Aqueous nonelectrolyte solutions. Part XIII. Ice and hydrate freezing points of aqueous ethylene oxide solutions and the formula of congruent ethylene oxide hydrate

1995 ◽  
Vol 73 (6) ◽  
pp. 788-796 ◽  
Author(s):  
David N. Glew ◽  
Norman S. Rath
Keyword(s):  
Ethylene Oxide ◽  
Standard Error ◽  
Hydrate Formation ◽  
Standard Errors ◽  
Single Measurement ◽  
Method Of Least Squares ◽  
Oxide Hydrate ◽  
Dynamic Cooling ◽  
Freezing Temperatures ◽  
Freezing Curve

Ice freezing temperatures and hydrate formation temperatures have been measured by the dynamic cooling method for aqueous ethylene oxide (EO) solutions containing from 0 to 95 mol% EO. The ice and the congruent hydrate freezing temperatures exhibited standard errors on a single measurement of 0.004 °C and 0.013 °C, respectively. The ice–hydrate eutectic temperature was observed at −2.107 °C with standard error 0.001 °C and composition 1.991 mol% EO with standard error 0.008 mol% EO. The congruent hydrate was found to freeze at 11.083 °C with standard error 0.002 °C and composition 12.64 mol% EO with standard error 0.02 mol% EO. The formula of the congruent hydrate was EO•6.91H2O with standard error 0.013 mol water/mol EO. Only a single hydrate was found over the whole composition range down to −26 °C: the shoulder of the hydrate freezing curve above 40 mol% EO resulted from the high activity coefficients to dilute water in concentrated EO solutions. Equations and best values for the ice freezing temperatures and the hydrate formation temperatures together with their standard errors were evaluated by the method of least squares. Keywords: clathrate hydrate of ethylene oxide, freezing of water – ethylene oxide, ethylene oxide hydrate.

Aqueous nonelectrolyte solutions. Part XIV. D-ice and D-hydrate freezing points of deuterium oxide – ethylene oxide solutions and the formula of congruent ethylene oxide D-hydrate

1996 ◽  
Vol 74 (10) ◽  
pp. 1830-1835
Author(s):  
David N. Glew ◽  
Norman S. Rath
Keyword(s):  
Ethylene Oxide ◽  
Composition Range ◽  
Deuterium Oxide ◽  
Hydrate Formation ◽  
Single Measurement ◽  
Method Of Least Squares ◽  
Cooling Method ◽  
Dynamic Cooling ◽  
Freezing Temperatures ◽  
Freezing Curve

D-ice freezing temperatures and D-hydrate formation temperatures have been measured by the dynamic cooling method for deuterium oxide – ethylene oxide (EO) solutions containing from 0 to 95.5 mol% EO. The D-ice and the congruent EO D-hydrate freezing temperatures exhibited standard errors (SEs) on a single measurement of 0.004 °C and 0.017 °C, respectively. The D-ice–D-hydrate eutectic temperature was observed at 1.500 °C with standard error (SE) 0.002 °C and at composition 2.207 mol% EO with SE 0.010 mol% EO. The congruent EO D-hydrate was found to freeze at 13.242 °C with SE 0.007 °C and at composition 12.60 mol% EO with SE 0.07 mol% EO. The formula of the congruent EO D-hydrate was EO•6.93D2O with SE 0.045 mol D2O/mol EO. Only one type of D-hydrate was found over the whole composition range down to −23 °C: the shoulder of the D-hydrate freezing curve above 40 mol% EO resulted from the high activity coefficients of dilute deuterium oxide in concentrated EO solutions. Equations and best values for the D-ice freezing temperatures and the D-hydrate formation temperatures together with their SEs were evaluated by the method of least squares. Properties of EO D-hydrate are compared with those of EO hydrate. Key words: clathrate D-hydrate of ethylene oxide, freezing of deuterium oxide – ethylene oxide, ethylene oxide D-hydrate, formula of ethylene oxide D-hydrate.

