Absolute Scales Research Articles

Evolution of intelligence

The social sciences are really the “hard sciences” and the physical sciences are the “easy” sciences. One of the great contributors to making the job of the social scientist very difficult is the lack of fundamental dimensions on the basis of which absolute (i.e. ratio) scales can be formulated and in which relationships could be realized as the [allegedly] coveted equations of physics. This deficiency leads directly to the uses of statistical methods of various types. However it is possible, as shown, to formulate equations and to use them to obtain ratio/absolute scales and relationships based on them. This paper uses differential/integral equations, fundamental ideas from the processing view of the brain‐mind, multiple scale approximation via Taylor series, and basic reasoning some of which may be formulated as infinite‐valued logic, and which is related to probability theory (the theoretical basis of statistics) to resolve some of the basic issues relating to learning theory, the roles of nature and nurture in intelligence, the measurement of intelligence itself, and leads to the correct formulation of the potential‐actual type behaviors (specifically intelligence) and dynamical‐temporal model of intelligence development. Specifically, it is shown that the: (1) basic model for intelligence in terms of genetics and environment has to be multiplicative, which corresponds to a logical‐AND, and is not additive; (2) related concept of “genetics” creating its own environment is simply another way of saying that the interaction of genetics and environment is multiplicative as in (1); (3) timing of environmental richness is critical and must be modeled dynamically, e.g. in the form of a differential equation; (4) path functions, not point functions, must be used to model such phenomena; (5) integral equation formulation shows that intelligence at any time t, is a a sum over time of the past interaction of intelligence with environmental and genetic factors; (6) intelligence is about 100 per cent inherited on a global absolute (ratio) scale which is the natural (dimensionless) scale for measuring variables in social science; (7) nature of the approximation assumptions implicit in statistical methods leads to “heritability” calculations in the neighborhood of 0.5. and that short of having controlled randomized experiments such as in animal studies these are expected sheerely due to the methods used; (8) concepts from AI, psychology, epistemology and physics coincide in many respects except for the terminology used, and these concepts can be modeled nonlinearly.

A New Cluster Pair Method of Determining Absolute Single Ion Solvation Energies Demonstrated in Water and Applied to Ammonia

A new method of determining standard absolute solvation energies (enthalpies and Gibbs free energies) for individual ions is presented. This method originated from the cluster pair based approximation used in earlier work [Tissandier et al., J. Phys. Chem. A 1998, 102, 7787] and is called the cluster pair correlation scheme. Unlike the earlier approximation, the new scheme makes analysis possible in solvent systems for which bulk ion-solvation data are complemented by cluster ion data, either experimental or theoretical, for clusters containing only a single solvent molecule. The correlation scheme features linear plots of half the difference between standard conventional cluster solvation energies for anions and cations containing equal numbers of solvent molecules in the cluster vs their bulk counterparts. All of the correlation lines should intersect at a point whose ordinate defines the unknown shift between the conventional and absolute energy scales, the standard absolute energy of formation of the ...

STRATIGRAPHY IN PHYLOGENY RECONSTRUCTION—RESPONSE

I too welcome this informed debate on the subject of the place of stratigraphy in phylogenetic reconstruction. Fisher et al. and Wagner have had the opportunity to clarify and expand on their respective approaches while Alroy chides me for not understanding the realities of correlation. The key areas of disagreement lie in how much reliance we think can be put on modeling evolution and to what extent we can prejudge the quality of the fossil record. Alroy emphasises that there is a practical limit on the resolution achievable from relative and absolute time scales. In the example he cites, a realistic lower bound is reached when time intervals are of about 0.7 Ma duration. In other situations different levels of resolution may be possible that are independent of taxonomic data. For example, our recent work (Gale et al., 2000) uses chalk-marl couplets that are thought to reflect Milankovitch cyclicity to define 20,000 yr time intervals. These units are correlatable over at least 100 km largely independent of biostratigraphic information. So limits on resolution imposed by technical difficulties of correlation are hardly objective, though they represent real thresholds/barriers. There is, however, an upper bound, reached when all occurrences are treated as falling within a single time interval, which is objective. Working at the upper bound corresponds to ignoring stratigraphic data in phylogeny reconstruction, while anything less than the upper bound uses stratigraphic information. What those wanting to use stratocladistics fail to clarify is why analyses should be carried out at, or close to, the finest scale of precision achievable. If the fossil record is both seriously incomplete and heterogeneous in terms of the environments that are preserved and rock outcrop area, as I (Smith, 2001) and others (e.g., Jackson and Johnson, 2001) think it is, then working with high precision could …

Lifetimes, Branching Fractions, and Oscillator Strengths of Doubly Ionized Tungsten

A first small set of W III oscillator strengths has been obtained from combined lifetime and branching fraction measurements. The branching fractions in the wavelength region of 154–334 nm were measured with a Penning discharge and a Fourier transform spectrometer. Three levels have been calibrated on absolute scales with lifetimes measured with the time-resolved laser-induced fluorescence technique. The f-values derived have uncertainties of about 8% at best. A comparison with Cowan-code calculations is given since no other data are available in the literature.

