Calibration Scale Research Articles

Climatic framework of the end of the pleistocene and the Holocene: paleoclimatic variations during the last 35,000 years

Paleoclimatic changes are recorded by several methods. These fluctuations follow cycles of different rank and duration. Seen in a global scale, there can be little doubt that the climatic changes generally occurred simultaneously all over the globe. This does not mean that they are equally expressed; on the contrary, these changes are quite locally expressed. It is the coincidence in time that reveals the global climatic background. The Gothenburg Magnetic Excursion and Flip, characterized by Pacific VGP positions, provide a new tool for global correlations. The radiocarbon calibration scale is extended back at least to 10,000 BP via a new method based on shorelines and varves. Because of necessary good dating control, the present analysis is confined to the last 35,000 years. 1) Correlations of global climatic data indicate a worldwide synchronism without any detectable time-lag between different variables. 2) Climatic, glacial and eustatic fluctuations follow four main cycles: a 21,000-yr cycle, a 5250-yr cycle, an irregular 1000-3600-yr cycle, an irregular 230-1000-yr cycle. 3) Geoidal-eustasy is a new factor which is related to fundamental geophysical processes. 4) Integrated studies of multiple parameters in the same long Holocene sediment cores have revealed a detailed correlation between climatic changes, eustatic changes, paleomagnetic intensity and polarity changes, atmospheric 14C production changes, etc, suggesting a mutual origin. 5) The main cause of the 5250-yr cycle and the two irregular cycles seems to be changes of the core/ mantle coupling and interface according to two different systems. This explains the correlations established and the absence of any time-lag.

Influence of radiation damage on ruby as a pressure gauge

This study tackles the question if ruby crystals, irradiated with energetic heavy ions, can still be used as reliable pressure sensors. The problem is linked to novel irradiation experiments, exposing pressurized samples to swift heavy-ion beams. In order to test and quantify a possible influence of radiation damage on the laser-induced fluorescence lines of ruby $({\text{Al}}_{2}{\text{O}}_{3}:{\text{Cr}}^{3+})$, small crystals were exposed to different heavy ions (Xe, Au, and U) with kinetic energies of several giga-electron volt at ambient as well as high-pressure conditions. With increasing fluence $(\text{ions}/{\text{cm}}^{2})$, the ${R}_{1}$ and ${R}_{2}$ lines shift both to lower wavelengths which leads to an underestimation of the pressure. An empirical correction term $\ensuremath{\epsilon}$ is proposed to include the irradiation damage effect into the commonly employed ruby calibration scale.

A Comparison of Cheap Talk and Alternative Certainty Calibration Techniques in Contingent Valuation

A field test of cheap talk and two types of certainty calibration in contingent valuation of public lands indicated that cheap talk does not reduce WTP estimates. Use of a ten point certainty calibration scale reduces WTP estimates by about half. However, adjusting for uncertainty using a 'Not Sure' option does not reduce WTP estimates but increases the variance in responses. There may be a conceptual difference between these two ways of accounting for respondents' uncertainty, which may suggest why they provide different WTP value estimates and variances.

Fabrication of a Calibration Scale for Biological Fluorescence Microscopy Using Nano Imprinting

Using nano imprinting technology, a scale tool was fabricated for evaluating image properties of a biological fluorescence microscope. Evaluation of the properties given by a laser scanning microscope could be demonstrated. On this scale, a minute scale pattern with 100 nm structure could be transcribed on the usual type of cover glass with a dyed resist. This fabrication technique can provide a disposable scale tool at a low cost, which is very suitable for calibrating the optical performance given by novel microscopy as well as the conventional one.

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere

Abstract. Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of literature increasing substantially over recent years, calibration issues complicate the comparison of results and limit the utility of building larger-scale databases that would enable further development of the science (e.g. sea-air flux quantification, model validation, etc.). With this in mind, thirty-one scientists from both atmospheric and oceanic halocarbon communities in eight nations gathered in London in February 2008 to discuss the scientific issues and plan an international effort toward developing common calibration scales (http://tinyurl.com/c9cg58). Here, we discuss the outputs from this meeting, suggest the compounds that should be targeted initially, identify opportunities for beginning calibration and comparison efforts, and make recommendations for ways to improve the comparability of previous and future measurements.

