scholarly journals 34. Meteor mass distribution from underdense-trail echoes

1968 ◽  
Vol 33 ◽  
pp. 362-372 ◽  
Author(s):  
M. Šimek ◽  
B.A. McIntosh
Keyword(s):  
High Power ◽  
Statistical Error ◽  
Total Sample ◽  
Logarithmic Scale ◽  
Line Density ◽  
A Value ◽  
Electron Line ◽  
The Mean ◽  
Image Position

The amplitude of meteor echoes is recorded on a logarithmic scale by a high-power radar equipment (λ = 9·2 m, PT=3 MW, G = 5·6) at Springhill Meteor Observatory near Ottawa. The smallest amplitude measured corresponds to a pulse power of 10−12 W, which represents a minimum electron line density of about 7 × 1011 el/m or a radio magnitude of + 10.Distribution curves of number of echoes as a function of echo power have been obtained from some 50 samples of 500 meteors each, at various times of day on about 1 day per month. The slopes showed little variation throughout the year. The statistical error in the slope value for any one sample was small, ~ 2–3%. However, determination of the mass index s from these slopes involves several problems. On the basis of simplest theory we have obtained for the sporadic background, with no definite seasonal or diurnal variation.During shower periods, lower values of s were obtained. For the 1966 Leonids, s for the shower was determined by estimating the percentage of shower meteors in the total sample. A value s = 1·7 ± 0·1 was obtained as the mean of 6 samples. It is not known to what extent the height-ceiling effect influences the observation of this shower.

scholarly journals Effect of the New Equinox Definition on the Zero-Point of Longitude of the Indian Calendar

1990 ◽  
Vol 141 ◽  
pp. 186-186
Author(s):  
A. K. Bhatnagar
Keyword(s):  
Initial Point ◽  
Zero Point ◽  
The Mean ◽  
Image Position ◽  
Calendar Reform

Indian calendars follow a sidereal system of astronomy taking a fixed initial point on the ecliptic as the origin from which the longitudes are measured. Its position for the official Indian Calendar has been defined by the Calendar Reform Committee (1955) as the point on the ecliptic whose true tropical longitude was 23°15′00″ as on 21 March 1956, 0h UT. Its position was determined upto the year 1984 in accordance with Newcomb's value for general precession using the relation where T is in centuries of 36525 ephemeris days from 1900 January 0.5 ET. Recent changes in the location and the motion of the equinox with reference to the epoch J2000.0 have necessitated corresponding changes to be included in the determination of the mean and true positions of the above initial point. The new algorithm worked out is where T is in Julian centuries of 36525 days from J2000.0.

Regulatory Agency Acceptance of the Interpretation of the Freezing Point Value of Milk as Part of the Official Thermistor Cryoscopic Method

1970 ◽  
Vol 53 (3) ◽  
pp. 539-542
Author(s):  
R W Henningson
Keyword(s):  
Milk Sample ◽  
North American ◽  
Freezing Point ◽  
Sample Survey ◽  
Regulatory Agencies ◽  
A Value ◽  
Added Water ◽  
The Mean ◽  
Definition Of

Abstract A 1968 North American authentic milk sample survey determined that the mean freezing point value of milk is –0.5404°C. Statistical concepts permit the calculation of a value, –0.525°C, 2.326 standard deviations from a mean with 95% confidence that 99% of all subsequent observations will be below the value. Based on this survey, it was recommended that the Interpretation of the freezing point value of milk be made a part of the official final action thermistor cryoscopic method for the determination of the freezing point value of milk, and include the following: an upper limit for the freezing point value of milk, an official definition of an authentic milk sample, and a logical procedure for the confirmation of added water. A copy of the report and an explanatory letter were sent to approximately 100 North American regulatory agencies. Reports were received from 49 regulatory agencies with 39 favoring the recommendations, 6 opposing the recommendations, and 4 having no opinion. It is recommended that the Interpretation of the freezing point of milk be included in both the thermistor cryoscopic and the Hortvet methods.

scholarly journals Some Problems Connected with the Calculation of Stop Loss Premiums for Large Portfolios

1967 ◽  
Vol 4 (2) ◽  
pp. 170-174 ◽  
Author(s):  
Fredrik Esscher
Keyword(s):  
Distribution Function ◽  
Expected Number ◽  
Limit Values ◽  
Empirical Determination ◽  
The Mean ◽  
Premium Rates ◽  
Image Position ◽  
Stop Loss ◽  
The Given

