Temperature effects on long-period seismographs: an accurate method to determine the transfer function

1976 ◽  
Vol 66 (4) ◽  
pp. 1405-1412
Author(s):  
Walter Mitronovas
Keyword(s):  
Transfer Function ◽  
Least Squares ◽  
Vertical Component ◽  
Direct Determination ◽  
Phase Response ◽  
Calibration Data ◽  
Seasonal Temperature ◽  
Simple Method ◽  
Long Period

abstract A simple method for monitoring the transfer function of a long-period (LP) seismograph as a function of time is described. This method makes it possible, under certain restrictions, to estimate quite accurately (one order of magnitude better than the least-squares inversion of the calibration pulse) changes in the transfer function of a system using only the maximum amplitude information of the transient calibration pulses. The restrictions of this method are: (1) no change in the period of the horizontal seismometers (TS) and galvanometers (TG): (2) length of the spring of a vertical seismometer (boom position) is a function of temperature only; and (3) magnetic field is uniform in the range of expected boom (coil) excursions. In other words, the system parameters are affected only by temperature. Briefly, temperature affects mainly the resistance of the coils (copper) of seismometer (RS) and galvanometer (RG), which changes the current flowing in the circuit and hence the amplitude of the calibration pulse. The expected changes in the damping of the seismometer (hS), galvanometer (hG) and in the seismometer period (vertical component) have only negligible additional effect on the amplitude. Therefore, from the observed daily variation in the amplitude of the calibration pulses, it is simple to calculate changes in RS and RG and, hence, the in situ temperature as a function of time. The effect of temperature on the vertical seismometer boom position, and hence TS, can be determined beforehand (or at any time) for each instrument. From this, TS as a function of time can be inferred. Finally, from the calculated variations in RS and RG, variation in hG can be determined; from variations in RS, RG and TS, variation in hS and then the coupling factor (σ) can be determined. Analysis of the calibration data from a vertical component at Zurich for a 2-year period, 1972–73, is presented as an illustration of the method. The in situ seasonal temperature variation was inferred to be around ±4 C. In terms of the variation in the system phase response (delay), this amounts to about ±0.20 sec (at most) at a period of 100 sec, and less at shorter periods. This estimate is in good agreement with direct determination of the differences in phase delay for a similar system under controlled temperature conditions. It is also consistent with the fact that no systematic variation in phase response as a function of time was detected using the least-squares inversion of the calibration pulse (method not accurate enough). This indicates that the temperature effect on the phase response is fairly small and that under normal conditions modern LP instruments satisfy to a good approximation the requirements of this calibration method.

Electromagnetic seismograph constants by least-squares inversion

1969 ◽  
Vol 59 (3) ◽  
pp. 1335-1348
Author(s):  
B. J. Mitchell ◽  
M. Landisman
Keyword(s):  
Least Squares ◽  
Love Wave ◽  
Least Squares Method ◽  
Linear Trend ◽  
Wave Train ◽  
Vertical Component ◽  
Long Period ◽  
Electromagnetic Seismograph ◽  
Before And After

abstract A least-squares method has been developed to determine the free periods and damping constants of an electromagnetic seismograph from its calibration pulse. The resulting values are correct to within a few tenths of one per cent for synthetic calibration pulses, even when moderate levels of microseismic noise are present. The seismograph constants of the long-period vertical component at Dallas, Texas were determined from in situ measurements and compared with those calculated from the calibration pulse. The results agreed to within four per cent or better for the free periods and damping constants, after correcting for the linear trend and the base coordinate system of the observed pulse. The values differed by as much as 30 per cent when the linear trend and base coordinate corrections were ignored. Two sets of instrumental constants from an unmatched pair of horizontal seismographs were determined from their calibration pulses. Directions of particle motion for a Love wave train recorded on the same instruments were computed before and after instrumental corrections; the results differed by as much as 8 degrees.

Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

1981 ◽  
Vol 39 ◽  
pp. 550-551
Author(s):  
Dean A. Handley ◽  
Jack T. Alexander ◽  
Shu Chien
Keyword(s):  
Cell Growth ◽  
Cell Cultures ◽  
Molecular Interactions ◽  
Convenient Method ◽  
Petri Dish ◽  
Simple Method ◽  
Thin Section Microscopy ◽  
Thin Sectioning ◽  
Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

A Mild and Simple Method for Making MIDA Boronates

2020 ◽  
Author(s):  
Aidan Kelly ◽  
Peng-Jui (Ruby) Chen ◽  
Jenna Klubnick ◽  
Daniel J. Blair ◽  
Martin D. Burke
Keyword(s):  
Organic Synthesis ◽  
Boronic Acids ◽  
Simple Method ◽  
Direct Preparation ◽  
Synthesis Procedure ◽  
Harsh Conditions

<div> <div> <div> <p>Existing methods for making MIDA boronates require harsh conditions and complex procedures to achieve dehydration. Here we disclose that a pre-dried form of MIDA, MIDA anhydride, acts as both a source of the MIDA ligand and an in situ desiccant to enable a mild and simple MIDA boronate synthesis procedure. This method expands the range of sensitive boronic acids that can be converted into their MIDA boronate counterparts. Further utilizing unique properties of MIDA boronates, we have developed a MIDA Boronate Maker Kit which enables the direct preparation and purification of MIDA boronates from boronic acids using only heating and centrifuge equipment that is widely available in labs that do not specialize in organic synthesis. </p> </div> </div> </div>

scholarly journals Assessing an Atmospheric Correction Algorithm for Time Series of Satellite-Based Water-Leaving Reflectance Using Match-Up Sites in Australian Coastal Waters