Measurement delay associated with the Guardian RT continuous glucose monitoring system.

AimsUsing compartment modelling, we assessed the time delay between blood glucose and sensor glucose measured by the Guardian® RT continuous glucose monitoring system in young subjects with Type 1 diabetes (T1D).MethodsTwelve children and adolescents with T1D treated by continuous subcutaneous insulin infusion (male/female 7/5; age 13.1 ± 4.2 years; body mass index 21.9 ± 4.3 kg/m2; mean ± sd) were studied over 19 h in a Clinical Research Facility. Guardian® RT was calibrated every 6 h and sensor glucose measured every 5 min. Reference blood glucose was measured every 15 min using a YSI 2300 STAT Plus Analyser. A population compartment model of sensor glucose–blood glucose kinetics was adopted to estimate the time delay, the calibration scale and the calibration shift.ResultsThe population median of the time delay was 15.8 (interquartile range 15.2, 16.5) min, which was corroborated by correlation analysis between blood glucose and 15-min delayed sensor glucose. The delay has a relatively low intersubject variability, with 95% of individuals predicted to have delays between 10.4 and 24.3 min. Population medians (interquartile range) for the scale and shift are 0.800 (0.777, 0.823) (unitless) and 1.66 (1.47, 1.84) mmol/l, respectively.ConclusionsIn young subjects with T1D, the total time delay associated with the Guardian® RT system was approximately 15 min. This is twice that expected on physiological grounds, suggesting a 5- to 10-min delay because of data processing. Delays above 25 min are rarely to be observed.

Determination of Actual Object Size Distribution from Direct Imaging

Direct imaging is a technique commonly used in the study of particle, bubble, and droplet size distribution in a dynamic system. Objects such as particles, bubbles, and droplets can be present at various distances from the imaging device when images are captured. Hence, the location of the object will need to be known in order to determine the actual size of an individual object. However, the location of the object cannot be determined from a single image. A single calibration scale defined at the focusing plane is normally used for the determination of all the object sizes from images. When the focus is close to the imaging device, the change in magnification with location is large. The size distribution obtained from the use of a single calibration scale would thus give a considerable deviation from the actual size distribution. In this study, a statistical method is proposed to reconstruct the actual object size distribution from the experimental object size distribution obtained from images using a si...

Development of Suitable ISE Measurement Procedures for SI-Traceable Chemical Activity Determination

In clinical chemistry and medical diagnostics, the reliability of the results obtained by numerous testing protocols has a major impact on the critical decision-making processes. Considerable efforts are made by international institutes to promote and give guidance on measurement comparisons and metrological traceability using appropriate certified reference materials. The concentration values or amount of substance contents are usually assigned to chemical analytical results. In contrast, the most relevant quantity is the activity of ions in clinical chemistry. Activity corresponds to the available biologically active part of these components in a mixture. Many measurement methods and instruments currently in use do not differentiate between the total substance concentration and its biologically active component. In physiological solutions, such as blood plasma, the chemical activity makes a clear difference between ion or substrate concentration. Ion selective electrodes (ISE) are widely used to directly measure the activity of ions. Measurement by means of ion-selective electrodes is a standard method in point of care testing units (POCT) for continuous monitoring for e.g. haemodialysis, cardiac surgery and in intensive care units. A metrological approach to ISE potentiometric measurements is proposed, to determine the activity with their uncertainty. A prerequisite is to develop an activity calibration scale for complex electrolyte solutions with known and traceable ion activities.

