfresh, T.W.; Marshall, M.E.

1986-10-30

74

Real-time Upstream Monitoring System: Using ACE Data to Predict the Arrival of Interplanetary Shocks  

NASA Astrophysics Data System (ADS)

We have developed an algorithm to predict Earth arrival times for interplanetary (IP) shock events originating at the Sun. Our predictions are generated from real-time data collected by the Electron, Proton, and Alpha Monitor (EPAM) instrument on NASA's Advanced Composition Explorer (ACE) spacecraft. The high intensities of energetic ions that occur prior to and during an IP shock pose a radiation hazard to astronauts as well as to electronics in Earth orbit. The potential to predict such events is based on characteristic signatures in the Energetic Storm Particle (ESP) event ion intensities which are often associated with IP shocks. We have previously reported on the development and implementation of an algorithm to forecast the arrival of ESP events. Historical ion data from ACE/EPAM was used to train an artificial neural network which uses the signature of an approaching event to predict the time remaining until the shock arrives. Tests on the trained network have been encouraging, with an average error of 9.4 hours for predictions made 24 hours in advance, and an reduced average error of 4.9 hours when the shock is 12 hours away. The prediction engine has been integrated into a web-based system that uses real-time ACE/EPAM data provided by the NOAA Space Environment Center (http://sd-www.jhuapl.edu/UPOS/RISP/ index.html.) This system continually processes the latest ACE data, reports whether or not there is an impending shock, and predicts the time remaining until the shock arrival. Our predictions are updated every five minutes and provide significant lead-time, thereby supplying critical information that can be used by mission planners, satellite operations controllers, and scientists. We have continued to refine the prediction capabilities of this system; in addition to forecasting arrival times for shocks, we now provide confidence estimates for those predictions.

Donegan, M. M.; Wagstaff, K. L.; Ho, G. C.; Vandegriff, J.

2003-12-01

75

OneBusAway: Results from Providing Real-Time Arrival Information for Public Transit  

E-print Network

OneBusAway: Results from Providing Real-Time Arrival Information for Public Transit Brian Ferris@cs.washington.edu ABSTRACT Public transit systems play an important role in combating traffic congestion, reducing carbon emissions, and promot- ing compact, sustainable urban communities. The usability of public transit can

Anderson, Richard

76

STABILIZING PERFORMANCE IN NETWORKS OF QUEUES WITH TIME-VARYING ARRIVAL RATES  

E-print Network

-forward queueing networks of an algorithm to set staffing levels (the number of servers) to stabilize performance. Keywords: staffing algorithms for service systems; time-varying arrival rates; many-server queues allocating critical resources, such as the number of beds, nurses and associated equipment in a hospital ward

Whitt, Ward

77

Instate Travel Are departure and arrival times included on the travel expense statement?  

E-print Network

Instate Travel Are departure and arrival times included on the travel expense statement? Is expense attached? For overnight travel, are per diem rates on the day of departure and day of return listed at 75 utilized a personal vehicle for travel and departed from or returned to his/her personal residence

Arnold, Jonathan

78

Multiband Time-of-Arrival Positioning Technique for Cognitive Radio Systems  

E-print Network

Multiband Time-of-Arrival Positioning Technique for Cognitive Radio Systems Robin R. Thomas, Bassem.knopp}@eurecom.fr Abstract--Accurate information regarding a cognitive radio user's location and environment can enhance the adaptive and spectral awareness capabilities of cognitive radio systems. In this paper, a single

Gesbert, David

79

CONFIDENCE SCORING OF TIME DIFFERENCE OF ARRIVAL ESTIMATION FOR SPEAKER LOCALIZATION WITH MICROPHONE ARRAYS  

Microsoft Academic Search

Microphone arrays can be employed for passive acoustic source lo- calization using time difference of arrival (TDOA) estimates in microphone pairs. The most common method for this TDOA estimation is the generalized cross- correlation (GCC) method which is also used in this work. In an office room en- vironmental noise influences and reverberation effects complicate the TDOA esti- mation and

Dirk Bechler; Kristian Kroschel

80

Why Does Public Transport Not Arrive on Time? The Pervasiveness of Equal Headway Instability  

E-print Network

of the interplay between transport design and passenger behavior. Finally, we provide technological and socialWhy Does Public Transport Not Arrive on Time? The Pervasiveness of Equal Headway Instability Carlos´xico Abstract Background: The equal headway instability phenomenon is pervasive in public transport systems

Pineda, Luis

81

Does Seismometer Depth and Surrounding Materials Affect the Arrival Times of Seismic  

E-print Network

Does Seismometer Depth and Surrounding Materials Affect the Arrival Times of Seismic Waves at two. A working seismic station was installed in April,2002 in the Granary. One vertical component seismometer is buried in a shaft seventy feet into the limestone bedrock. Another vertical seismometer and two

Polly, David

82

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

83

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

NASA Technical Reports Server (NTRS)

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.

Erkmen, Baris I.; Moision, Bruce E.

2010-01-01

84

Carbon isotope turnover in blood as a measure of arrival time in migratory birds using isotopically distinct environments  

Microsoft Academic Search

Arrival time on breeding or non-breeding areas is of interest in many ecological studies exploring fitness consequences of\\u000a migratory schedules. However, in most field studies, it is difficult to precisely assess arrival time of individuals. Here,\\u000a we use carbon isotope turnover in avian blood as a technique to estimate arrival time for birds switching from one habitat\\u000a or environment to

Steffen Oppel; Abby N. Powell

2010-01-01

85

Near real-time predictions of the arrival at Earth of flare-related shocks during Solar Cycle 23  

Microsoft Academic Search

The arrival times at Earth of 166 flare-related shocks identified exiting the Sun (using metric radio drift data) during the maximum phase of Solar Cycle 23, were forecast in near-real time using the Shock Time of Arrival Model (STOA), the Interplanetary Shock Propagation Model (ISPM) and the Hakamada-Akasofu-Fry Model (version 2, HAFv.2). These predictions are compared with the arrival at

S. M. P. McKenna-Lawlor; M. Dryer; M. D. Kartalev; Z. Smith; C. D. Fry; W. Sun; C. S. Deehr; K. Kecskemety; K. Kudela

2006-01-01

86

Holographic p -wave superfluid  

NASA Astrophysics Data System (ADS)

In the probe limit, we numerically construct a holographic p -wave superfluid model in the four-dimensional (4D) and five-dimensional (5D) anti-de Sitter black holes coupled to a Maxwell-complex vector field. We find that, for the condensate with the fixed superfluid velocity, the results are similar to the s -wave cases in both 4D and 5D spacetimes. In particular, the Cave of Winds and the phase transition, always being of second order, take place in the 5D case. Moreover, we find that the translating superfluid velocity from second order to first order S/y? increases with the mass squared. Furthermore, for the supercurrent with fixed temperature, the results agree with the Ginzburg-Landau prediction near the critical temperature. In addition, this complex vector superfluid model is still a generalization of the SU(2) superfluid model, and it also provides a holographic realization of the H e3 superfluid system.

Wu, Ya-Bo; Lu, Jun-Wang; Zhang, Wen-Xin; Zhang, Cheng-Yuan; Lu, Jian-Bo; Yu, Fang

2014-12-01

87

Monitoring molecular interactions using photon arrival-time interval distribution analysis  

DOEpatents

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.

Laurence, Ted A. (Livermore, CA); Weiss, Shimon (Los Angels, CA)

2009-10-06

88

Incremental application of knowledge to continuously arriving time-oriented data  

Microsoft Academic Search

In our previous work, we introduced a computational architecture that effectively supports the tasks of continuous monitoring\\u000a and of aggregation querying of complex domain meaningful time-oriented concepts and patterns (temporal abstractions), in environments featuring large volumes of continuously arriving and accumulating time-oriented raw data. Examples include\\u000a provision of decision support in clinical medicine, making financial decisions, detecting anomalies and potential

Alex Spokoiny; Yuval Shahar

2008-01-01

89

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

NASA Technical Reports Server (NTRS)

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.

Heere, Karen R.; Zelenka, Richard E.

2000-01-01

90

A Detailed Study on the Equal Arrival Time Surface Effect in Gamma-Ray Burst Afterglows  

E-print Network

Due to the relativistic motion of gamma-ray burst remnant and its deceleration in the circumburst medium, the equal arrival time surfaces at any moment are not spherical, but should be distorted ellipsoids. This will leave some imprints in the afterglows. In this article, we study the effect of equal arrival time surfaces numerically under various conditions, i.e., for isotropic fireballs, collimated jets, density jump conditions, and energy injection events. For each condition, direct comparison between the two instances when the effect is and is not included, is presented. For isotropic fireballs and jets viewed on axis, the effect slightly hardens the spectra and postpones the peak time of afterglows, but does not change the shapes of the spectra and light curves significantly. In the cases when a density jump or an energy injection is involved, the effect smears the variability of the afterglows markedly.

Y. F. Huang; Y. Lu; A. Y. L. Wong; K. S. Cheng

2007-01-30

91

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

PubMed

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

Srinivasan, Lakshminarayan; da Silva, Marco

2011-06-01

92

Analyses of the Age of Genes and the First Arrival Times in a Finite Population  

PubMed Central

The age of a mutant gene is studied using the infinite allele model in which every mutant is new and selectively neutral. Based on a time reversal theory of Markov processes, we develop a method of mathematical analysis that is considerably simpler for calculating the various statistics of the age than previous methods. Formulas for the mean and variance and for the distribution of age are presented together with some examples of relevance to cases in natural populations.—Theoretical studies of the first arrival time of an allele to a specified frequency, given an initially monomorphic condition of the locus, are presented. It is shown that, beginning with an allele that has frequency p = 1 or an allele with frequency p = 1/2N, there is an initial lag phase in which there is virtually no chance of an allele with a specified intermediate frequency appearing in the population. The distribution of the first arrival time is also presented. The distribution shows several characteristics that are not immediately obvious from a consideration of only the mean and variance of first arrival time. Especially noteworthy is the existence of a very long tail to the distribution. We have also studied the distribution of the age of an allele in the population. Again, the distribution of this measure is shown to be more informative for several questions than are the mean and variance alone. PMID:17246178

Maruyama, Takeo; Fuerst, Paul A.

1983-01-01

93

Joint estimation of time of arrival and power profile for UWB localization  

Microsoft Academic Search

In time of arrival (TOA) estimation of received ultra-wideband (UWB) pulses, traditional maximum likelihood (ML) and generalized likelihood estimators become impractical due to their high sampling rate. Sub-nyquist ML-based TOA estimation currently assumes a priori knowledge of the UWB channels in the form of the average power delay profile (APDP). In this paper, instead of assuming a known APDP, we

Fang Shang; Benoit Champagne; Ioannis Psaromiligkos

2010-01-01

94

RELIABILITY MEASUREMENT OF TIME DIFFERENCE OF ARRIVAL ESTIMATIONS FOR MULTIPLE SOUND SOURCE LOCALIZATION  

Microsoft Academic Search

Time Difference Of Arrival (TDOA) estimates are used for pas- sive acoustic single sound source localization with microphone arrays. The technique of choice in most systems for TDOA esti- mation is the Generalized Cross-Correlation (GCC) method (1). For a multi-sound source scenario, cross-correlation terms of the active sound source signals as well as noise and reverberation ef- fects complicate the

Dirk Bechler; Kristian Kroschel

95

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

96

Time-of-Arrival Analysis Applied to ELF\\/VLF Wave Generation Experiments at HAARP  

Microsoft Academic Search

A time-of-arrival (TOA) analysis is applied to observations during ELF\\/VLF wave generation experiments performed at the High-frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska. This TOA technique provides measurements of the ELF\\/VLF current source with a ranging resolution of ˜2~km. Only recently has this TOA technique been applied to ELF\\/VLF waves generated by modulated HF heating of

S. Fujimaru; R. C. Moore

2010-01-01

97

Lateral density and arrival time distributions of Cherenkov photons in extensive air showers: A simulation study  

NASA Astrophysics Data System (ADS)

We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using the CORSIKA simulation package. The main thrust of this study is to see the effect of hadronic interaction models on the production pattern of Cherenkov photons with respect to distance from the shower core. Such studies are very important in ground based ?-ray astronomy for an effective rejection of huge cosmic ray background, where the atmospheric Cherenkov technique is being used extensively within the energy range of some hundred GeV to few TeV. We have found that for all primary particles, the density distribution patterns of Cherenkov photons follow the negative exponential function with different coefficients and slopes depending on the type of primary particle, its energy and the type of interaction model combinations. Whereas the arrival time distribution patterns of Cherenkov photons follow the function of the form t (r) =t0e?/r? , with different values of the function parameters. There is no significant effect of hadronic interaction model combinations on the density and arrival time distributions for the ?-ray primaries. However, for the hadronic showers, the effects of the model combinations are significant under different conditions.

Hazarika, P.; Goswami, U. D.; Chitnis, V. R.; Acharya, B. S.; Das, G. S.; Singh, B. B.; Britto, R. J.

2015-08-01

98

Lateral density and arrival time distributions of Cherenkov photons in extensive air showers: a simulation study  

E-print Network

We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using the CORSIKA simulation package. The main thrust of this study is to see the effect of hadronic interaction models on the production pattern of Cherenkov photons with respect to distance from the shower core. Such studies are very important in ground based $\\gamma$-ray astronomy for an effective rejection of huge cosmic ray background, where the atmospheric Cherenkov technique is being used extensively within the energy range of some hundred GeV to few TeV. We have found that for all primary particles, the density distribution patterns of Cherenkov photons follow the negative exponential function with different coefficients and slopes depending on the type of primary particle, its energy and the type of interaction model combinations. Whereas the arrival time distribution patterns of Cherenkov photons follow the function of the form $t (r) = t_{0}e^{\\Gamma/r^{\\lambda}}$, with different values of the function parameters. There is no significant effect of hadronic interaction model combinations on the density and arrival time distributions for the $\\gamma$-ray primaries. However, for the hadronic showers, the effects of the model combinations are significant under different conditions.

P. Hazarika; U. D. Goswami; V. R. Chitnis; B. S. Acharya; G. S. Das; B. B. Singh; R. J. Britto

2015-02-20

99

Determinants of central processing order in psychological refractory period paradigms: Central arrival times, detection times, or preparation?  

Microsoft Academic Search

Three psychological refractory period (PRP) experiments were conducted to assess the effect of central arrival times at the bottleneck on task order scheduling. In Experiment 1, a visual first task (plus–minus symbol discrimination) was combined with an auditory second task (left–right tone judgement) in a standard PRP paradigm with constant task order. In Experiment 2, the order of the tasks

Tanja Leonhard; Rolf Ulrich

2011-01-01

100

Comparing seismic tomographic images from automatically- and manually-detected arrival times  

NASA Astrophysics Data System (ADS)

In this work we compare local earthquake tomographic images obtained using arrival times detected by an automatic picking procedure and by an expert seismologist. For this purpose we select a reference dataset composed of 476 earthquakes occurred in the Trentino region (north-eastern Italy) in the period 1994-2007. Local magnitudes are comprised between 0.8 and 5.3. Original recordings are mainly from the Provincia Autonoma di Trento (PAT), and from other networks operating in the surrounding areas (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - INOGS; Istituto Nazionale di Geofisica e Vulcanologia - INGV; others available via the European Integrated Data Archive). The automatic picking of P and S phases is performed through a picker engine based on the Akaike information criterion (AIC). In particular, the proposed automatic phase picker includes: (i) envelope calculation, (ii) band-pass filtering, (iii) Akaike information criterion (AIC) detector for both P- and S-arrivals, (iv) checking for impulsive arrivals, (v) evaluation of expected S onset on the basis of a preliminary location derived from the P-arrival times, and (vi) quality assessment. Simultaneously, careful manual inspection by expert seismologists is applied to the same waveform dataset, to obtain manually-repicked phase readings. Both automatic and manual procedures generate a comparable amount of readings (about 6000 P- and 5000 S-phases). These data are used for the determination of two similar 3-D propagation models for the Trentino region, applying the SIMULPS code. In order to quantitatively estimate the difference of these two models we measure their discrepancies in terms of velocity at all grid points. The small differences observed among tomographic results allow us to demonstrate that the automatic picking engine adopted in this test can be used for reprocessing large amount of seismic recordings with the aim of perform a local tomographic study with an accuracy comparable to the one obtainable with a complete manual data revision.

Spallarossa, Daniele; Scafidi, Davide; Turino, Chiara; Ferretti, Gabriele; Viganò, Alfio

2013-04-01

101

Highly efficient arrival timing diagnostics for femtosecond X-ray and optical laser pulses  

NASA Astrophysics Data System (ADS)

We developed a diagnostic system for measuring the arrival timing between femtosecond X-ray free-electron laser (XFEL) and near-infrared laser pulses with high efficiency. The ultrafast change in optical transmittance induced by intense XFEL light was probed by a spatial decoding technique. For enhancing detection efficiency, we utilized an X-ray elliptical mirror that increases X-ray intensity by forming a line-focused profile. We found that the system is applicable to the timing diagnostics for 12 keV X-ray pulses with a pulse energy as small as 12 µJ.

Sato, Takahiro; Togashi, Tadashi; Ogawa, Kanade; Katayama, Tetsuo; Inubushi, Yuichi; Tono, Kensuke; Yabashi, Makina

2015-01-01

102

Backreacting p-wave Superconductors  

E-print Network

We study the gravitational backreaction of the non-abelian gauge field on the gravity dual to a 2+1 p-wave superconductor. We observe that as in the $p+ip$ system a second order phase transition exists between a superconducting and a normal state. Moreover, we conclude that, below the phase transition temperature $T_c$ the lowest free energy is achieved by the p-wave solution. In order to probe the solution, we compute the holographic entanglement entropy. For both $p$ and $p+ip$ systems the entanglement entropy satisfies an area law. For any given entangling surface, the p-wave superconductor has lower entanglement entropy.

Raúl E. Arias; Ignacio Salazar Landea

2013-01-28

103

Accurate tremor locations from coherent S and P waves  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

104

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

USGS Publications Warehouse

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.

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

1980-01-01

105

Ziv-Zakai bound on time-of-arrival estimation with statistical channel knowledge at the receiver  

E-print Network

Time-of-arrival (TOA) based localization plays an important role due to the possibility to exploit the fine delay resolution property when wideband signals are adopted. This paper investigates lower bounds on TOA estimation ...

Dardari, Davide

106

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

Microsoft Academic Search

Time-of-arrival (TOA) analysis is applied to ELF\\/VLF observationsTOA yields ability to separate direct and ionospherically reflected componentsTOA may provide ability to characterize the ELF\\/VLF source region currents

S. Fujimaru; R. C. Moore

2011-01-01

107

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

PubMed

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

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

2009-07-01

108

Comparative Study of Bunch Length And Arrival Time Measurements at FLASH  

SciTech Connect

Diagnostic devices to precisely measure the longitudinal electron beam profile and the bunch arrival time require elaborate new instrumentation techniques. At FLASH, two entirely different methods are used. The bunch profile can be determined with high precision by a transverse deflecting RF structure, but the method is disruptive and does not allow to monitor multiple bunches in a macro-pulse train. It is therefore complemented by two non-disruptive electrooptical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser system used for pump-probe experiments. Here, the temporal electron shape is encoded into the spatial dimension of the laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we present a comparative study of bunch length and arrival time measurements performed simultaneously with all three experimental techniques.

Schlarb, H.; Azima, A.; Dusterer, S.; Huning, M.; Knabbe, E.A.; Roehrs, M.; Rybnikov, V.; Schmidt, B.; Steffen, B.; /DESY; Ross, M.C.; /SLAC; Schmueser, P.; Winter, A.; /Hamburg U.

2007-04-16

109

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

PubMed

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

Johansson, Jacob; Jonzén, Niclas

2012-04-01

110

Timing of initial arrival at the breeding site predicts age at first reproduction in a long-lived migratory bird  

PubMed Central

In long-lived vertebrates, individuals generally visit potential breeding areas or populations during one or more seasons before reproducing for the first time. During these years of prospecting, they select a future breeding site, colony, or mate and improve various skills and their physical condition to meet the requirements of reproduction. One precondition of successful reproduction is arrival in time on the breeding grounds. Here, we study the intricate links among the date of initial spring arrival, body mass, sex, and the age of first breeding in the common tern Sterna hirundo, a long-lived migratory colonial seabird. The study is based on a unique, individual-based, long-term dataset of sexed birds, marked with transponders, which allow recording their individual arrival, overall attendance, and clutch initiation remotely and automatically year by year over the entire lifetime at the natal colony site. We show that the seasonal date of initial arrival at the breeding grounds predicts the individual age at first reproduction, which mostly occurs years later. Late first-time arrivals remain delayed birds throughout subsequent years. Our findings reveal that timing of arrival at the site of reproduction and timing of reproduction itself are coherent parameters of individual quality, which are linked with the prospects of the breeding career and may have consequences for fitness. PMID:18711134

Becker, Peter H.; Dittmann, Tobias; Ludwigs, Jan-Dieter; Limmer, Bente; Ludwig, Sonja C.; Bauch, Christina; Braasch, Alexander; Wendeln, Helmut

2008-01-01

111

Timing of initial arrival at the breeding site predicts age at first reproduction in a long-lived migratory bird.  

PubMed

In long-lived vertebrates, individuals generally visit potential breeding areas or populations during one or more seasons before reproducing for the first time. During these years of prospecting, they select a future breeding site, colony, or mate and improve various skills and their physical condition to meet the requirements of reproduction. One precondition of successful reproduction is arrival in time on the breeding grounds. Here, we study the intricate links among the date of initial spring arrival, body mass, sex, and the age of first breeding in the common tern Sterna hirundo, a long-lived migratory colonial seabird. The study is based on a unique, individual-based, long-term dataset of sexed birds, marked with transponders, which allow recording their individual arrival, overall attendance, and clutch initiation remotely and automatically year by year over the entire lifetime at the natal colony site. We show that the seasonal date of initial arrival at the breeding grounds predicts the individual age at first reproduction, which mostly occurs years later. Late first-time arrivals remain delayed birds throughout subsequent years. Our findings reveal that timing of arrival at the site of reproduction and timing of reproduction itself are coherent parameters of individual quality, which are linked with the prospects of the breeding career and may have consequences for fitness. PMID:18711134

Becker, Peter H; Dittmann, Tobias; Ludwigs, Jan-Dieter; Limmer, Bente; Ludwig, Sonja C; Bauch, Christina; Braasch, Alexander; Wendeln, Helmut

2008-08-26

112

Relaxing the closure assumption in single-season occupancy models: staggered arrival and departure times  

USGS Publications Warehouse

Occupancy statistical models that account for imperfect detection have proved very useful in several areas of ecology, including species distribution and spatial dynamics, disease ecology, and ecological responses to climate change. These models are based on the collection of multiple samples at each of a number of sites within a given season, during which it is assumed the species is either absent or present and available for detection while each sample is taken. However, for some species, individuals are only present or available for detection seasonally. We present a statistical model that relaxes the closure assumption within a season by permitting staggered entry and exit times for the species of interest at each site. Based on simulation, our open model eliminates bias in occupancy estimators and in some cases increases precision. The power to detect the violation of closure is high if detection probability is reasonably high. In addition to providing more robust estimation of occupancy, this model permits comparison of phenology across sites, species, or years, by modeling variation in arrival or departure probabilities. In a comparison of four species of amphibians in Maryland we found that two toad species arrived at breeding sites later in the season than a salamander and frog species, and departed from sites earlier.

Kendall, William L.; Hines, James E.; Nichols, James D.; Grant, Evan H. Campbell

2013-01-01

113

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

114

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

SciTech Connect

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.

Wong, V.; Frez, J.

1981-01-01

115

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

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2014-07-01

116

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

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2011-07-01

117

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

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2013-07-01

118

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

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2012-07-01

119

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

120

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

PubMed

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. PMID:25173255

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

2014-08-01

121

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

SciTech Connect

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.

Bionta, M. R., E-mail: mina.bionta@irsamc.ups-tlse.fr [Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, F-31062 Toulouse (France); CNRS, UMR 5589, F-31062 Toulouse (France); The Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Hartmann, N. [The Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Institute of Applied Physics, University of Bern, Sidlerstr. 5, 3012 Bern (Switzerland); 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. [The Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Nicholson, D. J. [The Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Cryan, J. P. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Baker, K. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States); Kane, D. J. [Mesa Photonics, LLC., 1550 Pacheco St., Santa Fe, New Mexico 87505 (United States); and others

2014-08-15

122

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

PubMed

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

Sanders, Geoff; Sinclair, Kamila

2011-12-01

123

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

NASA Astrophysics Data System (ADS)

We incorporate body-wave arrival time and surface-wave dispersion data into a joint inversion for three-dimensional P-wave and S-wave velocity structure of the crust surrounding the site of the San Andreas Fault Observatory at Depth. The contributions of the two data types to the inversion are controlled by the relative weighting of the respective equations. We find that the trade-off between fitting the two data types, controlled by the weighting, defines a clear optimal solution. Varying the weighting away from the optimal point leads to sharp increases in misfit for one data type with only modest reduction in misfit for the other data type. All the acceptable solutions yield structures with similar primary features, but the smaller-scale features change substantially. When there is a lower relative weight on the surface-wave data, it appears that the solution over-fits the body-wave data, leading to a relatively rough V s model, whereas for the optimal weighting, we obtain a relatively smooth model that is able to fit both the body-wave and surface-wave observations adequately.

Zhang, Haijiang; Maceira, Monica; Roux, Philippe; Thurber, Clifford

2014-11-01

124

The Advantage of Arriving First: Characteristic Times in Finite Size Populations of Error-Prone Replicators  

PubMed Central

We study the evolution of a finite size population formed by mutationally isolated lineages of error-prone replicators in a two-peak fitness landscape. Computer simulations are performed to gain a stochastic description of the system dynamics. More specifically, for different population sizes, we compute the probability of each lineage being selected in terms of their mutation rates and the amplification factors of the fittest phenotypes. We interpret the results as the compromise between the characteristic time a lineage takes to reach its fittest phenotype by crossing the neutral valley and the selective value of the sequences that form the lineages. A main conclusion is drawn: for finite population sizes, the survival probability of the lineage that arrives first to the fittest phenotype rises significantly. PMID:24376656

Marín, Arturo; Tejero, Héctor; Nuño, Juan Carlos; Montero, Francisco

2013-01-01

125

The advantage of arriving first: characteristic times in finite size populations of error-prone replicators.  

PubMed

We study the evolution of a finite size population formed by mutationally isolated lineages of error-prone replicators in a two-peak fitness landscape. Computer simulations are performed to gain a stochastic description of the system dynamics. More specifically, for different population sizes, we compute the probability of each lineage being selected in terms of their mutation rates and the amplification factors of the fittest phenotypes. We interpret the results as the compromise between the characteristic time a lineage takes to reach its fittest phenotype by crossing the neutral valley and the selective value of the sequences that form the lineages. A main conclusion is drawn: for finite population sizes, the survival probability of the lineage that arrives first to the fittest phenotype rises significantly. PMID:24376656

Marín, Arturo; Tejero, Héctor; Nuño, Juan Carlos; Montero, Francisco

2013-01-01

126

Priority Effects of Time of Arrival of Plant Functional Groups Override Sowing Interval or Density Effects: A Grassland Experiment  

PubMed Central

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

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

2014-01-01

127

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

PubMed

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

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

2014-01-01

128

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

NASA Astrophysics Data System (ADS)

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 ?-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 ?s. 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.

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

2013-04-01

129

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

130

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

SciTech Connect

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.

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

2008-05-01

131

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

132

Fault zone structure determined through the analysis of earthquake arrival times  

SciTech Connect

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.

Michelini, A.