ABSOLUTE VERSUS RELATIVE INTENSITY CLASSIFICATION OF PHYSICAL ACTIVITY: IMPLICATIONS FOR PUBLIC HEALTH POLICY

A major issue in evaluating the success of educational programs intended to improve public participation in physical activity is how to classify the intensity of activities performed. Currently, there are at least two approaches to estimating intensity of leisure time physical activity (LTPA), based on relative and absolute scales. We examined the impact of using relative versus absolute criteria on reaching physical activity goals set by the American College of Sports Medicine (ACSM; 2000) and the Surgeon General (United States Department of Health and Human Services, USDHHS, 1996). Subjects were healthy men (n = 619) and women (n = 497) aged 18-95 who were participants in the Baltimore Longitudinal Study of Aging. The percentage of subjects meeting the Surgeon General's recommendations for moderate and high intensity LTPA declined with age under the absolute classification system but increased with age when a relative intensity scale was used. Using ACSM recommendations, aging was associated with a decline in high absolute intensity LTPA. However, when a relative classification system was used, high relative intensity LTPA appeared to increase with age, inverting the relationship between high-intensity LTPA and cardiorespiratory fitness. The use of relative intensity LTPA criteria suggests that older subjects are meeting national standards for physical activity, raising questions about the appropriateness of such a scale to motivate older adults to improve their fitness.

THERMODYNAMICS OF DIPEPTIDES IN WATER Calorimetric determination of enthalpy change values related to proton transfer processes of a series of dipeptides in water

Calorimetric measurements on a series of dipeptides having methionine as first common term enabled us to determine the thermodynamic quantities related to the proton transfer processes at the free α-amino and α-carboxyl groups of the dipeptides using methionyl-methionine (MetMet) as reference compound. The drawing forces were found to be the solvation processes of zwitterions, ions and undissociated molecules of dipeptides, hydrophobic effects of side-chains playing an important role. The results were interpreted in terms of the reciprocal influence of the dipeptides components. Relative and absolute scales related to the enthalpic contribution to the acidity and basicity of the dipeptides studied are supplied.

Defining the clinically important difference in pain outcome measures

The purpose of this study was to determine the levels of change on standard pain scales that represent clinically important differences to patients. Data from analgesic studies are often difficult to interpret because the clinical importance of the results is not obvious. Differences between groups, as summarized by a change in mean values over time, can be difficult to apply to clinical care. Baseline scores vary widely and group mean differences could reflect large changes in a few patients, small changes in many patients, or any combination of these outcomes. Determination of the proportion of patients who have a clinically important improvement in their pain would provide a more interpretable result with direct clinical implications. However, determining a clinically important outcome requires information about the degree of change over time that is clinically important. Data from the titration phase of a multiple cross-over randomized clinical trial of oral transmucosal fentanyl citrate (OTFC) for the treatment of cancer-related breakthrough pain were re-analyzed to examine the differences in pain scores between treatment episodes that did and did not yield adequate pain relief. The scales evaluated were absolute pain intensity difference (PID, 0–10 scale), percentage pain intensity difference (PID%, 0–100% scale), pain relief (PR, 0 (none), 1 (slight), 2 (moderate), 3 (lots), 4 (complete)), sum of the pain intensity difference (SPID over 60 min), percentage of maximum total pain relief (% Max TOTPAR over 60 min), and global medication performance (0 (poor), 1 (fair), 2 (good), 3 (very good), 4 (excellent)). Adequate relief was defined by the patient's decision not to use another dose of opioid medication as a rescue, in addition to the study medication, to treat each painful episode. One hundred thirty OTFC naive patients contributed data on 1268 episodes of breakthrough pain. The scales that were converted to a percentage change yielded the best accuracy in predicting adequate relief, with balanced sensitivity and specificity. The best cut-off point for both the % Max TOTPAR and the PID% was 33%. The best cut-off points for the absolute scales were absolute pain intensity difference of 2, pain relief of 2 (moderate), and SPID of 2. The global medication performance of 2 (good) had excellent values as well. This study presents data-derived cut-off points for the changes in several pain scales, each reflecting the clinically important improvement for patients treating breakthrough cancer pain episodes with OTFC. Confirmation in other patient populations and different pain syndromes will be needed. The use of consistent clinically important cut-off points as the primary outcome in future pain therapy clinical trials will enhance their validity, comparability, and clinical applicability.

