Grand Average Research Articles

Analysis of variance applied to determinations of equilibrium constants

The statistical analysis of variance has been applied to the values of the equilibrium constants of the glycinate—proton and glycinate—nickel systems, determined in different laboratories by pH-titration in aqueous solution. The analysis shows how the main part of the error derives from the variability from one titration to another even in the same laboratory. Therefore the data for a single titration ( k) must be processed separately, thus yielding a mean value for the equilibrium constant logβ pqr ( k) of the species M p H q L r ; from these mean values for different titrations in each laboratory l, a within-laboratory grand average, logβ pqr ( l), can be calculated; the variance of this grand average measures the experimental error. A further analysis of the data from the different participating laboratories shows that there were no significant differences between laboratories for the constants reported. From these results it can be inferred that all the values of the mean constants logβ pqr ( k) for one species, as determined separately for each titration in four laboratories, belong to the same population. A χ 2 analysis of these populations demonstrates that the stability constants of the species HL, H 2L +, NiL +, NiL 2 (with L − = glycinate) are normally distributed, but not that for NiL − 3. Therefore, general mean values of the first four constants can be calculated and proposed as reliable standard values at 25° and I = 1.0 M Na(Cl): protonation of glycinate, log β 011 = 9.651(12), log β 021 = 12.071(26); nickel-glycinate complexes, log β 101 = 5.615(35), log β 102 = 10.363(62). These values indicate that the standard deviations are rather higher than those often reported in the literature.

A simple method for displaying the hydropathic character of a protein

A computer program that progressively evaluates the hydrophilicity and hydrophobicity of a protein along its amino acid sequence has been devised. For this purpose, a hydropathy scale has been composed wherein the hydrophilic and hydrophobic properties of each of the 20 amino acid side-chains is taken into consideration. The scale is based on an amalgam of experimental observations derived from the literature. The program uses a moving-segment approach that continuously determines the average hydropathy within a segment of predetermined length as it advances through the sequence. The consecutive scores are plotted from the amino to the carboxy terminus. At the same time, a midpoint line is printed that corresponds to the grand average of the hydropathy of the amino acid compositions found in most of the sequenced proteins. In the case of soluble, globular proteins there is a remarkable correspondence between the interior portions of their sequence and the regions appearing on the hydrophobic side of the midpoint line, as well as the exterior portions and the regions on the hydrophilic side. The correlation was demonstrated by comparisons between the plotted values and known structures determined by crystallography. In the case of membrane-bound proteins, the portions of their sequences that are located within the lipid bilayer are also clearly delineated by large uninterrupted areas on the hydrophobic side of the midpoint line. As such, the membrane-spanning segments of these proteins can be identified by this procedure. Although the method is not unique and embodies principles that have long been appreciated, its simplicity and its graphic nature make it a very useful tool for the evaluation of protein structures.

Automated Determination of Urea and Ammoniacal Nitrogen (NPN) in Animal Feeds

A minor modification in the automated analytical system of the official AOAC semiautomated method for determining crude proteins results in an automated method for determining urea and ammoniacal nitrogen in animal feeds and their ingredients. Urease enzyme which has high activity, yields a clear solution in water, has low ammonia impurity, and is inexpensive is used in the automated method. Weights from 1 to 2.5 g feed sample are dissolved in water, and sample solutions are analyzed at the rate of 40 samples/h. Five AAFCO feed check samples were analyzed repeatedly by the automated method, and results were compared with the grand averages from the check sample reports. The official AOAC manual urease method was used by AAFCO participants. Average recovery of urea and ammoniacal nitrogen was 100.6% by the automated method relative to the AAFCO reported averages. The range of recoveries as 98.5-102.7%. The non-protein nitrogen (NPN) concentrations, expressed as protein equivalent, ranged from 3.40 to 63.04% protein on these samples. The average relative standard deviation for the automated analyses was 0.77%, compared with 1.54% for the manual method. This method is an important adjunct to laboratories using or considering use of the semiautomated method for crude protein and needing further information on NPN.

A VSE equation of state for liquids. V. Poly(tetrafluoroethylene), 600–725 K

AbstractOur volume–entropy–energy (VSE) equation of state for liquids, first proposed in 1973 for use with low molecular weight homogeneous liquids, is here applied for the first time to a high molecular weight liquid that is heterogeneous in molecular weight, namely, a molten polymer. Four thermo‐dynamic quantities, T, s, cp, and ε are calculated over the range of 600–725 K at ambient pressure and are compared with experimental values, with excellent results. The grand average of the standard percentage errors (S.P.E.) for the 24 points is 0.1100%.