1991-10-01

133

Resolution for a local earthquake arrival time and ambient seismic noise tomography around the Eyjafjallajökull volcano  

NASA Astrophysics Data System (ADS)

The explosive summit eruption of Eyjafjallajökull volcano from 14 April to end of May 2010 was preceded by an effusive flank eruption of the volcano (at Fimmvörðuháls) March 20th - April 12th. These eruptions culminated 18 years of recurrent volcanic unrest in the area, with extensive seismicity and high deformation rates since beginning of January 2010. A national network of seismic stations in Iceland (the SIL network), operated by he Icelandic Meteorological Office, monitored the precursors and development of the eruptions, in real time. We analyse a seismic dataset available from SIL stations in the vicinity of the eruption area, as well as data from additional portable stations that were deployed during a period of unrest in 1999 and just before and during the eruptions in 2010. The SIL system detected and located 2328 events between early March and late May 2010 in the area around Eyjafjallajökull. Here we present a preliminary evaluation of resolution for a local earthquake arrival time tomography. Adding the portable stations to the pre-existing SIL data set is crucial in order to identify more seismic events and improve the data coverage for tomography. We also present a resolution analysis for Ambient Seismic Noise Tomography (ASNT) in the area. In this method ambient seismic noise, recorded at two seismic stations, is cross-correlated. This band-limited approximation of the Green's function between two stations is used to estimate surface wave velocities. The fundamental assumptions underlying this method is that the noise is constructed from a randomly distributed wavefield, but this may be violated by volcanic tremor during the eruptions. We evaluate the robustness of inter-station correlograms as a function of time during the unrest period as well as their frequency content for evaluation of depth resolution. The results can be compared to constraints on magma movements inside the volcano based on interpretation of crustal deformation and geochemical analyses.

Benediktsdóttir, Á.; Gudmundsson, Ö.; Tryggvason, A.; Bödvarsson, R.; Brandsdóttir, B.; Vogfjörd; K.; Sigmundsson, F.

2012-04-01

134

Combining Analyst and Waveform-Correlation-Based Arrival Time Measurements in the Bayesloc Multiple-Event Location Algorithm  

NASA Astrophysics Data System (ADS)

We implement an efficient waveform-correlation method to determine relative arrival times and we add relative arrival-time measurements to the Bayesloc multiple-event location algorithm. Because the arrival time of seismic phases is a powerful indicator of phase type, we use Bayesloc to probabilistically determine the phase labels for the correlation picks during simultaneous multiple-event location. Bayesloc is a formulation of joint probability over event locations, travel time corrections, phase labels, and arrival-time measurement errors. The Bayesloc formulation is hierarchical with distinct statistical models for each component of the multiple-event system, including prior constraints for any of the parameters. Bayes' Theorem allows calculation of the joint probability for hypothesized configurations of Bayesloc parameters, which facilitates using the Markov-Chain Monte Carlo (MCMC) method to draw samples from the joint probability function. The marginal posteriori distribution for each parameter or covariance between parameters is inferred from MCMC samples. Correlation-based picks are integrated into the Bayesloc formulation by including a new category of arrival time measurement that is derived from correlation of empirical waveforms. Because relative picks are derived from correlation between two waveforms and absolute-time picks are made by analysis of a single waveform - typically an analyst - error processes for relative and absolute arrival time measurements are modeled independently. Relative pick precision is formulated as a function of correlation coefficient and the time-bandwidth product of the correlated waveforms, and absolute arrival times precision - as described in previous work - is formulated as a function phase type, the station, and the individual event. We adopt widely used methodologies for computing differential times based on waveform cross correlation. We first collect all waveforms for a given station and event cluster. A user-specified, phase-specific bandpass filter is applied to each waveform and the phase window is cut from the seismogram based on either analyst picks or a theoretical arrival time. We then compute and save the Fourier transform of each phase-windowed seismogram. Complex multiplication in the frequency domain is used to compute auto correlation and cross correlation spectra. Cross correlation spectra are inverse transformed and normalized based on the average of the autocorrelation amplitudes to produce a normalized, time-domain correlation function. The correlation coefficient is the peak of the correlation function and the time shift is the offset of the peak from the center of the correlation function. The time shift and the correlation coefficient are refined by fitting a parabolic function to the sample points in the neighborhood of the peak in the time-domain correlation function, which allows sub-sample precision for the correlation pick. The difference in time between the arrivals is computed by differencing the start time of the phase windows and adding the correlation-based time shift. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-CONF-490688.

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

2011-12-01

135

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

NASA Technical Reports Server (NTRS)

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".

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

2012-01-01

136

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

PubMed Central

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

Roper, JulieAnne M.; Hassan, Shirin E.

2014-01-01

137

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

ERIC Educational Resources Information Center

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.…

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

2007-01-01

138

Observability of Multiply Reflected P Waves  

NASA Astrophysics Data System (ADS)

In order to constrain the shallow structure of the Earth in global tomography, Love and Rayleigh waves are often used. However these waves are mostly sensitive to the S wave velocity structure. P-wave energy is either evanescent, or leaking away at every surface reflection that generates an S wave which travels much deeper into the mantle. For that reason, to study the shallow P velocity structure of the Earth, we need to study P-waves at regional distances if a good seismic station coverage is available. Otherwise we can use multiple P reflections at teleseismic distance when regional data are not available (as in the oceans for instance). The major aim of this work was first of all to ensure that these multiply reflected P waves can adequately be observed in real data and also to investigate how many reflections at the surface these reflected waves can still be seen and to investigate how strongly the amplitude of multiply reflected P diminishes because of energy loss into S waves. For this study we are comparing the synthetic predictions computed with a Spectral Element Method for a spherically symmetric earth (Nissen-Meyer et al, 2007) with observed data. Attention will be made on Synthetics with and without oceanic reflection points and compare these with observations. We used 300 events recorded (90000 seismograms) from the dense network of US ARRAY, which allows us to make a very large number of observations. Our study shows that three times reflected PPP waves are very well observed for epicentral distances > 60 degrees and for events with Mw > 5.5 , despite the ray-theoretical prediction that at certain distances almost all of their compressional energy is converted to shear waves. However, the four times reflected PPPP waves do not appear everywhere clearly. PPPP can be observed for epicentral distances > 90 degrees.

Foundotos, Michel; Nolet, Guust

2010-05-01

139

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

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

140

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

NASA Astrophysics Data System (ADS)

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: ? ˜ = - 872 and ? ˜ = - 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 ? ˜ and ? ˜ , 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.

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

2015-01-01

141

Sexual selection and spring arrival times of red-necked and Wilson's phalaropes  

Microsoft Academic Search

Seasonal changes in sex ratios during a 4-year study of red-necked phalaropes and a 3-year study of Wilson's phalaropes showed that females preceded males to breeding and\\/or courtship areas. The degree to which females preceded males may have been constrained by harsh weather, as the arrival of red-necked phalaropes was synchronous in 1983, when spring was unusually late. Neither sex

John D. Reynolds; Mark A. Colwell; Fred Cooke

1986-01-01

142

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

NASA Astrophysics Data System (ADS)

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 ? -ray emission from it.

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

143

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

USGS Publications Warehouse

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.

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

1998-01-01

144

P-Wave Wave in a Slinky  

NSDL National Science Digital Library

This animation shows how P-waves (primary, or compressional, waves) travel through a Slinky toy. It is accompanied by a brief written explanation that describes some of the properties of P-waves and how they are generated in a real Slinky.

John Lahr

145

Josephson current between p-wave superconductors  

NASA Astrophysics Data System (ADS)

Josephson current in p-wave superconductor/diffusive normal metal (DN)/p-wave superconductor junctions is calculated by solving the Usadel equation under the Nazarov’s boundary condition extended to unconventional superconductors by changing the heights of the insulating barriers at the interfaces, the magnitudes of the resistance in DN, and the angles between the normal to the interface and the lobe directions of p-wave pair potentials. It is shown that the magnitude of the Josephson current strongly depends on the lobe directions of the p-wave pair potentials and the resulting magnitude of the Josephson current is large compared to that in the s-wave superconducting junctions due to the formation of the resonant states peculiar to p-wave superconductors.

Yokoyama, Takehito; Tanaka, Yukio; Golubov, Alexander; Asano, Yasuhiro

2006-10-01

146

Regional P wave velocity structure of the Northern Cascadia Subduction Zone  

Microsoft Academic Search

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

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

2006-01-01

147

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

DOEpatents

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.

Benjamin, R.F.

1983-10-18

148

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

DOEpatents

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.

Benjamin, Robert F. (315 Rover Blvd., Los Alamos, NM 87544)

1987-01-01

149

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

SciTech Connect

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.

Benjamin, R.F.

1987-03-10

150

The gravity dual of a p-wave superconductor  

E-print Network

We construct black hole solutions to the Yang-Mills equations in an AdS_4-Schwarzschild background which exhibit superconductivity. What makes these backgrounds p-wave superconductors is that the order parameter is a vector, and the conductivities are strongly anisotropic in a manner that is suggestive of a gap with nodes. The low-lying excitations of the normal state have a relaxation time which grows rapidly as the temperature decreases, consistent with the absence of impurity scattering. A numerical exploration of quasinormal modes close to the transition temperature suggests that p-wave backgrounds are stable against perturbations analogous to turning on a p+ip gap, whereas p+ip-wave configurations are unstable against turning into pure p-wave backgrounds.

Steven S. Gubser; Silviu S. Pufu

2008-08-28

151

Automated determination of S-phase arrival times using autoregressive prediction: application to local and regional distances  

NASA Astrophysics Data System (ADS)

We present an algorithm for automated S-phase arrival time determination of local, regional and teleseismic events based on autoregressive (AR) prediction of the waveform. The waveforms of the horizontal components are predicted using a scalar AR model for multicomponent recordings. The AR coefficients are estimated in a short moving window using a least-squares approach minimizing the forward prediction error. Synthetic tests with single-component data show that the least-squares approach yields similar or even better results than the Yule-Walker and Burg's algorithms. We discuss the choice of the AR model and show that the corresponding prediction error of the AR model, applied to both horizontal components, is sufficient to detect instantaneous changes in amplitude, frequency, phase and polarization. The rms prediction error of both horizontal components defines the characteristic function, to which an algorithm for the estimation of the arrival time is applied. The proposed algorithm also accounts for automatic quality assessment of the estimated S-onset times. Four quality criteria are used to define the weight of the automatically estimated S-arrival time. They are based on two different estimations of the slope of the characteristic function and on two signal-to-noise ratios (SNRs). The proposed algorithm is applied to a large data set recorded by a dense regional seismic network in the southern Aegean. The data set contains recordings of local and regional crustal as well as intermediate deep earthquakes. The reliability and the robustness of the picking algorithm is tested by comparing more than 2600 manual S readings, serving as reference picks, with the corresponding automatically derived S-onset times. We find an average deviation from the reference picks of 0.5 s ± 0.8 s. If only excellent automatic picks are considered, the average difference from the reference picks is reduced to -0.057 s ± 0.12 s. The proposed automatic quality weighting scheme yields similar weights for the individual S onsets as the ones set by the analysts. The presented algorithm works reliably and robust even when applied to a data set with heterogeneous SNRs. Furthermore, the proposed method may be suitable for the implementation in an earthquake early-warning system as additional, accurate S-wave arrival time estimates stabilize the location, especially the determination of the event depth.

Küperkoch, L.; Meier, T.; Brüstle, A.; Lee, J.; Friederich, W.

2012-02-01

152

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

NASA Astrophysics Data System (ADS)

Forecasting 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 the solar wind with planetary environments. We study the feasibility of using a heliospheric imager (HI) instrument, which is able to image the solar wind density along the full Sun to 1 AU distance, for connecting remote images to in situ observations of CMEs. Such an instrument is currently in operation on each of the two STEREO spacecraft. We compare the predictions for speed and arrival time for 22 different CME events (between 2008-2012), each observed remotely by one STEREO spacecraft, to the interplanetary coronal mass ejection (ICME) speed and arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). We use croissant modeling for STEREO/COR2, and with a single-spacecraft STEREO/HI instrument, we track each CME to 34.9 ± 7.1 degree elongation from the Sun with J-maps constructed with the SATPLOT tool. We then fit geometrical models to each track, assuming different CME front shapes (Fixed-?, Harmonic Mean, Self-Similar Expansion), and constant CME speed and direction. We find no significant preference in the predictive capability for any of the three geometrical modeling methods used on the full event list, consisting of front- and backsided, slow and fast CMEs (up to 2700 km s-1). The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.4 hours (rms value of 10.9h), and speeds are consistent within 284 ± 291 km s-1, including the geometric effects of CME apex or flank encounters. We derive new empirical corrections to the imaging results, enhancing the performance of the arrival time predictions to 6.1 ± 5.0 hours (rms value of 7.9h), and the speed predictions to 53 ± 50 km s-1, for this particular set of events. The prediction lead time is around 1 day (-26.4 ± 15.3h). CME directions given by the HI methods differ considerably, and biases are found on the order of 30-50 degree in heliospheric longitude, consistent with theoretical expectations. These results are of interest concerning future missions such as Solar Orbiter or a dedicated space weather mission positioned remotely from the Earth.

Möstl, Christian; Amla, Keshav; Hall, Jeff R.; Liewer, Paulett C.; DeJong, Eric M.; Colaninno, Robin C.; Veronig, Astrid M.; Rollett, Tanja; Temmer, Manuela; Peinhart, Vanessa; Davies, Jackie A.; Lugaz, Noé; Liu, Ying; Farrugia, Charles J.; Luhmann, Janet G.; Vrsnak, Bojan; Harrison, Richard A.; Galvin, Antoinette B.

2014-05-01

153

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

SciTech Connect

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).

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

2009-08-01

154

Near-surface seismic imaging using first arrival time inversion with pre-stack depth migration  

NASA Astrophysics Data System (ADS)

This paper presents a hybrid acquisition strategy for imaging near surface stratigraphy. Shallow seismic depth imaging studies typically involve data processing followed by velocity estimation and migration. Most researchers apply the commonly used conventional processing (stacking velocity analysis) for velocity model building that in turn is used in migration. However, we find that when it comes to shallow imaging, the conventional processing lacks accuracy in velocity model estimation, which consequently leads to poor quality in depth image. To improve the velocity model reliability, we followed an unconventional procedure: first arrival inversion combined with prestack Kirchhoff depth migration. We demonstrate the imaging application for an ultra shallow (<15m) geological target, which is a set of paleo-channels in the Bull Creek, Beaver County, Oklahoma. To demonstrate the concept two coincident profiles were acquired - one targeted towards inversion and the other towards migration. Besides migrating data with the inversion model, we also migrate the data with velocity model developed though conventional processing. We compare the results to illustrate that significant improvements can be made in imaging of the shallow subsurface by using velocity models created by traveltime inversion.

Woldearegay, Ammanuel Fesseha

155

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

156

An approach for history matching of reservoir pressure and arrival time - An example from the Ketzin pilot site, Germany  

NASA Astrophysics Data System (ADS)

The Ketzin site is the first pilot project for CO2 storage in Germany. The site is located in Brandenburg about 25 km from Berlin. Since June 2008, CO2 is injected into a saline aquifer in about 630 m to 650 m depth. The total amount of injected CO2 is much smaller (< 100.000 tons) than expected on industrial scales. However, the site is an excellent pilot project for monitoring and history matching. Beneath the injection well, two observation wells were drilled in 2007. An important task of the dynamic modelling activities is the history match of the reservoir pressure and the CO2 arrival at the observation wells. The number of degrees of freedom in a strongly heterogeneous domain is much too high for a well-posed inverse problem. Therefore, the history match requires a systematic successive procedure. What we present here is in a first step the attempt to match the pressure at the injection well since we expect the highest sensitivity to the data here. The pressure at the injection well and the first arrival time will be matched by using an inverse modelling technique. Therefore, three parameters, (1) permeability near the injection well, (2) the overall field permeability and (3) the porosity are varied. All other parameters are assumed to be known although this is a very severe restriction. In a second step the pressure at the second observation well will be matched as well. The second arrival time was observed much later than initially predicted by the models. One out of several possibilities to explain this delay is the existence of a low permeable barrier right below the top of a sand channel. The CO2 as the lighter one of the two fluid phases water and CO2 can be retained at this barrier and will start flowing beneath the barrier not before a certain threshold amount of CO2 reached the barrier.

Class, Holger; Walter, Lena

2013-04-01

157

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

...arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal...TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules §...

2010-07-01

158

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

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.

Arsene, N.; Rebel, H.; Sima, O. [Institute of Space Science (ISS), Bucharest-Magurele, P.O. Box MG-23 (Romania) and Physics Department, University of Bucharest, Bucharest-Magurele (Romania); Karlsruhe Institute of Technology, Karlsruhe (Germany); Physics Department, University of Bucharest, Bucharest-Magurele (Romania)

2012-11-20

159

Joint inversion of P-wave velocity and Vp-Vs ratio: imaging the deep structure in NE Japan  

NASA Astrophysics Data System (ADS)

A new inversion scheme is presented to obtain three-dimensional images of P-wave velocity (Vp) and P-S-wave velocity ratio (Vp/Vs) using P- and S-phase pairs, i.e., the same source-receiver pairs for the P- and S-wave arrival-time data. The S-wave velocity (Vs) was separately inverted using the S-phase arrival times. The earthquake hypocenters were simultaneously relocated in the joint inversion. The method considers the Vp/Vs anomaly as a model parameter in the inversion. The proposed method thus provides a more robust calculation of the Vp/Vs anomaly than the conventional method of dividing Vp by Vs. The method also takes into account the ray path difference between P- and S-waves, and hence yields a less biased Vp-Vs ratio than the method of inverting S-P-wave data for Vp and Vp/Vs anomalies under the assumption of identical P and S ray paths. The proposed method was used to image the crust and upper mantle in northeastern (NE) Japan taking advantage of a large number of high-quality arrival times of P- and S-wave source-receiver pairs. The inverted structures suggest that the subducting slab of the Pacific plate is an inclined zone of high-Vp and Vs anomalies with low Vp/Vs perturbation. The mantle wedge is characterized by low-Vp, low-Vs, and high-Vp/Vs anomalies at shallow depths beneath active volcanoes. These features are also observed at greater depths in the back-arc region. Although these features have been previously reported, the Vp/Vs anomaly pattern obtained in this study shows much less scatter and is much better correlated with the seismic velocity perturbation patterns than previous studies. The proposed method can be used, in conjunction with velocity anomaly patterns, to quantify thermal processes associated with plate subduction.

Wang, Zhi

2014-06-01

160

First arrival time tomography for a near vertical reflection seismic profile in the Kaokoland region in Northern Namibia - first results  

NASA Astrophysics Data System (ADS)

Within the LISPWAL project (part of the SAMPLE SPP), in 2012 a Near Vertical Reflection (NVR) Seismic profile was generated in the Kaokoland region in Northern Namibia. 150 (25kg) controlled source shots at ~1350 m spacing were conducted along a 200 km North-South profile. A spread of 300 seismic stations, spaced 100 m apart, was moved in a roll-along style, to collect data suitable for standard reflection seismic processing and first arrival time tomography. Travel time data of seismic phases are used as input data to derive shallow velocity models of compressional waves (P), shear waves (S) and the Vp/Vs ratio. Using First Arrival Seismic Tomography (FAST) software, we derive shallow tomographic models for the upper 1 to 1.5 km. All three models are characterized by significant differences between the northern and the southern part. In the south P- and S-velocities are higher and Vp/Vs ratios lower while in the north the P- and S-velocities are lower while the Vp/Vs ratios show higher values.

Braeuer, Benjamin; Ryberg, Trond; Haberland, Christian; Bauer, Klaus; Weber, Michael

2014-05-01

161

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

NASA Astrophysics Data System (ADS)

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.

Bunao, Joseph; Galapon, Eric A.

2015-02-01

162

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

SciTech Connect

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.

Mishra, Wageesh; Srivastava, Nandita, E-mail: wageesh@prl.res.in [Udaipur Solar Observatory, Physical Research Laboratory, P.O. Box 198, Badi Road, Udaipur 313 001 (India)

2013-07-20

163

Improved frequency and time of arrival estimation methods in search and rescue system based on MEO satellites  

NASA Astrophysics Data System (ADS)

This paper deals with several key points including parameter estimation such as frequency of arrival (FOA), time of arrival (TOA) estimation algorithm and signal processing techniques in Medium-altitude Earth Orbit Local User Terminals (MEOLUT) based on Cospas-Sarsat Medium-altitude Earth Orbit Search and Rescue system (MEOSAR). Based on an analytical description of distress beacon, improved TOA and FOA estimation methods have been proposed. An improved FOA estimation method which integrates bi-FOA measurement, FFT method, Rife algorithm and Gaussian window is proposed to improve the accuracy of FOA estimation. In addition, TPD algorithm and signal correlation techniques are used to achieve a high performance of TOA estimation. Parameter estimation problems are solved by proposed FOA/TOA methods under quite poor Carrier-to-Noise (C/N0). A number of simulations are done to show the improvements. FOA and TOA estimation error are lower than 0.1Hz and 11?s respectively which is very high system requirement for MEOSAR system MEOLUT.

Lin, Mo; Li, Rui; Li, Jilin

2007-11-01

164

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

SciTech Connect

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.

Thompson, C.B.; McArthur, R.D. [Univ. and Community College System of Nevada, Las Vegas, NV (United States); Hutchinson, S.W. [Mead Johnson Nutritional Group, Evansville, IN (United States)

1994-09-01

165

Semi-coherent time of arrival estimation using regression Alexander Apartsina)  

E-print Network

and the spectrum of a narrowband source pulse. A measurement performed in the presence of the threshold effect. The estimated two- way travel time (lag) can be used to calculate the distance to the target assuming the speed

Intrator, Nathan

166

Stabilizing Performance in a Single-Server Queue with Time-Varying Arrival Rate  

E-print Network

how server staffing (choosing a time-varying number of servers) can be used to achieve this goal is an idealization of what can occur in many service operations, such as hospital surgery rooms and airport security

Whitt, Ward

167

Supplementary Movie: Breaking the fixed-arrival-time restriction in reaching movements of neural prosthetic devices  

E-print Network

This supplementary movie demonstrates three neural prosthetic algorithms in the simulated control of an overactuated 3-dimensional virtual robotic arm with a real-time inverse kinematics engine. Specifically, this movie ...

Srinivasan, Lakshminarayan

2010-12-15

168

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

SciTech Connect

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.

Nie, You-Qi; Zhang, Jun, E-mail: zhangjun@ustc.edu.cn; Pan, Jian-Wei [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Hong-Fei; Wang, Jian [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhen; Ma, Xiongfeng [Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084 (China)

2014-02-03

169

Using Time-Varying Tolls to Optimize Truck Arrivals at Ports Xiaoming Chen  

E-print Network

quota, for each time window. A successful truck appointment system gains truck driver support the desirable level-of-service for truck drivers, and further reduce the attractiveness of the appointment equipment and labor resources and cause inconvenience for the truck drivers. To examine the relationship

Zhou, Xuesong

170

A TIME SERIES ANALYSIS OF THE UNCERTAINTY IN INTERNATIONAL TOURIST ARRIVALS TO THE CANARY ISLANDS  

Microsoft Academic Search

International tourism is an important source of service exports to Spain and its regions, particularly the Canary Islands. Tourism is the major industry in the Canary Islands, accounting for about 22% of GDP. This paper examines the time series properties of international tourism demand to the Canary Islands collected by the National Airport Administration (AENA) at airports from information regarding

Suhejla Hoti; Carmelo J. León; Michael McAleer

171

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

USGS Publications Warehouse

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.

Choy, G.L.; Boatwright, J.

2007-01-01

172

Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1984 Annual Report.  

SciTech Connect

Hatcheries released 9.3 million chinook salmon and 6.3 million steelhead smolts and presmolts upriver from Lower Granite Reservoir for migration in spring, 1984. Peak passage of yearling chinook salmon occurred the third week in April at both Whitebird and Snake River traps. Passage of steelhead was still increasing when high water stopped trapping in mid-May. Average migration rate between release sites and Snake River (the head of Lower Granite Reservoir) was 13.2 miles/day and from that point on through the reservoir to the dam, 1.9 miles/day. Salmon River discharge, when considered along with other environmental factors, had the greatest effect on migration rate of smolts branded both at hatcheries and at the Whitebird trap and migrating to the head of Lower Granite Reservoir. Migration rate for steelhead released from Dworshak Hatchery and recaptured at the Clearwater trap was 34 miles/day. Survival rates to the Snake River trap of branded chinook salmon smolts released at Hells Canyon Dam, Rapid River, South Fork Salmon and Decker Flat were 52%, 65%, 68% and 35%, respectively. Classical descaling, where at least 40% of the scales are missing from at least two of five areas on the side of a smolt, ranged from 0 to 5.3% at hatcheries for chinook salmon and was less than 1% for steelhead. Scattered descaling, where at least 10% of scales are missing from at least one side of a fish, was always more extensive than was classical descaling, ranging from 2.5 times greater for Clearwater hatchery steelhead to 6.8 times greater for Clearwater wild steelhead. Mean total length of chinook salmon yearlings was the same at all the traps, i.e., 128 mm (117 mm fork length) +- 1 mm.

Scully, Richard J.; Buettner, Edwin W.

1986-02-01

173

Acousto-ultrasonic input-output characterization of unidirectional fiber composite plate by P waves  

NASA Technical Reports Server (NTRS)

The single reflection problem for an incident P wave at a stress free plane boundary in a semi-infinite transversely isotropic medium whose isotropic plane is parallel to the plane boundary is analyzed. It is found that an obliquely incident P wave results in a reflected P wave and a reflected SV wave. The delay time for propagation between the transmitting and the receiving transducers is computed as if the P waves were propagating in an infinite half space. The displacements associated with the P waves in the plate and which may be detected by a noncontact NDE receiving transducer are approximated by an asymptotic solution for an infinite transversely isotropic medium subjected to a harmonic point load.

Liao, Peter; Williams, James H., Jr.

1988-01-01

174

P-wave and surface wave survey for permafrost analysis in alpine regions  

NASA Astrophysics Data System (ADS)

In various high mountain environments the estimate of mechanical properties of slope and sediments are relevant for the link of the geo-mechanical properties with the climate change effects. Two different locations were selected to perform seismic and georadar surveying, the Tsanteleina glacier (Gran Paradiso) and the Blue Lake in Val d'Ayas in the massif of Monterosa. The analysis of the seismic and GPR lines allowed to characterize the silty soil (top layer) and underlying bedrock. We applied seismic survey in time lapse mode to check the presence of "active" layer and estimate the mechanical properties of the moraines material and their sensitivity to the permafrost changes. Mechanical properties of sediments and moraines in glacial areas are related to the grain-size, the compaction of the material subjected to the past glacial activity, the presence of frozen materials and the reactivity of the permafrost to the climate changes. The test site of Tsanteleina has been equipped with sensors to monitor the temperature of soil and air and with time domain reflectometry to estimate the soil moisture and the frozen and thawing cycle of the uppermost material. Seismic reflections from the top of the permafrost layer are difficult to identify as they are embedded in the source-generated noise. Therefore we estimate seismic velocities from the analysis of traveltime refraction tomography and the analysis of surface wave. This approach provides information on compressional and shear waves using a single acquisition layout and a hammer acts as source. This reduces the acquisition time in complex logistical condition especially in winter period. The seismic survey was performed using 48 vertical geophones with 2 m spacing. The survey has been repeated in two different periods: summer 2011 and winter 2011. Common offset reflection lines with a 200 MHz GPR system (in summer) permitted to investigate the sediments and obtain information on the subsoil layering. The processing of seismic data involved the tomographic interpretation of traveltime P-wave first arrivals by considering the continuous refraction of the ray-paths. Several surface-wave dispersion curves were extracted in f-k domain along the seismic line and then inverted through a laterally constrained inversion algorithm to obtain a pseudo-2D section of S-wave velocity. Georadar investigation (about 2 km of georadar lines in the first site) confirmed the presence both of fine and coarse sediments in the uppermost layer; the seismic data allowed the moraines to be characterized down to 20-25 meters of depth. At the elevation of 2700 m asl, we observed a general decrease of the P-wave traveltimes collected in November, when the near surface layer was in frozen condition, respect to the data acquired in June. The frozen layer is responsible of the inversion of P-wave velocity with depth; the higher velocity layer (frozen) cannot be detected in the tomographic interpretation of refraction tomographic of the P-wave arrivals. Compressional wave velocity ranges from 700 m/s on the uppermost part, to 2000-2500 m/s in the internal part of the sediments reaching values higher than 5000 m/s at depth about 20 m. The analysis of surface wave permitted to estimate a slight increase from summer to winter of the S-wave velocity, in the depth range between 0 to 5 m.