Lowest uncertainty direct comparison of a mechanically-cooled and a helium-cooled cryogenic radiometer

Cryogenic radiometers are widely used as national primary standards for radiometric and photometric measurements. The most common comparisons are indirect, using various types of trap detector. The lowest limit of relative uncertainty achievable by indirect comparisons is not much less than 2 × 10−4 (k = 1). To improve this level of uncertainty, it is necessary to compare the cryogenic radiometers directly at the same position using an identical beam. In this case error sources such as beam size, beam power and scatter are significantly reduced. The comparison between the mechanically-cooled cryogenic radiometer (MCR) of the National Physical Laboratory (NPL), and the liquid-helium-cooled radiometer (LaseRad II) of the Physikalisch-Technische Bundesanstalt (PTB), was the fourth in a series of direct comparisons worldwide. It took place in the best environment presently available, at the transfer-optimized cryogenic radiometer in the class 1000 clean-room centre at the PTB in Braunschweig (class 100 is available). The two radiometers were sequentially positioned by a translation stage in the power-stabilized laser beam. In four different series of measurements, within two weeks, the average stated relative difference of the measurements of radiant power with these two very different cryogenic radiometers was only 3.2 × 105, which is currently the lowest obtained in a radiometric comparison of absolute scales.

Evolution of the Sun's Spectral Irradiance Since the Maunder Minimum

Because of the dependence of the Sun's irradiance on solar activity, reductions from contemporary levels are expected during the seventeenth century Maunder Minimum. New reconstructions of spectral irradiance are developed since 1600 with absolute scales traceable to space‐based observations. The long‐term variations track the envelope of group sunspot numbers and have amplitudes consistent with the range of Ca II brightness in Sun‐like stars. Estimated increases since 1675 are 0.7%, 0.2% and 0.07% in broad ultraviolet, visible/near infrared and infrared spectral bands, with a total irradiance increase of 0.2%.

The Construct Validity of Task Inventory Ratings: A Multitrait-Multimethod Analysis

This study investigated the construct validity of task inventory ratings from job incumbents and supervisors in 2 jobs on the 4 task dimensions of importance, criticality of error, difficulty to learn, and time spent. Job incumbents completed task ratings on either the typical relative scales or absolute scales developed for each dimension; supervisors completed relative ratings only. Relative ratings from incumbents and supervisors were each compared in multitrait-multimethod analyses with the absolute ratings. Ratings on all task dimensions demonstrated high convergent validity, and time spent and difficulty to learn ratings met criteria for discriminant validity in at least 1 job. Practical implications regarding redundancy among ratings on different task dimensions, the use of both incumbents and supervisors as job analysis respondents, and the use of absolute scales in task analysis are discussed.

Preparation of psychrometric charts for alcohol vapours in nitrogen

Psychrometric charts for three different systems involving condensing alcohol vapour in nitrogen are presented. The alcohols considered are methanol, ethanol and n-propanol. The charts are based upon semi-theoretical equations and make use of published physical property data and correlations. The behaviour of the vapour phase is characterised by the Virial Equation of State truncated at the third term. The solubility of nitrogen in the liquid alcohols is also considered. The charts are constructed with the dry bulb temperature and absolute humidity scales as the orthogonal axes. Curves of constant adiabatic saturation temperature, constant relative humidity, constant gas specific volume and constant enthalpy deviation are plotted on the charts.

Dimensionless units and numbers

The theory of measurement, scales is used to show that there is no foundation for attempting to extend the SI system to measurements of quantities and properties which are described by ordering and naming scales or by absolute scales. It is proposed that the units of planar and solid angles should be considered to be outside the system. Dimensionless quantities are conditionally classified. An analysis is made of specified order scales in which the concept of a “unit of measurement” is not applicable and for which it makes no sense to attribute dimensionality to the numbers and scale points used in them.