S- and p-wave neutron spectroscopy. Xe. Intermediate structure in 90Y and the generalized R-matrix theory

The resonance structure observed in the 89Y( n, n) 89Y total cross section measurements in the range of 0.3 to 1.2 MeV incident energy was investigated using the generalized R-matrix theory of nuclear reactions and the doorway interpretation of intermediate structure. The energies and wave functions of the doorway resonances were calculated in a 2-particle and 3 p-1 h basis of the shell model. The model space and the parameters of the model calculation chosen were consistent with other shell model calculations in the mass-90 region. Several strong p-wave doorways with J π = 0 +, 1 +, and 2 + were predicted by the model in the energy range studied. This is due to proximity of p-wave giant resonance. The escape widths Γ ↑ and the spreading widths Γ ↓ for these states were evaluated using the model wave functions and the R-matrix formalism. The calculated energy dependence of the total cross section shows that most of the predicted doorways are in general agreement with the observed anamolies with similar relative strength. More significantly, the underlying p-wave gross structure representing a grand average is of very similar shape in both theory and experiment. As expected in the mass 90-region, the s- and d-wave doorways contribute less significantly to the calculated resonance structure.

Detection of virus in water: sensitivity of the tentative standard method for drinking water

The sensitivity of several microporous virus-adsorbent media for reliably detecting low levels of poliovirus from 380 and 1,900 liters of drinking water by use of the tentative standard method was investigated. The virus-adsorbent media tested were (i) nitrocellulose membrane filters, (ii) epoxy-fiber glass-asbestos filters, (iii) yarn-wound fiber glass depth filters, and (iv) epoxy-fiber glass filter tubes. Virus was adsorbed to the filter media at pH 3.5 and eluted with glycine buffer, pH 11.5. The results from 44 samples demonstrated that poliovirus was detected with a 95% reliability at mean virus input levels of 3 to 7 plaque-forming units/380 liters when 1,900 liters of water was sampled. At mean virus input levels of less than 1 to 2 plaque-forming units/380 liters, the detection reliability was 66% in 76 samples when 1,900 liters of water was sampled. No significant difference in virus detection sensitivity was observed among the various virus adsorbent media tested. Overall virus recovery efficiency ranged from 28 to 42%, with a grand average of 35%. Members of the coxsackievirus groups A and B, echovirus, and adenovirus were also detected when 380 and 1,900 liters of water were sampled. These experimental observations attest to the sensitivity of the tentative standard method for detecting low levels of virus in large volumes of drinking water.

Crude Fiber Analysis Without Asbestos

Abstract Hoist reported on new filtration equipment that incorporates a vacuum manifold with an air metering device that provides the operator precise control over the vacuum applied. This equipment, which eliminated asbestos, was used in a study on acid-detergent fiber, cellulose, and lignin determinations. Improved precision and good accuracy were obtained with less time involved for each analysis. One analyst can complete 72 determinations in an 8 hr day. The data were in good agreement with the official AOAC method. Ten collaborative Association of American Feed Control Officials check feed samples (1973) were analyzed independently twice with this method and the results were in good agreement with the reported grand average of the data for the check feed samples. An average range of 0.066% fiber was obtained with an average difference from the reported grand average of +0.0195% fiber. In other experiments, over a 3 week period, 5 forage samples with a fiber content of 3–30% were analyzed singly each week by the reported method and the official final action AOAC method, 7.050–7.054. The average range for the AOAC method was 0.54% and for the crude fiber method without asbestos 0.29%. Important advantages of this method are precision, accuracy, rapidity, and the elimination of asbestos fibers and the hazardg associated with their inhalation.

New Collaborative Study of a Zincon Ion Exchange Method for the Quantitative Determination of Zinc in Fertilizer

Abstract A collaborative study was performed with 8 Magruder samples to evaluate a new zincon colorimetric method, an alternative to 2.137. The previous zincon method was modified, but the basic principle remains: 0.5N HCl retains a stable Zn(II) chloro-complex ion on an anion exchange resin but not interfering cations; 0.005N HCl elutes the Zn(II) ion which is determined colorimetrically in the presence of the indicator, zincon. Overall estimate of precision, Sr = 0.033, is similar to Sr = 0.030 for atomic absorption. Sb values (0.074 at 0.05%, 0.035 at 0.25%, and 0.054 at 1%) compare favorably with atomic absorption Sb values (0.072 at 0.05%, 0.036 at 0.25%, and 0.063 at 1%). F- and t-test results at the 95% confidence level indicate systematic error by both methods but do not discern a difference in the true value each method can measure. Average single sample values agree better with Magruder grand averages than corresponding averages by atomic absorption. While applicable to samples containing 0.05% zinc and higher, the method is quite time consuming when samples are low in zinc and have high iron—zinc ratios. This method has been adopted as official first action.