Godio, A.; Socco, L. V.; Garofalo, F.; Arato, A.; Théodule, A.

2012-04-01

175

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

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.

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

2004-01-01

176

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

SciTech Connect

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.

Moestl, C.; Rollett, T.; Temmer, M.; Veronig, A. M.; Biernat, H. K. [Institute of Physics, University of Graz, Graz A-8010 (Austria); Lugaz, N. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Farrugia, C. J.; Galvin, A. B. [Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03824 (United States); Davies, J. A.; Harrison, R. A.; Crothers, S. [RAL Space, Harwell Oxford, Didcot OX11 0QX (United Kingdom); Luhmann, J. G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Zhang, T. L.; Baumjohann, W., E-mail: christian.moestl@uni-graz.at [Space Research Institute, Austrian Academy of Sciences, Graz A-8042 (Austria)

2011-11-01

177

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

NASA Astrophysics Data System (ADS)

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.

Fujimaru, S.; Moore, R. C.

2011-06-01

178

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

SciTech Connect

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.

Supardiyono; Santosa, Bagus Jaya [Physics Department, Faculty of Mathematics and Natural Sciences, State University of Surabaya, Surabaya (Indonesia) and Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia); Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia)

2012-06-20

179

Prediction of the optimum time-of-arrival for the NExT mission at 9P/Tempel 1  

NASA Astrophysics Data System (ADS)

The Level 1 science requirements for the STARDUST/NExT mission to comet 9P/Tempel 1 include imaging coverage of at least 25% of the surface imaged by the Deep Impact (DI) mission at a resolution of 80 m/pixel or better. Secondary requirements include imaging the artificial crater created during the DI encounter the highest possible resolution, and new coverage of terrain not imaged by DI. Fulfilling these requirements requires precise knowledge of the spin state of the comet nucleus approximately one year ahead of the nominal time of encounter (Feb 14, 2011, ˜ 33 days after perihelion passage) and the development of a model of the acceleration of the spin state through perihelion passage. Determination of the spin state in January, 2010, was accomplished to the required precision using observations taken from the Hubble Space Telescope and from ground-based observatories. Independent development of two spin rate acceleration models was based on ˜ 12 years of observations of the rate and phase of spin of the comet's nucleus through two perihelion passages obtained with the Hubble and Spitzer space telescopes, many ground-based telescopes within the organization of an International World-Wide campaign (Meech et al., 2005), and the DI mission. The results of this study were used as input to a successful trajectory maneuver performed on Feb 17, 2010. We present the results and the predicted time-of-arrival that satisfies the mission science requirements. We also present a visualization of the encounter displaying the anticipated coverage of the surface of 9P/Tempel 1 by STARDUST/NExT, including the portion of the surface previously imaged by DI as well as new terrain that will be covered. Meech, K.J, and 210 coauthors. 2005. Deep Impact: Observations from a World-Wide Earth-based Campaign. Science 310, 265-269.

Belton, Michael; Chesley, Steven; Meech, Karen; Carcich, Brian; Veverka, Joseph

180

BGPR_Reconstruct: A MATLAB ® ray-tracing program for nonlinear inversion of first arrival travel time data from zero-offset borehole radar  

Microsoft Academic Search

A MATLAB program was developed to invert first arrival travel time picks from zero offset profiling borehole ground penetrating radar traces to obtain the electromagnetic wave propagation velocities in soil. Zero-offset profiling refers to a mode of operation wherein the centers of the bistatic antennae being lowered to the same depth below ground for each measurement. The inversion uses a

Dale F. Rucker; Ty P. A. Ferre

2004-01-01

181

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

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

Mori, J.

1991-01-01

182

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

NASA Astrophysics Data System (ADS)

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.

Dahm, Torsten; Fischer, Tomas

2014-02-01

183

Checklist for international AFTER ARRIVAL  

E-print Network

free to contact us at the International Office at any time. 1. International Office We kindly ask youChecklist for international students AFTER ARRIVAL INTERNATIONAL OFFICE #12;Welcome to Rostock! We to visit the International Office right after your arrival in Rostock. We would like to welcome you

Rostock, Universität

184

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

NASA Astrophysics Data System (ADS)

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.

Tian, You; Zhao, Dapeng

2013-12-01

185

Anomalous delays of teleseismic P waves in Yellowstone National Park  

USGS Publications Warehouse

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.

Iyer, H.M.

1975-01-01

186

P-Wave Electron-Hydrogen Scattering  

NASA Technical Reports Server (NTRS)

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.

Bhtia, Anand

2012-01-01

187

Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA  

Microsoft Academic Search

We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17–18 March 2011, we registered the first arrival of the airborne fission products 131I, 132I, 132Te, 134Cs, and 137Cs in Seattle, WA, USA, by identifying their characteristic gamma

J. Diaz Leon; D. A. Jaffe; J. Kaspar; A. Knecht; M. L. Miller; R. G. H. Robertson; A. G. Schubert

2011-01-01

188

Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA  

Microsoft Academic Search

We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products 131-I, 132-I, 132-Te, 134-Cs, and 137-Cs in Seattle, WA, USA, by identifying their characteristic gamma

J. Diaz Leon; D. A. Jaffe; J. Kaspar; A. Knecht; M. L. Miller; R. G. H. Robertson; A. G. Schubert

2011-01-01

189

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)

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.

Zhao, X.; Feng, X.

2013-12-01

190

Comparison of the Hospital Arrival Time and Differences in Pain Quality between Diabetic and Non-Diabetic STEMI Patients  

PubMed Central

The aim of our study was to determine whether diabetic ST segment elevation myocardial infarction (STEMI) patients arrive in the emergency room (ER) later than non-diabetics, compare the differences in pain quality and quantity between those groups, and measure differences in the outcome after an index hospitalization. A total of 266 patients with first presentation of STEMI were included in our study during a period of two years, 62 with diabetes and 204 without diabetes type 2. Pain intensity and quality at admission were measured using a McGill short form questionnaire. Diabetic patients did not arrive significantly later than non-diabetic (?2; p = 0.105). Most diabetic patients described their pain as “slight” or “none” (?2; p < 0.01), while most non-diabetic patients graded their pain as “moderate” or “severe” (?2; p < 0.01). The quality of pain tended to be more distinct in non-diabetic patients, while diabetic patients reported mainly shortness of breath (?2; p < 0.01). Diabetic patients were more likely to suffer a multi-vessel disease (?2; p < 0.01), especially in the late arrival group. Therefore, cautious evaluation of diabetic patients and adequate education of target population could improve overall survival while well-organized care like a primary PCI Network program could significantly reduce CV mortality. PMID:25633029

Gradišer, Marina; Dilber, Dario; Cmre?njak, Jasna; Ostri?ki, Branko; Bili?-?ur?i?, Ines

2015-01-01

191

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)

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.

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

192

Seismic Imaging of a Bimaterial Interface Along the Hayward Fault, CA, with Fault Zone Head Waves and Direct P Arrivals  

NASA Astrophysics Data System (ADS)

We observe fault zone head waves (FZHW) that are generated by and propagate along a roughly 80 km section of the Hayward fault in the San Francisco Bay area. Moveout values between the arrival times of FZHW and direct P waves are used to obtain average P-wave velocity contrasts across different sections of the fault. The results are based on waveforms generated by more than 5,800 earthquakes and recorded at up to 12 stations of the Berkeley digital seismic network (BDSN) and the Northern California seismic network (NCSN). Robust identification of FZHW requires the combination of multiple techniques due to the diverse instrumentation of the BDSN and NCSN. For single-component short-period instruments, FZHW are identified by examining sets of waveforms from both sides of the fault, and finding on one (the slow) side emergent reversed-polarity arrivals before the direct P waves. For three-component broadband and strong-motion instruments, the FZHW are identified with polarization analysis that detects early arrivals from the fault direction before the regular body waves which have polarizations along the source-receiver backazimuth. The results indicate average velocity contrasts of 3-8 % along the Hayward fault, with the southwest side having faster P wave velocities in agreement with tomographic images. A systematic moveout between the FZHW and direct P waves for about a 80 km long fault section suggests a single continuous interface in the seismogenic zone over that distance. We observe some complexities near the junction with the Calaveras fault in the SE-most portion and near the city of Oakland. Regions giving rise to variable FZHW arrival times can be correlated to first order with the presence of lithological complexity such as slivers of high-velocity metamorphic serpentinized rocks and relatively distributed seismicity. The seismic velocity contrast and geological complexity have important implications for earthquake and rupture dynamics of the Hayward fault, including a statistically preferred propagation direction of earthquake ruptures to the SE.

Allam, A. A.; Ben-Zion, Y.; Peng, Z.

2014-11-01

193

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

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.

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

1983-01-01

194

Sensitivity of seismic wide-angle wave-eld and rst arrival times to ne scale crustal structure and Moho topography  

Microsoft Academic Search

A sensitivity study of stochastic crustal and Moho models on Moho refracted rst arrivals is presented. The crustal model is a self-ane velocity structure super- posed on a linear velocity gradient. The Moho is represented by a rst-order discontinuity with a topography which is also self-ane. The sensitivity of both travel-time and wave-eld is considered. We found that the full

Thomas M. Hansen; Satish C. Singh; Bo H. Jacobsen

1999-01-01

195

Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA  

E-print Network

We report results of air monitoring started due to the recent natural catastrophe on March 11, 2011 in Japan and the severe ensuing damage to the Fukushima nuclear reactor complex. On March 17-18, 2011 we detected the first arrival of the airborne fission products 131-I, 132-I, 132-Te, 134-Cs, and 137-Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. The highest detected activity to date is <~32 mBq/m^3 of 131-I.

Leon, J Diaz; Knecht, A; Miller, M L; Robertson, R G H; Schubert, A G

2011-01-01

196

Signal-averaged P wave analysis for delineation of interatrial conduction – Further validation of the method  

PubMed Central

Background The study was designed to investigate the effect of different measuring methodologies on the estimation of P wave duration. The recording length required to ensure reproducibility in unfiltered, signal-averaged P wave analysis was also investigated. An algorithm for automated classification was designed and its reproducibility of manual P wave morphology classification investigated. Methods Twelve-lead ECG recordings (1 kHz sampling frequency, 0.625 ?V resolution) from 131 healthy subjects were used. Orthogonal leads were derived using the inverse Dower transform. Magnification (100 times), baseline filtering (0.5 Hz high-pass and 50 Hz bandstop filters), signal averaging (10 seconds) and bandpass filtering (40–250 Hz) were used to investigate the effect of methodology on the estimated P wave duration. Unfiltered, signal averaged P wave analysis was performed to determine the required recording length (6 minutes to 10 s) and the reproducibility of the P wave morphology classification procedure. Manual classification was carried out by two experts on two separate occasions each. The performance of the automated classification algorithm was evaluated using the joint decision of the two experts (i.e., the consensus of the two experts). Results The estimate of the P wave duration increased in each step as a result of magnification, baseline filtering and averaging (100 ± 18 vs. 131 ± 12 ms; P < 0.0001). The estimate of the duration of the bandpass-filtered P wave was dependent on the noise cut-off value: 119 ± 15 ms (0.2 ?V), 138 ± 13 ms (0.1 ?V) and 143 ± 18 ms (0.05 ?V). (P = 0.01 for all comparisons). The mean errors associated with the P wave morphology parameters were comparable in all segments analysed regardless of recording length (95% limits of agreement within 0 ± 20% (mean ± SD)). The results of the 6-min analyses were comparable to those obtained at the other recording lengths (6 min to 10 s). The intra-rater classification reproducibility was 96%, while the interrater reproducibility was 94%. The automated classification algorithm agreed with the manual classification in 90% of the cases. Conclusion The methodology used has profound effects on the estimation of P wave duration, and the method used must therefore be validated before any inferences can be made about P wave duration. This has implications in the interpretation of multiple studies where P wave duration is assessed, and conclusions with respect to normal values are drawn. P wave morphology and duration assessed using unfiltered, signal-averaged P wave analysis have high reproducibility, which is unaffected by the length of the recording. In the present study, the performance of the proposed automated classification algorithm, providing total reproducibility, showed excellent agreement with manually defined P wave morphologies. PMID:17925022

Holmqvist, Fredrik; Platonov, Pyotr G; Havmöller, Rasmus; Carlson, Jonas

2007-01-01

197

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)

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 2?, 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.

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

1988-06-01

198

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  

NASA Astrophysics Data System (ADS)

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 ? 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 ? 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.

Hess, Phillip; Zhang, Jie

2014-09-01

199

Arrival time and magnitude of airborne fission products from the Fukushima, Japan, reactor incident as measured in Seattle, WA, USA  

E-print Network

We report results of air monitoring started due to the recent natural catastrophe on 11 March 2011 in Japan and the severe ensuing damage to the Fukushima Dai-ichi nuclear reactor complex. On 17-18 March 2011, we registered the first arrival of the airborne fission products 131-I, 132-I, 132-Te, 134-Cs, and 137-Cs in Seattle, WA, USA, by identifying their characteristic gamma rays using a germanium detector. We measured the evolution of the activities over a period of 23 days at the end of which the activities had mostly fallen below our detection limit. The highest detected activity amounted to 4.4 +/- 1.3 mBq/m^3 of 131-I on 19-20 March.

J. Diaz Leon; D. A. Jaffe; J. Kaspar; A. Knecht; M. L. Miller; R. G. H. Robertson; A. G. Schubert

2011-08-23

200

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

PubMed

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

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

2012-07-01

201

Arrival Metering Precision Study  

NASA Technical Reports Server (NTRS)

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.

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

2015-01-01

202

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

NASA Astrophysics Data System (ADS)

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.

Zahradník, J.; Janský, J.; Plicka, V.

2015-04-01

203

A P wave velocity model of Earth's core  

NASA Astrophysics Data System (ADS)

Present Earth core models derived from the retrieval of global Earth structure are based on absolute travel times, mostly from the International Seismological Centre (ISC), and/or free-oscillation eigenfrequencies. Many core phase data are left out of these constructions, e.g., PKP differential travel times, amplitude ratios, and waveforms. This study is an attempt to utilize this additional information to construct a model of core P wave velocity which is consistent with the different types of core phase data available. In conjunction with our waveform modeling we used 150 differential time measurements and 87 amplitude ratio measurements, which were the highest-quality observations chosen from a large population of Global Digital Seismograph Network (GDSN) records. As a result of fitting these various data sets, a one-dimensional P wave velocity model of the core, PREM2, is proposed. This model, modified from the Preliminary Reference Earth Model (PREM) (Dziewonski and Anderson, 1981), shows a better fit to the combined data set than any of the existing core models. Major features of the model include a sharp velocity discontinuity at the inner core boundary (ICB), with a large jump (0.78 km/s), and a low velocity gradient at the base of the fluid core. The velocity is nearly constant over the lower 100 km of the outer core. The model features a depth-dependent Q? structure in the inner core such that a constant t* for the inner core fits the amplitude ratios and waveforms of short-period waves moderately well. This means the top of the inner core is more attenuating than the deeper part of the inner core. In addition, the P velocity in the lowermost mantle is reduced from that of PREM as a baseline adjustment for the observed separations of the DF and AB branches of PKP at large distances.

Song, Xiaodong; Helmberger, Don V.

1995-06-01

204

The effect of the Earth's oblate spheroid shape on the accuracy of a time-of-arrival lightning ground strike locating system  

NASA Technical Reports Server (NTRS)

The algorithm used in previous technology time-of-arrival lightning mapping systems was based on the assumption that the earth is a perfect spheroid. These systems yield highly-accurate lightning locations, which is their major strength. However, extensive analysis of tower strike data has revealed occasionally significant (one to two kilometer) systematic offset errors which are not explained by the usual error sources. It was determined that these systematic errors reduce dramatically (in some cases) when the oblate shape of the earth is taken into account. The oblate spheroid correction algorithm and a case example is presented.

Casper, Paul W.; Bent, Rodney B.

1991-01-01

205

Lithospheric structure north of Scotland-I. P-wave modelling, deep reflection profiles and gravity  

NASA Astrophysics Data System (ADS)

The W-reflector and the Flannan reflector are two enigmatic planar structures in the lithospheric mantle north of Scotland, mapped in three dimensions using deep reflection profiling. The Flannan reflector dips eastwards from the Moho to a depth of 80km at an angle of ~30°, whilst the W-reflector is subhorizontal, lying 10-20km beneath the Moho and terminating westwards against the Flannan. Both reflectors have a strong impedance contrast and are laterally coherent over tens of kilometres. Wide-angle seismic reflection and refraction data are used here to constrain the P-wave velocity structure of the lithosphere in this region and to investigate the physical properties and geometry of these reflective structures. We report the results from an integrated seismic survey in which a series of explosive shots fired at sea were recorded by ocean bottom seismographs, land stations and a streamer towed by a second ship in an expanding spread configuration. A well resolved P-wave velocity structure for the lithosphere above the mantle reflectors is derived by inverting the seismic traveltimes to optimize the fit of the model to the data, and by generating synthetic seismograms from the model to match the relative amplitudes of the observed seismic phases. A high-amplitude post-critical reflection indicates the existence of a discrete reflecting interface dipping gently westwards between 40 and 50km depth in the lithospheric mantle. The P-wave velocity model is converted to two-way reflection time and correlated with normal-incidence reflection data: the Moho structure agrees well, and the reflecting interface defined by the wide-angle data is coincident with the subhorizontal W-reflector. Less distinct later arrivals observed in the data are consistent with modelled reflections from the Flannan reflector in the mantle and from the extrapolated position of the Outer Isles Fault in the lower crust. Modelling of the relative amplitudes and critical distances of the wide-angle mantle reflection shows that the reflecting layer must be at least 3km thick and that it has considerably higher velocity (8.5kms-1) and density (3.5gcm-3) than normal mantle. Further modelling tests the vertical structure within the layer, and constrains the sharpness of the upper interface and whether the reflection amplitude could have been enhanced by internal layering. Gravity data measured over the region are consistent with the velocity model and with the high-density layer in the mantle, which is constrained by the gravity modelling to be less than 10km thick. Published laboratory measurements of the physical properties of mantle rocks indicate that mafic eclogite with high velocity and density satisfies all the observations from the mantle layer. Our preferred hypothesis for the origin for such a layer is that it is a fragment of oceanic crust that has been subducted and metamorphosed to eclogite facies.

Morgan, R. Peter LL.; Barton, Penny J.; Warner, Mike; Morgan, Joanna; Price, Claire; Jones, Kevin

2000-09-01

206

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)

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.

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

2012-12-01

207

Estimating the inter-arrival time density of Markov renewal processes under structural assumptions on the transition  

E-print Network

it is due to the relative motion of adjacent tectonic plates. See Shimazaki and Nakata (1980), Murray over time. An example is the size of a tectonic earthquake. Here the stress builds up over time because

Wefelmeyer, Wolfgang

208

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

209

Repeatable timing of northward departure, arrival and breeding in Black-tailed Godwits Limosa l. limosa , but no domino effects  

Microsoft Academic Search

When early breeding is advantageous, migrants underway to the breeding areas may be time stressed. The timing of sequential\\u000a events such as migration and breeding is expected to be correlated because of a “domino effect”, and would be of particular\\u000a biological importance if timings are repeatable within individuals between years. We studied a colour-marked population of\\u000a Black-tailed Godwits Limosa l.

Pedro M. Lourenço; Rosemarie Kentie; Julia Schroeder; Niko M. Groen; Jos C. E. W. Hooijmeijer; Theunis Piersma

210

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

SciTech Connect

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.

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

2014-09-01

211

Determination of three-dimensional velocity anomalies under a seismic array using first P arrival times from local earthquakes 1. A homogeneous initial model  

Microsoft Academic Search

Geiger's method of locating local earthquakes has been extended to include the effect of P velocity variation along the ray paths in three dimensions. The crustal structure was modeled by rectangular blocks, and a parameter was assigned to each block describing the perturbation of P wave slowness in the block. On the basis of an initial model, a set of

Keiiti Aki; W. H. K. Lee

1976-01-01

212

Analysis of near-source contributions to early P-wave coda for underground explosions. II. Frequency dependence  

SciTech Connect

Analysis of dispersion in more than 1600 teleseismic short-period P waves from 46 underground explosions has established that near-source effects are responsible for systematic frequency-dependent variations observed in the first 15 sec of the P signals. Explosions from the Nevada, Amchitka, and Novaya Zemlya test sites exhibit a common magnitude dependence of the dispersive behavior, with smaller events having relatively enriched low-frequency (0.4 to 0.8 Hz) energy in the coda. For the Nevada and Amchitka sites, the larger events have relatively enhanced high-frequency (0.8 to 1.1 hz) energy in the coda as well, which may be a consequence of diminished high-frequency content of the direct arrivals. The dispersive behavior also correlates well with known source depths for the Nevada Test Site and Amchitka events, and with estimated pP delay times for the Novaya Zemlya events, indicating that burial depth and/or explosion size are important factors. Pahute Mesa tests show a secondary dependence on position in the site, with centrally located events having stronger dispersion, as well as more pronounced slowly varying azimuthal patterns in frequency dependence. Stations at azimuths NNE from the Mesa have particularly strong dispersion for centrally located events. Spatial and azimuthal variations for Pahute Mesa events do not appear to be the result of aftershock radiation but instead are associated with frequency-dependent defocusing and scattering from a high-velocity structure beneath the test site.

Lay, T.

1987-08-01

213

Holographic p-wave superconductor models with Weyl corrections  

E-print Network

We study the effect of the Weyl corrections on the holographic p-wave dual models in the backgrounds of AdS soliton and AdS black hole via a Maxwell complex vector field model by using the numerical and analytical methods. We find that, in the soliton background, the Weyl corrections do not influence the properties of the holographic p-wave insulator/superconductor phase transition, which is different from that of the Yang-Mills theory. However, in the black hole background, we observe that similar to the Weyl correction effects in the Yang-Mills theory, the higher Weyl corrections make it easier for the p-wave metal/superconductor phase transition to be triggered, which shows that these two p-wave models with Weyl corrections share some similar features for the condensation of the vector operator.

Zhang, Lu; Jing, Jiliang

2015-01-01

214

Holographic p-wave superconductor models with Weyl corrections  

NASA Astrophysics Data System (ADS)

We study the effect of the Weyl corrections on the holographic p-wave dual models in the backgrounds of AdS soliton and AdS black hole via a Maxwell complex vector field model by using the numerical and analytical methods. We find that, in the soliton background, the Weyl corrections do not influence the properties of the holographic p-wave insulator/superconductor phase transition, which is different from that of the Yang-Mills theory. However, in the black hole background, we observe that similarly to the Weyl correction effects in the Yang-Mills theory, the higher Weyl corrections make it easier for the p-wave metal/superconductor phase transition to be triggered, which shows that these two p-wave models with Weyl corrections share some similar features for the condensation of the vector operator.

Zhang, Lu; Pan, Qiyuan; Jing, Jiliang

2015-04-01

215

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)

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.

Kempa, Wojciech M.

2010-10-01

216

P-Wave Holographic Insulator/Superconductor Phase Transition  

E-print Network

Using a five dimensional AdS soliton in an Einstein-Yang-Mills theory with SU(2) gauge group we study p-wave holographic insulator/superconductor phase transition. To explore the phase structure of the model we consider the system in the probe limit as well as fully back reacted solutions. We will also study zero temperature limit of the p-wave holographic superconductor in four dimensions.

Amin Akhavan; Mohsen Alishahiha

2011-03-12

217

Crustal thickness estimation in the Maule Region (Chile) from P-wave receiver function analysis  

NASA Astrophysics Data System (ADS)

A temporary passive seismic network of 31 broad-band stations was deployed in the region around Talca and Constitución between 35°S to 36°S latitude and 71°W to 72.5°W longitude. The network was operated between March and October 2008. Thus, we recorded data prior the magnitude Mw=8.8 earthquake of 27 February 2010 at a latitude of the major slip and surface uplift. The experiment was conducted to address fundamental questions on deformation processes, crustal and mantle structures, and fluid flow. We present first results of a teleseismic P receiver function study that covers the coastal region and reaches to the Andes. The aim is to determine the structure and thickness of the continental crust and constrain the state of hydration of the mantle wedge. The P-wave receiver function technique requires large teleseismic earthquakes from different distances and backazimuths. A few percent of the incident P-wave energy from a teleseismic event will be converted into S-wave (Ps) at significant and relatively sharp discontinuities beneath the station. A small converted S phase is produced that arrives at the station within the P wave coda directly after the direct P-wave. The converted Ps phase and their crustal multiples contain information about crustal properties, such as Moho depth and the crustal vp/vs ratio. We use teleseismic events with magnitudes mb > 5.5 at epicentral distances between 30° and 95° to examine P-to-S converted seismic phases. Our preliminary results provide new information about the thickness of the continental crust beneath the coastal region in Central Chile. At most of the stations we observed significant energy from P to S converted waves between 4 and 5 s after the direct P-wave within a positive phase interpreted as the Moho, occurring at 35 to 40 km. Thus, the great Maule earthquake of 27 February 2010 nucleated up-dip of the continental Moho and hence ruptured along a plate contact between subducted sediments and continental crust. Further, the Moho reflection show a positive polarity, indicating that the mantle is either dry or only moderately hydrated.

Dannowski, A.; Grevemeyer, I.; Thorwart, M. M.; Rabbel, W.; Flueh, E. R.

2010-12-01

218

Sub-femtosecond precision measurement of relative X-ray arrival time for free-electron lasers  

NASA Astrophysics Data System (ADS)

Today's brightest coherent X-ray sources, X-ray free-electron lasers, produce ultrafast X-ray pulses for which full-width at half-maximum durations as short as 3?fs have been measured. There has been a marked increase in the popularity of such short pulses now that optical timing techniques have begun to report an X-ray/optical delay below ?10?fs r.m.s. errors. As a result, sub-10?fs optical pulses have been implemented at the Linac Coherent Light Source (LCLS) X-ray beamlines, thus warranting a push to reduce the error in X-ray/optical delay measurements to the 1?fs level. Here, we report a unique two-dimensional spectrogram measurement of the relative X-ray/optical delay. This easily scalable relative delay measurement already surpasses previous techniques by an order of magnitude with its sub-1?fs temporal resolution and opens up the prospect of time-resolved X-ray measurements to the attosecond community.

Hartmann, N.; Helml, W.; Galler, A.; Bionta, M. R.; Grünert, J.; L. Molodtsov, S.; Ferguson, K. R.; Schorb, S.; Swiggers, M. L.; Carron, S.; Bostedt, C.; Castagna, J.-C.; Bozek, J.; Glownia, J. M.; Kane, D. J.; Fry, A. R.; White, W. E.; Hauri, C. P.; Feurer, T.; Coffee, R. N.

2014-09-01

219

Optimal arrival traffic spacing via dynamic programming  

E-print Network

Optimal arrival traffic spacing via dynamic programming Alexandre M. Bayen DGA - LRBA Vernon of the spacing to perturbations. Keywords: Dynamic programming, fast-time simulation, arrival spacing. Tomlin§ Yinyu Ye¶ Jiawei Zhang Stanford University Palo Alto, CA We present the application of dynamic

220

Discretized versus continuous models of p-wave interacting fermions in one dimension  

SciTech Connect

We present a general mapping between continuous and lattice models of Bose and Fermi gases in one dimension, interacting via local two-body interactions. For s-wave interacting bosons we arrive at the Bose-Hubbard model in the weakly interacting, low-density regime. The dual problem of p-wave interacting fermions is mapped to the spin-1/2 XXZ model close to the critical point in the highly polarized regime. The mappings are shown to be optimal in the sense that they produce the least error possible for a given discretization length. As an application we examine the ground state of an interacting Fermi gas in a harmonic trap, calculating numerically real-space and momentum-space distributions as well as two-particle correlations. In the analytically known limits the convergence of the results of the lattice model with the continuous one is shown.

