Low Frequency Gyrotron Amplifier Investigation. Phase 2

1989 ◽  
Author(s):  
Bernard R. Cheo
Keyword(s):  
Low Frequency ◽  
Phase 2 ◽  
Gyrotron Amplifier

scholarly journals Improved earthquake detection as a probe for active fault structures in New Zealand's central Southern Alps

2021 ◽  
Author(s):  
◽  
Calum Chamberlain
Keyword(s):  
Cross Correlation ◽  
Matched Filter ◽  
Low Frequency ◽  
Southern Alps ◽  
Phase 2 ◽  
Earthquake Detection ◽  
Alpine Fault ◽  
Drill Site ◽  
Python Package ◽  
Drilling Project

<p>This thesis concerns the detection and analysis of micro-seismicity and low-frequency earthquakes in New Zealand's central Southern Alps. We make use of the 6.5 year continuous seismic dataset collected using the Southern Alps Microearthquake Borehole Array (SAMBA), alongside other temporary and permanent seismic deployments nearby. The small station spacing of this deployment allows for high resolution seismic studies near the Alpine Fault, a dextral-transpressive plate boundary fault between the Pacific and Australian plates.  Using this dataset we have documented the rst evidence of low-frequency earthquakes on or near the deep extent of the Alpine Fault. By using a network based crosscorrelation detection method we have generated a 3 year catalogue of 14 low-frequency earthquake families. These low-frequency earthquake families locate close to other indicators and models of the deep extent of the Alpine Fault, and we interpret these low-frequency earthquakes to represent shear failure on or near the deep extent of the Alpine Fault. These low-frequency earthquakes highlight a near-continuous background rate of deformation, punctuated by short periods of tremor. We also observe higher rates of low-frequency earthquake generation after large regional earthquakes. The magnitudes of our low-frequency earthquakes range from Mʟ‒0.8‒1.8, and appear to follow an exponential distribution, implying that there might be a characteristic length-scale of failure.  We have extended the catalogue of low-frequency earthquake templates using the full 6.5 year dataset and an objective synthetic detection methodology. We developed a new methodology for template detection after other methods failed, or were not feasible. This method employs simple synthetic template events, which, rather than trying to capture all of the complexities of the body waves we try to detect, approximate a simple waveform that does not correlate well with background noise. To undertake this method we have developed a multi-parallel Python package, which is highly portable (we have run this on computers ranging from dual-core, 8GB RAM laptops to a 393 node, 6349 CPU cluster computer) and distributed via an open-source model. This package was run through the 6.5 year dataset on the New Zealand E-Science PAN cluster to e fficiently (<48 hours clock-time) generate a spatially and temporally continuous catalogue of low-frequency earthquake templates. Using this method to detect an initial suite of over 25,000 detections grouped into 600 families we have generated 600 good quality, discrete stacked waveforms for use in further matched-filter detection routines. We have shown that, for templates with both P and S-phase picks, these templates locate near to our previously determined low-frequency earthquake family locations.  Using a network matched- filter detection technique we have generated a catalogue of micro-seismicity in a region of low-seismicity near the Whataroa Valley, motivated by the Deep-Fault Drilling Project; Phase-2. We detected 300 earthquakes that include a selection of near-repeating earthquakes. We find that most detected events are not similar enough to be termed repeating. For 106 earthquakes we are able to generate high-precision magnitudes calculated by singular-value decomposition of similar waveforms. We find a high b-value of 1.44 for these earthquakes, with no earthquakes above Mʟ1.6. By generating high precision cross-correlation derived picks for individual detections and employing a double-difference location methodology we show that seismicity does not delineate a single structure; rather we interpret the detected seismicity as temporally-limited earthquake sequences on small asperities adjacent to the Alpine Fault. Focal mechanisms for the best recorded events show dominantly strike-slip mechanisms, with lesser reverse and normal components.  During the drilling of the Deep-Fault Drilling Project: Phase-2 borehole we operated a real-time earthquake detection system around the drill-site. This was a multi-national effort involving 16 seismologists in three countries monitoring the automatic detections in shifts. During the 5 month real-time monitoring period we detected and located 493 earthquakes, none of which occurred within 3km of the drill-site, nor required changes to the drilling operations. We undertook this monitoring using open-source software, which employed a standard energy based detection scheme.  This thesis has contributed four complementary earthquake catalogues, a further three years of continuous seismic data from the central Southern Alps, and an opensource Python package for detection and analysis of earthquakes using cross-correlation techniques. The characteristics of these catalogues highlight deformation modes on and near one of the world's major strike-slip plate boundaries, both at depth, and at the upper extent of the seismogenic zone.</p>