Kinetics of formation of ethylene oxide hydrate. Part I. Experimental method and congruent solutions

1968 ◽  
Vol 46 (24) ◽  
pp. 3857-3865 ◽  
Author(s):  
D. N. Glew ◽  
M. L. Haggett
Keyword(s):  
Heat Transfer ◽  
Ethylene Oxide ◽  
Experimental Method ◽  
Hydrate Formation ◽  
Controlling Factor ◽  
Oxide Hydrate ◽  
Mechanical Stirring ◽  
Magnetic Stirring ◽  
Kinetics Of Formation ◽  
Kinetics Of

A dilatometer was constructed for studying the formation of ethylene oxide hydrate. In unstirred, congruent solutions heat transfer appeared to be the significant rate-controlling factor. Initial hydrate formation rates were independent of stirring at speeds greater than approximately 100 r.p.m. Magnetic stirring was inadequate due to hydrate build-up on the walls of the dilatometer bulb. Mechanical stirring eliminated this build-up and gave satisfactory results.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Ethylene oxide hydrate non-stoichiometry: measurements and implications

2002 ◽  
Vol 57 (5) ◽  
pp. 705-713 ◽  
Author(s):  
Zhongxin Huo ◽  
Marc D. Jager ◽  
Kelly T. Miller ◽  
E.Dendy Sloan
Keyword(s):  
Ethylene Oxide ◽  
Oxide Hydrate

On the Smoothing of Observed Data

1937 ◽  
Vol 33 (4) ◽  
pp. 444-450 ◽  
Author(s):  
Harold Jeffreys
Keyword(s):  
Standard Error ◽  
Random Error ◽  
Simple Function ◽  
Standard Errors ◽  
Random Errors ◽  
Previous Theory ◽  
Know How ◽  
True Value ◽  
Actual Error ◽  
Range Of Variation

1. It often happens that we have a series of observed data for different values of the argument and with known standard errors, and wish to remove the random errors as far as possible before interpolation. In many cases previous considerations suggest a form for the true value of the function; then the best method is to determine the adjustable parameters in this function by least squares. If the number required is not initially known, as for a polynomial where we do not know how many terms to retain, the number can be determined by finding out at what stage the introduction of a new parameter is not supported by the observations*. In many other cases, again, existing theory does not suggest a form for the solution, but the observations themselves suggest one when the departures from some simple function are found to be much less than the whole range of variation and to be consistent with the standard errors. The same method can then be used. There are, however, further cases where no simple function is suggested either by previous theory or by the data themselves. Even in these the presence of errors in the data is expected. If ε is the actual error of any observed value and σ the standard error, the expectation of Σε2/σ2 is equal to the number of observed values. Part, at least, of any irregularity in the data, such as is revealed by the divided differences, can therefore be attributed to random error, and we are entitled to try to reduce it.

scholarly journals Integration of macromolecular diffraction data

1999 ◽  
Vol 55 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
A. G. W. Leslie
Keyword(s):  
Diffraction Data ◽  
Standard Error ◽  
Standard Errors ◽  
X Ray ◽  
Poisson Statistics ◽  
Profile Fitting ◽  
X Ray Background

Diffraction intensities can be evaluated by two distinct procedures: summation integration and profile fitting. Equations are derived for evaluating the intensities and their standard errors for both cases, based on Poisson statistics. These equations highlight the importance of the contribution of the X-ray background to the standard error and give an estimate of the improvement which can be achieved by profile fitting. Profile fitting offers additional advantages in allowing estimation of saturated reflections and in dealing with incompletely resolved diffraction spots.

Improved method for estimating Ca uptake in vascular smooth muscle using compartmental analysis

1990 ◽  
Vol 259 (1) ◽  
pp. R172-R183 ◽  
Author(s):  
H. A. Massaldi ◽  
J. Copello ◽  
A. Muller ◽  
M. F. Villamil
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Standard Error ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Parameter Estimate ◽  
Estimation Methods ◽  
Standard Errors ◽  
Influx Rate ◽  
Ca Uptake

A comparative study on the modeling aspects of Ca uptake in vascular smooth muscle is presented with particular emphasis on determination of the influx rate and its standard error for one- and two-compartment models. Experimental data from our laboratory of 45Ca uptake by dog carotid arteries were optimally fitted to a one-compartment model and were used to compare different estimation methods and experiment designs. Reparameterization of the model equation yielded an expression that allows direct estimation of the influx rate and its standard error. Experiment design with replicated sampling at three to four times were found to provide the highest estimation precision and successful comparisons of influx rates under treatment and control conditions. Two-compartment model data reported in the literature for Ca uptake by cells were reprocessed, yielding standard errors for the rate constant of the fast component an order of magnitude larger than the mean estimate. For this case, a three-parameter variant of the one-compartment model was developed that described the data with acceptable standard errors. Overall we found that the choice of the model that fitted Ca uptake data best required consideration of parameter estimate precision comparisons in addition to F tests of significance between alternate models.

scholarly journals Hipparcos, Three Years After Launch

1993 ◽  
Vol 156 ◽  
pp. 1-10
Author(s):  
J. Kovalevsky ◽  
M. Froeschlé
Keyword(s):  
Standard Error ◽  
Present Status ◽  
Double Star ◽  
New Method ◽  
Standard Errors ◽  
First Year ◽  
Mass Determination ◽  
Mission Duration ◽  
The Mean