Information on the absolute length scales of ion transport processes in glasses from electrical conductivity and tracer diffusion data

We show that absolute values for the time-dependent mean-square displacement of mobile ions in glasses can be obtained from a combined analysis of electrical conductivity and tracer diffusion data. By applying this method to sodium germanate glasses of different compositions, we find that the distances the ions cover in characteristic stages of the transport process increase considerably with decreasing sodium oxide content. At low sodium oxide contents, we observe a linear relation between the transport distances and the interionic separation distances, while this relation is lost at high sodium oxide contents. The same is found to be true for other alkali ion conducting glassy systems. The analysis of this effect is important for discriminating between the influence of the network structure and of the interionic Coulomb interactions on the ion dynamics.

Establishment of absolute diffuse reflectance scales using the NPL Reference Reflectometer

Absolute scales of radiance factor and diffuse reflectance are being established at the NPL using the Reference Reflectometer. In the basic instrument, a reflecting sample and a detector can be rotated about a common vertical axis to any angular positions relative to an incident light beam. The sample can also be displaced horizontally and vertically, allowing examination of its uniformity and removal for direct measurement of the incident beam. The polarization of the incident light is defined by a Rochon prism, and wavelengths are selected by means of interference filters or a double monochromator. The wavelength range has been extended into the near ultraviolet and the near infrared using UV-enhanced silicon and Peltier-cooled InGaAs photodiodes. For absolute measurement of radiance factor, the light reaching the detector passes through a circular aperture whose diameter and distance from the reflecting surface are determined. The flux distribution is made closely similar when observing the incident beam and the reflected beam. Diffuse reflectance is then derived by numerical integration of results over a full hemisphere, avoiding errors due to nonuniformity of an integrating sphere and giving a direct link between radiance factor and diffuse reflectance scales.

Regularities of Line Strengths in Spectra of NI, FI, and NeII

Recently experimentally determined individual (fine structure) line strengths for the spectra of NI, FI, and NeII are analysed, searching for regu- larities resulting from similarities in the structure of these species. Strengths of spectral lines of the prominent 3S-3p and 3p-3d transition arrays are investigated. The absolute scales of these experimentally derived data are based on independently determined lifetimes for excited levels of NI, FI, and NeII. The simple Coulomb approximation method was applied for calcula- tions of the matrix elements for the jumping electron in order to obtain an average trend in line strengths of the studied emitters. In the case of the isoelectronic species (FI, NeII), additionally the trend resulting from the perturbation theory is taken for comparison. Except the trend study of the absolute scale, the strengths of individual lines within analogous multiplets (in a relative scale) are investigated and compared with data resulting from LS coupling scheme and with semi-empirical calculations.

An investigation of dynamical density functional theory for solvation in simple mixtures

Linear and nonlinear versions of time dependent density functional theory are solved for a single solute particle in a simple binary solvent. All particles interact with Lennard-Jones potentials. The theoretical results are compared with molecular dynamics calculations. It is shown that the nonlinear theory is necessary in order to obtain a good quantitative description of selective solvation dynamics. The linear theory is only of qualitative value. Also, attention is drawn to a previously little appreciated problem which arises when one attempts to compare time dependent density functional theory with computer simulation or experimental results. The difficulty involves matching the theoretical and absolute time scales and is discussed in detail in this paper.

Application of Wavelet Analysis to Upscaling of Rock Properties

Summary Although numerous upscaling techniques are reported in the literature, efficiently computing reasonably accurate equivalent rock properties from geological data at fine scale remains difficult. This is especially true for facies with multiple lithologies under multiphase-flow conditions. Because of the nature of multiscale heterogeneity inherent in petroleum reservoirs, the equivalent rock and flow properties will vary with the scales of heterogeneity. Therefore, upscaled properties under multiphase-flow conditions cannot be estimated without reference to the absolute scales of heterogeneity. Wavelet analysis is a multiresolution framework; thus, it is well suited for upscaling rock and flow properties in a multiscale heterogeneous reservoir. The compact support property of the wavelet transform assures efficient computation. Choice of regularity provides a flexible way to control the smoothness of the resulting up-scaling properties. In this study, we developed a new procedure to improve significantly the computational efficiency and accuracy of upscaling for generating equivalent rock and rock-fluid properties under various geological and flow conditions based on multiresolution analysis of wavelet transforms. Additionally, we explored a wavelet reconstruction method to provide a basis for downsampling fine-scale rock property fields from information at various levels of coarser scale. The beauty of the method is that because the equivalent properties at different length scales are computed recursively, the interdependent influences of the heterogeneities on the scales are included effectively. We demonstrate the method by successfully applying it to upscale interbedset and interfacies reservoir properties of Almond formation outcrops under multiphase-flow conditions.