When experience is insufficient to permit a direct empirical determination of the premium rates of a Stop Loss Cover, we have to fall back upon mathematical models from the theory of probability—especially the collective theory of risk—and upon such assumptions as may be considered reasonable.The paper deals with some problems connected with such calculations of Stop Loss premiums for a portfolio consisting of non-life insurances. The portfolio was so large that the values of the premium rates and other quantities required could be approximated by their limit values, obtained according to theory when the expected number of claims tends to infinity.The calculations were based on the following assumptions.Let F(x, t) denote the probability that the total amount of claims paid during a given period of time is ≤ x when the expected number of claims during the same period increases from o to t. The net premium II (x, t) for a Stop Loss reinsurance covering the amount by which the total amount of claims paid during this period may exceed x, is defined by the formula and the variance of the amount (z—x) to be paid on account of the Stop Loss Cover, by the formula As to the distribution function F(x, t) it is assumed that wherePn(t) is the probability that n claims have occurred during the given period, when the expected number of claims increases from o to t,V(x) is the distribution function of the claims, giving the conditioned probability that the amount of a claim is ≤ x when it is known that a claim has occurred, andVn*(x) is the nth convolution of the function V(x) with itself.V(x) is supposed to be normalized so that the mean = I.

Measurement of radio-meteor ionization profiles

1969 ◽  
Vol 47 (14) ◽  
pp. 1467-1473 ◽  
Author(s):  
J. Jones
Keyword(s):  
Ambipolar Diffusion ◽  
Line Density ◽  
Automatic Determination ◽  
Density Profiles ◽  
Electron Line ◽  
Cosmic Noise

The theory of a method for the determination of electron line density profiles of underdense radio meteors is developed, and the effects of cosmic noise, winds in the meteor region, and ambipolar diffusion on the measured profiles are estimated. The design of a device for the automatic determination of radiometeor ionization profiles is described, together with some results obtained using it in conjunction with the Ottawa–London (Ontario) backscatter system.

Determination of mean inner potential and thickness in wedge shaped specimens by interferometry and electron holography

1992 ◽  
Vol 50 (2) ◽  
pp. 990-991
Author(s):  
R.A. Herring ◽  
T. Tanji ◽  
A. Tonomura
Keyword(s):  
Microstructural Analysis ◽  
Electron Holography ◽  
Relativistic Energy ◽  
Fringe Shift ◽  
Holographic Image ◽  
Energy Correction ◽  
The Mean ◽  
Image Position

Knowlege of a specimens' mean innner potential and thickness is important for many purposes including holography, analytical (AEM) and microstructural analysis. This paper shows that both electron interferometry and holography can easily be used to determine the mean inner potential, as well as, the thickness at every point within a TEM specimen. The relative fringe shift, Δs/s , in a hologram by an object is linearly proportional to the object's mean inner potential, V, and thickness, d, and is given by,where C is considered a constant and described by the relativistic energy correction divided by the acceleration energy, E, and wavelength, λ, i.e. [(1 + eE/mc2)/(l + eE/2mc2)/2Eλ]. Inorder to separate d and V another holographic image is required to provide another image equation. This image equation is easily provided by rotating the specimen a known angle, Δθ, such that d becomes a function of Δθ.

scholarly journals Defining normal jugular venous pressure with ultrasonography

CJEM ◽  
2010 ◽  
Vol 12 (04) ◽  
pp. 320-324 ◽  
Author(s):  
Steven J. Socransky ◽  
Ray Wiss ◽  
Ron Robins ◽  
Alexandre Anawati ◽  
Marc-Andre Roy ◽  
...  
Keyword(s):  
Physical Examination ◽  
Interrater Reliability ◽  
Venous Pressure ◽  
Jugular Venous Pressure ◽  
Normal Range ◽  
Convenience Sample ◽  
A Value ◽  
The Mean ◽  
Research Assistants

