A study of the isotopic abundance of boron from various sources

1968 ◽  
Vol 5 (4) ◽  
pp. 921-927 ◽  
Author(s):  
E. K. Agyei ◽  
C. C. McMullen
Keyword(s):  
Boric Acid ◽  
Atomic Weight ◽  
Igneous Rocks ◽  
Tokyo Bay ◽  
Standard Errors ◽  
Isotopic Ratios ◽  
Isotopic Abundance ◽  
A Value ◽  
The Mean ◽  
The Absolute

The absolute ratio of 11B/10B has been determined for boron from different terrestrial sources with a precision of 0.2% (two standard errors) and a reproducibility of 0.2% (half-range). Values fall in the range 4.108 to 3.987 (i.e. 3% variation) and give a corresponding range in the boron atomic weight of 10.814 to 10.810 (0.04% variation). The absolute ratios are 7% lower than those reported by early workers, but are in accord with the results of recent investigations. Igneous rocks and boric acid are found to have high isotopic ratios, whereas Tokyo Bay water possesses a value for 11B/10B near the mean.

scholarly journals The Parallaxes of U Gem Variables

1979 ◽  
Vol 53 ◽  
pp. 494-494
Author(s):  
Karl W. Kamper
Keyword(s):  
Confidence Level ◽  
Absolute Magnitude ◽  
Weighted Mean ◽  
Quiescent Phase ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Absolute Magnitudes

An Allegheny parallax series of SS Cyg, consisting of 52 exposures obtained on 15 nights, was recently measured on the PDS microphotometer at the David Dunlap Observatory, and a value of (m.e.) derived for the absolute parallax. This is close to the mean of the two previous discordant measures for this star given in the table below. The weighted mean of the three determinations implies that the absolute magnitude, at quiescent phase, of the star is between 7.0 and 9.0 formally at a 90% confidence level. Recent parallax determinations made at Lick by Vasilevskls et al. (1975) for three other stars, listed below along with the Mt. Wilson value for U Gem, imply even fainter absolute magnitudes.

scholarly journals The secondary cathode rays expelled from metals by molybdenum K α radiations

1935 ◽  
Vol 149 (868) ◽  
pp. 587-595 ◽  
Keyword(s):  
Magnetic Field ◽  
Recent Work ◽  
Photoelectric Effect ◽  
Specific Charge ◽  
Secondary Electrons ◽  
X Ray ◽  
A Value ◽  
The Mean ◽  
The Absolute ◽  
Gold Platinum

Kretschmar has recently described a series of accurate measurements of the energies of the electrons expelled by molybdenum K α 1 radiations from targets of gold, platinum, silver and copper. He deduced his electron energies from deflections in an accurately known magnetic field, and it is obviously important to compare his results with those of similar recent work in which other primary radiations (copper and chromium K-rays) were used to excite secondary electrons from the same targets. Kretschmar applies his results to the deduction of a value for the specific charge, e / m 0 , of the electron. In doing this he has to assume a value for e / h , as well as values of X-ray wave-lengths. He eliminates part (not all) of the effect of uncertainty in the absolute values of the wave-lengths by using the X-ray (inverse photoelectric effect) value for e / h . He takes, in fact, e / h = 7·2796 × 10 16 e. s. u. erg -1 sec -1 —the mean of the values given by Duane, Palmer and Yeh and by Feder. He then deduces, as the mean result of his own deflection experiments, 1·757 × 10 7 e. m. u. gm -1 as the most probable value of e / m 0 .

scholarly journals IV. A determination of the electromotive force of the weston normal cell in semi-absolute volts

1914 ◽  
Vol 214 (509-522) ◽  
pp. 147-198 ◽  
Keyword(s):  
Electromotive Force ◽  
Order Of Accuracy ◽  
Absolute Determination ◽  
A Value ◽  
Great Progress ◽  
The Mean ◽  
The Absolute ◽  
The Times ◽  
Made In