Late Cretaceous (Santonian-Maastrichtian) Integrated Coccolith-Globotruncanid Biostratigraphy of Pelagic Limestones from the Accretionary Prism of Manipur, Northeastern India

Employing special preparation techniques, a rich and moderately preserved assemblage of planktonic foraminifera and coccoliths is documented from pelagic limestones of Melange Zone of Manipur ophiolite belt around Ukhrul area in northeastern India. Integrated biostratigraphy of five exotic limestone blocks encompassing a Late Santonian / Early Campanian to Late Maastrichtian time slice is established; the low-latitude calcareous plankton zones of deep-sea facies identified in such a convergent plate margin terrain, are correlated with published new biostratigraphic, geomagnetic and absolute time scale data. Initial rifting and birth of the Indo-Myanmar ocean took place prior to Latest Santonian / Earliest Campanian and suturing was initiated by Latest Maastrichtian, as suggested by our study. INTRODUCTION Along the eastern border between India and Myanmar, the ophiolites and the associated suite of rocks are exposed in thickly forested hills of Nagaland and Manipur (text-fig. 1); these represent a part of northerly extension of Sunda ArchTrench System linking the Alpine-Himalaya and the Andaman-Nicobar Islands (Ranga Rao 1983; Acharyya et al. 1986, 1989). Rock units exposed in the Nagaland-Manipur hills can be broadly grouped from west to east, representing various stages of basin evolution and orogeny into the following: Facies Molasse Flysch Olistostromal deposits Ophiolite suite Metamorphic Lithounits Barail Group Disang Formation Melange Zone Oceanic Pelagic Sediments, Nagaland Ophiolite/Manipur Ophiolite Naga Metamorphic Complex Structurally, each of these units is overthrust by the next from the east and folded all together. The flyschoid Disang Formation gradually merges into the post-orogenic mollassic Barail Group of rocks towards the west. In the northern part of Manipur ophiolite belt in the Ukhrul district, the Melange Zone occurs along linear zones within the flyschoid shales of Disang Formation (text-fig. 1). The Melange Zone is characterised by the occurrence of exotic blocks of varying size (a few centimetres to tens of meters) composed of micritic limestone, marl, sandstone, basic rocks and conglomerate embedded in matrix of flyschoid rocks. The olistolithic blocks of pelagic limestones and chert could be hitherto dated as Late Cretaceous (Late Santonian to Late Maastrichtian) (Acharyya et al. 1986; Mitra et al. 1986, Chungkham 1996 and Chungkham and Caron 1996). Generally, the microfossil assemblages recovered from pelagic limestone blocks are comprised of coccoliths, planktonic foraminifera (plates 1-4), benthic foraminifera, radiolaria, ostracodes and a few shark placoid scales. Only selected index species of coccoliths and planktonic foraminifera are documented in the present work. Since high resolution age determination by using calcareous planktonic microfossils is crucial for understanding the basin evolution involving rifting, disruption and suturing events of ocean-floor in this arch-trench system, the objectives of the present work are: 1. To study the taxonomy and distribution of planktonic foraminifera and coccoliths, for constructing an integrated biostratigraphy based on the examination of the same sample. 2. To correlate the integrated biozonation with more recently published geomagnetic and absolute time scales for transoceanic correlations. 3. To contribute to the dating of the basin evolution. MATERIAL AND METHODS 120 samples were collected by one of us (P. Chungkham) from three main areas namely, Kangkhui, Hundung and Lambui. Five sections from five exotic blocks were studied specifically, Kangkhui, Hundung North Upper Band, Hundung North Lower Band, Hundung South and Mova (text-figs. 1-4). The Kangkhui section lying close to the ophiolite suite, served as the type for local intrabasinal correlations. Only limited number of samples taken from control points were analysed for the integrated coccolith-globotruncanid study. It is well known that olistolithic pelagic limestone blocks are found in chaotic disposition within a highly sheared matrix, thus hampering the sampling in strict stratigraphic order and regular interval. Considering heavy vegetation cover, the positions of sections were clearly marked on each block by driving iron nails. Planktonic foraminifera The limestones were processed with a modified maceration technique earlier developed by Zolnaj (1979). 300 to 500 specimens from each sample were picked from 60 to 100 mesh size (ASTM) fractions and studied in detail under a normal binocumicropaleontology, vol. 44, no. 1, pp. 69-83, text-figures 1-4, plates 1-4, 1998 69 This content downloaded from 157.55.39.78 on Tue, 21 Jun 2016 07:06:32 UTC All use subject to http://about.jstor.org/terms Prithiraj Chungkham and Sved A. Jafar: Late Cretaceous integrated Coccolith-Globotruncanid biostratigraphv, northeastern India