Some temporal properties of intracranial self-stimulation.

Abstract Response rates observed under continuous and variable-interval schedules of brain-stimulation reinforcement were analyzed in terms of the component interresponse times. There was a clear suppression of very short interresponse times when rates were observed to decline with high-intensity stimulation. The suppression of short interresponse times may constitute a temporal description of disruptive motor activity under high-intensity stimulation. Grouping responses into interresponse time classes revealed the existence of orderly functional relations between the conditional probability of individual interresponse times and brain stimulation intensity. No one of these individual probability-intensity functions necessarily mirrored the trend of the rate-intensity function (which reflects a grand average of all interresponse times), suggesting that overall increases or decreases in response rate cannot be simply related to a hypothetical, unitary concept of brain-stimulation “reinforcement value”.

Automatic Flame Photometric Determination of Potassium in Fertilizers. A. Elimination of Anion Exchange Cleanup. B. Using Direct Available P2O5 Extract

Abstract Three primary standard grade potassium salts, eight Magruder check samples, and 18 commercial fertilizer samples were analyzed by three methods. Primary standards gave an average recovery of 100.0% and an average range of 0.21% K20. Magruder check samples averaged 0.09% K20 higher by the modified flame photometric method than the grand averages of the STPB results on the respective Magruder reports. The modified flame photometric method averaged 0.02% K20 lower than the official flame photometric method and 0.11% K20 higher than the official STPB method on 18 commercial fertilizer samples. The automatic flame photometric method, without anion exchange cleanup, is rapid enough for routine analysis and is as accurate and precise as the AOAC official methods. The method was also applied to the direct available P205 extract. Results on three primary grade potassium salts, seven Magruder check samples, and 13 commercial fertilizer samples were as accurate and precise as the official STPB method.

Isotopic composition of silver in iron meteorites

With a view to developing a new dating method based on extinct 6.8 m.y. Pd/sup 107/, silver was isolated from 18 samples of the iron meteorites Bristol, Canyon Diablo, Grant, Odessa, Pinon, Sandia Mountains, and Toluca. The silver concentation (11 to 197 ppb) was determined on an aliquot by isotope dilution and also by neutron activation analysis of separate samples. The isotopic composition was measured by surface ionization on a mass spectrometer. No enrichment of Ag/sup 107/ was detected in any of the samples: the delta Ag/sup 107/ values for Canyon Diablo and toluca were 1.2 plus or minus 2.3 and 3.5 plus or minus 3.7 per mil, compared with Murthy's values of 40 plus or minus 4 and 22 plus or minus 4 per mil. The grand average of all analyses was 0 plus or minus 1.5 per mil. That this discrepancy was not due to contamination is shown by the low blanks (<5 per cent), by the agreement of the neutron activation and isotope dilution results, and by other evidence. Sampling error is also not a likely explanation, since its probability is < 1.6 x 10/sup -3/ under the most favorable assumptions. Possibly the apparent anomalies found bymore » Murthy are in some way related to the anomalous value he obtained for terrestrial silver (Ag/ sup 107//Ag/sup 109/ = 1.064 plus or minus 0.002, compared with 1.082 plus or minus 0.002, the average ratio found by four other investigators). (auth)« less

New semiconductor components

Evoked cortical field potentials are widely used in neurophysiological studies into cortical functioning, but insight in the underlying neural mechanisms is severely hampered by ambiguities in the interpretation of the field potentials. The present study aimed at identifying the precise relationships between the primary evoked cortical field potential (the positive-negative [P1–N1]response) and the temporal and spatial sequence in which different local cortical micro-circuits are recruited. We electrically stimulated the median nerve and recorded field potentials using a 12-channel depth probe in somatosensory cortex of ketamine anesthetized rats. Current source density analysis was used and a grand average was constructed based on all individual animals taking into account individual differences in cortical layering. Manipulation of stimulus strength, selective averaging of single trial responses, and double-pulse stimulation, were used to help disentangle overlapping dipoles and to determine the sequence of neuronal events. We discriminated three phases in the generation of the P1–N1 wave. In the first phase, specific thalamic afferents depolarize both layer III and layer V pyramidal cells. In the second phase, superficial pyramidal cells are depolarized via supragranular intracortical projections. In the third phase, population spikes are generated in layer Vb pyramidal cells, associated with a distinct fast (approximately 1 ms) sink/source configuration. Axon-collaterals of layer Vb pyramidal cells produce an enhanced activation of the supragranular pyramidal cells in layer I–II, which generates N1.