Muth, Dominik; Fleischhauer, Michael; Schmidt, Bernd [Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universitaet Kaiserslautern, D-67663 Kaiserslautern (Germany); Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet Frankfurt, D-60438 Frankfurt am Main (Germany)

2010-07-15

221

Seismic Arrival Time Tomography as a Complementary Geophysical Exploration Tool in the Characterization of Structural Settings of Mineral Ore Deposits in Chile  

NASA Astrophysics Data System (ADS)

The abundant earthquake activity in the Chilean crust and upper mantle make Chile an outstanding environment for applications of seismological arrival time tomography. For the most part, applications of this type of imaging technique, which involves the joint determination of hypocenters and P- and S-wavespeed variations from the arrival times of primary phases, have focused on seismotectonics associated with subduction along the Andean margin. Recent images that we have obtained using these types of observation from networks in Chile, combined with a few explosions related to mining activity, show that passive source tomography can be effectively applied in refining the definition of structures within the upper 20-30 km, making it a useful geophysical tool in the regional characterization of ore deposits. Specifically, we are able to characterize more precisely the spatial distribution and depth of seismically active fault systems and anomalies associated with intrusive bodies. Our images reveal several heterogeneous regions within the Chilean crust with dimensions on the order of tens of km with wavespeed contrasts on the order of 10-15% for Vp, Vs and Vp/Vs. We find that all of the largest Cu-porphyry deposits in Central Chile are located at the edges of these structures, or in other words where the gradient in wavespeeds is greatest. Moreover, these areas are associated with high levels of ambient seismic activity, suggesting the presence of deep faulting in these regions. One possible interpretation of this pattern is that the late-stage intrusives that formed these deposits were transported along zones of weakness at the borders of existing structures, exploiting zones of relative weakness between them. These patterns show that passive source tomography can illuminated deep (i.e., mid-crustal) structures related to the genesis of mineral deposits and provide a useful tool for mining exploration in extensive areas covered by post-mineral deposits. Application of this type of tool is particularly advantageous in an area like Chile where ambient levels of seismicity can provide an adequate amount of observations within a few months.

Charrier, R.; Comte, D.; García, M.; Carrizo, D.; Roecker, S.

2010-12-01

222

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

SciTech Connect

During this period, the principal investigator wrote an abstract and research accomplishments which was published in the journal of the historically black colleges and universities and other minority institutions contract review meeting of June 2003. Interpretations and analysis of data from the study area shows that incident full-elastic seismic wavefield reflected four different wave modes, P, fast-S (SH) , slow-S (SV) and C. These four wave modes image unique geologic stratigraphy and facies and at the same time reflect independent stratal surfaces. 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.

Innocent J. Aluka

2004-01-12

223

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

PubMed

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

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

2015-04-01

224

Global P-wave tomography of mantle plumes and subducting slabs  

NASA Astrophysics Data System (ADS)

There are many volcanoes on the Earth which can be generally classified into 3 categories: island arc volcanoes, mid-ocean ridge volcanoes, and hotspot volcanoes. Hotspot volcanoes denote intraplate volcanoes like Hawaii, or anomalously large mid-ocean ridge volcanoes like Iceland. So far many researchers have studied the origin of hotspot volcanoes and have used mantle plume hypothesis to explain them. However, we still have little knowledge about mantle plumes yet. In this study, we determined a new model of whole mantle P-wave tomography to understand the origin of hotspot volcanoes. We used the global tomography method of Zhao (2001, 2004). A 3-D grid net was set up in the mantle, and velocity perturbations at every grid nodes were taken as unknown parameters. The iasp91 velocity model (Kennett and Engdahl, 1991) was taken as the 1-D initial model. We selected 9106 earthquakes from the events occurred in the last forty years from the ISC catalog. About 1.6 million arrival-time data of five-type P phases (P, pP, PP, PcP, and Pdiff) were used to conduct the tomographic inversion. In our previous model (Zhao, 2004), the grid interval in the E-W direction is too small in the polar regions. In this study, in order to remedy this problem, we use a flexible-grid approach to make the lateral grid intervals in the polar regions nearly the same as the other portions of the mantle. As a result, the tomographic images in the polar regions are remarkably improved. Our new tomographic model shows huge low-velocity (low-V) zones in the entire mantle under Tahiti and Lake Victoria, which reflect the Pacific and African superplumes, being consistent with the previous studies. A clear low-V zone is revealed under Mt. Erebus volcano in Antarctica. Other major hotspots also exhibit significant low-V zones in the mantle under their surface locations. Beneath Bering Sea, we found that the Pacific slab is subducting from the Aleutian trench and it is stagnant in the mantle transition zone. In Bering Sea, there are several intraplate volcanoes such as St. Paul island. Given the existence of the stagnant Pacific slab and very low-V mantle wedge above the slab, we think that the origin of the intraplate volcanoes in Bering Sea is most likely related to the deep subduction of the Pacific slab and its stagnancy in the mantle transition zone, similar to the Changbai and Wudalianchi volcanoes in Northeast Asia (Zhao, 2004). Zhao, D. (2001) Earth Planet. Sci. Lett. 192, 251-265. Zhao, D. (2004) Phys. Earth Planet. Inter. 146, 3-34.

Yamamoto, Y.; Zhao, D.

2008-12-01

225

A near-optimal low complexity sensor fusion technique for accurate indoor localization based on ultrasound time of arrival measurements from low-quality sensors  

NASA Astrophysics Data System (ADS)

A fusion-based localization technique for location-based services in indoor environments is introduced herein, based on ultrasound time-of-arrival measurements from multiple off-the-shelf range estimating sensors which are used in a market-available localization system. In-situ field measurements results indicated that the respective off-the-shelf system was unable to estimate position in most of the cases, while the underlying sensors are of low-quality and yield highly inaccurate range and position estimates. An extensive analysis is performed and a model of the sensor-performance characteristics is established. A low-complexity but accurate sensor fusion and localization technique is then developed, which consists inof evaluating multiple sensor measurements and selecting the one that is considered most-accurate based on the underlying sensor model. Optimality, in the sense of a genie selecting the optimum sensor, is subsequently evaluated and compared to the proposed technique. The experimental results indicate that the proposed fusion method exhibits near-optimal performance and, albeit being theoretically suboptimal, it largely overcomes most flaws of the underlying single-sensor system resulting in a localization system of increased accuracy, robustness and availability.

Mitilineos, Stelios A.; Argyreas, Nick D.; Thomopoulos, Stelios C. A.

2009-05-01

226

Mapping P-wave anisotropy of the Honshu arc from Japan Trench to the back-arc  

NASA Astrophysics Data System (ADS)

We determined a 3-D P-wave anisotropic tomography beneath the entire Honshu arc using about 448,000 high-quality P-wave arrival times from 18,335 local earthquakes that occurred beneath the Northeast (NE) Japan land area and the fore-arc area under the Pacific Ocean. Our results show that low-velocity (low-V) zones exist beneath the active arc volcanoes in the crust and in the central portion of the mantle wedge above the subducting Pacific slab. The low-V anomalies are related to the arc magmatism. Low-V zones are also revealed in the fore-arc area, which are probably caused by large volumes of water releasing upwards from dehydration of the subducting oceanic crust and sediments. The anisotropic amplitude in the upper crust is weaker than that in other portions under NE Japan. In the mantle wedge, the fast velocity direction (FVD) is generally trench-normal in back-arc area, which may reflect that the olivine a axis aligns with the transport direction induced by the slab-driven corner flow. The FVD becomes trench-parallel in the central portion of the fore-arc mantle wedge, which is possibly induced by the olivine of B-type fabric in the slab-driven corner flow. The FVD shows trench-parallel in the low-V zones in the fore-arc mantle wedge close to the upper boundary of the Pacific slab, which may reflect the B-type olivine fabric dominating in those areas, or it may be induced by the dextral shearing of the overlying crust. The trench-parallel FVD is also revealed beneath the volcanic front, indicating complex 3-D mantle flows in the mantle wedge. The FVD in the subducting Pacific slab is mostly trench-parallel, which may reflect one or more of the following possibilities: (1) the original fossil anisotropy of the Pacific plate formed at the mid-ocean ridge, (2) cracks within the slab, and (3) the olivine fabric transition due to the changes in water content, stress, and temperature.

Wang, Jian; Zhao, Dapeng

2010-10-01

227

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

228

Using an Adjusted Serfling Regression Model to Improve the Early Warning at the Arrival of Peak Timing of Influenza in Beijing  

PubMed Central

Serfling-type periodic regression models have been widely used to identify and analyse epidemic of influenza. In these approaches, the baseline is traditionally determined using cleaned historical non-epidemic data. However, we found that the previous exclusion of epidemic seasons was empirical, since year-year variations in the seasonal pattern of activity had been ignored. Therefore, excluding fixed ‘epidemic’ months did not seem reasonable. We made some adjustments in the rule of epidemic-period removal to avoid potentially subjective definition of the start and end of epidemic periods. We fitted the baseline iteratively. Firstly, we established a Serfling regression model based on the actual observations without any removals. After that, instead of manually excluding a predefined ‘epidemic’ period (the traditional method), we excluded observations which exceeded a calculated boundary. We then established Serfling regression once more using the cleaned data and excluded observations which exceeded a calculated boundary. We repeated this process until the R2 value stopped to increase. In addition, the definitions of the onset of influenza epidemic were heterogeneous, which might make it impossible to accurately evaluate the performance of alternative approaches. We then used this modified model to detect the peak timing of influenza instead of the onset of epidemic and compared this model with traditional Serfling models using observed weekly case counts of influenza-like illness (ILIs), in terms of sensitivity, specificity and lead time. A better performance was observed. In summary, we provide an adjusted Serfling model which may have improved performance over traditional models in early warning at arrival of peak timing of influenza. PMID:25756205

Wang, Xiaoli; Wu, Shuangsheng; MacIntyre, C. Raina; Zhang, Hongbin; Shi, Weixian; Peng, Xiaomin; Duan, Wei; Yang, Peng; Zhang, Yi; Wang, Quanyi

2015-01-01

229

Using an adjusted serfling regression model to improve the early warning at the arrival of peak timing of influenza in beijing.  

PubMed

Serfling-type periodic regression models have been widely used to identify and analyse epidemic of influenza. In these approaches, the baseline is traditionally determined using cleaned historical non-epidemic data. However, we found that the previous exclusion of epidemic seasons was empirical, since year-year variations in the seasonal pattern of activity had been ignored. Therefore, excluding fixed 'epidemic' months did not seem reasonable. We made some adjustments in the rule of epidemic-period removal to avoid potentially subjective definition of the start and end of epidemic periods. We fitted the baseline iteratively. Firstly, we established a Serfling regression model based on the actual observations without any removals. After that, instead of manually excluding a predefined 'epidemic' period (the traditional method), we excluded observations which exceeded a calculated boundary. We then established Serfling regression once more using the cleaned data and excluded observations which exceeded a calculated boundary. We repeated this process until the R2 value stopped to increase. In addition, the definitions of the onset of influenza epidemic were heterogeneous, which might make it impossible to accurately evaluate the performance of alternative approaches. We then used this modified model to detect the peak timing of influenza instead of the onset of epidemic and compared this model with traditional Serfling models using observed weekly case counts of influenza-like illness (ILIs), in terms of sensitivity, specificity and lead time. A better performance was observed. In summary, we provide an adjusted Serfling model which may have improved performance over traditional models in early warning at arrival of peak timing of influenza. PMID:25756205

Wang, Xiaoli; Wu, Shuangsheng; MacIntyre, C Raina; Zhang, Hongbin; Shi, Weixian; Peng, Xiaomin; Duan, Wei; Yang, Peng; Zhang, Yi; Wang, Quanyi

2015-01-01

230

Laboratory monitoring of P-waves in partially saturated sand  

NASA Astrophysics Data System (ADS)

Seismic data depends on a variety of hydrogeological properties of the prospected porous media such as porosity, permeability and fluid saturation. We have performed a laboratory experiment in the kiloHertz range in order to analyze the role of partial saturation on direct propagating P-waves phase velocity and attenuation. The experiment consists of a sand-filled tank 107 cm x 34 cm x 35cm equipped with accelerometers and water capacitance probes. The P-waves seismic propagation is generated by hitting a steel ball on a granite plate on the one lateral side of the container. Several imbibition/drainage cycles are performed between the water residual saturation and the gas residual saturation. The laboratory seismic data are processed by two Continuous Wavelet Transforms using one real mother wavelet (Mexican hat) and one complex (Morlet) to recover velocity and attenuation as a function of frequency. Phase velocity of direct P-wave decreases with an increase of water content and is quite consistent with the low frequency limit of the Biot's theory both for imbibition and drainage. The interpretation of the P-waves attenuation needs to go beyond the macroscopic fluid flow of Biot's theory and to introduce a viscoelastic contribution linked to the grain to grain overall losses which are described by a constant Q-model. A strong hysteresis between imbibition and drainage is observed and explained by introducing an effective permeability depending on water and gas relative permeabilities (Van Genuchten model).

Barrière, J.; Bordes, C.; Brito, D.; Sénéchal, P.; Perroud, H.

2011-12-01

231

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

NASA Astrophysics Data System (ADS)

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 ?2 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.

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

2014-03-01

232

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

NASA Astrophysics Data System (ADS)

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 .

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

2015-03-01

233

Effect of electrocardiographic P-wave axis on mortality.  

PubMed

Although P-wave axis is routinely reported on the printouts of most contemporary electrocardiograms, the prognostic significance of its abnormality has not been systematically evaluated. We examined the association between abnormal P-wave axis and cardiovascular and all-cause mortality in 7,501 participants (53% women, mean age 59 years) from the United States Third National Health and Nutrition Examination Survey. P-wave axis of 0° to 75° was considered normal. Participants were linked to the National Death Index to identify the underlying cause of death listed on the death certificates using the International Classification of Disease. During a median follow-up of 13.8 years, a total of 2,541 deaths occurred; of which 1,077 were due to a cardiovascular cause. Abnormal P-wave axis was associated with 55% increased risk of all-cause mortality (hazard ratio [HR] 1.55, 95% confidence interval [CI] 1.43 to 1.69, p <0.01) and 41% increased risk of cardiovascular mortality (HR 1.41, 95% CI 1.24 to 1.62, p <0.01). After adjustment for age, gender, race/ethnicity, diabetes, systolic blood pressure, body mass index, smoking status, total/high-density lipoprotein cholesterol ratio, previous cardiovascular disease, chronic obstructive pulmonary disease, bronchial asthma, heart rate, and use of antiarrhythmic or atrioventricular nodal blocking drugs, the risk of mortality remained significantly high (HR 1.24 95% CI 1.13 to 1.36, p <0.01 for all-cause mortality and HR 1.19 95% CI 1.03 to 1.38, p = 0.02 for cardiovascular mortality) and was consistent across several subgroups of the participants. In conclusion, abnormal P-wave axis is associated with an increased risk of death, findings that call for attention to this routinely reported finding on contemporary electrocardiographic machines. PMID:24176072

Li, Yabing; Shah, Amit J; Soliman, Elsayed Z

2014-01-15

234

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)

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.

Abers, Geoffrey A.

1994-03-01

235

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)

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 ?s 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 ?s 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 ?s 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 ?s 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.

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

2012-12-01

236

Revealing the architecture of the upper boundary of the Philippine Sea Plate beneath the northern tip of the Izu-Tanzawa Collision Zone, Central Japan, using later-phase of P waves  

NASA Astrophysics Data System (ADS)

In Izu-Tanzawa Collision Zone (ITCZ), Izu arc collides with Japan arc due to subduction of the Philippine Sea plate (PHP). Recent studies by Kikuchi (2008) and Arai et al. (2009) have revealed that the upper boundary of PHP has a complex geometry in this area. High seismicity near the top boundary of PHP is reported in the front (northern) edge of the ITCZ, which is the transition zone from collision to subduction of PHP, whereas an aseismic zone is located on the western part of the high seismicity region. This spatial variation of seismicity is probably related to the shape of PHP caused by the difference between collisional vs. subductive movements. To better correlate the spatial distribution of seismicity and the plate configuration, we attempt to find a discontinuous surface near the upper boundary of PHP using later phases of P waves. We used seismic-waveform data from the website of Hi-net seismic network. In the high seismicity region, clear later phases of P waves (X phases) are observed in vertical component seismograms recorded at the stations above the high seismicity region. The X phases arrive 0.5s to 2.0s after P arrivals. Time difference between P and X arrivals (X-P times) increases with distances between the plate boundary and the hypocenters. Similarly, X-P times increase as the distances from the northwestern edge of the high seismicity region to the hypocenters increase. These observations suggest two possibilities for the origin of the X phases: (1) a converted wave at the upper boundary of PHP or (2) a reflected wave from the edge of the high seismicity region. First we searched a suitable plane for which calculated X-P times can match the observed X-P times, by assuming the X phases are converted waves. We found that two converted planes located at different depths would best explain all observed X-P times simultaneously; the depth of the estimated plane in the western side of the high seismicity zone is deeper than that of the eastern side. Next, we determined reflection points for which the observed X-P times can fit: estimated reflection points were concentrated in the northwestern edge of the high seismicity region. In either case, generation points of X phases are located near the top boundary of PHP and it would be expected that the detailed structure near the top boundary of the PHP could be clarified using these later phases. Acknowledgement: We thank the National Research Institute for Earth Science and Disaster Prevention of Japan for providing the Hi-net data.

Shuri, Y.; Tsumura, N.

2010-12-01

237

Holographic p-wave superconductors from Gauss-Bonnet gravity  

SciTech Connect

We study the holographic p-wave superconductors in a five-dimensional Gauss-Bonnet gravity with an SU(2) Yang-Mills gauge field. In the probe approximation, we find that when the Gauss-Bonnet coefficient grows, the condensation of the vector field becomes harder, both the perpendicular and parallel components, with respect to the direction of the condensation, of the anisotropic conductivity decrease. We also study the mass of the quasiparticle excitations, the gap frequency and the DC conductivities of the p-wave superconductor. All of them depend on the Gauss-Bonnet coefficient. In addition, we observe a strange behavior for the condensation and the relation between the gap frequency and the mass of quasiparticles when the Gauss-Bonnet coefficient is larger than 9/100, which is the upper bound for the Gauss-Bonnet coefficient from the causality of the dual field theory.

Cai Ronggen; Nie Zhangyu; Zhang Haiqing [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China)

2010-09-15

238

Holographic p-wave superconductors from Gauss-Bonnet gravity  

Microsoft Academic Search

We study the holographic p-wave superconductors in a five-dimensional Gauss-Bonnet gravity with an SU(2) Yang-Mills gauge field. In the probe approximation, we find that when the Gauss-Bonnet coefficient grows, the condensation of the vector field becomes harder, both the perpendicular and parallel components, with respect to the direction of the condensation, of the anisotropic conductivity decrease. We also study the

Rong-Gen Cai; Zhang-Yu Nie; Hai-Qing Zhang

2010-01-01

239

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)

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.

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

2013-12-01

240

First in line or first in time? Effects of settlement order and arrival date on reproduction in a group-living beetle Dendroctonus ponderosae.  

PubMed

1. In group-living organisms, individuals that initiate aggregations, termed pioneers, may suffer higher mortality costs than individuals that join established aggregations. Here we examine the hypothesis that aggregation initiators achieve higher reproductive success in the early phases of colonization, potentially through lower competition and increased access to the resource (finder's advantage), and that this benefit is sufficient to outweigh the costs of pioneering. 2. We also examine the role of arrival date (irrespective of order within the aggregation) on reproductive success, because individuals in seasonal environments may gain an advantage by arriving early. We test these hypotheses using mountain pine beetles, Dendroctonus ponderosae (Coleoptera: Curculionidae, Scolytinae), an obligately aggregating insect wherein pioneers suffer high mortality due to tree defences. We measured reproductive success at the start of winter when most components of final offspring number were likely to be determined. 3. Surviving pioneers that successfully recruited conspecifics had smaller broods than individuals that joined aggregations, refuting our hypothesis. The later that a beetle settled within an aggregation, the higher its reproductive success. However, beetles that settled early in the season produced more offspring than those that settled later in the season, and this effect was generally stronger than settlement order within an aggregation. Our study highlights the importance of examining the effects of both settlement order and arrival date on the costs and benefits of pioneering aggregations. PMID:19292705

Latty, Tanya M; Reid, Mary L

2009-05-01

241

High-frequency P-wave seismic noise driven by ocean winds Jian Zhang,1  

E-print Network

High-frequency P-wave seismic noise driven by ocean winds Jian Zhang,1 Peter Gerstoft,1 and Peter M] Earth's background vibrations at frequencies below about 0.5 Hz have been attributed to ocean-wave of continuous P-waves originating offshore, and (2) the power of the P-wave noise is highly correlated

Shearer, Peter

242

Hydrodynamic Modes of a holographic $p-$ wave superfluid  

E-print Network

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.

Raul E. Arias; Ignacio Salazar Landea

2014-11-04

243

p-Wave Cold Collisions in an Optical Lattice Clock  

SciTech Connect

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.

Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Ludlow, A. D. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Stecher, J. von; Rey, A. M. [JILA, NIST, and University of Colorado, Department of Physics, Boulder, Colorado 80309 (United States)

2011-09-02

244

Hydrodynamic modes of a holographic p-wave superfluid  

NASA Astrophysics Data System (ADS)

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.

Arias, Raúl E.; Landea, Ignacio Salazar

2014-11-01

245

Electron-H P-Wave Elastic Scattering  

NASA Technical Reports Server (NTRS)

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.

Bhatia, A. K.

2004-01-01

246

First high resolution P wave velocity structure beneath Tenerife Island, (Canary Islands, Spain)  

NASA Astrophysics Data System (ADS)

3D velocity structure distribution has been imaged for first time using high resolution traveltime seismic tomography of the active volcano of Tenerife Island (Canary Islands, Spain). It is located in the Atlantic Ocean. In this island is situated the Teide stratovolcano (3718 m high) that is part of the Cañadas-Teide-Pico Viejo volcanic complex. Las Cañadas is a caldera system more than 20 kilometers wide where at least four distinct caldera processes have been identified. Evidence for many explosive eruptions in the volcanic complex has been found; the last noticeable explosive eruption (sub-plinean) occurred at Montaña Blanca around 2000 years ago. During the last 300 years, six effusive eruptions have been reported, the last of which took place at Chinyero Volcano on 18 November 1909. In January 2007, a seismic active experiment was carried out as part of the TOM-TEIDEVS project. About 6850 air gun shots were fired on the sea and recorded on a dense local seismic land network consisting of 150 independent (three component) seismic stations. The good quality of the recorded data allowed identifying P-wave arrivals up to offsets of 30-40 km obtaining more than 63000 traveltimes used in the tomographic inversion. The images have been obtained using ATOM-3D code (Koulakov, 2009). This code uses ray bending algorithms in the ray tracing for the forward modelling and in the inversion step it uses gradient methods. The velocity models show a very heterogeneous upper crust that is usual in similar volcanic environment. The tomographic images points out the no-existence of a magmatic chamber near to the surface and below Pico Teide. The ancient Las Cañadas caldera borders are clearly imaged featuring relatively high seismic velocity. Moreover, we have found a big low velocity anomaly in the northwest dorsal of the island. The last eruption took place in 1909 in this area. Furthermore, in the southeast another low velocity anomaly has been imaged. Several resolution and accuracy tests were carried out to quantify the reliability of the final velocity models. Checkerboard tests show that the well-resolved are located up to 6-8 km depth. Also we carried out synthetic tests in which we successfully reproduce single anomalies observed in the velocity models. Especially we have study carefully the low velocity anomalies found in the NW and SE, which have been recovered successfully. The jack-knife technique have been used and our results are stable if we remove the 50% of the data for different stations, but if we reject all the data for some stations, the velocity models can change. These tests assure the uniqueness of the first 3D velocity model that characterizes the internal structure of the Tenerife Island. As main conclusions of our work we can remark: a) This is the first 3-D velocity image of the area; b) we have observed low velocity anomalies near to surface that could be associated to the presence of magma, water reservoirs and volcanic landslides; c) high velocity anomalies could be related to ancient volcanic episodes or basement structures; d) our results could help to resolve many questions relate to the evolution of the volcanic system, as the presence or not of big landslides, calderic explosions or others; e) this image is a very important tool to improve the knowledge of the volcanic hazard, and therefore volcanic risk. We would like to highlight the importance of take into account the risk of eruption in other areas besides Pico Teide-Las Cañadas system.

Garcia-Yeguas, Araceli; Ivan, Koulakov; Ibañez Jesus, M.; Valenti, Sallarès.

2010-05-01

247

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

SciTech Connect

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.

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

2012-01-10

248

Fracture detection by using full azimuth P wave attributes  

NASA Astrophysics Data System (ADS)

A type of specific fractured hydrocarbon reservoir, a shale fractured reservoir, exists in the Shengli oilfield. Due to very small porosity of this type, low sensitivity to the variation of petrochemical property parameters, and strong anisotropy, it is very difficult to explore for them. So far, there is no set of mature methods for recognition of direction, distribution, and density of the fractures by an integrated analysis of geologic, geophysical, well log, drilling data, and etc. This paper presents a new method for acoustic impedance variation with azimuth (IPVA), based on existing fracture detection methods. Seismic acquisition, processing, and recognition techniques were developed for detecting directional vertical fractures using multi-azimuth P wave data in combination with the seismic and geological features of shale fractures in the Luojia area. The IPVA research is carried out for recognizing the distribution, strike, and density of fractures based on the study of velocity variation with azimuth (VVA) and amplitude variation with azimuth (AVA) for full azimuth P wave data at different CMP positions. Through practical application in the Luojia area, primary results have been obtained which verifies that the IPVA method provides good potential for quantitative detection of parallel, high angle, shale fractures.

Shouli, Qu; Yuxin, Ji; Xin, Wang; Xiuling, Wang; Xinrong, Chen; Guoqiang, Shen

2007-09-01

249

Fermionic Operator Mixing in Holographic p-wave Superfluids  

E-print Network

We use gauge-gravity duality to compute spectral functions of fermionic operators in a strongly-coupled defect field theory in p-wave superfluid states. The field theory is (3+1)-dimensional N=4 supersymmetric SU(Nc) Yang-Mills theory, in the 't Hooft limit and with large coupling, coupled to two massless flavors of (2+1)-dimensional N=4 supersymmetric matter. We show that a sufficiently large chemical potential for a U(1) subgroup of the global SU(2) isospin symmetry triggers a phase transition to a p-wave superfluid state, and in that state we compute spectral functions for the fermionic superpartners of mesons valued in the adjoint of SU(2) isospin. In the spectral functions we see the breaking of rotational symmetry and the emergence of a Fermi surface comprised of isolated points as we cool the system through the superfluid phase transition. The dual gravitational description is two coincident probe D5-branes in AdS5 x S5 with non-trivial worldvolume SU(2) gauge fields. We extract spectral functions from...

Ammon, Martin; Kaminski, Matthias; O'Bannon, Andy

2010-01-01

250

Investigating Consistency in Passenger Arrivals - Insights from Longitudinal Ticket Validations  

Microsoft Academic Search

Waiting for public transport is recognised as being more onerous that travel time itself. Previous research has established that one category of public transport users 'target' their arrival at a time shortly before the service is scheduled. Another group of users arrive randomly, seemingly unaffected by timetable schedules. The time of day plus service characteristics, such as headway and reliability,

Daniel Csikos; Graham Currie

251

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

USGS Publications Warehouse

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.

Mendoza, C.

2000-01-01

252

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

NASA Astrophysics Data System (ADS)

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).