The measurement of the E. M. F. of the Weston cell affords the best means of comparing the performances of different methods and instruments for the absolute determination of the ampere. Great progress has been made in the last six years, but the most recent determinations by independent methods, giving equal promise of accuracy, still show discrepancies covering a range of 2 parts in 10,000, which must be debited for the most part to the difficulty of the absolute determination of current. Each method in itself appears to give an order of accuracy of repetition approaching, or even exceeding, 1 in 100,000. It is therefore of special interest and importance to compare the results of methods differing as widely as possible in experimental details in endeavouring to arrive at a value comparatively free from the constant errors which may beset any particular type of method. The measurements described by Mr. Shaw in the following paper were made by the method of the Weber bifilar electrodynamometer, as modified by Clerk Maxwell and Latimer Clark, which has not hitherto been employed for work of the highest accuracy, and which merits attention on account of its many fundamental points of difference from recent methods. The instrument originally supplied to McGill College for this purpose was a faithful copy of Clerk Maxwell’s instrument at Cambridge, of which the theory is given together with a figure and description in his ‘ Electricity and Magnetism,’ vol, 2, p. 367. The chief sources of error in this instru­ment were (1) the uncertainty of insulation of the coils, which proved to be of the order of nearly one half of 1 per cent.; (2) the difficulty of determining the mean radii of the coils, which were wound with silk-covered wire; (3) the want of rigidity of the pulley arrangement for equalising the tensions of the suspending wires, and the imperfect elasticity of the control, which depended too much on torsion, and made it impossible to obtain readings consistent to 1 in 1000 for the deflections or the times of oscillation. These defects were so fatal to accurate work even of the order of 1 in 10,000, which was all that it was originally contemplated, that it was found necessary to reconstruct the instrument entirely until nothing remained of the original except the frame, and even that required stiffening to a material extent.

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.

THE EFFECT OF ALTERATION OF THYROXINE BINDING CAPACITY ON THE DIALYZABLE AND ABSOLUTE FRACTIONS OF TRIIODOTHYRONINE IN CIRCULATION

1973 ◽  
Vol 72 (2) ◽  
pp. 265-271 ◽  
Author(s):  
J. H. Dussault ◽  
D. A. Fisher ◽  
J. T. Nicoloff ◽  
V. V. Row ◽  
R. Volpe
Keyword(s):  
Correlation Coefficient ◽  
Inverse Relationship ◽  
Binding Capacity ◽  
Hormone Concentration ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
A Value ◽  
The Mean ◽  
Male Subjects ◽  
Female Subjects

ABSTRACT In order to determine the effect of alterations in binding capacity of thyroxine binding globulin (TBG) on triiodothyronine (T3) metabolism, studies were conducted in 10 patients with idiopathically low (7 subjects) or elevated (3 subjects) TBG levels and 10 subjects given norethandrolone (7 male subjects) or oestrogen (3 female subjects). Measurements of serum thyroxine (T4) concentration, maximal T4 binding capacity, serum T3 concentration and per cent dialyzable T3 were conducted. Serum T3 was measured both by chemical and radioimmunoassay methods. In patients with idiopathically low TBG, the mean serum T4 concentration was low (2.4 μg/100 ml), the mean serum T3 level low (55 ng/100 ml), the mean per cent dialyzable T3 increased (0.52%), and the calculated free T3 concentration normal (186 pg/100 ml). In patients with idiopathically high TBG levels the mean T4 concentration was high (10.3 μg/100 ml), the mean T3 level slightly elevated (127 ng/100 ml), the% dialyzable T3 low (0.10%) and the calculated free T3 concentration low normal (123 pg/100 ml). The correlation coefficient between the per cent dialyzable T3 and maximal TBG binding capacity in the 20 subjects was 0.68, a value significant at the P < 0.01 level. Thus, alterations in binding capacity of TBG seem to influence T3 and T4 metabolism similarly; the inverse relationship between the % of dialyzable hormone and total hormone concentration tends to keep the absolue levels of free hormones stable.

