scholarly journals Vibrational Correction for Methylamine and Determination of the Zero-Point Average Structure

1986 ◽  
Vol 59 (3) ◽  
pp. 853-858 ◽  
Author(s):  
Takao Iijima
Keyword(s):  
Zero Point ◽  
Average Structure ◽  
Vibrational Correction

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.

Vibrational Properties of the Isotopomers of the Water Dimer Derived from Experiment and Computations

2014 ◽  
Vol 67 (3) ◽  
pp. 426 ◽  
Author(s):  
Robert Kalescky ◽  
Wenli Zou ◽  
Elfi Kraka ◽  
Dieter Cremer
Keyword(s):  
Binding Energy ◽  
Zero Point ◽  
Binding Energies ◽  
Water Dimer ◽  
General Observation ◽  
Reduced Pressure ◽  
Point Energy ◽  
Deuterium Substitution ◽  
Mass Increase

The water dimer and its 11 deuterated isotopomers are investigated utilizing coupled cluster theory and experimental data as input for a perturbational determination of the isotopomer frequencies. Deuterium substitution reduces the H-bond stretching frequency by maximally 12 cm–1 from 143 to 131 cm–1, which makes a spectroscopic differentiation of H- and D-bonds difficult. However, utilizing the 132 frequencies obtained in this work, the identification of all isotopomers is straightforward. The CCSD(T)/CBS value of the binding energy De is 5.00 kcal mol–1. The binding energy D0 of the water dimer increases upon deuterium substitution from 3.28 to maximally 3.71 kcal mol–1 reflecting a decrease in the zero point energy contribution. The entropy values of the D-isotopomers increase from 73 to 77 entropy units in line with the general observation that a mass increase leads to larger entropies. All 12 isotopomers possess positive free binding energies at 80 K and a reduced pressure of 110 Pa, which means that they can be spectroscopically observed under these conditions.

scholarly journals ON DETERMINATION OF THE GEOMETRIC COSMOLOGICAL CONSTANT FROM THE OPERA EXPERIMENT OF SUPERLUMINAL NEUTRINOS

2012 ◽  
Vol 27 (11) ◽  
pp. 1250041 ◽  
Author(s):  
MU-LIN YAN ◽  
SEN HU ◽  
WEI HUANG ◽  
NENG-CHAO XIAO
Keyword(s):  
Dark Energy ◽  
Cosmological Constant ◽  
Fundamental Constant ◽  
Zero Point ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Point Energy ◽  
Sitter Spacetime ◽  
Effective Cosmological Constant

The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant Λ eff which is the sum of the quantum zero point energy Λ dark energy and the geometric cosmological constant Λ. The OPERA experiment can be applied to determine the geometric cosmological constant Λ. It is the first study to distinguish the contributions of Λ and Λ dark energy from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter spacetime symmetry.

scholarly journals The interpretation and analysis of diffuse scattering using Monte Carlo simulation methods

2007 ◽  
Vol 64 (1) ◽  
pp. 23-32 ◽  
Author(s):  
T. R. Welberry ◽  
D. J. Goossens
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Diffuse Scattering ◽  
Simulation Methods ◽  
Neutron Sources ◽  
X Ray ◽  
Average Structure

Studies of diffuse scattering had a prominent place in the first issue ofActa Crystallographica60 years ago at a time when conventional crystallography (determination of the average structure from Bragg peaks) was in its infancy. Since that time, conventional crystallography has developed enormously while diffuse-scattering analysis has seemingly lagged well behind. The paper highlights some of the extra difficulties involved in the measurement, interpretation and analysis of diffuse scattering and plots the progress that has been made. With the advent of the latest X-ray and neutron sources, area detectors and the ever-increasing power of computers, most disorder problems are now tractable. Two recent contrasting examples are described which highlight what can be achieved by current methods.

Recently Developed Distance Criteria

1983 ◽  
Vol 6 ◽  
pp. 289-300 ◽  
Author(s):  
G. Paturel
Keyword(s):  
Globular Clusters ◽  
Zero Point ◽  
Great Distance ◽  
Distance Scale ◽  
The Earth ◽  
Distant Galaxies ◽  
Preceding Step ◽  
External Galaxies ◽  
Nearby Galaxies

The problem of the determination of distances in astronomy (the so-called problem of the distance scale) is a very old and important problem. About 280 BC Aristarchus of Samos, the famous greek astronomer of the Alexandrian school, already devised a method to find the relative distances to the Sun and Moon in terms of the size of the Earth. Later, Eratosthenes (about 200 BC), another greek astronomer, measured the Earth’s diameter; so the zero-point of this first distance scale was fixed.Now we are interested by extragalactic distances but the same approach is made : (i) determination of relative distances (ii) determination of the zero-point to obtain absolute distances.Some distance criteria can be used to determine the zero-point. These criteria cannot generally be used at a great distance. They permit a comparison between galactic objects, like Cepheids, Novae, Supergiants ..., globular clusters..., and the same counterparts recognized in external galaxies. Often application is limited to nearby galaxies. In a first section we will briefly present this kind of distance criteria. For more distant galaxies other criteria must be employed, the zero-point being here fixed with nearby galaxies whose distances are known from the preceding step. We will discuss these criteria in a second section.

Determination of the effective zero point of contact for spherical nanoindentation

2008 ◽  
Vol 23 (1) ◽  
pp. 204-209 ◽  
Author(s):  
Alexander J. Moseson ◽  
Sandip Basu ◽  
Michel W. Barsoum
Keyword(s):  
Accurate Determination ◽  
Zero Point ◽  
Sample Surface ◽  
Fused Silica ◽  
Contact Radius ◽  
Stiffness Measurement ◽  
Continuous Stiffness Measurement ◽  
First Contact ◽  
Versus Strain

Accurate determination of the “zero point,” the first contact between an indenter tip and sample surface, has to date remained elusive. In this article, we outline a relatively simple, objective procedure by which an effective zero point can be determined accurately and reproducibly using a nanoindenter equipped with a continuous stiffness measurement option and a spherical tip. The method relies on applying a data shift, which ensures that curves of stiffness versus contact radius are linear and go through the origin. The method was applied to fused silica, sapphire single crystals, and polycrystalline iron with various indenter sizes to a zero-point resolution of ≈2 nm. Errors of even a few nanometers can drastically alter plots and calculations that use the data, including curves of stress versus strain.

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