Role Of Maternal Immunization Against Low Frequency Human Platelet Antigens (LFHPA) In Neonatal Alloimmune Thrombocytopenia (NAIT)

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 38-38
Author(s):  
Julie A. Peterson ◽  
Maria Gitter ◽  
Daniel W. Bougie ◽  
Shannon Pechauer ◽  
Kathleen Hopp ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Conflicts Of Interest ◽  
Human Platelet ◽  
Phase 1 ◽  
Low Frequency ◽  
Maternal Serum ◽  
Screening Methods ◽  
Phase 2 ◽  
Maternal Immunization ◽  
Alloimmune Thrombocytopenia

Abstract Neonatal alloimmune thrombocytopenia (NAIT) is largely caused by maternal immunization against Human Platelet Antigens (HPA) inherited by a fetus from its father. In about 70% of apparent NAIT cases, however, maternal HPA antibodies are not detected by standard serologic testing. At least 24 low frequency HPAs (LFHPA) have now been implicated in NAIT. Fathers are not ordinarily typed for these antigens and the corresponding antibodies can be difficult to detect. We studied paternal and maternal blood samples from suspected NAIT cases to investigate the extent to which maternal immunization against LFHPAs causes “antibody-negative” NAIT. In Phase 1, we studied paternal DNA in 244 NAIT cases not resolved by standard laboratory testing in which there was compelling clinical and/or serologic evidence for NAIT. LFHPAs were identified by full length sequencing of relevant exons encoding platelet glycoproteins (GP). Sixteen LFHPAs (6.6% of cases) were identified. HPA-4b, 6bw, 11bw, 12bw, 13bw, 19bw, 20bw, 21bw, 22bw, and 23bw were found in single cases and HPA-9bw in 6 cases. In 15 of the 16 cases, a maternal antibody reactive with paternal platelets and/or a platelet GP was identified. Cases studied in Phase 1 were highly selected. To obtain an unbiased estimate of the extent to which LFHPAs trigger NAIT, we determined the prevalence of 22 recognized LFHPAs in fathers of 1067 consecutive “antibody-negative” NAIT cases using high throughput screening methods (Phase 2). Mothers of 1338 cases were similarly typed to assess the normal prevalence of LFHPAs in a population racially/ethnically similar to the fathers. Of the 1067 fathers, 28 (2.6%) were positive for a LFHPA. LFHPAs identified were HPA-4b (1 case), 6bw (2), 8bw (1), 9bw (17), 12bw (4) and 21bw (3). Of the 1338 mothers, 27 (2.0%) were positive for a LFHPA. Maternal LFPAs identified were 4b (2 cases), 6bw (5), 9bw (12), 12bw (4), 13bw (3) and 21bw (1). Of the LFHPAs identified, only HPA-9bw was significantly more common in fathers than in mothers (P=0.02). Serologic evaluations done in the Phase 2 cases provided evidence for maternal antibodies against paternal GPIIb/IIIa in only 2 of 23 instances in which the paternal low frequency antigen was located on this GP complex. Findings made in Phase 1, show that efforts to identify a paternal LFHPA in unresolved NAIT cases can be rewarding when maternal serum reacts with paternal platelets and the clinical picture strongly suggests NAIT. The Phase 2 studies of consecutive unresolved NAIT cases show that, with the exception of HPA-9b, the prevalence of LFHPAs is about the same in mothers and fathers of apparent NAIT cases not attributable to maternal immunization against “common” HPAs. It is clear that maternal immunization against an LFHPA can account for only a small fraction of the apparent “diagnostic gap” in serologic diagnosis of NAIT. HPA-9bw is by far the most important immunogen among the recognized LFHPAs and consideration should be given to typing fathers of suspected NAIT cases routinely for this antigen. Recent studies suggest that “low avidity” HPA antibodies not detected using conventional serology may account for an unknown fraction of the “antibody-negative” NAIT cases. Whether HLA antibodies cause NAIT more often than has been thought also deserves re-examination. Disclosures: No relevant conflicts of interest to declare.

