POTASSIUM–ARGON DATES OF BASIC INTRUSIVE ROCKS OF THE DISTRICT OF MACKENZIE, N.W.T.

1966 ◽  
Vol 3 (3) ◽  
pp. 389-412 ◽  
Author(s):  
Alice Payne Leech
Keyword(s):  
World Wide ◽  
Precise Determination ◽  
Radiometric Dating ◽  
Lake Area ◽  
Tholeiitic Magma ◽  
Slave Province ◽  
Best Value ◽  
The World ◽  
Intrusive Rocks

Samples were taken from diabase dykes and related contact rocks and from a differentiated intrusive body of the District of Mackenzie in the Yellowknife–Prosperous Lake area, the Lac de Gras area, the Point Lake area, and the Tree River – Coronation Gulf area. In addition, several samples were taken from basic intrusions of Ontario, and some of the results obtained from these are included.Radiometric dating by the potassium–argon method indicated at least four periods of diabase dyke intrusion in the Slave Province of the Precambrian shield about 2 200–2 400 m.y. ago, 1 900–2 100 m.y. ago, 1 100–1 200 m.y. ago, and 600–700 m.y. ago. Scatter in the radiometric dates prevents recognition of other possible events by use of the whole-rock method, where the age of intrusion is older than Middle Proterozoic.Chemical and petrologic studies were carried out in conjunction with the radiometric dating. Precise determination of potassium proved difficult; in most cases, a best value for each sample was selected from the results of three independent determinations. There is some suggestion of an increase in the potassium content of diabase dykes in the Canadian shield throughout Precambrian time. Alkali–silica ratios show that all of the diabase dykes studied belong to the world-wide tholeiitic magma type.

New techniques for the determination of surface wave phase velocities

1968 ◽  
Vol 58 (3) ◽  
pp. 1021-1034 ◽  
Author(s):  
S. Bloch ◽  
A. L. Hales
Keyword(s):  
Phase Velocity ◽  
Rayleigh Waves ◽  
World Wide ◽  
Velocity Dispersion ◽  
Cross Product ◽  
New Techniques ◽  
Phase Velocities ◽  
Phase Velocity Dispersion ◽  
The World

abstract A number of new techniques have been developed for the determination of phase velocities from the digitized seismograms from pairs of stations. One of these techniques is to Fourier analyze the sum (or difference) of the two seismograms after time shifting in steps to correspond to steps in phase velocity. The amplitude of the summed seismogram is a maximum for any particular period when both seismograms are in phase at that period. Another method is to pass both seismograms through a narrow bandpass digital filter centered at various periods and form the cross product of the filtered seismograms, after time shifting. The average of the resultant time series is a maximum when the two signals are in phase. The computer output is a matrix consisting of amplitudes or averages as a function of phase velocity and period. The phase velocity dispersion is determined from the contoured matrix. Using these techniques, interstation phase velocities of Rayleigh waves have been determined for the “World Wide Network Standard Stations” at Pretoria, Bulawayo and Windhoek. The method using cross-products is the most efficient.

Megalithic monumentality in Africa: from graves to stone circles at Wanar, Senegal

Antiquity ◽  
2012 ◽  
Vol 86 (332) ◽  
pp. 409-427 ◽  
Author(s):  
L. Laporte ◽  
H. Bocoum ◽  
J-P. Cros ◽  
A. Delvoye ◽  
R. Bernard ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Middle Ages ◽  
Precise Determination ◽  
World Heritage Site ◽  
Burial Ground ◽  
Heritage Site ◽  
The World ◽  
Cutting Out ◽  
The Indian Ocean

The World Heritage Site of Wanar in Senegal features 21 stone circles, remarkable not least because they were erected in the twelfth and thirteenth century AD, when Islam ruled the Indian Ocean and Europe was in its Middle Ages. The state of preservation has benefited the exemplary investigation currently carried out by a French-Senegalese team, which we are pleased to report here. The site began as a burial ground to which monumental stones were added, perhaps echoing the form of original funerary houses. Found in a neighbouring field were scoops left from the cutting out of the cylindrical monoliths from surface rock. While the origins of Wanar lie in a period of state formation, the monuments are shown to have had a long ritual use. The investigation not only provides a new context for one of the most important sites in West Africa but the precise determination of the sequence and techniques used at Wanar offers key pointers for the understanding of megalithic structures everywhere.