The Speed of Light

Numerous measurements of the speed of light published during the last 30 years lead to widely divergent results as compared with the assigned experimental uncertainties. Because of wide diversity in the methods employed in the measurements, all of the data may not be combined effectively in a grand average. Sufficient data had been obtained by the geodimeter method to group them and derive a statistical estimate of the uncertainty in the speed of light by this method. This result, and conclusions reached from careful examination of several experiments, leads to the conclusion that the value 299,792.5 km which has been internationally adopted for use in radio propagation and geodetic work is very close to the best value and not likely to be in error by as much as one part in one million.

Total and organic phosphorus in waters of the Bering Sea, Aleutian Trench and Gulf of Alaska

Total phosphorus was determined on some 170 samples from eleven stations in the Bering Sea, the Aleutian Trench, and the Gulf of Alaska. Samples ranged in depth from the surface to 7000 m. In these samples organic phosphorus, estimated as the difference between total and inorganic phosphorus, bears an inverse relationship to the distribution of inorganic phosphorus. Surface waters, generally low in inorganic phosphorus, contain up to 1·0 μg. at./L organic phosphorus, with a grand average of 0·27 μg. at./L for the upper 200 m. The amount of organic phosphorus present in surface waters reaches values as high as 47 per cent of the total. On the other hand, waters below about 200 m. have little or no measurable amounts of organic phosphorus. In its vertical distribution, total phosphorus varies at the most by a factor of three and is more or less uniform with depth compared to the inorganic phosphorus. Inferences are drawn concerning the nature of organic matter and the state of organic phosphorus in deep waters. The observed distribution of various forms of phosphorus substantiates the theory that the major part of the phosphorus cycle is enacted in the surface layers.

On the Local Difference of Stature among Japanese Adults

Data published in reports of a Scientific Research Group sponsored by the Government and those collected by the author were analysed in terms of geographical, social and environmental differences, and the following result was obtained.1. Stature of the Japanese race is the highest in urban communities followed by fisliing villages and low in inland rural communities, especially in mountainous places. Inhabitants of small towns and fishing villages are of about the same stature. 2. As grand averages the author presents160, 43cm for men149.13cm for womenof the Japanese race to date (1950-1952). These figuresare slightly greater than those of Javanese and smaller than those of most Asian races: Chinese, Koreans, Mongolians, Burmese, Siamese, Nepal and Indian people.3. Major factors causing the difference between urban and inland rural inhabitants are to be sought in environmental and livelihood conditions rather than selective effect of urbanization.4. Inhabitants of Tsushima (Tusima) Island in ICorean Channel are exceptionally tall (male, 161.91 and female, 149.83), perhaps mostly due to racial genetic factors related to its geographical location.

The Age, Growth, and Feeding Habits of the Whitefish, Coregonus Clupeaformis (Mitchell), of Lake Champlain

This study is based on 120 whitefish collected in northern Lake Champlain (Missisquoi Bay) in 1930 and on 175 whitefish taken in southern Lake Champlain in 1931. Since the whitefish population had not been exploited commercially after 1912 in United States waters and after 1915 in Canadian waters, its study should be of interest in showing the characteristics of a population practically untouched by man. Data have been presented on length frequencies, age composition, growth, coefficient of condition, sex ratio, standard length-total length relationship, and feeding habits. The data indicated that the Missisquoi Bay population was disturbed (probably by the early fall seining of 1930) before our samples were taken so that the original length distributions no longer existed. The southern Lake Champlain material, however, showed a consistency which indicated that the population had not been exploited to any extensive degree, if at all. When the northern population was compared with the southern the former was found to differ from the latter in the following respects, which differences pointed to some disturbance of the northern stock in the lake By possession of lower modes and smaller grand averages of length. By absence of very old individuals. By absence of a series of equally abundant age groups or, in other words, by the presence of a decided dominance of one or two age groups. By a radical disagreement between the sexes in their age-frequency distribution. By a disagreement between the sexes with respect to maximum lengths attained. All of the differences between the two collections could, however, not be attributed to exploitation. The following characteristics indicated the presence of two distinct populations in the lake Presence of a spawning ground at each end of the lake. Differences in calculated lengths and increments of length (growth rates). Differences in the actual lengths and weights of corresponding age groups at capture. Differences in the coefficient of condition and the length-weight relationship. The discovery of the presence of apparently two separate populations of whitefish in Lake Champlain was wholly unexpected by us.