scholarly journals The Relationship between the Madden–Julian Oscillation and U.S. Violent Tornado Outbreaks in the Spring

2013 ◽  
Vol 141 (6) ◽  
pp. 2087-2095 ◽  
Author(s):  
Daniel B. Thompson ◽  
Paul E. Roundy
Keyword(s):  
Standard Deviation ◽  
Large Scale ◽  
Low Frequency ◽  
The United States ◽  
Madden Julian Oscillation ◽  
Phase 2 ◽  
Frequency Pattern ◽  
Mean Values ◽  
The Relationship ◽  
Tornado Outbreaks

Abstract The Madden–Julian oscillation (MJO) has been linked to weather variability in the midlatitudes via its associated overturning circulations and Rossby wave trains that redistribute the thermal and mass fields at higher latitudes. This work examines the relationship between the MJO and violent tornado outbreaks in the United States. A census of events shows that violent tornado outbreaks during March–April–May (MAM) are more than twice as frequent during phase 2 of the Real-time Multivariate MJO (RMM) index as during other phases or when the MJO was deemed inactive. Composite analyses show the global circulation patterns simultaneously associated with the MJO and the tornado outbreaks and also indicate the most favored low-frequency circulation pattern that precedes tornado outbreaks in RMM phase 2. An index of 300-hPa geopotential height data is generated by projecting 60-day mean values onto the composite low-frequency pattern. When that index exceeds one standard deviation and the MJO is in RMM phase 2 with an amplitude exceeding one standard deviation during MAM, violent tornado outbreaks occur 50% of the time, relative to the average frequency of less than 4%. Results demonstrate that the anomalous large-scale midlatitude circulation modulated by the MJO and lower-frequency signals can make conditions more or less favorable for tornado outbreaks.

scholarly journals Improved earthquake detection as a probe for active fault structures in New Zealand's central Southern Alps

2021 ◽  
Author(s):  
◽  
Calum Chamberlain
Keyword(s):  
Cross Correlation ◽  
Matched Filter ◽  
Low Frequency ◽  
Southern Alps ◽  
Phase 2 ◽  
Earthquake Detection ◽  
Alpine Fault ◽  
Drill Site ◽  
Python Package ◽  
Drilling Project