Accepting Dominion Status as a Way of Reconciliation of British-Irish Disputes?

2021 ◽  
Vol 14 (1) ◽  
pp. 1-21
Author(s):  
Jaroslav Valkoun
Keyword(s):  
British Empire ◽  
Precise Determination ◽  
Point Of View ◽  
British Colonialism ◽  
The World ◽  
Political Scene

The article is focused on an analysis of British-Irish relations in 1921. From the British point of view, the best solution to the conflict seemed to be the granting of Dominion status. It was based on the assumption that the British Empire represented the largest community of free sister nations in the world. On the contrary, Irish officials did not have the confidence to participate in various colonial or imperial projects because they considered themselves a victim of British colonialism. The question of the accepting of the Dominion status divided the Irish political scene into supporters and opponents of the Anglo-Irish treaty. Supporters of the agreement calmed their own sympathizers by claiming that freedom and equality derive directly from Dominion status. However, the lack of precise determination of the rights and duties of the Dominions was a complication of the situation. The question arises as to whether negotiations on reconciliation between Britain and Ireland led from the British and Irish perspectives, in the context of the then unclear situation of what precisely it means to be a Dominion, to a fair solution to the British-Irish Disputes.

scholarly journals New reproduction number and acceleration parameter introduced and applied to COVID-19

2021 ◽  
Author(s):  
Eckhard Rebhan
Keyword(s):  
Exponential Growth ◽  
Reproduction Number ◽  
Analytical Form ◽  
Precise Determination ◽  
Acceleration Parameter ◽  
Infection Dynamics ◽  
The World

Abstract To characterize the progression of a pandemic, a well interpretable reproduction number is introduced which is easily applicable to many different situations due to its handy analytical form. On the basis of its derivation it can be understood as a cross between a volatile instantaneous reproduction number and the more robust effective reproduction number commonly used. Starting from it, a further quantity, termed acceleration parameter, is introduced, which facilitates a more differentiated characterization of the infection dynamics. In particular, it enables the precise determination of when the limit to exponential growth is reached and exceeded. A variety of possible developments is examined, including linear and exponential growth of the infection numbers as well as sub- and super-exponential growth. It turned out useful to incorporate the incidence as a further epidemiological indicator. It is used for calculating the trace that the progression of the pandemic leaves behind on a plain spanned by itself and the acceleration parameter. This plane can be divided into a dangerous area, where the pandemic becomes uncontrollable, and a safer area that must be the target of mitigation efforts. At present, many countries and the world as a whole are mired in the dangerous area.

Polyclonal antibodies against fusaproliferin

1999 ◽  
Vol 45 (1) ◽  
pp. 45-50 ◽  
Author(s):  
Simona M Monti ◽  
Vincenzo Fogliano ◽  
Giacomino Randazzo ◽  
Giuseppe Peluso ◽  
Antonio Logrieco ◽  
...  
Keyword(s):  
World Wide ◽  
Polyclonal Antibodies ◽  
Fusarium Proliferatum ◽  
Competitive Elisa ◽  
Toxic Metabolite ◽  
Teratogenic Effects ◽  
Toxic Activity ◽  
High Background ◽  
The World

Fusaproliferin (FP), a toxic metabolite of the world-wide maize pathogens Fusarium proliferatum and Fusarium subglutinans, was recently found to be a natural contaminant of maize. Its toxic activity on haematopoietic human cell lines and its teratogenic effects on chicken embryos has been recently proved. Therefore a sensitive, rapid, and inexpensive screening test to detect FP in agricultural commodities is necessary to protect human health. FP-hemiglutarate conjugated to modified bovine serum albumin was synthesized, characterized, and used as an antigen for raising polyclonal antibodies by immunizing rabbits. Indirect and competitive ELISA and immunoblotting analyses were performed to determine antibody specificity towards the mycotoxin. The determination of 10 µg of free FP/mL was achieved using antibodies purified by means of affinity chromatography on a FP-lysine-Sepharose column. This unsatisfactory detection limit is due to high background values; thus, this method is not competitive with traditional UV-HPLC methods.Key words: fusaproliferin, ELISA, mycotoxin, immunoassay, corn, Fusarium.