ABSTRACT Objective: Determination of jugular venous pressure (JVP) by physical examination (E-JVP) is unreliable. Measurement of JVP with ultrasonography (U-JVP) is easy to perform, but the normal range is unknown. The objective of this study was to determine the normal range for U-JVP. Methods: We conducted a prospective anatomic study on a convenience sample of emergency department (ED) patients over 35 years of age. We excluded patients who had findings on history or physical examination suggesting an alteration of JVP. With the head of the bed at 45°, we determined the point at which the diameter of the internal jugular vein (IJV) began to decrease on ultrasonography (“the taper”). Research assistants used 2 techniques to measure U-JVP in all participants: by measuring the vertical height (in centimetres) of the taper above the sternal angle, and adding 5 cm; and by recording the quadrant in the IJV's path from the clavicle to the angle of the jaw in which the taper was located. To determine interrater reliability, separate examiners measured the U-JVP of 15 participants. Results: We successfully determined the U-JVP of all 77 participants (38 male and 39 female). The mean U-JVP was 6.35 (95% confidence interval 6.11–6.59) cm. In 76 participants (98.7%), the taper was located in the first quadrant. Determination of interrater reliability found κ values of 1.00 and 0.87 for techniques 1 and 2, respectively. Conclusion: The normal U-JVP is 6.35 cm, a value that is slightly lower than the published normal E-JVP. Interrater reliability for U-JVP is excellent. The top of the IJV column is located less than 25% of the distance from the clavicle to the angle of the jaw in the majority of healthy adults. Our findings suggest that U-JVP provides the potential to reincorporate reliable JVP measurement into clinical assessment in the ED. However, further research in this area is warranted.

scholarly journals 47. Cosmology

1976 ◽  
Vol 16 (3) ◽  
pp. 137-157
Author(s):  
M. S. Longair
Keyword(s):  
Deceleration Parameter ◽  
Hubble Constant ◽  
Density Parameter ◽  
Massive Galaxies ◽  
A Value ◽  
The Mean ◽  
Points Of View ◽  
The Universe

A major procedural advance in the determination of the H0 and Ω has been that the problem is now being attacked from many different points of view and to some extent the observations are converging on preferred values of H0 and Ω (Ω = density parameter = 8πGρ0/3H0 where ρ0 is the mean density of matter in the Universe and H0 is the Hubble constant; Ω = 2q0 where q0 is the deceleration parameter). The classical approaches through the redshift-magnitude relation for the most massive galaxies in clusters suggest a value of H0 = 60 km s-1 Mpc (see the review by Tammann in IAU Symp. 63).

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.

The determination of convex bodies from the mean of random sections

1992 ◽  
Vol 112 (2) ◽  
pp. 419-430 ◽  
Author(s):  
Paul Goodey ◽  
Wolfgang Weil
Keyword(s):  
Convex Bodies ◽  
Random Set ◽  
Compact Sets ◽  
Random Line ◽  
Random Sections ◽  
The Mean ◽  
Linear Sections ◽  
Image Position ◽  
Interior Points

Random sectioning of particles (compact sets in ℝ3 with interior points) is a familiar procedure in stereology where it is used to estimate particle quantities like volume or surface area from planar or linear sections (see, for example, the survey [23] or the book [20]). In the following, we study the problem whether the whole shape of a convex particle K can be estimated from random sections. If E is an IUR (isotropic, uniform, random) line or plane intersecting K then the intersection Xk = K ∩ E is a (k-dimensional, k = 1 or 2) random set. It is clear that the distribution of Xk determines K uniquely and that if E1,…, En are such flats, the most natural estimator for K would be the convex hull

scholarly journals Asteroid Masses and Densities

1971 ◽  
Vol 12 ◽  
pp. 33-39 ◽  
Author(s):  
Joachim Schubart
Keyword(s):  
Total Mass ◽  
Direct Determination ◽  
Absolute Magnitude ◽  
Strong Increase ◽  
Minor Planets ◽  
Solar Mass ◽  
A Value ◽  
The Mean ◽  
The Masses

Before 1966, when Hertz (1966) published his first direct determination of the mass of Vesta, all our knowledge on asteroid masses was based on estimates. The masses of the first four minor planets resulted from the measured diameters by Barnard (1900) (see the paper by Dollfus in this volume) and from estimated mean densities. The diameters of the smaller objects were derived from their brightness and an estimate of their reflectivity (usually the reflectivity of the Moon was adopted). In 1901, Bauschinger and Neugebauer (1901) derived a value for the total mass of the first 458 asteroids. All the diameters were computed from the brightness with an assumed value for the reflectivity. The diameter of Ceres found in this way is very close to Barnard’s (1900) value. The mean density of the 458 asteroids was put equal to that of Earth, and their total mass resulted as 3 X 10-9 solar mass. Stracke (1942) used the same method with an increased material, but the addition of more than 1000 faint asteroids did not bring a significant change in the estimate of the total mass. The report on the McDonald asteroid survey (Kuiper et al., 1958) does not contain another estimate of the total mass of the asteroid ring, but it points to the possibility of a very rapid increase in the number of asteroids with decreasing absolute brightness. If this increase is strong enough, each interval of 1 mag in absolute magnitude can contribute the same amount to the total mass. In the range of magnitudes covered by the Palomar-Leiden survey (PLS) (van Houten et al., 1970), there are no indications for such a strong increase.

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