2021 ◽  
Vol 13 (10) ◽  
pp. 1927
Author(s):  
Fuqin Li ◽  
David Jupp ◽  
Thomas Schroeder ◽  
Stephen Sagar ◽  
Joshua Sixsmith ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Atmospheric Correction ◽  
Correction Method ◽  
In Situ Measurements ◽  
Landsat 8 ◽  
Correction Algorithm ◽  
Simple Method ◽  
North East ◽  
The Impact

An atmospheric correction algorithm for medium-resolution satellite data over general water surfaces (open/coastal, estuarine and inland waters) has been assessed in Australian coastal waters. In situ measurements at four match-up sites were used with 21 Landsat 8 images acquired between 2014 and 2017. Three aerosol sources (AERONET, MODIS ocean aerosol and climatology) were used to test the impact of the selection of aerosol optical depth (AOD) and Ångström coefficient on the retrieved accuracy. The initial results showed that the satellite-derived water-leaving reflectance can have good agreement with the in situ measurements, provided that the sun glint is handled effectively. Although the AERONET aerosol data performed best, the contemporary satellite-derived aerosol information from MODIS or an aerosol climatology could also be as effective, and should be assessed with further in situ measurements. Two sun glint correction strategies were assessed for their ability to remove the glint bias. The most successful one used the average of two shortwave infrared (SWIR) bands to represent sun glint and subtracted it from each band. Using this sun glint correction method, the mean all-band error of the retrieved water-leaving reflectance at the Lucinda Jetty Coastal Observatory (LJCO) in north east Australia was close to 4% and unbiased over 14 acquisitions. A persistent bias in the other strategy was likely due to the sky radiance being non-uniform for the selected images. In regard to future options for an operational sun glint correction, the simple method may be sufficient for clear skies until a physically based method has been established.

Least‐squares inversion of in‐situ sonic Q measurements: Stability and resolution

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 378-385 ◽  
Author(s):  
Aristotelis Dasios ◽  
Clive McCann ◽  
Timothy Astin
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Instantaneous Frequency ◽  
Spectral Ratio ◽  
Full Waveform ◽  
Multiple Measurements ◽  
Sandstone Reservoir ◽  
Gas Bearing

We minimize the effect of noise and increase both the reliability and the resolution of attenuation estimates obtained from multireceiver full‐waveform sonics. Multiple measurements of effective attenuation were generated from full‐waveform sonic data recorded by an eight‐receiver sonic tool in a gas‐bearing sandstone reservoir using two independent techniques: the logarithmic spectral ratio (LSR) and the instantaneous frequency (IF) method. After rejecting unstable estimates [receiver separation <2 ft (0.61 m)], least‐squares inversion was used to combine the multiple estimates into high‐resolution attenuation logs. The procedure was applied to raw attenuation data obtained with both the LSR and IF methods, and the resulting logs showed that the attenuation estimates obtained for the maximum receiver separation of 3.5 ft (1.07 m) provide a smoothed approximation of the high‐resolution measurements. The approximation is better for the IF method, with the normalized crosscorrelation factor between the low‐ and high‐resolution logs being 0.90 for the IF method and 0.88 for the LSR method.

scholarly journals 762 A combination of functional biomarkers improves identification of the tumor-specific reactive T cell repertoire

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A810-A810
Author(s):  
Arianna Draghi ◽  
Katja Harbst ◽  
Inge Svane ◽  
Marco Donia
Keyword(s):  
T Cells ◽  
T Cell ◽  
De Novo ◽  
Autologous Tumor ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Simple Method ◽  
Functional Biomarkers

BackgroundDetecting the entire repertoire of tumor-specific reactive T cells is essential for investigating the broad range of T cell functions in the tumor-microenvironment. At present, assays identifying tumor-specific functional activation measure either upregulation of specific surface molecules, de novo production of the most common antitumor cytokines or mobilization of cytotoxic granules.MethodsIn this study, we combined transcriptomic analyses of tumor-specific reactive tumorinfiltrating lymphocytes (TILs), TIL-autologous tumor cell co-cultures and commonly used established detection protocols to develop an intracellular flow cytometry staining method encompassing simultaneous detection of intracellular CD137, de novo production of TNF and IFNy and extracellular mobilization of CD107a.ResultsThis approach enabled the identification of a larger fraction of tumor-specific reactive T cells in vitro compared to standard methods, revealing the existence of multiple distinct functional clusters of tumor-specific reactive TILs. Publicly available datasets of fresh tumor single-cell RNA-sequencing from four cancer types were investigated to confirm that these functional biomarkers identified distinct functional clusters forming the entire repertoire of tumor-specific reactive T cells in situ.ConclusionsIn conclusion, we describe a simple method using a combination of functional biomarkers that improves identification of the tumor-specific reactive T cell repertoire in vitro and in situ.

Sign in / Sign up

Export Citation Format

Share Document