Gene homology resources on the World Wide Web

2002 ◽  
Vol 11 (3) ◽  
pp. 165-177 ◽  
Author(s):  
Alexander Turchin ◽  
Isaac S. Kohane
Keyword(s):  
Systematic Review ◽  
World Wide Web ◽  
Sequence Homology ◽  
World Wide ◽  
Evolutionary Development ◽  
Unit Of Analysis ◽  
The Public ◽  
The World ◽  
Gene Homology

As the amount of information available to biologists increases exponentially, data analysis becomes progressively more challenging. Sequence homology has been a traditional tool in the researchers’ armamentarium; it is a very versatile instrument and can be employed to assist in numerous tasks, from establishing the function of a gene to determination of the evolutionary development of an organism. Consequently, numerous specialized tools have been established in the public domain (most commonly, the World Wide Web) to help investigators use sequence homology in their research. These homology databases differ both in techniques they use to compare sequences as well as in the size of the unit of analysis, which can be the whole gene, a domain, or a motif. In this paper, we aim to present a systematic review of the inner details of the most commonly used databases as well as to offer guidelines for their use.

scholarly journals Classical Cepheids and Galactic Structure

1995 ◽  
Vol 155 ◽  
pp. 155-164
Author(s):  
J.D. Fernie
Keyword(s):  
World Wide Web ◽  
Recent Work ◽  
World Wide ◽  
Galactic Plane ◽  
Galactic Structure ◽  
Space Distribution ◽  
Galactic Centre ◽  
Classical Cepheids ◽  
The World

AbstractIn this review I consider recent results on the space distribution of classical Cepheids, first dealing with their Z-distribution normal to the galactic plane, and second considering their X,Y components in the plane. In doing so, use is made of a new database of 505 stars known to be or likely to be classical Cepheids which has recently been compiled by Fernie et al. (1995) and which is available electronically on the World Wide Web at the URL http://ddo.astro.utoronto.ca/cepheids.html, and by anonymous ftp at perseus.astro.utoronto.ca (128.100.77.18) in the directory pub/cepheids.Following the discussion of space distribution, a review of recent work on Cepheid kinematics and the resulting determination of the distance to the galactic centre will be given.

Rotational Characteristics of the Green Solar Corona: 1947-1991

1994 ◽  
Vol 144 ◽  
pp. 139-141 ◽  
Author(s):  
J. Rybák ◽  
V. Rušin ◽  
M. Rybanský
Keyword(s):  
Solar Corona ◽  
World Wide ◽  
Rotation Period ◽  
Original Data ◽  
Coronal Emission ◽  
Time Intervals ◽  
Data Set ◽  
The World ◽  
Coronal Emission Line ◽  
Homogeneous Data

AbstractFe XIV 530.3 nm coronal emission line observations have been used for the estimation of the green solar corona rotation. A homogeneous data set, created from measurements of the world-wide coronagraphic network, has been examined with a help of correlation analysis to reveal the averaged synodic rotation period as a function of latitude and time over the epoch from 1947 to 1991.The values of the synodic rotation period obtained for this epoch for the whole range of latitudes and a latitude band ±30° are 27.52±0.12 days and 26.95±0.21 days, resp. A differential rotation of green solar corona, with local period maxima around ±60° and minimum of the rotation period at the equator, was confirmed. No clear cyclic variation of the rotation has been found for examinated epoch but some monotonic trends for some time intervals are presented.A detailed investigation of the original data and their correlation functions has shown that an existence of sufficiently reliable tracers is not evident for the whole set of examinated data. This should be taken into account in future more precise estimations of the green corona rotation period.

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