Background measurement with UVSTAR

1998 ◽  
Author(s):  
A. Gregorio ◽  
R. Stalio ◽  
P. Trampus ◽  
L. Scarsi
Keyword(s):  
Background Measurement

scholarly journals Comparison of aerosol properties from the Indian Himalayas and the Indo-Gangetic plains

2011 ◽  
Vol 11 (4) ◽  
pp. 11417-11453 ◽  
Author(s):  
T. Raatikainen ◽  
A.-P. Hyvärinen ◽  
J. Hatakka ◽  
T. S. Panwar ◽  
R. K. Hooda ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Monsoon Season ◽  
Data Sets ◽  
New Delhi ◽  
Gangetic Plains ◽  
Diurnal Cycles ◽  
Measurement Site ◽  
Background Measurement ◽  
The Difference ◽  
Boundary Layer Dynamics

Abstract. Gual Pahari is a polluted semi-urban background measurement site at the Indo-Gangetic plains close to New Delhi and Mukteshwar is a relatively clean background measurement site at the foothills of the Himalayas about 270 km NE from Gual Pahari and about 2 km above the nearby plains. Two years long data sets including aerosol and meteorological parameters as well as modeled backward trajectories and boundary layer heights were compared. The purpose was to see how aerosol concentrations vary between clean and polluted sites not very far from each other. Specifically, we were exploring the effect of boundary layer evolution on aerosol concentrations. The measurements showed that especially during the coldest winter months, aerosol concentrations are significantly lower in Mukteshwar. On the other hand, the difference is smaller and also the concentration trends are quite similar from April to October. With the exception of the monsoon season, when rains are affecting on aerosol concentrations, clear but practically opposite diurnal cycles are observed. When the lowest daily aerosol concentrations are seen during afternoon hours in Gual Pahari, there is a peak in Mukteshwar aerosol concentrations. In addition to local sources and long-range transport of dust, boundary layer dynamics can explain the observed differences and similarities. When mixing of air masses is limited during the relatively cool winter months, aerosol pollutions are accumulated to the plains, but Mukteshwar is above the pollution layer. When mixing increases in the spring, aerosol concentrations are increased in Mukteshwar and decreased in Gual Pahari. The effect of mixing is also clear in the diurnal concentration cycles. When daytime mixing decreases aerosol concentrations in Gual Pahari, those are increased in Mukteshwar.

scholarly journals Modeling PM10 Originating from Dust Intrusions in the Southern Iberian Peninsula Using HYSPLIT

2011 ◽  
Vol 26 (2) ◽  
pp. 236-242 ◽  
Author(s):  
A. F. Stein ◽  
Y. Wang ◽  
J. D. de la Rosa ◽  
A. M. Sanchez de la Campa ◽  
Nuria Castell ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Statistical Analysis ◽  
Iberian Peninsula ◽  
North Africa ◽  
Saharan Dust ◽  
Hysplit Model ◽  
Spatial And Temporal Distributions ◽  
Background Measurement ◽  
Good Agreement ◽  
Surface Background

Abstract The Hybrid Single-Particle Lagrangian Integrated Trajectories (HYSPLIT) model has been applied to calculate the spatial and temporal distributions of dust originating from North Africa. The model has been configured to forecast hourly particulate matter ≤10 μm (PM10) dust concentrations focusing on the impacts over the southern Iberian Peninsula. Two full years (2008 and 2009) have been simulated and compared against surface background measurement sites. A statistical analysis using discrete and categorical evaluations is presented. The model is capable of simulating the occurrence of Saharan dust episodes as observed at the measurement stations and captures the generally higher levels observed in eastern Andalusia, Spain, with respect to the western Andalusia station. But the simulation tends to underpredict the magnitude of the dust concentration peaks. The model has also been qualitatively compared with satellite data, showing generally good agreement in the spatial distribution of the dust column.

