Time Domain Regional Discriminants

The time and frequency domains are equivalent displays of seismic trace, information, though some qualities of the signal are more easily observed in one domain than the other. The relative frequency excitation of Lg, for instance, is most easily viewed in the frequency domain, but such waveform qualities as the sequence in which pulses arrive in the wave train or the sharpness of pulse onset are most easily studied in the time domain (Murphy and Bennett, 1982, Blandford, 1981). Because of the tremendous complexity of high frequency regional data, most attempts at using it for discrimination purposes have involved analysis of the frequency content of the various arrivals either through transforming selected windows or through multiple bandpass filtering. We report here on our initial attempts to explore the alternative and to discriminate events using those waveform characteristics most easily observed in the time domain. A second advantage of time domain analysis approaches is that they permit a deeper insight into the physical processes creating a seismic signal's character. For this reason, they can be more e3silv used to evaluate the transportabilty of a discriminant to varying geophysical and tectonic regimes. This is an especially important feature in the development of regional discriminants. The most prominent and successful spectral regional discriminants have been empirically developed. This means that they must be redeveloped and reverified in each new area. As we shall show in the following, through rigorous time domain analysis such features as regional depth phases can be identified and used to discriminate. Discriminants based on such simple physical features as source depth should be transportable anywhere. In work recently completed under the treaty verification program, we have proved that such time domain discriminants do exist. In analyzing a test discrimination data set from the western U. S., we have discovered that the onset of P_n is always very similar for explosions and that few earthquakes have this unique waveform character. This information can be constructed into a simple discrimination scheme by testing the correlation of observed P_n waveform onsets with average waveforms observed from explosions. High correlations indicate explosions and low correlations earthquakes. We have also discovered that the regional phase P_g is actually composed of a sequence of sub-arrivals which correspond to successively higher orders of reverberation in the crust. In realistic crust models, the depth phases play an important role in the waveshapes of these sub-arrivals. By selecting an appropriate frequency band to analyze, we have been able to accurately model this type of data from explosions in the western United States. Over the very relevant regional distance ranges of 200 to 600 km, it appears that a discrimination procedure very similar to the one which is known to work for P_n will also be effective for P_g. We are investigating whether similar discriminants can be constructed based on the phases S_n and S_g in areas where those phases are prominent arrivals

Time Domain Regional Discriminants

The time and frequency domains are equivalent displays of seismic trace, information, though some qualities of the signal are more easily observed in one domain than the other. The relative frequency excitation of Lg, for instance, is most easily viewed in the frequency domain, but such waveform qualities as the sequence in which pulses arrive in the wave train or the sharpness of pulse onset are most easily studied in the time domain (Murphy and Bennett, 1982, Blandford, 1981). Because of the tremendous complexity of high frequency regional data, most attempts at using it for discrimination purposes have involved analysis of the frequency content of the various arrivals either through transforming selected windows or through multiple bandpass filtering. We report here on our initial attempts to explore the alternative and to discriminate events using those waveform characteristics most easily observed in the time domain. A second advantage of time domain analysis approaches is that they permit a deeper insight into the physical processes creating a seismic signal's character. For this reason, they can be more e3silv used to evaluate the transportabilty of a discriminant to varying geophysical and tectonic regimes. This is an especially important feature in the development of regional discriminants. The most prominent and successful spectral regional discriminants have been empirically developed. This means that they must be redeveloped and reverified in each new area. As we shall show in the following, through rigorous time domain analysis such features as regional depth phases can be identified and used to discriminate. Discriminants based on such simple physical features as source depth should be transportable anywhere. In work recently completed under the treaty verification program, we have proved that such time domain discriminants do exist. In analyzing a test discrimination data set from the western U. S., we have discovered that the onset of P_n is always very similar for explosions and that few earthquakes have this unique waveform character. This information can be constructed into a simple discrimination scheme by testing the correlation of observed P_n waveform onsets with average waveforms observed from explosions. High correlations indicate explosions and low correlations earthquakes. We have also discovered that the regional phase P_g is actually composed of a sequence of sub-arrivals which correspond to successively higher orders of reverberation in the crust. In realistic crust models, the depth phases play an important role in the waveshapes of these sub-arrivals. By selecting an appropriate frequency band to analyze, we have been able to accurately model this type of data from explosions in the western United States. Over the very relevant regional distance ranges of 200 to 600 km, it appears that a discrimination procedure very similar to the one which is known to work for P_n will also be effective for P_g. We are investigating whether similar discriminants can be constructed based on the phases S_n and S_g in areas where those phases are prominent arrivals

MATRICS cognitive consensus battery (MCCB) performance in children, adolescents, and young adults

Background: Neurodevelopmental models of schizophrenia suggest that cognitive deficits may be observed during childhood and adolescence, long before the onset of psychotic symptoms. Elucidating the trajectory of normal cognitive development during childhood and adolescence may therefore provide a basis for identifying specific abnormalities related to the development of schizophrenia. The MATRICS Consensus Cognitive Battery (MCCB), which was designed for use in clinical trials targeting cognitive deficits most common in schizophrenia, may provide a mechanism to understand this trajectory. To date, however, there is no performance data for the MCCB in healthy children and adolescents. The present study sought to establish performance data for the MCCB in healthy children, adolescents, and young adults. Methods: The MCCB was administered to a community sample of 190 healthy subjects between the ages of 8 and 23 years. All MCCB domain scores were converted to T-scores using sample means and standard deviations and were compared for significant performance differences between sex and age strata. Results: Analyses revealed age effects following quadratic trends in all MCCB domains, which is consistent with research showing a leveling off of childhood cognitive improvement upon approaching late adolescence. Sex effects after controlling for age only presented for one MCCB domain, with males exhibiting well-known spatial reasoning advantages. Conclusions: Utilizing this performance data may aid future research seeking to elucidate specific deficits that may be predictive of later development of SZ. (C) 2013 Elsevier B.V. All rights reserved

Recording advances for neural prosthetics

An important challenge for neural prosthetics research is to record from populations of neurons over long periods of time, ideally for the lifetime of the patient. Two new advances toward this goal are described, the use of local field potentials (LFPs) and autonomously positioned recording electrodes. LFPs are the composite extracellular potential field from several hundreds of neurons around the electrode tip. LFP recordings can be maintained for longer periods of time than single cell recordings. We find that similar information can be decoded from LFP and spike recordings, with better performance for state decodes with LFPs and, depending on the area, equivalent or slightly less than equivalent performance for signaling the direction of planned movements. Movable electrodes in microdrives can be adjusted in the tissue to optimize recordings, but their movements must be automated to be a practical benefit to patients. We have developed automation algorithms and a meso-scale autonomous electrode testbed, and demonstrated that this system can autonomously isolate and maintain the recorded signal quality of single cells in the cortex of awake, behaving monkeys. These two advances show promise for developing very long term recording for neural prosthetic applications

Sunflowers, 1980

Cover title."This first report of results is a contribution of the Department of Agronomy, University of Missouri Agricultural Experiment Station, which reports on Research Projet 363"--P. 3

PRISIM: a computer program that makes PRA useful

PRISIM is an IBM personal computer program that translates probabilistic risk assessment (PRA) information and calculates additional PRA type information for use by those who are not PRA experts. Specifically, PRISIM was developed for the US Nuclear Regulatory Commission for use by their resident inspectors at nuclear power plants. Inspector activities are either scheduled or are in response to a particular status of a plant. PRISIM is useful for either activity