Li, Xiaobo; Dong, Liangguo; Zhao, Qun

2014-12-01

253

New insights on the structure of La Soufriere dome from joint inversion of P-wave velocity and density  

NASA Astrophysics Data System (ADS)

One objective of the french project Domoscan (2009-2013) was to obtain better constraints on the geological structure of La Soufriere hydrothermal system, that is the dome inner structure but also its basement that has not yet been imaged, while it may play an essential role in potential flank destabilization. In this framework, we performed a 3D gravity and P-wave travel time joint inversion to obtain density and P-wave velocity images of La Soufriere hydrothermal system (Coutant et al., 2012). The joint inversion approach was proposed to overcome the lack of resolution of the two methods taken separately. In this study, the coupling between P-wave velocity and density relies on a relationship derived from laboratory measurements on 58 samples from La Soufriere and Mt Pelee deposits. The laboratory data cover a large range of porosity (1-73%) with P wave velocity ranging from 2 to 5.4 km/s and density from 1.5 to 2.8 g/cm3 in water saturated samples. The joint inversion results show that P wave velocity model benefits from density resolution at the volcano summit, while density resolution improves at depth. The improved images allow new insights on La Soufriere structures. As an example the resistive zones that have been so far only seen by electromagnetic surveys may not be due only to argilization but may also be explained by the presence of dense massive zones, that we interpret as andesite spines resulting from 3100 B.P. or 1530 A.D eruptions. These dense bodies may have implication on the stability of the edifice and then the destabilization risks at La Soufriere of Guadeloupe. This work also shows that laboratory studies on physical properties of volcanic rocks and their relationships can be useful in the interpretation of geophysical observations on structurally complex areas such as volcano or geothermal system.

Bernard, Marie-Lise; Coutant, Olivier; Beauducel, Francois

2014-05-01

254

Topological states in normal and superconducting p-wave chains  

NASA Astrophysics Data System (ADS)

We study a two-band model of fermions in a 1d chain with an antisymmetric hybridization that breaks inversion symmetry. We find that for certain values of its parameters, the sp-chain maps formally into a p-wave superconducting chain, the archetypical 1d system exhibiting Majorana fermions. The eigenspectra, including the existence of zero energy modes in the topological phase, agree for both models. The end states too share several similarities, such as the behavior of the localization length, the non-trivial topological index and robustness to disorder. However, we show that the excitations in the ends of a finite sp chain are conventional fermions though endowed with protected topological properties. Our results are obtained by a scattering approach in a semi-infinite chain with an edge defect treated within the T-matrix approximation. We present exact numerical diagonalization results that extend our analysis to arbitrary parameters and to disordered systems.

Continentino, Mucio A.; Caldas, Heron; Nozadze, David; Trivedi, Nandini

2014-10-01

255

P-Wave hyperons in nonperturbative quark dynamics  

SciTech Connect

We carry out an investigation of the P-wave hyperons {Lambda} {Sigma}, and {xi} employing the field correlator method in QCD. This method allows us to derive the effective Hamiltonian (EH) approach successfully applied to the meson and ground-state baryon spectra. The EH is written in the form of the nonrelativistic three-quark Hamiltonian with perturbative Coulomb-like and nonperturbative string interactions and the specific mass term. We solve the three-quark problem using the hyperspherical approach. With only two parameters, the string tension {sigma} and the strong coupling constant {alpha}{sub s}, a unified quantitative description of the ground and excited hyperon states is achieved. In particular, we predict that all the hyperon states have the similar cost (in {Delta}) {approx}460 MeV.

Driga, O. N., E-mail: driga@itep.ru; Narodetskii, I. M., E-mail: naro@itep.ru; Veselov, A. I., E-mail: veselov@itep.ru [Institute for Theoretical and Experimental Physics (Russian Federation)

2008-02-15

256

Determining surface wave arrival angle anomalies  

Microsoft Academic Search

A new method for measuring arrival angles of teleseismic Love and Rayleigh waves is developed. The new method utilizes estimates of surface wave dispersion to create a phase-matched filter to isolate the Love or Rayleigh wave in three-component recordings. The polarization of the filtered wave group is determined in the time domain by application of a variation of the complex

Erik W. F. Larson; Göran Ekström

2002-01-01

257

Monitoring of the ultrasonic P-wave velocity in early-age concrete with embedded piezoelectric transducers  

NASA Astrophysics Data System (ADS)

This note deals with the use of embedded piezoelectric transducers to monitor the ultrasonic P-wave velocity evolution during the setting and hardening phases of concrete subsequent to casting time. The main advantage of the technique is the possibility of overcoming the limitations of traditional methods which prevent the application of specific mechanical boundary conditions during the measurement. The embedded transducers are based on the ‘smart aggregates’ concept previously developed at the University of Houston, Texas. Two piezoelectric transducers are embedded in a prismatic mold and the evolution of the P-wave velocity is recorded for the first 24 h in concrete after the casting time. The results are very promising and show a good agreement with classical ultrasonic tests using external transducers.

Dumoulin, Cédric; Karaiskos, Grigoris; Carette, Jérôme; Staquet, Stéphanie; Deraemaeker, Arnaud

2012-04-01

258

Age-related changes in P wave morphology in healthy subjects  

PubMed Central

Background We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects. Methods 120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies. Results Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed. Conclusion Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided. PMID:17662128

Havmoller, Rasmus; Carlson, Jonas; Holmqvist, Fredrik; Herreros, Alberto; Meurling, Carl J; Olsson, Bertil; Platonov, Pyotr

2007-01-01

259

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

SciTech Connect

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.

Zhang Jianrong; Huang Mingqiu [Department of Physics, National University of Defense Technology, Hunan 410073 (China)

2011-02-01

260

Signal processing and tracking of arrivals in ocean acoustic tomography.  

PubMed

The signal processing for ocean acoustic tomography experiments has been improved to account for the scattering of the individual arrivals. The scattering reduces signal coherence over time, bandwidth, and space. In the typical experiment, scattering is caused by the random internal-wave field and results in pulse spreading (over arrival-time and arrival-angle) and wander. The estimator-correlator is an effective procedure that improves the signal-to-noise ratio of travel-time estimates and also provides an estimate of signal coherence. The estimator-correlator smoothes the arrival pulse at the expense of resolution. After an arrival pulse has been measured, it must be associated with a model arrival, typically a ray arrival. For experiments with thousands of transmissions, this is a tedious task that is error-prone when done manually. An error metric that accounts for peak amplitude as well as travel-time and arrival-angle can be defined. The Viterbi algorithm can then be adapted to the task of automated peak tracking. Repeatable, consistent results are produced that are superior to a manual tracking procedure. The tracking can be adjusted by tuning the error metric in logical, quantifiable manner. PMID:25373953

Dzieciuch, Matthew A

2014-11-01

261

[A P-wave detection method based on multi-feature].  

PubMed

Generally, P-wave is the wave of low-frequency and low-amplitude, and it could be affected by baseline drift, electromyography (EMG) interference and other noises easily. Not every heart beat contains the P-wave, and it is also a major problem to determine the P-wave exist or not in a heart beat. In order to solve the limitation of suiting the diverse morphological P-wave using wavelet-amplitude-transform algorithm and the limitation of selecting the pseudo-P-wave sample using the wavelet transform and neural network, we presented new P-wave detecting method based on wave-amplitude threshold and using the multi-feature as the input of neural networks. Firstly, we removed the noise of ECG through the wavelet transform, then determined the position of the candidate P-wave by calculating modulus maxima of the wavelet transform, and then determine the P-wave exist or not by wave-amplitude threshold method initially. Finally we determined whether the P-wave existed or not by the neural networks. The method is validated based on the QT database which is supplied with manual labels made by physicians. We compared the detection effect of ECG P-waves, which was obtained with the method developed in the study, with the algorithm of wavelet threshold value and the method based on "wavelet-amplitude-slope", and verified the feasibility of the proposed algorithm. The detected ECG signal, which is recorded in the hospital ECG division, was consistent with the doctor's labels. Furthermore, after detecting the 13 sets of ECG which were 15 min long, the detection rate for the correct P-wave is 99.911%. PMID:25039128

Song, Lixin; Guan, Lili; Wang, Qian; Wang, Yuhong

2014-04-01

262

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

PubMed

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

Kahraman, S

2007-11-01

263

P-wave charmed baryons from QCD sum rules  

E-print Network

We study the P-wave charmed baryons using the method of QCD sum rule in the framework of heavy quark effective theory (HQET). We consider systematically all possible baryon currents with a derivative for internal rho- and lambda-mode excitations. We have found good working window for the currents corresponding to the rho-mode excitations for Lambda_c(2595), Lambda_c(2625), Xi_c(2790) and Xi_c(2815) which complete two SU(3) 3F_bar multiplets of J(P)=1/2(-) and 3/2(-), while the currents corresponding to the lambda-mode excitations seem also consistent with the data. Our results also suggest that there are two Sigma_c(2800) states of J(P)=1/2(-) and 3/2(-) whose mass splitting is 14 \\pm 7 MeV, and two Xi_c(2980) states whose mass splitting is 12 \\pm 7 MeV. They have two Omega_c partners of J(P) = 1/2(-) and 3/2(-), whose masses are around 3.25 \\pm 0.20 GeV with mass splitting 10 \\pm 6 MeV. All of them together complete two SU(3) 6F multiplets of J(P)=1/2(-) and 3/2(-). They may also have J(P)=5/2(-) partners. X...

Chen, Hua-Xing; Mao, Qiang; Hosaka, Atsushi; Liu, Xiang; Zhu, Shi-Lin

2015-01-01

264

P -wave charmed baryons from QCD sum rules  

NASA Astrophysics Data System (ADS)

We study the P -wave charmed baryons using the method of QCD sum rule in the framework of heavy quark effective theory. We consider systematically all possible baryon currents with a derivative for internal ? - and ? -mode excitations. We have found a good working window for the currents corresponding to the ? -mode excitations for ?c(2595 ), ?c(2625 ), ?c(2790 ), and ?c(2815 ) that complete two S U (3 ) 3¯F multiplets of JP=1 /2- and 3 /2-, while the currents corresponding to the ? -mode excitations seem also consistent with the data. Our results also suggest that there are two ?c(2800 ) states of JP=1 /2- and 3 /2- whose mass splitting is 14 ±7 MeV , and two ?c(2980 ) states whose mass splitting is 12 ±7 MeV . They have two ?c partners of JP=1 /2- and 3 /2-, whose masses are around 3.25 ±0.20 GeV with mass splitting 10 ±6 MeV . All of them together complete two S U (3 ) 6F multiplets of JP=1 /2- and 3 /2-. They may also have JP=5 /2- partners. ?c(3080 ) may be one of them, and the other two are ?c(5 /2-) and ?c(5 /2-), whose masses are 85 ±23 MeV and 50 ±27 MeV larger.

Chen, Hua-Xing; Chen, Wei; Mao, Qiang; Hosaka, Atsushi; Liu, Xiang; Zhu, Shi-Lin

2015-03-01

265

Magnetic-field effects on $p$-wave phase transition in Gauss-Bonnet gravity  

E-print Network

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.

Ya-Bo Wu; Jun-Wang Lu; Yong-Yi Jin; Jian-Bo Lu; Xue Zhang; Si-Yu Wu; Cui Wang

2014-07-08

266

Magnetic-field effects on p-wave phase transition in Gauss-Bonnet gravity  

NASA Astrophysics Data System (ADS)

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.

Wu, Ya-Bo; Lu, Jun-Wang; Jin, Yong-Yi; Lu, Jian-Bo; Zhang, Xue; Wu, Si-Yu; Wang, Cui

2014-07-01

267

Magnitude determination using initial P waves: A single-station Yih-Min Wu,1  

E-print Network

Magnitude determination using initial P waves: A single-station approach Yih-Min Wu,1 Hsin-Yi Yen,1 the magnitudes of earthquakes and the properties of the first three seconds of the P waves at a single station within 100-km epicentral distance, we found a linear correlation between the magnitudes

Wu, Yih-Min

268

Increases in P-Wave Dispersion Predict Postoperative Atrial Fibrillation After Coronary Artery Bypass Graft Surgery  

Microsoft Academic Search

Atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. In this study we examined the effect of surgery on atrial elec- trophysiology as measured by P-wave characteristics and to determine the potential predictive value of P-wave characteristics on the incidences of postopera- tive AF in patients undergoing CABG surgery. Patients undergoing elective CABG surgery were

Joby Chandy; Toshiko Nakai; Randall J. Lee; Wayne H. Bellows; Samir Dzankic; Jacqueline M. Leung

2004-01-01

269

Eternal inflation with arrival terminals  

NASA Astrophysics Data System (ADS)

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.

Stoltenberg, Henry; Albrecht, Andreas

2015-01-01

270

Upper-mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone revealed by P-wave traveltime tomography  

NASA Astrophysics Data System (ADS)

This study images upper-mantle structure beneath different tectonic and geomorphological provinces in southern Scandinavia by P-wave traveltime tomography based on teleseismic events. We present results using integrated data from several individual projects (CALAS, MAGNUS, SCANLIPS, CENMOVE and Tor) with a total of 202 temporary seismological stations deployed in southern Norway, southern Sweden, Denmark and the northernmost part of Germany. These stations, together with 18 permanent stations, yield a high density data coverage and enable presentation of the first high resolution 3D seismic velocity model for the upper mantle for this region, which includes the entire northern part of the prominent Tornquist Zone and the Southern Scandes Mountains. P-wave arrival time residuals of up to ±1 s are observed indicating large seismic velocity contrasts at depths. Relative regional as well as absolute global tomographic inversion is carried out and consistently show upper-mantle velocity variations relative to the ak135 global reference model of up to ±2-3 per cent corresponding to P-wave velocity differences of 0.4-0.5 km s-1 from depths of about 100 km to more than 300 km. High upper-mantle velocities are observed to great depth to the east in Baltic Shield areas of southwestern Sweden suggesting the existence of a deep lithosphere keel. Lower velocities are found to the west and southwest beneath the Danish and North German sedimentary basins and in most of southern Norway. A well defined, generally narrow and deep boundary is observed between areas of contrasting upper-mantle seismic velocity. In the southern part of the study area, this boundary is localized along and east of the Sorgenfrei-Tornquist Zone. It seems to follow the eastern boundary of a zone of significant Late Carboniferous-Permian volcanic activity from southwestern Sweden to the Oslo Graben area. To the north, it crosses shield units, Caledonides as well as areas of high topography. Supported by independent results of surface wave studies, we interpret this velocity boundary as a first order lithosphere boundary representing the southwestern edge of thick shield lithosphere. In basin areas to the southwest, low upper-mantle velocities are associated with asthenosphere beneath thinned lithosphere and velocity contrasts are likely to arise mainly from temperature differences. To the north structural and geodynamic relations are more complex and both temperature and compositional differences may play a part. Reduced upper-mantle velocity beneath southern Norway also seems, despite relatively low heat flow, to be associated with areas of thinned lithosphere, pointing towards increased temperatures and reduced density in the upper mantle. This feature extends over large areas and seems not directly correlated to the shorter wavelength high topography of the Scandes Mountains, but may contribute with some isostatic buoyancy on a regional scale. For this northern area, there is no obvious geodynamic explanation to reduced upper-mantle velocity. A number of candidates are available including deep transient thermal influence from basin areas to the southwest.

Medhus, A. B.; Balling, N.; Jacobsen, B. H.; Weidle, C.; England, R. W.; Kind, R.; Thybo, H.; Voss, P.

2012-06-01

271

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)

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.

Villemaire, M.; Darbyshire, F. A.; Bastow, I. D.

2012-12-01

272

Increased P-wave dispersion in patients with newly diagnosed lichen planus  

PubMed Central

OBJECTIVE: Lichen planus is a chronic inflammatory autoimmune mucocutaneous disease. Recent research has emphasized the strong association between inflammation and both P-wave dispersion and dyslipidemia. The difference between the maximum and minimum P-wave durations on an electrocardiogram is defined as P-wave dispersion. The prolongation of P-wave dispersion has been demonstrated to be an independent risk factor for developing atrial fibrillation. The aim of this study was to investigate P-wave dispersion in patients with lichen planus. METHODS: Fifty-eight patients with lichen planus and 37 age- and gender-matched healthy controls were included in this study. We obtained electrocardiographic recordings from all participants and used them to calculate the P-wave variables. We also assessed the levels of highly sensitive C-reactive protein, which is an inflammatory marker, and the lipid levels for each group. The results were reported as the means ± standard deviations and percentages. RESULTS: The P-wave dispersion was significantly higher in lichen planus patients than in the control group. Additionally, highly sensitive C-reactive protein, LDL cholesterol, and triglyceride levels were significantly higher in lichen planus patients compared to the controls. There was a significant positive correlation between highly sensitive C-reactive protein and P-wave dispersion (r?=?0.549, p<0.001) in lichen planus patients. CONCLUSIONS: P-wave dispersion increased on the surface electrocardiographic measurements of lichen planus patients. This result may be important in the early detection of subclinical cardiac involvement. Increased P-wave dispersion, in terms of the tendency for atrial fibrillation, should be considered in these patients. PMID:23778479

Sahin, Musa; Bilgili, Serap Gunes; Simsek, Hakki; Akdag, Serkan; Akyol, Aytac; Gumrukcuoglu, Hasan Ali; Yaman, Mehmet; Bayram, Yasemin; Karadag, Ayse Serap

2013-01-01

273

Analysis of individual packet loss in a finite buffer queue with heterogeneous Markov modulated arrival processes: a study of traffic burstiness and priority packet discarding  

Microsoft Academic Search

The authors consider a queuing system with a finite buffer and multiple heterogeneous arrival streams. They focus on Markov modulated arrival processes with different burstings and investigate the loss of individual arrival streams when the parameters of the heterogeneous arrival streams are varied. The analysis includes both continuous-time and discrete-time treatments of multiplexed heterogeneous Markov modulated arrivals. Loss probabilities are

JAIME JUNGOK BAE; TATSUYA SUDA; RAHUL SIMHA

1992-01-01

274

Evidence for back scattering of near-podal seismic P'P' waves from the 150-220 km zone in Earth's upper mantle  

SciTech Connect

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.

Tkalcic, H; Flanagan, M P; Cormier, V F

2005-07-15

275

Deep seafloor arrivals: An unexplained set of arrivals in long-range ocean acoustic propagation  

E-print Network

Deep seafloor arrivals: An unexplained set of arrivals in long-range ocean acoustic propagation to predicted ocean acoustic arrivals and deep shadow zone arrivals leaking below turning points , "deep on the hydrophone array, are observed. These deep seafloor arrivals are an unexplained set of arrivals in ocean

Frandsen, Jannette B.

276

Electric car arrives - again  

SciTech Connect

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.

Dunn, S.

1997-03-01

277

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

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%.

Rucci, A.; Vasco, D.W.; Novali, F.

2010-04-01

278

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)

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.

Jang, Soojeong; Moon, Y.-J.; Lee, Jae-Ok; Na, Hyeonock

2014-09-01

279

High-resolution molecular orbital imaging using a p-wave STM tip.  

PubMed

Individual pentacene and naphthalocyanine molecules adsorbed on a bilayer of NaCl grown on Cu(111) were investigated by means of scanning tunneling microscopy using CO-functionalized tips. The images of the frontier molecular orbitals show an increased lateral resolution compared with those of the bare tip and reflect the modulus squared of the lateral gradient of the wave functions. The contrast is explained by tunneling through the p-wave orbitals of the CO molecule. Comparison with calculations using a Tersoff-Hamann approach, including s- and p-wave tip states, demonstrates the significant contribution of p-wave tip states. PMID:21929180

Gross, Leo; Moll, Nikolaj; Mohn, Fabian; Curioni, Alessandro; Meyer, Gerhard; Hanke, Felix; Persson, Mats

2011-08-19

280

A Powerful Twin Arrives  

NASA Astrophysics Data System (ADS)

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-gu

1999-11-01

281

Scheduling and Separating Departures Crossing Arrival Flows in Shared Airspace  

NASA Technical Reports Server (NTRS)

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.

Chevalley, Eric; Parke, Bonny K.; Lee, Paul; Omar, Faisal; Lee, Hwasoo; Beinert, Nancy; Kraut, Joshua M.; Palmer, Everett

2013-01-01

282

Coexistence and competition of ferromagnetism and p-wave superconductivity in holographic model  

E-print Network

By combining a holographic p-wave superconductor model and a holographic ferromagnetism model, we study the coexistence and competition of ferromagnetism and p-wave superconductivity. It is found that the results depend on the self-interaction of magnetic moment of the complex vector field and which phase appears first. In the case that the ferromagnetic phase appears first, if the interaction is attractive, the system shows the ferromagnetism and superconductivity can coexist in low temperatures. If the interaction is repulsive, the system will only be in a pure ferromagnetic state. In the case that the superconducting phase appears first, the attractive interaction will leads to a magnetic p-wave superconducting phase in low temperatures. If the interaction is repulsive, the system will be in a pure p-wave superconducting phase or ferromagnetic phase when the temperature is lowered.

Rong-Gen Cai; Run-Qiu Yang

2014-11-03

283

Evolution of upper mantle beneath East Asia and the Tibetan Plateau from P-wave tomography  

E-print Network

The main objective of the research presented in this thesis is to improve our understanding for the evolution of the upper mantle beneath East Asia and the Tibetan Plateau through high resolution P-wave tomography. The ...

Li, Chang, Ph.D.

2007-01-01

284

Coexistence and competition of ferromagnetism and p -wave superconductivity in holographic model  

NASA Astrophysics Data System (ADS)

By combining a holographic p -wave superconductor model and a holographic ferromagnetism model, we study the coexistence and competition of ferromagnetism and p -wave superconductivity. It is found that the results depend on the self-interaction of magnetic moment of the complex vector field and which phase appears first. In the case where the ferromagnetic phase appears first, if the interaction is attractive, the system shows the ferromagnetism and superconductivity can coexist at low temperatures. If the interaction is repulsive, the system will only be in a pure ferromagnetic state. In the case where the superconducting phase appears first, the attractive interaction will lead to a magnetic p -wave superconducting phase at low temperatures. If the interaction is repulsive, the system will be in a pure p -wave superconducting phase or a ferromagnetic phase when the temperature is lowered.

Cai, Rong-Gen; Yang, Run-Qiu

2015-01-01

285

Analysis of P-wave seismic response for fracture detection: modelling and case studies   

E-print Network

This thesis addresses a few specific issues in the use of wide azimuth P-wave seismic data for fracture detection based on numerical modelling and real data. These issues include the seismic response of discrete fractures, ...

Xu, Yungui

2012-06-25

286

Crustal thickness estimate at AAE (Addis-Ababa, Ethiopia) and NAI (Nairobi, Kenya) using teleseismic P-wave conversions  

NASA Astrophysics Data System (ADS)

Long-period teleseismic P waves recorded at AAE (Addis Ababa, Ethiopia) and NAI (Nairobi, Kenya) show comparable P s conversions on the radial component of ground motion. The timing and amplitude of the P s conversions are modeled with synthetic seismograms to get an estimate of crustal thickness under both stations. Instrument response and effective source time function are removed from the data using a P-wave equalization procedure. The timing of the P s conversions, relative to direct P, suggests that both stations have similar crustal thickness. Using constraints on crustal velocities determined by previous surface wave dispersion and travel-time studies, the P s-P timing suggests a crust of 41 km thickness. This agrees reasonably well with previous crustal estimates. Tangential wave forms exhibit large amplitudes and are consistent at most backazimuths. However, these wave forms could not be explained with models containing simple planar dipping interfaces. The crustal thickness of 41 km taken in conjunction with the close proximity of the stations to the rift zone suggests that crustal thinning is localized to the rift itself.

Hebert, Louis; Langston, Charles A.

1985-02-01

287

Near-surface seismic attenuation of P-waves in West Texas  

E-print Network

(Member) Robert R. Berg (Member) el S. Watkins (Head of Department) August 1992 ABSTRACT Near-surface Seismic Attenuation of P-Waves in West Texas. (August 1992) Said Awdhah AI-Zahrani, B. S, University of Petroleum and Minerals, Dhahran, Saudi... Arabia Chair of Advisory Committee: Dr. Steven H. Harder Field experiments were conducted near Monahans, Texas, to measure the seismic P-wave attenuation of near-surface sediments. The field measurements consisted of recording two dynamite shots at a...

Al-Zahrani, Said Awdhah

1992-01-01

288

Observation of p-wave threshold behavior in electron attachment to F2 molecules.  

PubMed

Using the high resolution laser photoelectron attachment method, we demonstrate that the cross section for F- formation due to electron capture by F2(X{1}Sigma{g}{+}) molecules at very low energies exhibits p-wave threshold behavior. This finding confirms the theoretical expectation that low-energy attachment to F2 proceeds through the F2{-}(2Sigma{u}{+}) p-wave shape resonance in contrast with previous experimental claims for s-wave threshold behavior. PMID:18233518

Braun, M; Ruf, M-W; Fabrikant, I I; Hotop, H

2007-12-21

289

Observation of p-Wave Threshold Behavior in Electron Attachment to F2 Molecules  

NASA Astrophysics Data System (ADS)

Using the high resolution laser photoelectron attachment method, we demonstrate that the cross section for F- formation due to electron capture by F2(X?g+1) molecules at very low energies exhibits p-wave threshold behavior. This finding confirms the theoretical expectation that low-energy attachment to F2 proceeds through the F2-(?u+2) p-wave shape resonance in contrast with previous experimental claims for s-wave threshold behavior.

Braun, M.; Ruf, M.-W.; Fabrikant, I. I.; Hotop, H.

2007-12-01

290

Spatial variations of P wave attenuation in the mantle beneath North America  

Microsoft Academic Search

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

Yong Keun Hwang; Jeroen Ritsema; Saskia Goes

2009-01-01

291

Collaborative Arrival Planning: Data Sharing and User Preference Tools  

NASA Technical Reports Server (NTRS)

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.

Zelenka, Richard E.; Edwards, Thomas A. (Technical Monitor)

1998-01-01

292

Short-Term Repeatability of Electrocardiographic P Wave Indices and PR Interval  

PubMed Central

Background P wave indices and PR interval from 12-lead electrocardiograms (ECGs) are predictors of cardiovascular morbidity and mortality, but their repeatability has not been examined. Objectives Determine the short-term repeatability of P wave indices (P axis, maximum P area and duration, P dispersion and P terminal force in V1) and PR interval. Methods Participants (n=63) underwent two standard ECGs at each of two visits, two weeks apart. We calculated the intra-class correlation coefficient (ICC), weighted Kappa, and minimal detectable change and difference. Results ICCs were 0.93 for PR interval, 0.78 for P axis, 0.77 for maximum P area, and 0.58 for maximum P duration. Within- and between-visit Kappa were 0.30 and 0.11 for P dispersion, and 0.68 and 0.46 for P terminal force. Conclusion Repeatability of PR duration was excellent, that of P wave axis and maximum area was fair, and maximum P wave duration and terminal force was poor. Repeatability of P wave dispersion was fair within visit, yet poor between visits. These results illustrate potential biases when measurement error of some P wave indices is ignored in clinical and epidemiologic studies. PMID:24360345

Snyder, Michelle L; Soliman, Elsayed Z; Whitsel, Eric A; Gellert, Kapuaola S; Heiss, Gerardo

2014-01-01

293

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

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.

Frenzel, Peter F.; Abeyta, Cynthia G.

1999-01-01

294

P-wave velocity variation in the upper mantle beneath Tibetan Plateau  

NASA Astrophysics Data System (ADS)

We produced a P-wave model of the upper mantle beneath Tibeatan Plateau from a combination of International Seismological Centre (ISC) P and pP data, processed by Engdahl et al. (1998), P data of the Annual Bulletin of Chinese Earthquake (ABCE) [IG-CSB, 1990-1998], and travel times of P phases recorded at temporary arrays around Tibetan Plateau, including arrays operated by (a) MIT and the Chengdu Institute of Geology and Mineral Resources (MIT-CIGMR) - 09/2003-09/2004; (b) Lehigh university and CIGMR - 07/2003-10/2004; (c) the INDEPTH (InterNational DEep Profiling of Tibet and the Himalaya) project - 05/1994-10/1994, 07/1997-06/1999; and (d) various French and Chinese groups - 07/1991-06/1992. Incorporating the travel times of phases recorded at arrays allow us to constrain upper mantle structure with much greater resolution and confidence than before, and the preliminary models reveal intriguing variations in P-wavespeed in the upper mantle beneath Tibetan Plateau. Our images suggest that the Indian lithosphere subducts from the foreland basin and underlies only the southwestern margin of the Tibetan Plateau, implying that much of the Tibetan Plateau is not underlain by Indian but by Asian lithosphere. Some of the seismically slow structures beneath the eastern part of the plateau may connect to structures, and presumably, processes in the upper mantle beneath the South China Sea.