PRESSURE MEASUREMENT OF INDUCED EXTERNAL ATMOSPHERE ON THE RUSSIAN SEGMENT OF THE INTERNATIONAL SPACE STATION IN EXPERIMENT «CONTROL»

2021 ◽  
pp. 100-113
Author(s):  
Eduard N. ALEKSANDROV ◽  
Maya S. ANTIPOVA ◽  
Andrey N. KRYLOV ◽  
Aleksandr V. KASHKOVSKIY ◽  
Anna A. RODICHEVA
Keyword(s):  
International Space Station ◽  
Statistical Modeling ◽  
Pressure Sensor ◽  
Space Station ◽  
Correction Function ◽  
International Space ◽  
Scientific Equipment ◽  
Background Measurement ◽  
Experiment Control ◽  
Outer Atmosphere

The goals and objectives of space experiment Control to study parameters of the induced external atmosphere of the Russian Segment of the International Space Station are presented. The processing and analysis procedure for telemetry data obtained using scientific equipment Indicator - ISS is described. Numerical calculations were performed by direct statistical modeling of the flow around the pressure sensor by incoming flotation the Earth's outer atmosphere in the background measurement conditions, as well as in disturbed conditions with two vernier engines of the Zvezda module being operated. A correction function of the pressure sensor is obtained depending on the orientation, temperature factor and selected model of interaction of incident flow molecules with the internal and external device surfaces. The results of numerical modeling of the jet discharges of the the Zvezda vernier engine were compared with the data obtained in full-scale pressure measurements in experiment Control. Key words: pressure sensor, orbital station, induced external atmosphere, direct statistical modeling method.

Multipoint Background Analysis: Gaining Precision and Accuracy in Microprobe Trace Element Analysis

2019 ◽  
Vol 25 (1) ◽  
pp. 30-46 ◽  
Author(s):  
Julien M. Allaz ◽  
Michael L. Williams ◽  
Michael J. Jercinovic ◽  
Karsten Goemann ◽  
John Donovan
Keyword(s):  
Mass Spectrometry ◽  
Trace Elements ◽  
Trace Element ◽  
Spectral Region ◽  
Trace Element Analysis ◽  
Background Intensity ◽  
Element Analysis ◽  
Accuracy And Precision ◽  
Background Measurement ◽  
Background Curvature

AbstractElectron microprobe trace element analysis is a significant challenge. Due to the low net intensity of peak measurements, the accuracy and precision of such analyses relies critically on background measurements, and on the accuracy of any pertinent peak interference corrections. A linear regression between two points selected at appropriate background positions is a classical approach for electron probe microanalysis (EPMA). However, this approach neglects the accurate assessment of background curvature (exponential or polynomial), and the presence of background interferences, a hole in the background, or an absorption edge can dramatically affect the results if underestimated or ignored. The acquisition of a quantitative wavelength-dispersive spectrometry (WDS) scan over the spectral region of interest remains a reasonable option to determine the background intensity and curvature from a fitted regression of background portions of the scan, but this technique can be time consuming and retains an element of subjectivity, as the analyst has to select areas in the scan which appear to represent background. This paper presents a new multi-point background (MPB) method whereby the background intensity is determined from up to 24 background measurements from wavelength positions on either side of analytical lines. This method improves the accuracy and precision of trace element analysis in a complex matrix through careful regression of the background shape, and can be used to characterize the background over a large spectral region covering several elements to be analyzed. The overall efficiency improves as systematic WDS scanning is not required to assess background interferences. The method is less subjective compared to methods that rely on WDS scanning, including selection of two interpolation points based on WDS scans, because “true” backgrounds are selected through an exclusion method of possible erroneous backgrounds. The first validation of the MPB method involves blank testing to ensure the method can accurately measure the absence of an element. The second validation involves the analysis of U-Th-Pb in several monazite reference materials of known isotopic age. The impetus for the MPB method came from efforts to refine EPMA monazite U-Th-Pb dating, where it was recognized that background errors resulting from interference or strong background curvature could result in errors of several tens of millions of years on the calculated date. Results obtained on monazite reference materials using two different microprobes, a Cameca SX-100 Ultrachron and a JEOL JXA-8230, yield excellent agreement with ages obtained by isotopic methods (Thermal Ionization Mass Spectrometry [TIMS], Sensitive High-Resolution Ion MicroProbe [SHRIMP], or Secondary Ion Mass Spectrometry [SIMS]). Finally, the MPB method can be used to model the background over a large spectrometer range to improve the accuracy of background measurement of minor and trace elements acquired on a same spectrometer, a method called the shared background measurement. This latter significantly improves the accuracy of minor and trace element analysis in complex matrices, as demonstrated by the analysis of Rare Earth Elements (REE) in REE-silicates and phosphates and of trace elements in scheelite.