Absolute scale determination for photoabsorption spectra and the calculation of molecular properties using dipole sum-rules

An assessment of the absolute scales of photoabsorption differential oscillator strength (d f/d E) spectra which were originally normalized using valence shell TRK (i.e. S(O)) sum-rule normalization is presented for a series of dipole (e,e) measurements for 5 noble gases and 52 small molecules. This comprehensive data set involves previously published absolute high resolution dipole (e,e) spectra of the valence shell discrete region combined with very wide range low resolution measurements in the ionization continuum for each atom or molecule. The absolute scales established for the dipole (e,e) spectra using the S(O) sum-rule in the originally published works (data available on the world wide web at ftp://chem.ubc.ca/pub/cooper or by anonymous ftp - see end of present paper for more details) are assessed by deriving static dipole polarizabilities for each atom and molecule using the S(−2) sum-rule. These values are found to be highly consistent with experimental and theoretical literature values of the static dipole polarizability and in almost all cases well within the estimated ±5% accuracy of the originally published TRK sum-rule normalized absolute photoabsorption differential oscillator strength spectra. Significant errors of 8% and 19% in the previously published absolute oscillator strength scales for CCl 4 (G.R. Burton, W.F. Chan, G. Cooper, C.E. Brion, Chem. Phys. 181 (1994) 147) and SiF 4 (X. Guo, G. Cooper, W.F. Chan, G.R. Burton, C.E. Brion, Chem. Phys. 161 (1992) 453, 471) respectively are revealed by the dipole polarizability analysis and approproate corrections are recommended. Alternative methods of absolute scale determination for photoabsorption spectra using static or dynamic dipole polarizabilities from refractive index or dielectric constant measurements are also considered. These are found to be particularly useful especially where data are restricted to lower photon energies (< 60 eV) or where phenomena such as low lying inner shells, continuum shape resonances or Cooper minima preclude the use of the valence shell TRK sum-rule. As a result of the assessment of the absolute scales for the published dipole (e,e) spectra and since polarizabilities and refractive index data can typically be obtained with even higher precision (+-1%), these data have been used to further refine the measured differential oscillator strength scales. On this basis, dipole oscillator strength sums S( u) ( u = −1, −2, −3, −4, −5, −6, −7, −10) and L( u) ( u = −1, −2, −3, −4, −5, −6) are obtained from the d f/d E spectra. For many of the systems considered, the presently reported dipole sums are derived molecular properties are more accurate than previously reported values. In fact, for 28 of the 52 small molecules these sum-rule values represent the only available values. The dipole sums can be used to calculate normal Verdet constants which are involved in the Faraday effect. It is also shown that accurate values of the rotationally averaged C 6( A, B) dispersion coefficients for the long-range interaction of all possible pairs of atomic and/or molecular species can be obtained from the measured differential oscillator strength spectra. Alternatively, an approximation to C 6( A, B), requiring only the S(−2) and L(−2) sums, is shown to provide very reliable estimates of C 6( A, B).

Comparison of absolute d/O diffuse reflectance factor scales of the NRC and the PTB

A comparison of the absolute diffuse reflectance factor scales of the National Research Council (NRC, Canada) and the Physikalisch-Technische Bundesanstalt (PTB, Germany) for radiance factor measurements in the d/0 geometry was carried out in 1996. The spectral range of the comparison was 360 nm to 830 nm. The transfer standards exchanged were two matte opal glasses, one of which was similar to those used in a 1981 international comparison between the NRC, the NBS, and the PTB. The current NRC/PTB agreement is within 0,15 % from 370 nm to 830 nm, which is well within the combined relative standard uncertainties for the two laboratories. These results are generally in good agreement with those of the 1981 exchange but are significantly improved for wavelengths below 420 nm, where discrepancies of up to 0,5 % were previously reported at 390 nm. The improvement at shorter wavelengths is largely due to improvements in the uniformity of the radiance of the sphere wall and out-of-band blocking of the interference filters used for wavelength separation.