Inter-comparison of three instruments for measuring regional background carbon monoxide

Three CO instruments, i.e., vacuum ultraviolet resonance fluorescence (VUV-RF), gas chromatography/reduction gas detection (GC/RGD), and non-dispersive infrared (NDIR) spectrometry, were inter-compared at a background site, i.e., Lulin Atmospheric Baseline Station (LABS) in central Taiwan. For a period of 18 days of continuous measurements, highly coherent results were observed between the three instruments. Calibration of the GC/RGD and VUV-RF was based on the same batch of CO standards, producing results that agreed within 4%. Nevertheless, NDIR displayed a significant bias with a large offset compared to the other two instruments (about −63.1 ppb), due mainly to its over-simplified calibration procedure. The NDIR bias was then removed by aligning the NDIR data to those of GC/RGD in a process termed “post-run correction”. Through this practice, the NDIR was linked to the same calibration scale as that of GC/RGD. As a result, by simultaneously exploiting both GC/RGD and NDIR to measure background CO, both time-resolution and accuracy can be secured.

A GLOBAL AUTOCORRELATION STUDY AFTER THE FIRST AUGER DATA: IMPACT ON THE NUMBER DENSITY OF UHECR SOURCES

We perform an autocorrelation study of the Auger data with the aim to constrain the number density n{sub s} of ultrahigh energy cosmic ray (UHECR) sources, estimating at the same time the effect on n{sub s} of the systematic energy scale uncertainty and of the distribution of UHECR. The use of global analysis has the advantage that no biases are introduced, either in n{sub s} or in the related error bar, by the a priori choice of a single angular scale. The case of continuous, uniformly distributed sources is nominally disfavored at 99% CL and the fit improves if the sources follow the large-scale structure of matter in the universe. The best-fit values obtained for the number density of proton sources are within a factor {approx}2 around n{sub s} {approx_equal} 1 x 10{sup -4}Mpc{sup -3} and depend mainly on the Auger energy calibration scale, with lower densities being preferred if the current scale is correct. The data show no significant small-scale clustering on scales smaller than a few degrees. This might be interpreted as a signature of magnetic smearing of comparable size, comparable with the indication of a {approx}3 deg. magnetic deflection coming from cross-correlation results. The effects of somemore » approximations done on the above results are also discussed.« less

Design and application of a screening and training protocol for odour testers in the field of personal care products

The assessment of odours and in particular of human axillary odour is an integral part of the research and development of deodorant and anti-perspirant products. One method to perform odour assessment is the odour evaluation that is carried out by experts, designated as odour testers or sniffers. Product development decisions are therefore based on human assessment. As for every scientific measurement, the influencing factors need to be standardized or regularly calibrated as effectively as possible for reasons of quality assurance. We therefore developed a screening and training concept aiming to examine the general suitability of odour testers by determining the individual odour sensitivity for relevant odours. This newly developed method is based on the national and international standards and guidelines EN 13725:2003, VDI 3882 sheet 1 and ASTM-1207. Suitable odour testers are subsequently trained to correlate their individual odour intensity perception with an intensity calibration scale in order to achieve reproducible results. Training sessions held on a regular basis help to achieve a greater homology in the response of an existing panel. Our established screening and training protocol has already been successfully put into practice and is also subject to permanent improvement with regard to practical requirements.

Harmonization is more important than experience—results of the first Nordic–Baltic diatom intercalibration exercise 2007 (stream monitoring)

The goal of this study was a harmonization of diatom identification and counting among diatomists from the Scandinavian and Baltic countries to improve the comparison of diatom studies in this geographical area. An analysis of the results of 25 diatomists following the European standard EN 14407 during an intercalibration exercise showed that a high similarity was achieved by harmonization and not because of a long experience with diatoms. Sources of error were wrong calibration scales, overlooking of small taxa, especially small Navicula s.l., misidentifications (Eunotia rhomboidea was mistaken for Eunotia incisa) and unclear separation between certain taxa in the identification literature. The latter was discussed during a workshop with focus on the Achnanthes minutissima group, the separation of Fragilaria capucina var. gracilis from F. capucina var. rumpens, and Nitzschia palea var. palea from N. palea var. debilis. The exercise showed also that the Swedish standard diatom method tested here worked fine with acceptable error for the indices IPS (Indice de Polluo-sensibilite Specifique) and ACID (ACidity Index for Diatoms) when diatomists with a low similarity (Bray–Curtis <60%) with the auditor in at least one of the samples are excluded.