In a first part, the present status of the HIPPARCOS mission is described. Despite the degradations and failures of gyroscopes, it is still hoped that a 4 1/2 mission duration will be reached. The first-year of data has been reduced by both FAST and NDAC consortia. For the best 46200 observed stars, the distribution of standard errors in positions has a maximum of 1.5 mas in latitude and 1.8 mas in longitude and the mean standard error for parallaxes is of the order of 3 mas. The comparison of results obtained by both consortia shows that the differences are small and quite consistent with the announced internal precisions. Magnitude measurements are precise to 0.02 magnitude for a 4 second observation. The precision to be expected for double star observations is also given. The main new result is that the magnitudes of the components are obtained with a few hundredths of a magnitude precision. This allows to devise a new method of mass determination based upon the parallax and a recalibrated mass-luminosity diagram. The parallax dependence of the results is much more favourable than in the case of the classical determination of masses using orbital motions.

Comparative analysis of five methods for recovering rhizobacteria from cotton roots

1991 ◽  
Vol 37 (12) ◽  
pp. 953-957 ◽  
Author(s):  
Joseph W. Kloepper ◽  
Walter F. Mahaffee ◽  
John A. McInroy ◽  
Paul A. Backman
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Standard Error ◽  
Root Colonization ◽  
Glass Beads ◽  
Standard Errors ◽  
Subtilis Strain ◽  
Bacterial Populations ◽  
Recovery Method ◽  
Cotton Seeds

A variety of methods have been used for recovering introduced bacteria from plant roots. The objective of this study was to compare systematically five methods: agitation in buffer, agitation with glass beads in buffer, mixing in a StomacherR lab-blender, sonication, and trituration with mortar and pestle. Cotton seeds were treated with two previously reported rhizobacterial strains, Pseudomonas fluorescens strain Pf-5 and Bacillus subtilis strain GB03. The efficiency of recovery by each method was determined 3 weeks later by comparing average bacterial populations from whole root systems, single 2.0-cm root segments, and two root regions (the uppermost 5 cm of taproot and the lowermost 5 cm). Treatment with the StomacherR blender yielded significantly higher (P = 0.05) mean populations of GB03 compared with all other methods and significantly higher mean populations of Pf-5 compared with agitation with glass beads. From the lowermost 5 cm of taproot, populations of Pf-5 recovered by the StomacherR treatment were significantly higher than all other methods. The inclusion of glass beads for agitation treatments resulted in neither consistently higher absolute numbers of recovered bacteria nor reductions in variability. The mean standard error of each recovery method varied among root sources, and no single method consistently had the highest or lowest mean standard error. Mean standard errors for strain GB03 were generally lower than those for Pf-5 with each root source and each method of recovery. When viewed in composite, the data suggest that the StomacherR treatment was the best for recovering the greatest absolute numbers of rhizobacteria; however, this treatment had high mean standard errors. Investigations of root colonization by introduced rhizobacteria should include several recovery methods to optimize recovered numbers or to decrease variability, depending on the experimental objectives. Key words: root colonization, rhizobacteria, Pseudomonas fluorescens, Bacillus subtilis, cotton.

Using Placebo Laws to Test "More Guns, Less Crime"

2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Eric Helland ◽  
Alexander Tabarrok
Keyword(s):  
Public Policy ◽  
Standard Error ◽  
Serial Correlation ◽  
Error Function ◽  
Standard Errors ◽  
Grouped Data ◽  
Natural Experiments ◽  
Statistical Assumptions ◽  
Gun Laws ◽  
Empirical Standard

Abstract We reexamine Mustard and Lott’s controversial study on the effect of “shall-issue” gun laws on crime using an empirical standard error function randomly generated from “placebo” laws. We find that the effect of shall-issue laws on crime is much less well-estimated than the Mustard and Lott (1997) and Lott (2000) results suggest. We also find, however, that the cross equation restrictions implied by the Lott-Mustard theory are supported. A boomlet has occurred in recent years in the use of quasi-natural experiments to answer important questions of public policy. The intuitive power of this approach, however, has sometimes diverted attention from the statistical assumptions that must be made, particularly regarding standard errors. Failing to take into account serial correlation and grouped data can dramatically reduce standard errors suggesting greater certainty in effects than is actually the case. We find that the placebo law technique (Bertrand, Duflo and Mullainathan 2002) is a useful addition to the econometrician’s toolkit.

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