<p>This thesis concerns the detection and analysis of micro-seismicity and low-frequency earthquakes in New Zealand's central Southern Alps. We make use of the 6.5 year continuous seismic dataset collected using the Southern Alps Microearthquake Borehole Array (SAMBA), alongside other temporary and permanent seismic deployments nearby. The small station spacing of this deployment allows for high resolution seismic studies near the Alpine Fault, a dextral-transpressive plate boundary fault between the Pacific and Australian plates.  Using this dataset we have documented the rst evidence of low-frequency earthquakes on or near the deep extent of the Alpine Fault. By using a network based crosscorrelation detection method we have generated a 3 year catalogue of 14 low-frequency earthquake families. These low-frequency earthquake families locate close to other indicators and models of the deep extent of the Alpine Fault, and we interpret these low-frequency earthquakes to represent shear failure on or near the deep extent of the Alpine Fault. These low-frequency earthquakes highlight a near-continuous background rate of deformation, punctuated by short periods of tremor. We also observe higher rates of low-frequency earthquake generation after large regional earthquakes. The magnitudes of our low-frequency earthquakes range from Mʟ‒0.8‒1.8, and appear to follow an exponential distribution, implying that there might be a characteristic length-scale of failure.  We have extended the catalogue of low-frequency earthquake templates using the full 6.5 year dataset and an objective synthetic detection methodology. We developed a new methodology for template detection after other methods failed, or were not feasible. This method employs simple synthetic template events, which, rather than trying to capture all of the complexities of the body waves we try to detect, approximate a simple waveform that does not correlate well with background noise. To undertake this method we have developed a multi-parallel Python package, which is highly portable (we have run this on computers ranging from dual-core, 8GB RAM laptops to a 393 node, 6349 CPU cluster computer) and distributed via an open-source model. This package was run through the 6.5 year dataset on the New Zealand E-Science PAN cluster to e fficiently (<48 hours clock-time) generate a spatially and temporally continuous catalogue of low-frequency earthquake templates. Using this method to detect an initial suite of over 25,000 detections grouped into 600 families we have generated 600 good quality, discrete stacked waveforms for use in further matched-filter detection routines. We have shown that, for templates with both P and S-phase picks, these templates locate near to our previously determined low-frequency earthquake family locations.  Using a network matched- filter detection technique we have generated a catalogue of micro-seismicity in a region of low-seismicity near the Whataroa Valley, motivated by the Deep-Fault Drilling Project; Phase-2. We detected 300 earthquakes that include a selection of near-repeating earthquakes. We find that most detected events are not similar enough to be termed repeating. For 106 earthquakes we are able to generate high-precision magnitudes calculated by singular-value decomposition of similar waveforms. We find a high b-value of 1.44 for these earthquakes, with no earthquakes above Mʟ1.6. By generating high precision cross-correlation derived picks for individual detections and employing a double-difference location methodology we show that seismicity does not delineate a single structure; rather we interpret the detected seismicity as temporally-limited earthquake sequences on small asperities adjacent to the Alpine Fault. Focal mechanisms for the best recorded events show dominantly strike-slip mechanisms, with lesser reverse and normal components.  During the drilling of the Deep-Fault Drilling Project: Phase-2 borehole we operated a real-time earthquake detection system around the drill-site. This was a multi-national effort involving 16 seismologists in three countries monitoring the automatic detections in shifts. During the 5 month real-time monitoring period we detected and located 493 earthquakes, none of which occurred within 3km of the drill-site, nor required changes to the drilling operations. We undertook this monitoring using open-source software, which employed a standard energy based detection scheme.  This thesis has contributed four complementary earthquake catalogues, a further three years of continuous seismic data from the central Southern Alps, and an opensource Python package for detection and analysis of earthquakes using cross-correlation techniques. The characteristics of these catalogues highlight deformation modes on and near one of the world's major strike-slip plate boundaries, both at depth, and at the upper extent of the seismogenic zone.</p>

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Lectin Binding to Human Breast Tumor Cells

1976 ◽  
Vol 34 ◽  
pp. 34-35
Author(s):  
Robert E. Nordquist ◽  
J. Hill Anglin ◽  
Michael P. Lerner
Keyword(s):  
Carcinoma Cell ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Low Frequency ◽  
Breast Carcinoma Cell Line ◽  
Human Breast ◽  
Human Breast Tumor ◽  
Duct Carcinoma ◽  
Specific Antigens ◽  
Ricin Agglutinin

A human breast carcinoma cell line (BOT-2) was derived from an infiltrating duct carcinoma (1). These cells were shown to have antigens that selectively bound antibodies from breast cancer patient sera (2). Furthermore, these tumor specific antigens could be removed from the living cells by low frequency sonication and have been partially characterized (3). These proteins have been shown to be around 100,000 MW and contain approximately 6% hexose and hexosamines. However, only the hexosamines appear to be available for lectin binding. This study was designed to use Concanavalin A (Con A) and Ricinus Communis (Ricin) agglutinin for the topagraphical localization of D-mannopyranosyl or glucopyranosyl and D-galactopyranosyl or DN- acetyl glactopyranosyl configurations on BOT-2 cell surfaces.

Practical High Resolution Microscopy

1968 ◽  
Vol 26 ◽  
pp. 302-303
Author(s):  
P. A. Marsh ◽  
T. Mullens ◽  
D. Price
Keyword(s):  
High Resolution ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Resolving Power ◽  
Careful Attention ◽  
Electron Microscopes ◽  
The Relationship ◽  
High Resolution Microscopy ◽  
New Facilities

It is possible to exceed the guaranteed resolution on most electron microscopes by careful attention to microscope parameters essential for high resolution work. While our experience is related to a Philips EM-200, we hope that some of these comments will apply to all electron microscopes.The first considerations are vibration and magnetic fields. These are usually measured at the pre-installation survey and must be within specifications. It has been our experience, however, that these factors can be greatly influenced by the new facilities and therefore must be rechecked after the installation is completed. The relationship between the resolving power of an EM-200 and the maximum tolerable low frequency interference fields in milli-Oerstedt is 10 Å - 1.9, 8 Å - 1.4, 6 Å - 0.8.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

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