Intercomparison and harmonization of UV Index measurements from multiband filter radiometers

Multiband filter radiometers (MBFRs) are extensively used in national measurement networks for UV climate monitoring and for informing the public about potential health risks from excessive solar UV exposure. Results from the first international intercomparison of MBFRs, arranged in Oslo in 2005, are presented. Forty‐three radiometers of type GUV, NILU‐UV, and UVMFR‐7 were assembled, representing monitoring stations on several continents. The first objective was to conduct a blind intercomparison of Global UV Index (UVI) processed by the instrument owners. Eleven independent data sets were compared, eight of which agreed with the reference to within ±5% and ten to within ±10%. The second objective was to provide a harmonized calibration scale for all instruments. When this scale was applied, the UVI agreed to within ±5% (2‐sigma) for solar zenith angles (SZAs) up to 90°. The results demonstrate that MBFRs provide accurate UVI measurements for realistic sky conditions and a wide range of SZAs, provided the calibration functions are optimized. The harmonized UVI scale is traceable to the European QASUME reference spectroradiometer.

A framework for comparing remotely sensed and in-situ CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; concentrations

Abstract. A framework has been developed that allows validating CO2 column averaged volume mixing ratios (VMRs) retrieved from ground-based solar absorption measurements using Fourier transform infrared spectrometry (FTS) against measurements made in-situ (such as from aircrafts and tall towers). Since in-situ measurements are done frequently and at high accuracy on the global calibration scale, linking this scale with FTS total column retrievals ultimately provides a calibration scale for remote sensing. FTS, tower and aircraft data were analyzed from measurements during the CarboEurope Regional Experiment Strategy (CERES) from May to June 2005 in Biscarrosse, France. Carbon dioxide VMRs from the MetAir Dimona aircraft, the TM3 global transport model and Observations of the Middle Stratosphere (OMS) balloon based experiments were combined and integrated to compare with the FTS measurements. The comparison allows for calibrating the retrieved carbon dioxide VMRs from the FTS. The Stochastic Time Inverted Lagrangian Transport (STILT) model was then utilized to identify differences in surface influence regions or footprints between the FTS and the aircraft CO2 concentrations. Additionally, the STILT model was used to compare carbon dioxide concentrations from a tall tower situated in close proximity to the FTS station. The STILT model was then modified to produce column concentrations of CO2 to facilitate comparison with the FTS data. These comparisons were additionally verified by using the Weather Research and Forecasting – Vegetation Photosynthesis and Respiration Model (WRF-VPRM). The differences between the model-tower and the model-FTS were then used to calculate an effective bias of approximately −2.5 ppm between the FTS and the tower. This bias is attributed to the scaling factor used in the FTS CO2 data, which was to a large extent derived from the aircraft measurements made within a 50 km distance from the FTS station: spatial heterogeneity of carbon dioxide in the coastal area caused a low bias in the FTS calibration. Using STILT for comparing remotely sensed CO2 data with tower measurements of carbon dioxide and quantifying this comparison by means of an effective bias, provided a framework or a "transfer standard" that allowed validating the FTS retrievals versus measurements made in-situ.