Li, C.; van der Hilst, R.; Chen, Z.; Anne, M.

2005-12-01

295

When Did the First Americans Arrive?  

NSDL National Science Digital Library

Who were the first Americans, when did they arrive, and from where did they come? With limited evidence, scientists have long proposed a hypothesis that linked the migration route and the timing of the migration of these ancient people to the end of the last ice age. This video segment, adapted from a NOVA television broadcast, describes how archaeologists have uncovered new evidence suggesting that the first Americans may have been able to migrate down the coast of North America, rather than waiting for an ice-free corridor to develop, implying that migration could have occurred earlier than previously thought. The segment is five minutes forty seconds in length.

296

Spatial and Temporal Variations in t s \\/t p and in P Wave Residuals at Blue Mountain Lake, New York: Application to Earthquake Prediction  

Microsoft Academic Search

Renewed earthquake activity at Blue Mountain Lake (BML), New York, in July 1973 provided an excellent opportunity to monitor the travel time ratio of $ to P waves (ts\\/t,) in real time and to test the ts\\/t, technique as a predictive tool. From a mean value of 1.73 on July 30, 1973, ts\\/t, decreased to about 1.5 over the next

Yash P. Aggarwal; Lynn R. Sykes; David W. Simpson; Paul G. Richards

1975-01-01

297

Upper mantle P wave velocity structure of the eastern Snake River Plain and its relationship to geodynamic models of the region  

Microsoft Academic Search

Tomographic inversions of ~5( teleseismic P wave travel time residuals image a narrow, deep, low-velocity region centered beneath the eastern Snake River Plain, Idaho. Aligned in the direction of North American plate motion, the eastern Snake River Plain is the locus of time-progressive volcanism leading to the Yellowstone hotspot. The low-velocity ano- maly extends to depths of at least 200

Rebecca L. Saltzer; Eugene D. Humphreys

1997-01-01

298

A P wave-based, on-site method for earthquake early warning  

NASA Astrophysics Data System (ADS)

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.

Colombelli, S.; Caruso, A.; Zollo, A.; Festa, G.; Kanamori, H.

2015-03-01

299

Inversion of Source Parameters for Moderate Earthquakes Using Short-Period Teleseismic P Waves  

NASA Astrophysics Data System (ADS)

In this paper, we introduce a new method for estimating the source parameters of moderate earthquakes ( M w ~5.0) by modeling short-period teleseismic waveforms. This method uses a grid-search algorithm to minimize misfits between observed data and synthetic seismograms in depth, magnitude, and mechanism domain in a relative high-frequency range of 0.8-2.0 Hz, similar to the traditional cut-and-paste method used in regional modeling ( Zhu and Helmberger, Bull Sesimol Soc Am 86:1634-1641, 1996). In this frequency range, a significant challenge is determining the initial P-wave polarity because of a low signal-to-noise ratio (SNR). Therefore we first determine source properties for a master earthquake with a relative strong SNR. Both the travel time and amplitude corrections are developed relative to the reference 1D model along each path used in inverting the master event. We then applied these corrections to other earthquakes clustered in the same area to constrain the initial P polarities. Thus the focal mechanisms can be determined reasonably well. We inverted focal mechanisms for a small set of events beneath Qeshm Island in southern Iran and demonstrate the importance of radiation pattern at short periods.

Chu, Risheng; Ni, Sidao; Pitarka, Arben; Helmberger, Don V.

2014-07-01

300

Fluorescence Assay for Polymerase Arrival Rates  

E-print Network

To engineer complex synthetic biological systems will require modular design, assembly, and characterization strategies. The RNA polymerase arrival rate (PAR) is defined to be the rate that RNA polymerases arrive at a ...

Che, Austin

2003-08-31

301

Fluorescence assay for polymerase arrival rates  

E-print Network

To engineer complex synthetic biological systems will require modular design, assembly, and characterization strategies. The RNA polymerase arrival rate (PAR) is defined to be the rate that RNA polymerases arrive at a ...

Che, Austin, 1979-

2004-01-01

302

What Do s- and p-Wave Neutron Average Radiative Widths Reveal  

SciTech Connect

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.

Mughabghab, S.F.

2010-04-30

303

Saskatoon | Saskatchewan | Canada Pre-Arrival  

E-print Network

Saskatoon | Saskatchewan | Canada Pre-Arrival Guidefor International Students Studious Ingenious to the University of Saskatchewan (U of S). We are very pleased that you have chosen our university as your place Outstanding Documentation | 21 University of Saskatchewan Pre-Arrival Guide 1 #12;BeforeYouArrive Apply

Peak, Derek

304

How do I collect my key on arrival at Lister House? Keys are collected directly from Lister House office, but please read the separate `arrival  

E-print Network

How do I collect my key on arrival at Lister House? Keys are collected directly from Lister House time and do need to know your date and time of arrival in advance. How close is the Lister House to the University? Lister House is approx 20/25 mins walk to the main campus, a 40 mins walk to St Andrew's Building

Glasgow, University of

305

P-wave-enhanced spin field effect transistor and recent patents.  

PubMed

P-wave-enhanced spin field-effect transistor made of AlGaN/GaN heterostructure was designed for the spintronic devices operated at high power and high temperature. The operation theory is based on the spin-polarized field-effect transistor designed by Datta and Das [Appl. Phys. Lett. 56, 665 (1990)]. The mechanism of the p-wave enhancement in AlGaN/GaN heterostructure was investigated. The recent development and related patents in the spin-polarized field-effect transistor were reviewed. In particular, we will focus on the recent patents which could enhance p-wave probability and control of spin precession of 2DEG in the AlGaN/GaN transistor structure. PMID:19076030

Gau, Ming-Hong; Lo, Ikai; Wang, Wan-Tsang; Chiang, Jih-Chen; Chou, Mitch Ming-Chi

2007-01-01

306

Vanishing edge currents in non-p -wave topological chiral superconductors  

NASA Astrophysics Data System (ADS)

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. 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.

Huang, Wen; Taylor, Edward; Kallin, Catherine

2014-12-01

307

P wave changes in body surface potential maps due to increasing heart rate during exercise in normals.  

PubMed

Exercise-induced changes in P maps were investigated in normal subjects (n = 20) in order to clarify the basic changes in P maps caused by exercise in patients with ischemic heart disease or by exercise-induced dysfunction of the left ventricle in patients with various heart diseases. Maps were obtained using an 87 lead-point system (HPM-6500, Chunichi-Denshi Corporation) and were recorded at rest and at heart rates up to 140/min in 20/min steps under graded bicycle ergometric exercise. P waves were divided into 3 phases (initial, middle and terminal) by locating the maximum. Maps were characterized by the distribution pattern of the positive and negative potentials in each frame. Peak voltages increased proportionally to the increase in heart rate. We observed a decrease in P wave duration concomitant with the increase in heart rate. Time from P onset to peak voltage increased slightly. We believe these findings to be due to the acceleration of sympathetic nerve tone accompanying exercise. We observed 2 patterns: type A showed the relatively short middle and terminal phases, and type B a prolongation of the middle phase and a shortening of the terminal phase. We consider the differences between types A and B to be partly due to individual differences in the degree of increase in pulmonary air volume and sympathetic nerve tone influence on the atria. In evaluating the exercise-induced P map changes, special consideration should be paid to the changes due to increase in heart rate. PMID:3385916

Watanabe, Y; Kohgame, Y; Nakano, H; Abo, Y; Mizuno, Y

1988-04-01

308

Detection of azimuthal anisotropy from 3-D p-wave seismic data  

E-print Network

DETECTION OF AZIMUTHAL ANISOTROPV FROM 3-D P-WAVE SEISMIC DATA A Thesis by ALI YILDIZEL Submitted to the Office of Graduate Studies of Texas AkM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May... 1992 Major Subject: Geophysics DETECTION OF AZIMUTHAL ANISOTROPY FROM 3-D P-WAVE SEISMIC DATA A Thesis by ALI YILDIZEL Approved as to style and content by: Steve I . Iarder (Chair of Committee) Joel S. Watkins (Member) Robert R. Berg...

Yildizel, Ali

1992-01-01

309

Destruction of p-wave weakly bound molecules in a gas of spin-polarized fermions  

NASA Astrophysics Data System (ADS)

We have studied collisional aspects which might affect the lifetime of p-wave molecules created in ultracold spin-polarized fermi gases near a Feshbach resonance [1]. Atom-molecule inelastic collisions might be the main process in which the collision products can be released from typical traps. Our study allows us describe the dependence of the collision rates on the p-wave scattering length, which is crucial for understanding the stability of such molecules in the strongly interacting regime. [1] H. Suno, B. D. Esry, and C. H. Greene, Phys. Rev. Lett. 90, 053202 (2003). This work was supported in part by the National Science Foundation.

D'Incao, Jose P.; Greene, Chris H.

2007-03-01

310

Rupture imaging of the Mw 7.9 12 May 2008 Wenchuan earthquake from back projection of teleseismic P waves  

NASA Astrophysics Data System (ADS)

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.

Xu, Yan; Koper, Keith D.; Sufri, Oner; Zhu, Lupei; Hutko, Alexander R.

2009-04-01

311

At the beginning of April 1911 Albert Einstein arrived in Prague to become full professor of theoretical physics at the German part of Charles University. It was there, for the first time, that  

E-print Network

At the beginning of April 1911 Albert Einstein arrived in Prague to become full professor anticipated what a future theory of gravity should look like. At the occasion of the Einstein and sightseeing (e.g., places associated with Einstein, Mach, Doppler, Kepler, and Brahe). We are considering

Cerveny, Vlastislav

312

Magnitude estimation using the first three seconds P-wave amplitude in earthquake early warning  

E-print Network

Magnitude estimation using the first three seconds P-wave amplitude in earthquake early warning Yih as a function of magnitude M, and obtained the following relationship: log (Pd) = Ã?3.463 + 0.729 Ã? M Ã? 1.374 Ã? to the epicenter, this relationship can be used to define a so-called ``Pd magnitude'' of earthquakes. Our result

Wu, Yih-Min

313

Upper mantle Q and thermal structure beneath Tanzania, East Africa from teleseismic P wave spectra  

E-print Network

Upper mantle Q and thermal structure beneath Tanzania, East Africa from teleseismic P wave spectra-focus earthquakes recorded at broadband seismic stations of the Tanzania network to estimate regional variation of sublithospheric mantle attenuation beneath the Tanzania craton and the eastern branch of the East African Rift

Ritsema, Jeroen

314

High-precision earthquake location and three-dimensional P wave velocity determination at Redoubt Volcano, Alaska  

Microsoft Academic Search

Redoubt Volcano, Alaska poses significant volcanic hazard to the Cook Inlet region and overlying flight paths. During and following the most recent eruption in 1989–1990 the Alaska Volcano Observatory deployed up to 10 seismometers to improve real-time monitoring capabilities at Redoubt and continues to produce an annual earthquake catalog with associated arrival times for this volcano. We compute a three-dimensional

Heather R. DeShon; Clifford H. Thurber; Charlotte Rowe

2007-01-01

315

Anisotropic changes in P-wave velocity and attenuation during deformation and fluid infiltration of granite  

USGS Publications Warehouse

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.

Stanchits, S.A.; Lockner, D.A.; Ponomarev, A.V.

2003-01-01

316

Estimation of Atterberg limits and bulk mass density of an expansive soil from P-wave velocity measurements  

Microsoft Academic Search

This brief technical note reports the relationship between P-wave velocity and the Atterberg limits and bulk mass density\\u000a of an expansive soil from the Derince region of Turkey. Reasonably good correlations were found, which were improved when\\u000a the relationship was between P-wave velocity divided by water content.

Cengiz Kurtulus; Fadime Sertcelik; M. Mucella Canbay; ?brahim Sertcelik

2010-01-01

317

Designing Cyclic Appointment Schedules for Outpatient Clinics with Scheduled and Unscheduled Patient Arrivals  

E-print Network

of Twente, Postbox 217, 7500 AE Enschede, the Netherlands 2Center for Healthcare Operations Improvement arrivals on the day and one for the access process of scheduled arrivals. Appointment schedules that balance the waiting time at the facility for unscheduled patients and the access time for scheduled

Boucherie, Richard J.

318

Design Considerations for a New Terminal Area Arrival Scheduler  

NASA Technical Reports Server (NTRS)

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.

Thipphavong, Jane; Mulfinger, Daniel

2010-01-01

319

On effects of arrival rate and burstiness in the queueing system: Analysis of Lb \\/ D \\/1  

Microsoft Academic Search

This paper studies a single-server queueing system with deterministic service time in which arrivals are regulated by the leaky-bucket mechanism. This paper intends to improve quantitative understanding of the effects of arrival rate and burstiness on the average delay of queueing systems. The study is directed toward identifying the worst traffic of arrivals allowed by the leaky-bucket regulation and clarifying

Daniel Chonghwan Lee

1996-01-01

320

Prolonged Signal-Averaged P-wave Duration as an Intermediate Phenotype for Familial Atrial Fibrillation  

PubMed Central

OBJECTIVES To perform a genome-wide linkage analysis in a large atrial fibrillation (AF) kindred using AF and abnormally prolonged signal-averaged (SA) P-wave duration as the phenotype. BACKGROUND While inherited forms of AF exist, phenotypic complexity has limited efforts to ascertain mutation carriers and thus identify causal genes. The identification of intermediate or endophenotypes may accelerate this effort. METHODS A genome-wide linkage analysis was performed in a 4-generation AF kindred of 27 individuals, 8 with AF documented by ECG. The analysis was performed using AF as the phenotype, and repeated using an abnormally prolonged SA P-wave duration as the phenotype. RESULTS Linkage analysis and fine mapping generated a maximum multipoint logarithm of the odds (LOD) score of 3.0 at chromosome 5p15 between markers D5S406 and D5S635. Importantly, eight heterozygous carriers had a prolonged SA P-wave (203±21 msec) compared with 17 non-carriers (116±12 msec, P<0.00001). Using prolonged SA P-wave (conventionally defined as >155 msec) as an endophenotype, a maximum LOD score of 3.6 was obtained in the same region of chromosome 5p15, a span of 5.75 cM. CONCLUSIONS In a large AF kindred, we have identified a novel AF locus on chromosome 5p15 and demonstrated that affected individuals with AF and mutation carriers can be identified by a prolonged SA P-wave duration. Importantly, identification of an endophenotype in this kindred not only aided ascertainment of additional family members but also increased the LOD score providing increased support for linkage at this locus. Identification of the causal gene, mapped to chromosome 5p15, will advance our understanding of the molecular basis of AF. Condensed Abstract While inherited forms of atrial fibrillation (AF) exist, phenotypic complexity has limited efforts to ascertain mutation carriers and identify causal genes. In a large AF kindred, we have identified a new AF locus on chromosome 5p15 and demonstrated that that affected individuals with AF and mutation carriers can be identified by a prolonged signal-averaged (SA) P-wave duration. Identification of an intermediate or endophenotype not only aided ascertainment of additional family members but also increased the LOD score and will accelerate identification of the causal gene in this kindred. PMID:18342226

Darbar, Dawood; Hardy, Amanda; Haines, Jonathan L; Roden, Dan M

2008-01-01

321

Evaluation of QT and P Wave Dispersion and Mean Platelet Volume among Inflammatory Bowel Disease Patients  

PubMed Central

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

DOGAN, Yuksel; SOYLU, Aliye; EREN, Gulay A.; POTUROGLU, Sule; DOLAPCIOGLU, Can; SONMEZ, Kenan; DUMAN, Habibe; SEVINDIR, Isa

2011-01-01

322

Anchorage Arrival Scheduling Under Off-Nominal Weather Conditions  

NASA Technical Reports Server (NTRS)

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.

Grabbe, Shon; Chan, William N.; Mukherjee, Avijit

2012-01-01

323

P-wave resonant state of the He4? hypernucleus in the 4He (K- ,?-) reaction  

NASA Astrophysics Data System (ADS)

We theoretically investigate a possible existence of a p-wave He4? resonant state with J? =1-, T ? 1 / 2 above the ? threshold, using a coupled (3 N- ?) + (3 N- ?) model with a spreading potential. We calculate inclusive and ?-? conversion ?- spectra in a 4He (K- ,?-) reaction at 1.5 GeV/c, ?lab = 4- 12 ° by the Green's function method in a distorted-wave impulse approximation. The pole position for the p-wave ? resonant state in He4? is determined on the Riemann sheets in the complex E plane. The result shows that a peak of the He4? resonant state is clearly obtained in the conversion spectra above the ? threshold, and that the angular distributions of these spectra enable extraction of the contribution of the resonant state from the ?- spectra. Effects of the ?-nucleus potential and the interference between ? and ? on the spectra are also discussed.

Harada, Toru; Hirabayashi, Yoshiharu

2015-01-01

324

Zero field Hall effect in chiral p-wave superconductors near the Kosterlitz-Thouless transition  

NASA Astrophysics Data System (ADS)

A theory of vortex dynamics developed by Ambegaokar, Halperin, Nelson, and Siggia is employed to study two-dimensional chiral p-wave superconducting systems. Due to unequal values of drag coefficients of opposite vorticity specific to chiral p-wave cases, we find that a ``convective'' term, in addition to diffusivity, should enter the dynamical equations governing vortex pair unbinding process. As a consequence, we find a matrix form dielectric function and a new contribution to Hall conductance ?xy automatically follows even in zero magnetic field. We predict both the Hall conductance and power dissipation show a peak across the Kosterlitz-Thouless transition temperature. Their frequency dependence is also discussed. It is found that a set of frequency-dependent length scales, which controls the truncation of renormalization process, depends on both the convective and diffusive motion of vortices.

Kit Chung, Chun; Kato, Yusuke

2013-03-01

325

Electron-He(+) P-wave Elastic Scattering and Photoabsorption in Two-electron Systems  

NASA Technical Reports Server (NTRS)

In a previous paper [Bhatia, Phys. Rev. A 69,032714 (2004)], electron-hydrogen P-wave scattering phase shifts were calculated using the optical potential approach based on the Feshbach projection operator formalism. This method is now extended to the singlet and triplet electron-He(+) 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 the method of polarized orbitals and close-coupling calculations. The continuum functions calculated here are used to calculate photoabsorption cross sections. Photoionization cross sections of He and photodetachment cross sections of H(-) are calculated in the elastic region, i.e. leaving He(+) and H in their respective ground states, and compared with previous calculations. Radiative attachment rates are also calculated.

Bhatia, A. K.

2006-01-01

326

Modeling and Interpretation of Localized P-wave and S-wave Reflectivity in D  

Microsoft Academic Search

Detailed P-wave and S-wave velocity structures for the lowermost mantle beneath the central and eastern Pacific obtained by broadband waveform stacking and modeling procedures indicate distinctive characteristics of low- and high-velocity regions in the deep mantle. The central Pacific region is located within the tomographically-resolved large low shear velocity province (LLSVP) beneath the Pacific that is variously interpreted as a

T. Lay; A. R. Hutko; E. J. Garnero; M. S. Thorne

2008-01-01

327

P-wave shape changes observed in the surface electrocardiogram of subjects with obstructive sleep apnoea  

Microsoft Academic Search

Automated detection of sleep apnoea from the surface ECG is a challenge with potentially significant clinical benefit. The objective of this study is to explore a possible relation between P-wave shape changes and the presence of Obstructive Sleep Apnoea (OSA) episodes in ECG records. Our working hypothesis is that apnoea-related phenomena (e.g., hypoxia, changes in intra-thoracic pressure) influence the depolarisation

S. Boudaoud; C. Heneghan; H. Rix; O. Meste; C. O'Brien

2005-01-01

328

Spectral modulation effect in teleseismic P-waves from DPRK nuclear tests recorded at different azimuths  

NASA Astrophysics Data System (ADS)

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.

Gitterman, Yefim; Kim, So Gu; Hofstetter, Abraham

2014-05-01

329

Three-dimensional P wave azimuthal anisotropy in the lithosphere beneath China  

NASA Astrophysics Data System (ADS)

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.

Huang, Zhouchuan; Wang, Pan; Zhao, Dapeng; Wang, Liangshu; Xu, Mingjie

2014-07-01

330

STS-114: Discovery Crew Arrival  

NASA Technical Reports Server (NTRS)

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.

2005-01-01

331

Illuminating the near-sonic rupture velocities of the intracontinental Kokoxili Mw 7.8 and Denali fault Mw 7.9 strike-slip earthquakes with global P wave back projection imaging  

Microsoft Academic Search

The Denali and Kokoxili strike-slip earthquakes are two of the longest recent intracontinental ruptures. Previous studies report a range of rupture velocities. Here we image these earthquakes by reverse time migration of the intermediate-frequency P wave train recorded by global broadband seismometers. This technique permits a relatively direct measure of rupture velocity (speed and direction) as constrained by the radiated

Kristoffer T. Walker; Peter M. Shearer

2009-01-01

332

Finite difference modelling to evaluate seismic P wave and shear wave field data  

NASA Astrophysics Data System (ADS)

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.

Burschil, T.; Beilecke, T.; Krawczyk, C. M.

2014-08-01

333

Finite-difference modelling to evaluate seismic P-wave and shear-wave field data  

NASA Astrophysics Data System (ADS)

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.

Burschil, T.; Beilecke, T.; Krawczyk, C. M.

2015-01-01

334

Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals  

NASA Technical Reports Server (NTRS)

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.

Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

2008-01-01

335

Iterative direction-of-arrival estimation with wideband chirp signals  

NASA Astrophysics Data System (ADS)

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.

Wang, Genyuan; Xia, Xiang-Gen; Chen, Victor C.

1999-11-01

336

8 CFR 232.3 - Arriving aliens.  

Code of Federal Regulations, 2012 CFR

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...

2012-01-01

337

8 CFR 232.3 - Arriving aliens.  

Code of Federal Regulations, 2010 CFR

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...

2010-01-01

338

8 CFR 232.3 - Arriving aliens.  

Code of Federal Regulations, 2011 CFR

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...

2011-01-01

339

8 CFR 232.3 - Arriving aliens.  

Code of Federal Regulations, 2014 CFR

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...

2014-01-01

340

8 CFR 232.3 - Arriving aliens.  

Code of Federal Regulations, 2013 CFR

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...

2013-01-01

341

Improvement to Airport Throughput Using Intelligent Arrival Scheduling and an Expanded Planning Horizon  

NASA Technical Reports Server (NTRS)

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.

Glaab, Patricia C.

2012-01-01

342

Does Pet Arrival Trigger Prosocial Behaviors in Individuals with Autism?  

PubMed Central

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

Grandgeorge, Marine; Tordjman, Sylvie; Lazartigues, Alain; Lemonnier, Eric; Deleau, Michel; Hausberger, Martine

2012-01-01

343

Decays, contact P-wave interactions and hyperfine structure in Omega- exotic atoms  

E-print Network

Contact $P$-wave interactions connected to the Larmor interaction of a magnetic dipole and Thomas spin precession in the filed of an electric quadrupole are described and their implications for spectroscopy of exotic $\\Omega^{-}$-atoms are studied. In order to evaluate the magnitude of the contact $P$-wave interactions as compared to the conventional long-range interactions and the sensitivity of spectroscopic data to the $\\Omega^{-}$-hyperon quadrupole moment, we consider $2P$ states of $\\Omega ^{-}$ atoms formed with light stable nuclei with spins $I \\geq 1/2$ and atomic numbers $Z \\leq 10$. The energy level splitting caused by the contact interactions is 2-5 orders of magnitude smaller than the conventional long-range interactions. Strong decay widths of $p\\Omega ^{-}$ atoms due to reactions $p\\Omega^{-} \\to \\Lambda \\Xi^{0}$ and $p\\Omega^{-} \\to \\Sigma \\Xi$, induced by $t$-channel kaon exchanges, are calculated. $\\Omega ^{-}$ atoms formed with the light nuclei have strong widths 5-6 orders of magnitude higher than splitting caused by the contact interactions. The low-$L$ pattern in the energy spectra of intermediate- and high-$Z$ $\\Omega ^{-}$ atoms thus cannot be observed. The $\\Omega ^{-}$ quadrupole moment can be measured by observing $X$-rays from circular transitions between high-$L$ levels in $\\Omega^{-}$ exotic atoms. The effect of strong interactions in $^{208}$Pb$\\Omega ^{-}$ atoms is negligible starting from $L \\sim 10$. The contact $P$-wave interactions exist in ordinary atoms and $\\mu$-meson atoms.

M. I. Krivoruchenko; Amand Faessler

2008-04-05

344

8 CFR 251.1 - Arrival manifests and lists.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Arrival manifests and lists. 251.1 Section 251.1 Aliens...REGULATIONS ARRIVAL AND DEPARTURE MANIFESTS AND LISTS: SUPPORTING DOCUMENTS § 251.1 Arrival manifests and lists. (a) Vessels —(1)...

2010-01-01

345

P-wave pentaquark and its decay in the quark model with instanton induced interaction  

SciTech Connect

P-wave pentaquarks with strangeness +1, I=0, and J{sup P}=1/2{sup +} are studied in the nonrelativistic quark model with instanton induced interaction (III). We present their mass splittings and orbital-spin-isospin-color structures. It is found that decompositions of the wave functions are sensitive to III, while the mass splittings are insensitive. The decay of the lowest energy pentaquark, {theta}{sup +}, is found to be suppressed when the contribution of III is increased. Spin structure of the dominant components of the wave function is studied.

Shinozaki, Tetsuya; Oka, Makoto [Department of Physics, H-27, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose 204-8555 (Japan)

2006-09-01

346

Effective field theory for a p -wave superconductor in the subgap regime  

NASA Astrophysics Data System (ADS)

We construct an effective field theory for the 2 d spinless p -wave paired superconductor that faithfully describes the topological properties of the bulk state, and also provides a model for the subgap states at vortex cores and edges. In particular, it captures the topologically protected zero modes and has the correct ground-state degeneracy on the torus. We also show that our effective field theory becomes a topological field theory in a well defined scaling limit and that the vortices have the expected non-Abelian braiding statistics.

Hansson, T. H.; Kvorning, T.; Nair, V. P.; Sreejith, G. J.

2015-02-01

347

Comparison of P-wave and S-wave data in a fractured reservoir  

E-print Network

-Cambrian Lhno Uplift The San Marcos Arch created a relatively shallow-marine carbonate ramp where water depths gradually increased to the southeast, south and southwest. The Upper Cretaceous Austin Chalk is Coniacian (88. 5-86. 6 Mya) to Santonian (86. 6... in the Sacramento Valley in California The Putah Sink field produces gas in the Upper Cretaceous Winter formation. The P-wave and SH-wave seismic data collected fiom tbe 14 xegion displayed good reflecdon continuity and xesolution. The two sections were...

Al-Mustafa, Husam Mustafa

1993-01-01

348

High-resolution 3-D P-wave tomographic imaging of the shallow magmatic system of Erebus volcano, Antarctica  

NASA Astrophysics Data System (ADS)

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.

Zandomeneghi, D.; Aster, R. C.; Barclay, A. H.; Chaput, J. A.; Kyle, P. R.

2011-12-01

349

Analysis of sequencing and scheduling methods for arrival traffic  

NASA Technical Reports Server (NTRS)

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.

Neuman, Frank; Erzberger, Heinz

1990-01-01

350

p-wave Holographic Superconductors from Born-Infeld Black Holes  

E-print Network

We obtain (2+1) dimensional p-wave holographic superconductors from charged Born-Infeld black holes in the presence of massive charged vector fields in a bulk $AdS_4$ Einstein-Born-Infeld theory through the $AdS_4$-$CFT_3$ correspondence. Below a certain critical transition temperature the charged black hole develops vector hair that corresponds to charged vector condensate in the strongly coupled (2+1) dimensional boundary field theory that breaks both the $U(1)$ symmetry as well as the rotational invariance. The holographic free energy is computed for the boundary field theory which shows that the vector order parameter exhibits a rich phase structure involving zeroth order, first order, second order and retrograde phase transitions for different values of the backreaction and the Born-Infeld parameters. We numerically compute the ac conductivity for the p-wave superconducting phase of the strongly coupled (2+1) dimensional boundary field theory which also depends on the relative values of the parameters in the theory.