PENGARUH PENDIDIKAN KESEHATAN REPRODUKSI PADA PEER GROUP (TEMAN SEBAYA) TERHADAP PENGETAHUAN DAN PERSEPSI REMAJA TENTANG PENDEWASAAN USIA PERKAWINAN DI SMA NEGERI 1 KECAMATAN NAMORAMBE KAB. DELI SERDANG 2018

2020 ◽  
Vol 1 (2) ◽  
pp. 56-66
Author(s):  
Irma Linda
Keyword(s):  
Standard Deviation ◽  
Health Education ◽  
Reproductive Health ◽  
Peer Group ◽  
Peer Groups ◽  
A Value ◽  
Significant Difference ◽  
Reproductive Health Education ◽  
The Mean ◽  
Adolescent Perceptions

Background: Early marriages are at high risk of marital failure, poor family quality, young pregnancies at risk of maternal death, and the risk of being mentally ill to foster marriage and be responsible parents. Objective: To determine the effect of reproductive health education on peer groups (peers) on the knowledge and perceptions of adolescents about marriage age maturity. Method: This research uses the Quasi experimental method with One group pre and post test design, conducted from May to September 2018. The statistical analysis used in this study is a paired T test with a confidence level of 95% (α = 0, 05). Results: There is an average difference in the mean value of adolescent knowledge between the first and second measurements is 0.50 with a standard deviation of 1.922. The mean difference in mean scores of adolescent perceptions between the first and second measurements was 4.42 with a standard deviation of 9.611. Conclusion: There is a significant difference between adolescent knowledge on the pretest and posttest measurements with a value of P = 0.002, and there is a significant difference between adolescent perceptions on the pretest and posttest measurements with a value of p = 0.001. Increasing the number of facilities and facilities related to reproductive health education by peer groups (peers) in adolescents is carried out on an ongoing basis at school, in collaboration with local health workers as prevention of risky pregnancy.

The evolution of star formation in QSOs according to WISE

2020 ◽  
Vol 15 (S359) ◽  
pp. 33-34
Author(s):  
K. A. Cutiva-Alvarez ◽  
R. Coziol ◽  
J. P. Torres-Papaqui ◽  
H. Andernach ◽  
A. C. Robleto-Orús
Keyword(s):  
Star Formation ◽  
Gradual Increase ◽  
A Value ◽  
Star Formation Activity ◽  
The Mean ◽  
Lower Redshift

AbstractUsing WISE data, we calibrated the W2-W3 colors in terms of star formation rates (SFRs) and applied this calibration to a sample of 1285 QSOs with the highest flux quality, covering a range in redshift from z ˜ 0.3 to z ˜ 3.8. According to our calibration, the SFR increases continuously, reaching a value at z ˜ 3.8 about 3 times higher on average than at lower redshift. This increase in SFR is accompanied by an increase of the BH mass by a factor 100 and a gradual increase of the mean Eddington ratio from 0.1 to 0.3 up to z ˜ 1.5 – 2.0, above which the ratio stays constant, despite a significant increase in BH mass. Therefore, QSOs at high redshifts have both more active BHs and higher levels of star formation activity.

Interpretation and use of standard atomic weights (IUPAC Technical Report)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Adriaan M. H. van der Veen ◽  
Juris Meija ◽  
Antonio Possolo ◽  
David Brynn Hibbert
Keyword(s):  
Monte Carlo ◽  
Atomic Weight ◽  
Standard Uncertainty ◽  
Uncertainty In Measurement ◽  
Propagation Of Uncertainty ◽  
A Value ◽  
The Monte Carlo Method ◽  
Technical Report ◽  
Molecular Masses ◽  
Expression Of Uncertainty

Abstract Many calculations for science or trade require the evaluation and propagation of measurement uncertainty. Although relative atomic masses (standard atomic weights) of elements in normal terrestrial materials and chemicals are widely used in science, the uncertainties associated with these values are not well understood. In this technical report, guidelines for the use of standard atomic weights are given. This use involves the derivation of a value and a standard uncertainty from a standard atomic weight, which is explained in accordance with the requirements of the Guide to the Expression of Uncertainty in Measurement. Both the use of standard atomic weights with the law of propagation of uncertainty and the Monte Carlo method are described. Furthermore, methods are provided for calculating uncertainties of relative molecular masses of substances and their mixtures. Methods are also outlined to compute material-specific atomic weights whose associated uncertainty may be smaller than the uncertainty associated with the standard atomic weights.

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