DOCUMENTING WOUND AREAS VIA DIGITAL PHOTOGRAPHY

Problem Statement: A useful method to document and track a wound’s progress is via digital photography. Resultant photos can be used as reference and, via planimetry of digitized photographs, yield quantitative assessments of area changes. However, without care, this method can result in large apparent and absolute errors. Rationale: One important potential error source relates to the angle (θ) between the camera’s line-of-sight and wound plane. We sought to mathematically and experimentally estimate this area error. Our goal is to describe and illustrate potential errors of using digital photography to assess wound areas and to describe appropriate procedures to eliminate or substantially reduce these errors Methods: Shapes of known area, and shapes resembling complex wounds, were photographed with a digital camera at various angles. Photographs included horizontal and vertical scales for calibration. Areas were estimated by tracing the perimeter of the digitized image shape using computerized planimetry. Results: Mathematical analysis predicted shortening of the shape’s width in proportion to sinθ. For example, in comparison to a photo taken at θ=90o (pointing directly down to the wound), a photo taken at 30o has a projected width that is 1⁄2 of the true dimension. This results in an area estimate that is 1⁄2 of the actual wound area. The predicted area errors for various angles were confirmed by measurements of various shapes. Conclusions: The intrinsic potential error described can be overcome in two ways. (1) Take wound photos as close to 90o as possible – this yields no angular area error and a horizontal calibration is sufficient. (2) If this is not possible, and the photographic angle is less than 75o, then calibrating the image in both dimensions will eliminate most of the angular area error. This requires that calibration scales in both directions are included in the wound photograph.

Single‐ and Multiscale Remote Sensing Techniques, Multifractals, and MODIS‐Derived Vegetation and Soil Moisture

Scaling processes are increasingly understood to be the result of nonlinear dynamic mechanisms repeating scale after scale from large to small scales leading to nonclassical resolution dependencies. This means that the statistical properties systematically vary in strong, power‐law ways with the resolution. When present in geophysical and remotely sensed fields, it implies that when classical (single‐scale) remote sensing algorithms are used to determine surrogates of various geophysical fields, they can at most be correct at the unique (and subjective) calibration resolution. Scaling analysis and modeling techniques were applied to MODIS TERRA Bands 1 through 7 and to the standard derived vegetation and soil moisture indices in order to quantitatively characterize the wide range of scaling of these fields. The scaling exponents we found are not so large; however, they act across wide scale ranges and imply large effects. For example, for the statistics near the mean, the MODIS (500‐m) resolution would be biased by a factor of ∼1.52 when compared with similar results from an “ideal” sensor at 1‐mm resolution. Applying the standard index algorithms on lower and lower resolution satellite data, we obtained indices with significantly different statistical properties than if the same algorithm was used at the finest resolution and then degraded to an intermediate value (a difference of a factor ∼1.54). This shows that the algorithms can, at best, be accurate at the unique calibration scale and this points to the need to develop resolution‐independent algorithms based on the scaling exponents.

The Cosmic X‐Ray Background and the Population of the Most Heavily Obscured AGNs

We report on an accurate measurement of the CXB in the 15-50 keV range performed with the Phoswich Detection System (PDS) instrument aboard the BeppoSAX satellite. We establish that the most likely CXB intensity level at its emission peak (26-28 keV) is ~40 keV/cm2/s/sr, a value consistent with that derived from the best available CXB measurement obtained over 25 years ago with the first High Energy Astronomical Observatory satellite mission (HEAO-1; Gruber et al. 1999), whose intensity, lying well below the extrapolation of some lower energy measurements performed with focusing telescopes, was questioned in the recent years. We find that 90% of the acceptable solutions of our best fit model to the PDS data give a 20-50 keV CXB flux lower than 6.5E-08 erg/cm2/s/sr, which is 12% higher than that quoted by Gruber et al. (1999) when we use our best calibration scale. This scale gives a 20-50 keV flux of the Crab Nebula of 9.22E-09 erg/cm2/s, which is in excellent agreement with the most recent Crab Nebula measurements and 6% smaller than that assumed by Gruber et al. (1999). In combination with the CXB synthesis models we infer that about 25% of the intensity at ~30 keV arises from extremely obscured, Compton thick AGNs (absorbing column density N_H > 1.0E+24 H/cm2), while a much larger population would be implied by the highest intensity estimates. We also infer a mass density of supermassive BHs of ~3.0E+05 Msol/Mpc3. The summed contribution of resolved sources (Moretti et al. 2003) in the 2-10 keV band exceeds our best fit CXB intensity extrapolated to lower energies, but it is within our upper limit, so that any significant contribution to the CXB from sources other than AGNs, such as star forming galaxies and diffuse Warm-Hot Intergalactic Medium (WHIM), is expected to be mainly confined below a few keV.