Pankaj Chaturvedi; Gautam Sengupta

2015-01-28

351

p-wave Holographic Superconductors from Born-Infeld Black Holes  

E-print Network

We obtain (2+1) dimensional p-wave holographic superconductors from charged Born-Infeld black holes in the presence of massive charged vector fields in a bulk $AdS_4$ Einstein-Born-Infeld theory through the $AdS_4$-$CFT_3$ correspondence. Below a certain critical transition temperature the charged black hole develops vector hair that corresponds to charged vector condensate in the strongly coupled (2+1) dimensional boundary field theory that breaks both the $U(1)$ symmetry as well as the rotational invariance. The holographic free energy is computed for the boundary field theory which shows that the vector order parameter exhibits a rich phase structure involving zeroth order, first order, second order and retrograde phase transitions for different values of the backreaction and the Born-Infeld parameters. We numerically compute the ac conductivity for the p-wave superconducting phase of the strongly coupled (2+1) dimensional boundary field theory which also depends on the relative values of the parameters in...

Chaturvedi, Pankaj

2015-01-01

352

P-Wave to Rayleigh-wave conversion coefficients for wedge corners; model experiments  

USGS Publications Warehouse

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.

Gangi, A.F.; Wesson, R.L.

1978-01-01

353

P-wave Velocity, Density, and Vertical Stress Magnitude Along the Crustal Po Plain (Northern Italy) from Sonic Log Drilling Data  

NASA Astrophysics Data System (ADS)

In order to characterize better P-wave velocities for the shallow crust of the Po Plain and surrounding regions, we have selected 64 deep wells mainly located in the plain and also along the Apennine belt and Adriatic coast. In particular, we have analyzed the stratigraphic profiles for all wells, and the available sonic logs (37 out of 64). From these data we have examined the P-wave velocity trend with depth and estimated rock density following an empirical relationship between sonic velocity and density in sedimentary rocks. Then we have calculated, notably, for the first time in a large area of Italy, the overburden stress magnitude for each well. For instance, at a depth of 5 km we have found values varying from 105 to 130 MPa moving from the Adriatic coast to the Apennine belt. Consequently, the Apennine belt shows a maximum regional lithostatic gradient of around 26 MPa/km while the Po Plain and Adriatic region have values of around 21 MPa/km. The maximum density value that can be considered for the Apennine crustal belt corresponds to 2.65 g/cm3; in the Po Plain the mean density is around 2.25 g/cm3, while in the Adriatic area the average density has the lowest value in the region at 2.13 g/cm3. Although in this area a 2D crustal P-wave velocity model does not adequately constrain the complicated and uneven tectonics, we have nevertheless established a shallow model consisting of five separate layers. The strength of this paper lies in the possible use of these direct data, together with other derived geological and geophysical information, to build a 3D model of the area.

Montone, Paola; Mariucci, Maria Teresa

2015-01-01

354

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)

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.

Bhatia, A. K.

2012-01-01

355

NASA's SOFIA Arrives in Christchurch, New Zealand, July 14, 2013 - Duration: 1:41.  

NASA Video Gallery

NASA's Stratospheric Observatory for Infrared Astronomy airborne observatory arrived at Christchurch International Airport, New Zealand, July 14 at 12:14 p.m. (New Zealand Standard Time) to investi...

356

Controlling arrival for the machine repair problem with switching failure  

NASA Astrophysics Data System (ADS)

This study investigates the warm-standby machine repair problem which involves a controlling arrival policy and switching failure probability. It involves operating machines with S warm standbys and one single server. The failure times and repair times are assumed to follow an exponential distribution. For such system, some system performance measures are derived and a steady-state expected cost function per unit time is developed. By using Quasi-Newton method followed direct search method, we can find the joint optimal parameter values at maximum profit such that the availability constraint is satisfied.

Chang, Fu-Min; Ke, Jau-Chuan; Liou, Cheng-Hwai

2013-02-01

357

[Getting qi and arrival of qi].  

PubMed

In order to clarify the inter-relationship between getting qi and arrival of qi, the relevant theory in the Inner Canon of Yellow Emperor is re-considered, and then the relationship of the two concepts by combining with some opinions from scholars is compared and analyzed. Getting qi is the signal of acupuncture at an acupoint; also it is a sign of arrival of qi at an acupoint; what's more, it is the premise for reinforcing or reducing manipulation. The sensation of arrival of qi comes from both doctors and patients, characterized with explicit symptoms including "tight and swift", "sunken, sticky and tight", "light, loose and slow", "warm at the acupoint" or "cold at the acupoint" as well as implicit symptom including "qi moving along the meridians"; also there is the condition of qi regulation that is characterized with "paced and harmony" stomach qi. The arrival of qi could be divided into "qi moving to the needles" and "qi traveling to the diseases". The "qi moving to the needles" has similar meaning to getting qi. The "qi traveling to the diseases" is reflected as "qi arrival with efficacy" and characterized as an immediate effect or a delayed effect. There are differences between the concepts of getting qi and arrival of qi. Getting qi focuses on the importance of the doctor during acupuncture processes (differentiate the nature of qi, guard qi, manipulate qi), which also suggests the clinical significance of implicit getting qi. "Arrival of qi" emphasizes "qi arrival with efficacy", and indicates that during treatment the differences of the exterior or interior and deficit or surplus should be distinguished. For external and shallow diseases involving myofascia-related diseases, miu needling and shallow needling can achieve an immediate treatment effect; for deep, internal and deficient diseases, reinforcing or reducing manipulation should be used to achieve stomach qi, which has delayed effects but can be used as an indicator. It is believed that pulse diagnosis shall not be neglected in clinical treatment of acupuncture. PMID:25335272

Liu, Nong-Yu

2014-08-01

358

STS-93 Mission Specialist Coleman arrives at SLF for launch.  

NASA Technical Reports Server (NTRS)

STS-93 Mission Specialist Catherine G. 'Cady' Coleman (Ph.D.) smiles upon her arrival at KSC's Shuttle Landing Facility aboard a T-38 jet aircraft. She and other crew members Commander Eileen Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Steven A. Hawley (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES), are arriving for pre-launch activities. Coleman is making her second Shuttle flight. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected to unlock the secrets of supernovae, quasars and black holes.

1999-01-01

359

STS-93 Mission Specialist Coleman arrives at SLF for launch  

NASA Technical Reports Server (NTRS)

STS-93 Mission Specialist Catherine G. 'Cady' Coleman (Ph.D.) shows her sense of humor upon arriving at KSC's Shuttle Landing Facility aboard a T-38 jet aircraft. She and other crew members Commander Eileen Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Steven A. Hawley (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES), are arriving for pre-launch activities. Coleman is making her second Shuttle flight. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected to unlock the secrets of supernovae, quasars and black holes.

1999-01-01

360

Crustal structure of North Dakota from joint inversion of surface wave dispersion and teleseismic P-wave reciever functions  

NASA Astrophysics Data System (ADS)

Studying and determining crustal structure of the Earth is important for understanding the interior of the Earth. Using methods like receiver functions and surface wave dispersion allows the determination of differences in structure and composition through the crust. Jointly inverting receiver functions and surface wave dispersion reduces the error and over-interpretation of the crustal structure estimation. Receiver functions and surface wave dispersion invert well together because receiver functions are very sensitive to velocity contrasts and vertical travel times, and surface wave dispersion is sensitive to average velocity and insensitive to sharp velocity contrasts. By jointly inverting receiver functions and surface wave dispersion, shear wave velocity profiles can be created to determine the properties of the crustal structure and velocity contrasts. With the use of IRIS Transportable Array stations data throughout the United States, this thesis takes a closer look at the crustal structure of North Dakota through the joint inversion of surface wave dispersion and teleseismic P-wave receiver functions. The receiver functions in North Dakota show shallow sediment effects that affect the joint inversion process. In western North Dakota the Williston basin and in eastern North Dakota the Red River Valley cause ringing effects in the receiver functions. The shallow sediments in North Dakota control and overpower the rest of the crustal signal in the receiver functions, and thus affect the ability of determining the crustal shear wave velocity structure of North Dakota through the joint inversion of receiver functions and surface wave dispersion, thus the use of background geology is necessary.

Walsh, Braden Michael

361

Crustal P-wave velocity structure from Altyn Tagh to Longmen mountains along the Taiwan-Altay geoscience transect  

USGS Publications Warehouse

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.

Wang, Y.-X.; Mooney, W.D.; Han, G.-H.; Yuan, X.-C.; Jiang, M.

2005-01-01

362

Energy Harvesting Communications with Continuous Energy Arrivals  

E-print Network

Energy Harvesting Communications with Continuous Energy Arrivals Burak Varan Kaya Tutuncuoglu Aylin--This work considers an energy harvesting transmit- ter that gathers a continuous flow of energy from intermittent sources, thus relaxing the modeling assumption of discrete amounts of harvested energy present

Yener, Aylin

363

Dawn Arrives by Dr. Carle Pieters  

E-print Network

Dawn Arrives by Dr. Carle Pieters There once was a chosen mission named Dawn, That launched beyond Earth...and on and on.... Where less is more And o'er and o'er Its ion-propulsion thrust Dawn like a song. Success depends on the best flight team, And Dawn was blest with the darn right team: Through

364

Before you arrive... Drylands, Deserts & Desertification 2012  

E-print Network

1 Before you arrive... Drylands, Deserts & Desertification 2012 November 12-15, 2012 Sede Boqer that you can use to layer. Sde Boqer is part of the Negev desert, and will be cool in the mornings, warm on spending the weekend in any of the conference venues, please make sure to order food in advance, as almost

Prigozhin, Leonid

365

Before you arrive Complete your offer  

E-print Network

to open a UK bank account so bring enough money (£ Sterling) to cover your initial expenses. Your on our free airport pick-up service. Clothing When you arrive in the UK it could feel quite cool so make documents you will need. Register with the Health Centre and a dentist Register with the police If your

Evans, Paul

366

Wake Turbulence Mitigation for Arrivals (WTMA)  

NASA Technical Reports Server (NTRS)

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.

Williams, Daniel M.; Lohr, Gary W.; Trujillo, Anna C.

2008-01-01

367

Arrival Date: Departure Date: First Last (Gender)  

E-print Network

Arrival Date: Departure Date: Name First Last (Gender) Address Telephone City/Town Postal Code rates do NOT include applicable taxes and fees (5% GST, 4% tourism Levy and 2 % Destination Marketing Town Home - 2 rooms with double beds, 2 rooms with single beds. Living area, kitchen, TV, microwave

Kadiri, Habiba

368

Arriving Now At Gate 42: Measles  

MedlinePLUS

... please enable JavaScript. Arriving Now at Gate 42: Measles CDC report of transmission in U.S. air terminal ... Thursday, December 18, 2014 Related MedlinePlus Pages Immunization Measles Traveler's Health THURSDAY, Dec. 18, 2014 (HealthDay News) -- ...

369

While at Paranal Arrival at Reception (Logistics)  

E-print Network

While at Paranal Arrival at Reception (Logistics) Meals General Health Recommendations Safety member and most of their belongings are stored in the closets and/or room. Logistics can provide youLockers in the Control Building and base camp as well as a safe in the Logistics office are available to store your

Liske, Jochen

370

New Accessions Arriving at Field Records  

USGS Multimedia Gallery

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...

371

Superconducting Coherence Length and Magnetic Penetration Depth of a p-wave Holographic Superconductor  

E-print Network

A classical SU(2) Einstein-Yang-Mills theory in 3+1 dimensional anti-de Sitter spacetime is believed to be dual to a p-wave superconductor in 2+1 dimensional flat spacetime. In order to calculate the superconductiong coherence length $\\xi$ of the holographic superconductor near the superconducting phase transition point, we study the perturbation of the gravity theory analytically. The superconductiong coherence length $\\xi$ is found to be proportional to $(1-T/T_c)^{-1/2}$ near the critical temperature $T_c$. We also obtain the magnetic penetration depth $\\lambda\\propto(T_c-T)^{1/2}$ by adding a small external homogeneous magnetic field. The results agree with the Ginzburg-Landau theory.

Hua-Bi Zeng; Zhe-Yong Fan; Hong-Shi Zong

2010-04-16

372

Prediction of Building Limestone Physical and Mechanical Properties by Means of Ultrasonic P-Wave Velocity  

PubMed Central

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

Concu, Giovanna; De Nicolo, Barbara; Valdes, Monica

2014-01-01

373

AdS-plane wave and p p -wave solutions of generic gravity theories  

NASA Astrophysics Data System (ADS)

We construct the anti-de Sitter-plane wave solutions of generic gravity theory built on the arbitrary powers of the Riemann tensor and its derivatives in analogy with the p p -wave solutions. In constructing the wave solutions of the generic theory, we show that the most general two-tensor built from the Riemann tensor and its derivatives can be written in terms of the traceless Ricci tensor. Quadratic gravity theory plays a major role; therefore, we revisit the wave solutions in this theory. As examples of our general formalism, we work out the six-dimensional conformal gravity and its nonconformal deformation as well as the tricritical gravity, the Lanczos-Lovelock theory, and string-generated cubic curvature theory.

Gürses, Metin; ?i?man, Tahsin ?a?r?; Tekin, Bayram

2014-12-01

374

Three-body bound states in atomic mixtures with resonant p-wave interaction.  

PubMed

We employ the Born-Oppenheimer approximation to find the effective potential in a three-body system consisting of a light particle and two heavy ones when the heavy-light short-range interaction potential has a resonance corresponding to a nonzero orbital angular momentum. In the case of an exact resonance in the p-wave scattering amplitude, the effective potential is attractive and long range; namely, it decreases as the third power of the interatomic distance. Moreover, we show that the range and power of the potential, as well as the number of bound states, are determined by the mass ratio of the particles and the parameters of the heavy-light short-range potential. PMID:24074084

Efremov, Maxim A; Plimak, Lev; Ivanov, Misha Yu; Schleich, Wolfgang P

2013-09-13

375

Doubly excited P-wave resonance states of H{sup ?} in Debye plasmas  

SciTech Connect

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.

Jiao, L. G.; Ho, Y. K. [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan (China)] [Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan (China)

2013-08-15

376

Holographic phase transitions of p-wave superconductors in Gauss-Bonnet gravity with backreaction  

SciTech Connect

We investigate the phase transitions of holographic p-wave superconductors in (4+1)-dimensional Einstein-Yang-Mills-Gauss-Bonnet theories, in a grand canonical ensemble. Turning on the backreaction of the Yang-Mills field, it is found that the condensations of vector order parameter become harder if the Gauss-Bonnet coefficient grows up or the backreaction becomes stronger. In particular, the vector order parameter exhibits the features of first order and second order phase transitions, while only the second order phase transition is observed in the probe limit. We discuss the roles that the Gauss-Bonnet term and the backreaction play in changing the order of phase transition.

Cai Ronggen; Nie Zhangyu; Zhang Haiqing [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China)

2011-03-15

377

Leading-twist light cone distribution amplitudes for p-wave heavy quarkonium states  

E-print Network

In this paper, a study of light-cone distribution amplitudes for p-wave heavy quarkonium states are presented. Within the light-front framework, the leading twist light-cone distribution amplitudes, and their relevant decay constants, have some simple relations. These relations can be further simplified when the non-relativistic limit and the wave function as a function of relative momentum |\\vec\\kappa| are taken into consideration. In addition, the \\kappa_\\perp integrations in the equations of LCDAs and \\xi-moments can be completed analytically when the Gaussian-type wave function is considered. After fixing the parameters that appear in the wave function, the curves and the corresponding decay constants of the LCDAs are plotted and calculated for the charmonium and bottomonium states. The first three \\xi-moments of the LCDAs are estimated and are consistent with those of other theoretical approaches.

Chien-Wen Hwang

2009-10-26

378

Prediction of building limestone physical and mechanical properties by means of ultrasonic P-wave velocity.  

PubMed

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 r(2) 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

Concu, Giovanna; De Nicolo, Barbara; Valdes, Monica

2014-01-01

379

P-wave and QT dispersion in patients with conversion disorder  

PubMed Central

Objective The aim of this study was to investigate QT dispersion (QTd), which is the noninvasive marker of ventricular arrhythmia and sudden cardiac death, and P-wave dispersion, which is the noninvasive marker of atrial arrhythmia, in patients with conversion disorder (CD). Patients and methods A total of 60 patients with no known organic disease who were admitted to outpatient emergency clinic and were diagnosed with CD after psychiatric consultation were included in this study along with 60 healthy control subjects. Beck Anxiety Inventory and Beck Depression Scale were administered to patients and 12-lead electrocardiogram measurements were obtained. Pd and QTd were calculated by a single blinded cardiologist. Results There was no statistically significant difference in terms of age, sex, education level, socioeconomic status, weight, height, and body mass index between CD patients and controls. Beck Anxiety Inventory scores (25.2±10.8 and 3.8±3.2, respectively, P<0.001) and Beck Depression Scale scores (11.24±6.15 and 6.58±5.69, respectively, P<0.01) were significantly higher in CD patients. P-wave dispersion measurements did not show any significant differences between conversion patients and control group (46±5.7 vs 44±5.5, respectively, P=0.156). Regarding QTc and QTd, there was a statistically significant increase in all intervals in conversion patients (416±10 vs 398±12, P<0.001, and 47±4.8 vs 20±6.1, P<0.001, respectively). Conclusion A similar relation to that in literature between QTd and anxiety and somatoform disorders was also observed in CD patients. QTc and QTd were significantly increased compared to the control group in patients with CD. These results suggest a possibility of increased risk of ventricular arrhythmia resulting from QTd in CD patients. Larger samples are needed to evaluate the clinical course and prognosis in terms of arrhythmia risk in CD patients.

Izci, Filiz; Hocagil, Hilal; Izci, Servet; Izci, Vedat; Koc, Merve Iris; Acar, Rezzan Deniz

2015-01-01

380

Does the arrival index predict physiological stress reactivity in children.  

PubMed

Knowledge about children's stress reactivity and its correlates is mostly based on one stress task, making it hard to assess the generalizability of the results. The development of an additional stress paradigm for children, that also limits stress exposure and test time, could greatly advance this field of research. Research in adults may provide a starting point for the development of such an additional stress paradigm, as changes in salivary cortisol and alpha-amylase (sAA) over a 1-h pre-stress period in the laboratory correlated strongly with subsequent reactivity to stress task (Balodis et?al., 2010, Psychoneuroendocrinology 35:1363-73). The present study examined whether such strong correlations could be replicated in 9- to 11-year-old children. Cortisol and sAA samples were collected from 158 children (83 girls) during a 2.5-h visit to the laboratory. This visit included a 1-h pre-stress period in which children performed some non-stressful tasks and relaxed before taking part in a psychosocial stress task (TSST-C). A higher cortisol arrival index was significantly and weakly correlated with a higher AUCg but unrelated to cortisol reactivity to the stressor. A higher sAA arrival index was significantly and moderately related to lower stress reactivity and to a lower AUCi. Children's personality and emotion regulation variables were unrelated to the cortisol and sAA arrival indices. The results of this study do not provide a basis for the development of an additional stress paradigm for children. Further replications in children and adults are needed to clarify the potential meaning of an arrival index. PMID:24930802

de Veld, Danielle M J; Riksen-Walraven, J Marianne; de Weerth, Carolina

2014-09-01

381

Zero-Field Vortex-Induced Hall Effect and Polar Kerr Effect in Chiral p-Wave Superconductors near Kosterlitz-Thouless Transition  

NASA Astrophysics Data System (ADS)

In this work, we investigate polar Kerr effect and Ohmic conductivity induced by vortex dynamics in a chiral p-wave superconducting thin film near Kosterlitz-Thouless (KT) transition without explicitly applying magnetic field. Due to the broken time reversal symmetry in the superconducting state and the breaking of Galilean invariance by forces originated from impurities, a conductivity tensor with nonzero off-diagonal element is expected. We generalize the dynamical theory developed by Ambegaokar, Halperin, Nelson, and Siggia to obtain a matrix dielectric function describing vortex screening, which is further related to the conductivity tensor. Polar Kerr effect due to the nonzero Hall conductivity is studied. The corresponding Kerr angle is shown to be proportional to the imaginary part of off-diagonal component of the dielectric function in certain parameter regime. While the frequency and temperature dependence of dissipation in chiral p-wave context behave similarly to those of s-wave results, the Kerr angle exhibits some novel features near the KT transition. As a result, Kerr angle measurement in experiment can provide a probe of vortex dynamics described in this work.

Chung, C. K.; Kato, Y.

2014-04-01

382

Improvement of epicenter estimation in real-time by using single-station data  

NASA Astrophysics Data System (ADS)

1. Introduction The single-station method (on-site method), by which epicenter location and magnitude are estimated from single-station data, is now in use for the present Earthquake Early Warning systems of both Japan Meteorological Agency and Shinkansen (bullet train). In this method, epicenter location is estimated from combination of the following two kinds of algorithms. The one is the Principle Component Analysis (Meteorological Research Institute, 1985) by which the back-azimuth is determined by the 1st principle component of the particle motion for initial P-wave, and the other is the B-Delta method (Odaka et al., 2003) by which the epicentral distance (Delta) is determined by a coefficient B of a fitting function Bt*exp (-At) applied to initial P-wave envelope. Instead of the B-Delta method, Yamamoto et al. (2010) proposed another method, which uses a simple function C*t. It is called the C-Delta method. It is obvious that the coefficients B and C represent increasing rate of amplitude of initial P-wave. In this study, we propose new techniques to improve the estimation accuracy of back-azimuth and epicentral distance in the single-station method. 2. Improvement in accuracy of back-azimuth estimation In the conventional method, the back-azimuth is estimated by using fixed-length time window. However, by analyzing K-NET dataset, it is found that P-wave data cut by the window are often contaminated by trailing scattered waves, which cause increase of estimation errors. In order to use purer direct P-wave, we propose a variable time window method for calculation of back-azimuth. In this study, the variable time window is defined by the first half cycle of wavelength of initial P-wave. In the practical real-time analysis, its window length is determined as the elapsed time after P-wave arrival to the first zero-cross point of band-pass displacement. Consequently, the lengths of time window vary according to the characteristics of the initial P-wave. By analyzing the K-NET dataset, it is demonstrated that the estimation accuracy by the new method is improved approximately 28% compared with the one by the conventional method. 3. Improvement in accuracy of epicentral distance estimation In the conventional method, the relationship between the coefficient B or C and Delta is expressed by an equation taking only geometrical attenuation of seismic waves into account. However, since the coefficients B and C are highly correlated with the amplitude, it is more appropriate to take not only geometrical attenuation but also viscous attenuation into account, in the same way as general attenuation relations of amplitude. In this study, a new relation equation is determined by taking both geometrical and viscous attenuation into account, and then estimation accuracy by the new equation is evaluated by using the K-NET dataset. Consequently, the estimation accuracy by the new equation is improved approximately 8% compared with the one by the conventional equation. This improvement is more remarkable especially in the data recorded at stations whose epicentral distance exceeds approximately 100km, because the effect of viscous attenuation is increased physically with the increase of epicentral distance.

Noda, S.; Yamamoto, S.; Sato, S.; Iwata, N.; Korenaga, M.; Ashiya, K.; Ito, Y.

2011-12-01

383

Natural selection for earlier male arrival to breeding grounds through direct and indirect effects in a migratory songbird  

PubMed Central

For migratory birds, the earlier arrival of males to breeding grounds is often expected to have fitness benefits. However, the selection differential on male arrival time has rarely been decomposed into the direct effect of male arrival and potential indirect effects through female traits. We measured the directional selection differential on male arrival time in the pied flycatcher (Ficedula hypoleuca) using data from 6 years and annual number of fledglings as the fitness proxy. Using structural equation modeling, we were able to take into account the temporal structure of the breeding cycle and the hierarchy between the examined traits. We found directional selection differentials for earlier male arrival date and earlier female laying date, as well as strong selection differential for larger clutch size. These selection differentials were due to direct selection only as indirect selection for these traits was nonsignificant. When decomposing the direct selection for earlier male arrival into direct and indirect effects, we discovered that it was almost exclusively due to the direct effect of male arrival date on fitness and not due to its indirect effects via female traits. In other words, we showed for the first time that there is a direct effect of male arrival date on fitness while accounting for those effects that are mediated by effects of the social partner. Our study thus indicates that natural selection directly favored earlier male arrival in this flycatcher population.

Velmala, William; Helle, Samuli; Ahola, Markus P; Klaassen, Marcel; Lehikoinen, Esa; Rainio, Kalle; Sirkiä, Päivi M; Laaksonen, Toni

2015-01-01

384

Natural selection for earlier male arrival to breeding grounds through direct and indirect effects in a migratory songbird.  

PubMed

For migratory birds, the earlier arrival of males to breeding grounds is often expected to have fitness benefits. However, the selection differential on male arrival time has rarely been decomposed into the direct effect of male arrival and potential indirect effects through female traits. We measured the directional selection differential on male arrival time in the pied flycatcher (Ficedula hypoleuca) using data from 6 years and annual number of fledglings as the fitness proxy. Using structural equation modeling, we were able to take into account the temporal structure of the breeding cycle and the hierarchy between the examined traits. We found directional selection differentials for earlier male arrival date and earlier female laying date, as well as strong selection differential for larger clutch size. These selection differentials were due to direct selection only as indirect selection for these traits was nonsignificant. When decomposing the direct selection for earlier male arrival into direct and indirect effects, we discovered that it was almost exclusively due to the direct effect of male arrival date on fitness and not due to its indirect effects via female traits. In other words, we showed for the first time that there is a direct effect of male arrival date on fitness while accounting for those effects that are mediated by effects of the social partner. Our study thus indicates that natural selection directly favored earlier male arrival in this flycatcher population. PMID:25859326

Velmala, William; Helle, Samuli; Ahola, Markus P; Klaassen, Marcel; Lehikoinen, Esa; Rainio, Kalle; Sirkiä, Päivi M; Laaksonen, Toni

2015-03-01

385

Ultrasonic P-wave and S-wave attenuation in partially frozen porous material saturated with brine  

NASA Astrophysics Data System (ADS)

Ultrasonic wave transmission measurements were conducted in order to examine the influence of ice-brine coexisting system grown in porous material on ultrasonic P- and S-waves. We observed the variations of a transmitted wave with a frequency content of 150-1000 kHz through a liquid system to a solid-liquid coexistence system, changing its temperature from 20°C to -15°C. We quantitatively estimated attenuation for porous materials with two different porosities (37.3 and 48.2 %) during the freezing of salty water in porous material by considering different distances between the source and receiver transducers. This paper is concerned with attenuation at ultrasonic frequencies of 500-1000 kHz for P-waves and 100-400 kHz for S-waves. The waveform analyses indicate that the attenuation curves reach their peak at a temperature of -3°C and gradually decrease with decreasing temperature. We found a positive correlation between the attenuation of ultrasonic waves and the existence of unfrozen brine estimated by the pulsed nuclear magnetic resonance (NMR) technique. Thus, the laboratory experiments of the present study demonstrated that ultrasonic waves with such a frequency range are significantly affected by the existence of a solid-liquid coexistence system in the porous material. In terms of a plausible mechanism for attenuation, we must consider the physical interactions between pore fluid and ice, that is, the pore microstructure and permeability in such system is important. Furthermore, We demonstrate a method that derives a more accurate measurement of ultrasonic attenuation by using sweep-type signals than by using impulse-type signals. We obtained spectral amplitude of the sweep signal in frequency-time domain using the continuous wavelet transform (CWT) and estimated attenuation in the time-frequency domain using the spectral-ratio method. The advantage of this method is independent on the effect of windowing. Finally we demonstrated the possibility of sweep signal to estimate attenuation.

Matsushima, J.; Suzuki, M.; Kato, Y.; Rokugawa, S.