scholarly journals Activity Assays and Immunoassays for Plasma Renin and Prorenin: Information Provided and Precautions Necessary for Accurate Measurement

2009 ◽  
Vol 55 (5) ◽  
pp. 867-877 ◽  
Author(s):  
Duncan J Campbell ◽  
Juerg Nussberger ◽  
Michael Stowasser ◽  
A H Jan Danser ◽  
Alberto Morganti ◽  
...  
Keyword(s):  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Inhibitor Therapy ◽  
Renin Activity ◽  
Renin Inhibitor ◽  
Blood Samples ◽  
Hypertensive Patients ◽  
Active Renin ◽  
Open Conformation ◽  
Background Measurement

AbstractBackground: Measurement of plasma renin is important for the clinical assessment of hypertensive patients. The most common methods for measuring plasma renin are the plasma renin activity (PRA) assay and the renin immunoassay. The clinical application of renin inhibitor therapy has thrown into focus the differences in information provided by activity assays and immunoassays for renin and prorenin measurement and has drawn attention to the need for precautions to ensure their accurate measurement.Content: Renin activity assays and immunoassays provide related but different information. Whereas activity assays measure only active renin, immunoassays measure both active and inhibited renin. Particular care must be taken in the collection and processing of blood samples and in the performance of these assays to avoid errors in renin measurement. Both activity assays and immunoassays are susceptible to renin overestimation due to prorenin activation. In addition, activity assays performed with peptidase inhibitors may overestimate the degree of inhibition of PRA by renin inhibitor therapy. Moreover, immunoassays may overestimate the reactive increase in plasma renin concentration in response to renin inhibitor therapy, owing to the inhibitor promoting conversion of prorenin to an open conformation that is recognized by renin immunoassays.Conclusions: The successful application of renin assays to patient care requires that the clinician and the clinical chemist understand the information provided by these assays and of the precautions necessary to ensure their accuracy.

Rare-earth element determination in minerals by electron-probe microanalysis: application of spectrum synthesis

1998 ◽  
Vol 62 (1) ◽  
pp. 1-8 ◽  
Author(s):  
S. J. B. Reed ◽  
A. Buckley
Keyword(s):  
Rare Earth ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Distribution Patterns ◽  
Correction Factors ◽  
Relative Precision ◽  
Element Determination ◽  
X Ray ◽  
Background Measurement ◽  
Spectrum Synthesis

AbstractElectron-probe microanalysis (EPMA) is applicable to rare-earth elements (REE) in minerals with relatively high REE concentrations (e.g. hundreds of parts per million). However, given that each of the 14 REE has at least 12 X-ray lines in the L spectrum, finding peak-free regions for background measurement can be problematical. Also, measured peak intensities are liable to require correction for interferences. Hitherto, little attention has been paid to the optimisation of background offsets and the implications of the wide variation in REE distribution patterns in different minerals. The ‘Virtual WDS’ program, which enables complex multi-element spectra to be synthesised, has been used to refine the conditions used for different REE distributions. Choices include whether to use the Lβ1 rather than the Lα1 line, background offsets, and counting times for comparable relative precision. Correction factors for interferences affecting peak and background measurements have also been derived.

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