Oxford Miniature Vaporiser output with reversed gas flows

This study was undertaken to investigate and calibrate the isoflurane output of an Oxford Miniature Vaporiser (OMV) draw-over vaporiser with reversed gas flows. Plenum or Boyles type machines have gas flowing left to right through the apparatus. Draw over anaesthesia systems, in contrast, traditionally have the carrier gas, air plus oxygen, flowing right to left through the vaporiser. There are a number of variations in the external design of the OMV vaporiser: 1) a back bar mounted draw-over vaporiser with 23-mm taper and left to right gas flow, 2) the Tri-Service with 22-mm taper and left to right gas flow, and 3) the traditional draw-over OMV with right to left gas flow with a variety of tapers. Non-uniformity leads to a variety of possible connections. The predictable output of the OMV vaporiser assumes the correct direction of gas flows for the device. There are many second hand right to left OMV vaporisers for sale to developing countries where the nuances of vaporiser orientation add unnecessarily to the desired simplicity of anaesthesia. A simple calibration scale for reversed gas flows through the OMV vaporiser would be useful.

The NOAA nitrous oxide standard scale for atmospheric observations

A new nitrous oxide (N2O) calibration scale has been developed for atmospheric observations. The NOAA‐2006 N2O scale is based on gravimetrically prepared compressed gas standards. This scale supercedes the NOAA‐2000 scale, which was accepted by the community of experts within the World Meteorological Organization Global Atmosphere Watch program (GAW) as the GAW reference standard. The new scale is defined by thirteen “daughter” standards with dry air mole fractions ranging from 261–371 parts‐per‐billion (nmol mol−1, ppb). These were derived from four part‐per‐million (mmol mol−1, ppm) level “parents”. Standards were evaluated using gas chromatography with electron capture detection. The daughter standards are internally consistent with a standard deviation of residuals of 0.33 ppb, and there is essentially no detectable difference among “cousins” (standards prepared from different parents). The NOAA‐2006 scale is 0.19 ppb lower than the NOAA‐2000 scale at 320 ppb. The global mean N2O mixing ratio (dry air mole fraction), calculated from in situ observations at five monitoring sites was 318.46 ppb in 2004 on the new scale. The NOAA‐2006 scale compares well with other scales based on comparisons of compressed gas standards. The NOAA‐2006 scale is, on average, 0.23% higher than that defined by NIST Standard Reference Materials 2608 and 2609, and an average of 0.01% lower than the Scripps Institution of Oceanography SIO‐98 scale over the range 298–319 ppb.

Analysis of MODIS–MISR calibration differences using surface albedo around AERONET sites and cloud reflectance

MODIS and MISR are two Earth Observing System instruments flown onboard the Terra satellite. Their synergistic use could greatly benefit the broad user community by ensuring a global view of the Earth with high-quality products. A necessary condition for data fusion is radiometric calibration agreement between the two instruments. Earlier studies showed about 3% absolute radiometric difference between MISR and respective MODIS land bands in the visible and near-IR spectrum, which are also used in aerosol and cloud research. This study compared two surface albedo products derived from MODIS and MISR L1B data using the AERONET-based Surface Reflectance Validation Network (ASRVN). The ASRVN shows a positive MISR–MODIS albedo bias of + (0.01–0.03). Cross-sensor calibration inconsistencies were identified as a primary cause of the albedo biases. To establish an independent MODIS–MISR calibration link, top-of-atmosphere MODIS and MISR reflectances were regressed against each other over liquid water clouds. The empirical regression results have been adjusted for the differences in the respective MISR and MODIS spectral responses using radiative transfer simulations. The MISR–MODIS band gain differences for the top-of-atmosphere reflectance estimated with this technique are + 6.0% in the Blue, + 3.3% in the Green, + 2.7% in the Red, and + 0.8% in the NIR band. Applying the derived values to rescale the MODIS or MISR L1B data is shown to significantly reduce the cross-sensor ASRVN surface albedo biases. An absolute calibration scale for both sensors could be established based on independent ground-based measurements of the surface albedo at selected AERONET sites.