2010-12-01

386

Spring arrival response to climate change in birds: a case study from eastern Europe  

Microsoft Academic Search

This paper analyses the dependence of the first spring arrival dates of short\\/medium- and long-distance migrant bird species\\u000a on climate warming in eastern Europe. The timing of arrival of the selected species at the observation site correlates with\\u000a the North Atlantic Oscillation (NAO) index, air temperature, atmospheric pressure, precipitation and wind characteristics.\\u000a A positive correlation of fluctuations in winter and

Mecislovas Zalakevicius; Galina Bartkeviciene; Liutauras Raudonikis; Justinas Janulaitis

2006-01-01

387

Optimal Integration of Departure and Arrivals in Terminal Airspace  

NASA Technical Reports Server (NTRS)

Coordination of operations with spatially and temporally shared resources such as route segments, fixes, and runways improves the efficiency of terminal airspace management. Problems in this category include scheduling and routing, thus they are normally difficult to solve compared with pure scheduling problems. In order to reduce the computational time, a fast time algorithm formulation using a non-dominated sorting genetic algorithm (NSGA) was introduced in this work and applied to a test case based on existing literature. The experiment showed that new method can solve the whole problem in fast time instead of solving sub-problems sequentially with a window technique. The results showed a 60% or 406 second delay reduction was achieved by sharing departure fixes (more details on the comparison with MILP results will be presented in the final paper). Furthermore, the NSGA algorithm was applied to a problem in LAX terminal airspace, where interactions between 28% of LAX arrivals and 10% of LAX departures are resolved by spatial segregation, which may introduce unnecessary delays. In this work, spatial segregation, temporal segregation, and hybrid segregation were formulated using the new algorithm. Results showed that spatial and temporal segregation approaches achieved similar delay. Hybrid segregation introduced much less delay than the other two approaches. For a total of 9 interacting departures and arrivals, delay reduction varied from 4 minutes to 6.4 minutes corresponding flight time uncertainty from 0 to 60 seconds. Considering the amount of flights that could be affected, total annual savings with hybrid segregation would be significant.

Xue, Min; Zelinski, Shannon Jean

2012-01-01

388

Modeling and Interpretation of Localized P-wave and S-wave Reflectivity in D"  

NASA Astrophysics Data System (ADS)

Detailed P-wave and S-wave velocity structures for the lowermost mantle beneath the central and eastern Pacific obtained by broadband waveform stacking and modeling procedures indicate distinctive characteristics of low- and high-velocity regions in the deep mantle. The central Pacific region is located within the tomographically-resolved large low shear velocity province (LLSVP) beneath the Pacific that is variously interpreted as a relatively hot 'superplume' or large, dense chemically distinct 'pile'. The localized seismic reflectivity in this region includes rapidly varying depth of a simultaneous P-wave and S-wave velocity increase (D" discontinuity), evidence for a paired S-wave velocity decrease within the D" layer, and a thin ultra-low velocity zone (ULVZ) for both P- and S-waves right above the core-mantle boundary (CMB). The eastern Pacific region is located within the circum-Pacific band of high shear velocity that is variously interpreted as a relatively cold 'slab graveyard' and/or region with post- perovskite being present. The localized reflectivity in this region includes anti-correlated bulk-sound velocity and S-wave velocity contrasts at the D" discontinuity, small P- and S-wave velocity increases and changes in velocity gradient within the D" layer, and an S-wave velocity decrease in the lowermost 50-75 km of the mantle that may be paired with the D" discontinuity, but no resolvable ULVZ. The feature identified as the D" discontinuity has been attributed to the post-perovskite phase transition occurring in both regions, with regional differences in bulk chemistry and thermal structure being invoked to account for the observations. We consider whether predicted effects of Fe and Al variations on the perovskite-to-post-perovskite transition elasticity can be reconciled with the distinct P- and S-wave reflectivity structure in each region, including the D" discontinuity, the paired discontinuities that may involve reverse transformations back to perovskite, and the presence/absence of ULVZ.

Lay, T.; Hutko, A. R.; Garnero, E. J.; Thorne, M. S.

2008-12-01

389

Climate and the complexity of migratory phenology: sexes, migratory distance, and arrival distributions  

NASA Astrophysics Data System (ADS)

The intra- and inter-season complexity of bird migration has received limited attention in climatic change research. Our phenological analysis of 22 species collected in Chicago, USA, (1979 2002) evaluates the relationship between multi-scalar climate variables and differences (1) in arrival timing between sexes, (2) in arrival distributions among species, and (3) between spring and fall migration. The early migratory period for earliest arriving species (i.e., short-distance migrants) and earliest arriving individuals of a species (i.e., males) most frequently correlate with climate variables. Compared to long-distance migrant species, four times as many short-distance migrants correlate with spring temperature, while 8 of 11 (73%) of long-distance migrant species’ arrival is correlated with the North Atlantic Oscillation (NAO). While migratory phenology has been correlated with NAO in Europe, we believe that this is the first documentation of a significant association in North America. Geographically proximate conditions apparently influence migratory timing for short-distance migrants while continental-scale climate (e.g., NAO) seemingly influences the phenology of Neotropical migrants. The preponderance of climate correlations is with the early migratory period, not the median of arrival, suggesting that early spring conditions constrain the onset or rate of migration for some species. The seasonal arrival distribution provides considerable information about migratory passage beyond what is apparent from statistical analyses of phenology. A relationship between climate and fall phenology is not detected at this location. Analysis of the within-season complexity of migration, including multiple metrics of arrival, is essential to detect species’ responses to changing climate as well as evaluate the underlying biological mechanisms.

Macmynowski, Dena P.; Root, Terry L.

2007-05-01

390

Analysis of the Arrival Directions of Ultrahigh Energy Cosmic Rays  

E-print Network

The arrival directions of ultrahigh energy extensive air showers (EAS) by Yakutsk, AGASA and SUGAR array data are considered. For the first time, the maps of equal exposition of celestial sphere for the distribution of particles by AGASA and SUGAR array data have been constructed. The large-scale anisotropy of E>4.10^19 eV cosmic rays from the side of Input and Output of the Galaxy Local Arm by Yakutsk, AGASA and SUGAR array data has been detected. The problem of cosmic ray origin is discussed.

A. A. Mikhailov

2007-05-17

391

Determining Direction of Arrival at a Y-Shaped Antenna Array  

NASA Technical Reports Server (NTRS)

An algorithm computes the direction of arrival (both azimuth and elevation angles) of a lightning-induced electromagnetic signal from differences among the times of arrival of the signal at four antennas in a Y-shaped array on the ground. In the original intended application of the algorithm, the baselines of the array are about 90 m long and the array is part of a lightning-detection-and-ranging (LDAR) system. The algorithm and its underlying equations can also be used to compute directions of arrival of impulsive phenomena other than lightning on arrays of sensors other than radio antennas: for example, of an acoustic pulse arriving at an array of microphones.

Starr, Stan

2003-01-01

392

Higher Fock states and power counting in exclusive P-wave quarkonium decays  

E-print Network

Exclusive processes at large momentum transfer Q factor into perturbatively calculable short-distance parts and long-distance hadronic wave functions. Usually, only contributions from the leading Fock states have to be included to leading order in 1/Q. We show that for exclusive decays of P-wave quarkonia the contribution from the next-higher Fock state |Q Qbar g> contributes at the same order in 1/Q. We investigate how the constituent gluon attaches to the hard process in order to form colour-singlet final-state hadrons and argue that a single additional long-distance factor is sufficient to parametrize the size of its contribution. Incorporating transverse degrees of freedom and Sudakov factors, our results are perturbatively stable in the sense that soft phase-space contributions are largely suppressed. Explicit calculations yield good agreement with data on chi_{c J} decays into pairs of pions, kaons, and etas. We also comment on J/psi decays into two pions.

Jan Bolz; Peter Kroll; Gerhard A. Schuler

1997-04-22

393

Hybrid Theory of P-Wave Electron-Hydrogen Elastic Scattering  

NASA Technical Reports Server (NTRS)

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.

Bhatia, Anand

2012-01-01

394

Automated Conflict Resolution, Arrival Management and Weather Avoidance for ATM  

NASA Technical Reports Server (NTRS)

The paper describes a unified solution to three types of separation assurance problems that occur in en-route airspace: separation conflicts, arrival sequencing, and weather-cell avoidance. Algorithms for solving these problems play a key role in the design of future air traffic management systems such as NextGen. Because these problems can arise simultaneously in any combination, it is necessary to develop integrated algorithms for solving them. A unified and comprehensive solution to these problems provides the foundation for a future air traffic management system that requires a high level of automation in separation assurance. The paper describes the three algorithms developed for solving each problem and then shows how they are used sequentially to solve any combination of these problems. The first algorithm resolves loss-of-separation conflicts and is an evolution of an algorithm described in an earlier paper. The new version generates multiple resolutions for each conflict and then selects the one giving the least delay. Two new algorithms, one for sequencing and merging of arrival traffic, referred to as the Arrival Manager, and the other for weather-cell avoidance are the major focus of the paper. Because these three problems constitute a substantial fraction of the workload of en-route controllers, integrated algorithms to solve them is a basic requirement for automated separation assurance. The paper also reviews the Advanced Airspace Concept, a proposed design for a ground-based system that postulates redundant systems for separation assurance in order to achieve both high levels of safety and airspace capacity. It is proposed that automated separation assurance be introduced operationally in several steps, each step reducing controller workload further while increasing airspace capacity. A fast time simulation was used to determine performance statistics of the algorithm at up to 3 times current traffic levels.

Erzberger, H.; Lauderdale, Todd A.; Chu, Yung-Cheng

2010-01-01

395

Direction of Arrival Estimation of Wide-Band Emitters  

NASA Astrophysics Data System (ADS)

Most published algorithms for DOA (Direction of Arrival) estimation of incoming signals by spatially dispersed electromagnetic or acoustic sources rely on the narrow -band approximation. This approach is inadequate from at least two standpoints. First, the approximation breaks down in many practical situation of interest; and, second, it inhibits the exploitation of intrinsic degrees of freedom of wide-band emitters to achieve additional improvements in angular resolution. In this dissertation the direction of arrival estimation problem is examined without employing the customary narrow-band restriction. A class of algorithms that has been successfully employed for DOA estimation of narrow-band signals exploits the eigenstructure of the array correlation matrix. Although they are sub-optimum, these algorithms enjoy substantial computational advantages over the optimum maximum likelihood approaches. It is shown that the frequency domain representation of the array output leads to a spectral coherence matrix that exhibits an eigenstructure similar to the correlation matrix used under the narrow-band approximation. As a consequence, narrow-band eigenbased algorithms can be adopted to DOA estimation without restrictions on signal bandwidth. The Spectral Coherence Technique (SCT) is applied in conjunction with the MUSIC, the Root-Music and a modified form of the Pisarenko algorithms to DOA estimation of wide -band emitters using linear arrays. Simulation indicate that all three algorithms afford comparable performance: the variance of the angle of arrival estimate decreases approximately inversely with the signal time bandwidth product. They differ, however, with regard to computational efficiency. In particular, the wide-band version of the algorithm MUSIC requires substantially more processing time than either the Pisarenko or the Root-Music algorithms. These algorithms also yield comparable performance to an alternative approach using frequency segmentation (WiDE), which has a computational efficiency comparable to MUSIC.

Hojati, Shahram

396

Automated Measurement of P- and S-Wave Differential Times for Imaging Spatial Distributions of Vp/Vs Ratio, with Moving-Window Cross-Correlation Technique  

NASA Astrophysics Data System (ADS)

A high-resolution Vp/Vs ratio estimate is one of the key parameters to understand spatial variations of composition and physical state within the Earth. Lin and Shearer (2007, BSSA) recently developed a methodology to obtain local Vp/Vs ratios in individual similar earthquake clusters, based on P- and S-wave differential times. A waveform cross-correlation approach is typically employed to measure those differential times for pairs of seismograms from similar earthquakes clusters, at narrow time windows around the direct P and S waves. This approach effectively collects P- and S-wave differential times and however requires the robust P- and S-wave time windows that are extracted based on either manually or automatically picked P- and S-phases. We present another technique to estimate P- and S-wave differential times by exploiting temporal properties of delayed time as a function of elapsed time on the seismograms with a moving-window cross-correlation analysis (e.g., Snieder, 2002, Phys. Rev. E; Niu et al. 2003, Nature). Our approach is based on the principle that the delayed time for the direct S wave differs from that for the direct P wave. Two seismograms aligned by the direct P waves from a pair of similar earthquakes yield that delayed times become zero around the direct P wave. In contrast, delayed times obtained from time windows including the direct S wave have non-zero value. Our approach, in principle, is capable of measuring both P- and S-wave differential times from single-component seismograms. In an ideal case, the temporal evolution of delayed time becomes a step function with its discontinuity at the onset of the direct S wave. The offset in the resulting step function would be the S-wave differential time, relative to the P-wave differential time as the two waveforms are aligned by the direct P wave. We apply our moving-window cross-correlation technique to the two different data sets collected at: 1) the Wakayama district, Japan and 2) the Geysers geothermal field, California. The both target areas are characterized by earthquake swarms that provide a number of similar events clusters. We use the following automated procedure to systematically analyze the two data sets: 1) the identification of the direct P arrivals by using an Akaike Information Criterion based phase picking algorithm introduced by Zhang and Thurber (2003, BSSA), 2) the waveform alignment by the P-wave with a waveform cross-correlation to obtain P-wave differential time, 3) the moving-time window analysis to estimate the S-differential time. Kato et al. (2010, GRL) have estimated the Vp/Vs ratios for a few similar earthquake clusters from the Wakayama data set, by a conventional approach to obtain differential times. We find that the resulting Vp/Vs ratios from our approach for the same earthquake clusters are comparable with those obtained from Kato et al. (2010, GRL). We show that the moving-window cross-correlation technique effectively measures both P- and S-wave differential times for the seismograms in which the clear P and S phases are not observed. We will show spatial distributions in Vp/Vs ratios in our two target areas.

Taira, T.; Kato, A.

2013-12-01

397

7 CFR 319.37-11 - Arrival notification.  

Code of Federal Regulations, 2011 CFR

...ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Nursery Stock, Plants, Roots, Bulbs, Seeds, and Other Plant Products 1,2 § 319.37-11 Arrival notification. Promptly upon arrival...

2011-01-01

398

14 CFR 93.29 - International Arrival Authorizations.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false International Arrival Authorizations...Reduction at Chicago O'Hare International Airport § 93.29 International Arrival Authorizations...regardless of any codeshare or marketing arrangement unless...

2010-01-01

399

7 CFR 352.7 - Notice of arrival.  

Code of Federal Regulations, 2011 CFR

... § 352.7 Notice of arrival. Immediately upon arrival of any shipment of plants or plant products (including noxious weeds) subject to this part and covered by a specific permit, the importer shall submit in duplicate through the...

2011-01-01

400

7 CFR 352.7 - Notice of arrival.  

Code of Federal Regulations, 2014 CFR

... § 352.7 Notice of arrival. Immediately upon arrival of any shipment of plants or plant products (including noxious weeds) subject to this part and covered by a specific permit, the importer shall submit in duplicate through the...

2014-01-01

401

9 CFR 98.7 - Declaration upon arrival.  

Code of Federal Regulations, 2010 CFR

...IMPORTATION OF CERTAIN ANIMAL EMBRYOS AND ANIMAL SEMEN Ruminant and Swine Embryos from Regions Free of Rinderpest and Foot-and-Mouth Disease; and Embryos of Horses and Asses § 98.7 Declaration upon arrival. Upon arrival of an...

2010-01-01

402

Modeling warning times for the Israel's earthquake early warning system  

NASA Astrophysics Data System (ADS)

In June 2012, the Israeli government approved the offer of the creation of an earthquake early warning system (EEWS) that would provide timely alarms for schools and colleges in Israel. A network configuration was chosen, consisting of a staggered line of ˜100 stations along the main regional faults: the Dead Sea fault and the Carmel fault, and an additional ˜40 stations spread more or less evenly over the country. A hybrid approach to the EEWS alarm was suggested, where a P-wave-based system will be combined with the S-threshold method. The former utilizes first arrivals to several stations closest to the event for prompt location and determination of the earthquake's magnitude from the first 3 s of the waveform data. The latter issues alarms, when the acceleration of the surface movement exceeds a threshold for at least two neighboring stations. The threshold will be chosen to be a peak acceleration level corresponding to a magnitude 5 earthquake at a short distance range (5-10 km). The warning times or lead times, i.e., times between the alarm signal arrival and arrival of the damaging S-waves, are considered for the P, S, and hybrid EEWS methods. For each of the approaches, the P- and the S-wave travel times and the alarm times were calculated using a standard 1D velocity model and some assumptions regarding the EEWS data latencies. Then, a definition of alarm effectiveness was introduced as a measure of the trade-off between the warning time and the shaking intensity. A number of strong earthquake scenarios, together with anticipated shaking intensities at important targets, namely cities with high populations, are considered. The scenarios demonstrated in probabilistic terms how the alarm effectiveness varies depending on the target distance from the epicenter and event magnitude.

Pinsky, Vladimir

2014-09-01

403

Modeling warning times for the Israel's earthquake early warning system  

NASA Astrophysics Data System (ADS)

In June 2012, the Israeli government approved the offer of the creation of an earthquake early warning system (EEWS) that would provide timely alarms for schools and colleges in Israel. A network configuration was chosen, consisting of a staggered line of ˜100 stations along the main regional faults: the Dead Sea fault and the Carmel fault, and an additional ˜40 stations spread more or less evenly over the country. A hybrid approach to the EEWS alarm was suggested, where a P-wave-based system will be combined with the S-threshold method. The former utilizes first arrivals to several stations closest to the event for prompt location and determination of the earthquake's magnitude from the first 3 s of the waveform data. The latter issues alarms, when the acceleration of the surface movement exceeds a threshold for at least two neighboring stations. The threshold will be chosen to be a peak acceleration level corresponding to a magnitude 5 earthquake at a short distance range (5-10 km). The warning times or lead times, i.e., times between the alarm signal arrival and arrival of the damaging S-waves, are considered for the P, S, and hybrid EEWS methods. For each of the approaches, the P- and the S-wave travel times and the alarm times were calculated using a standard 1D velocity model and some assumptions regarding the EEWS data latencies. Then, a definition of alarm effectiveness was introduced as a measure of the trade-off between the warning time and the shaking intensity. A number of strong earthquake scenarios, together with anticipated shaking intensities at important targets, namely cities with high populations, are considered. The scenarios demonstrated in probabilistic terms how the alarm effectiveness varies depending on the target distance from the epicenter and event magnitude.

Pinsky, Vladimir

2015-01-01

404

Performance of Real-time Earthquake Information System in Japan  

NASA Astrophysics Data System (ADS)

Horiuchi et al. (2005) developed a real-time earthquake information system (REIS) using Hi-net, a densely deployed nationwide seismic network, which consists of about 800 stations operated by NIED, Japan. REIS determines hypocenter locations and earthquake magnitudes automatically within a few seconds after P waves arrive at the closest station and calculates focal mechanisms within about 15 seconds. Obtained hypocenter parameters are transferred immediately by using XML format to a computer in Japan Meteorological Agency (JMA), who started the service of EEW to special users in June 2005. JMA also developed EEW using 200 stations. The results by the two systems are merged. Among all the first issued EEW reports by both systems, REIS information accounts for about 80 percent. This study examines the rapidity and credibility of REIS by analyzing the 4050 earthquakes which occurred around the Japan Islands since 2005 with magnitude larger than 3.0. REIS re-determines hypocenter parameters every one second according to the revision of waveform data. Here, we discuss only about the results by the first reports. On rapidness, our results show that about 44 percent of the first reports are issued within 5 seconds after the P waves arrives at the closest stations. Note that this 5-second time window includes time delay due to data package and transmission delay of about 2 seconds. REIS waits till two stations detect P waves for events in the network but four stations outside the network so as to get reliable solutions. For earthquakes with hypocentral distance less than 100km, 55 percent of earthquakes are warned in 5 seconds and 87 percent are warned in 10 seconds. Most of events having long time delay are small and triggered by S wave arrivals. About 80 percent of events have difference in epicenter distances less than 20km relative to JMA manually determined locations. Because of the existence of large lateral heterogeneity in seismic velocity, the difference depends on regions and tends to increase when earthquakes occurred outward the network. Depth differences for 70 percent of events are less than 20km and original time differences for 48 percent within one second. In addition to JMA magnitude (MJMA), which is estimated from moment magnitude, REIS estimates a new scaling parameter called intensity magnitude (MI), which is defined from observed P wave seismic intensity (Yamamoto et al., 2008). Our statistical results show that these two kinds of magnitudes are reasonably determined. Either MJMA or MI by REIS for 94 percent of events has differences less than 1.0 compared with reported JMA catalog. However, the difference increases with values of the magnitude. There is an apparent underestimation of MJMA for large earthquakes because the first report is issued when the rupture is still undergoing. Moreover, there are cases when most of Hi-net seismograms close to epicenter are clipped, but still these data are used for the determination of the lower limit of magnitude. We are making an EEWS using real-time strong motion network data for the better estimate of earthquake magnitude and seismic intensity.

Nakamura, H.; Horiuchi, S.; Wu, C.; Yamamoto, S.

2008-12-01

405

Measurement of parity-nonconserving rotation of neutron spin in the 0.734-eV p-wave resonance of $^{139}La$  

E-print Network

The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave resonance of $^{139}La$ was measured with the neutron transmission method. Two optically polarized $^3He$ cells were used before and behind a a 5-cm long $^{139}La$ target as a polarizer and an analyzer of neutron spin. The rotation angle was carefully measured by flipping the direction of $^3He$ polarization in the polarizer in sequence. The peak-to-peak value of the spin rotation was found to be $ (7.4 \\pm 1.1) \\times 10^{-3} $ rad/cm which was consistent with the previous experiments. But the result was statisticallly improved. The s-p mixing model gives the weak matrix element as $xW = (1.71 \\pm 0.25)$ meV. The value agrees well with the one deduced from the parity-nonconserving longitudinal asymmetry in the same resonance.

T. Haseyama; K. Asahi; J. D. Bowman; P. P. J. Delheij; H. Funahashi; S. Ishimoto; G. Jones; A. Masaike; Y. Masuda; Y. Matsuda; K. Morimoto; S. Muto; S. I. Penttilä; V. R. Pomeroy; K. Sakai; E. I. Sharapov; D. A. Smith; V. W. Yuan

2001-11-21

406

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2014 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2014-01-01

407

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2010 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2010-01-01

408

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2012 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2012-01-01

409

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2013 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2013-01-01

410

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2011 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2011-01-01

411

Patterns of spring arrival dates differ in two hirundines  

Microsoft Academic Search

We examined the first arrival dates in the UK over a 56 yr period of 2 hirundines, sand martin Riparia riparia and barn swallow Hirundo rustica, in relation to temperatures along migration routes and at destination. Changes in arrival dates have been much greater for sand martin than for barn swallow, and the arrival order of the 2 species now

Tim Sparks; Piotr Tryjanowski

2007-01-01

412

'To arrive where we started, and know the place for the first time': Heidegger, phenomenology, the way human beings first appear in the world, and fresh perspectives on the abortion debate.  

PubMed

Intellectual stalemate in the abortion debate can be traced in part to its being framed as a standoff between religion and secular philosophy. While the former is thought to generate a broadly 'pro-life' position, the latter is associated with more 'pro-choice' thinking. This essay attempts to break free of this framing by criticising the philosophy informing 'pro-choice' positions, but not by resorting immediately to religious arguments but rather by drawing upon a rival philosophical tradition--the movement within twentieth and twenty-first Continental philosophy which was and is phenomenology. A phenomenological approach to human 'emergence', and in particular an application of the framework Heidegger developed in Being and Time (1927), leads to a radical questioning of whether contemporary English-speaking beginning-of-life ethics have adequately taken into account the way human beings come forth in the world. PMID:25109125

Mumford, James

2013-01-01

413

Tuning p-Wave Interactions in an Ultracold Fermi Gas of Atoms C. A. Regal, C. Ticknor, J. L. Bohn, and D. S. Jin*  

E-print Network

Tuning p-Wave Interactions in an Ultracold Fermi Gas of Atoms C. A. Regal, C. Ticknor, J. L. Bohn have measured a p-wave Feshbach resonance in a single-component, ultracold Fermi gas of 40K atoms. We temperature regime accessible in atomic physics is characterized by collision energies so low that centrifugal

Jin, Deborah

414

STS-78 crew arrive for TCDT  

NASA Technical Reports Server (NTRS)

The STS-78 flight crew speaks to the news media after arriving at KSC's Shuttle Landing Facility to participate in the Terminal Countdown Demonstration Test (TCDT). From left are Alternate Payload Specialist Luca Urbani, Italian Space Agency (ASI); Payload Specialist Robert Brent Thirsk, Canadian Space Agency (CSA); Mission Specialists Charles E. Brady, Jr. and Richard M. Linnehan; Payload Commander Susan J. Helms; Mission Commander Terence T. 'Tom' Henricks; Pilot Kevin R. Kregel; Payload Specialist Jean-Jacques Favier, French Space Agency (CNES); and Alternate Payload Specialist Pedro Duque, European Space Agency (ESA).

1996-01-01

415

P-1 truss arrival at KSC  

NASA Technical Reports Server (NTRS)

On July 26, 2000 the P-1 truss arrived at Kennedy Space Center's Shuttle Landing Facility aboard its 'Super Guppy' transport. The P-1 truss, scheduled to fly in spring of 2002, is part of a total 10-truss, girder-like structure that will ultimately extend the length of a football field. Astronauts will attach the 14-by-15 foot structure to the port side of the center truss, SO, during the spring assembly flight. The 33,000-pound P- 1 will house the thermal radiator rotating joint (TRRJ) that will rotate the International Space Station's radiators away from the sun to increase their maximum cooling efficiency.

2000-01-01

416

33 CFR 146.405 - Safety and Security notice of arrival for vessels arriving at a place on the OCS.  

Code of Federal Regulations, 2012 CFR

...false Safety and Security notice of arrival...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ...SHELF ACTIVITIES OPERATIONS Vessels-Safety and Security Notice of Arrival...National Vessel Movement Center (NVMC):...

2012-07-01

417

33 CFR 146.405 - Safety and Security notice of arrival for vessels arriving at a place on the OCS.  

Code of Federal Regulations, 2013 CFR

...false Safety and Security notice of arrival...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ...SHELF ACTIVITIES OPERATIONS Vessels-Safety and Security Notice of Arrival...National Vessel Movement Center (NVMC):...

2013-07-01

418

33 CFR 146.405 - Safety and Security notice of arrival for vessels arriving at a place on the OCS.  

Code of Federal Regulations, 2014 CFR

...false Safety and Security notice of arrival...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ...SHELF ACTIVITIES OPERATIONS Vessels-Safety and Security Notice of Arrival...National Vessel Movement Center (NVMC):...

2014-07-01

419

33 CFR 146.405 - Safety and Security notice of arrival for vessels arriving at a place on the OCS.  

Code of Federal Regulations, 2011 CFR

...false Safety and Security notice of arrival...DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ...SHELF ACTIVITIES OPERATIONS Vessels-Safety and Security Notice of Arrival...National Vessel Movement Center (NVMC):...

2011-07-01

420

Order of arrival structures arbuscular mycorrhizal colonization of plants.  

PubMed

Priority effects - the impact of a species' arrival on subsequent community development - have been shown to influence species composition in many organisms. Whether priority effects among arbuscular mycorrhizal fungi (AMF) structure fungal root communities is not well understood. Here, we investigated whether priority effects influence the success of two closely related AMF species (Rhizophagus irregularis and Glomus aggregatum), hypothesizing that a resident AMF suppresses invader success, this effect is time-dependent and a resident will experience reduced growth when invaded. We performed two glasshouse experiments using modified pots, which permitted direct inoculation of resident and invading AMF on the roots. We quantified intraradical AMF abundances using quantitative PCR and visual colonization percentages. We found that both fungi suppressed the invading species and that this effect was strongly dependent on