Frequency Stability of Quartz Crystals at Very Low Temperatures: Preliminary Results

1984 ◽  
Author(s):  
G. Robichon ◽  
J. Groslambert ◽  
J.J. Gagnepain
Keyword(s):  
Low Temperatures ◽  
Frequency Stability ◽  
Quartz Crystals ◽  
Preliminary Results

Dielectric Loss in Li- and Na-Swept α-Quartz and the Effect of Irradiation

1983 ◽  
Vol 24 ◽  
Author(s):  
J. Toulouse ◽  
A.S. Nowick
Keyword(s):  
Dielectric Loss ◽  
Low Temperature ◽  
Low Temperatures ◽  
Quantum Effects ◽  
Frequency Stability ◽  
Distorted Tetrahedron ◽  
High Quality ◽  
Quartz Crystals ◽  
Alkali Ions ◽  
Synthetic Crystals

ABSTRACTAlkali ions, which compensate for substitional Al3+, play an important role in the frequency stability of α-quartz crystals. In this work, low temperature dielectricloss measurements (between 2.9 and 300 K) are carried out on crystals that have been “swept” so as to introduce either Li+ or Na+. High quality synthetic crystals as well as natural crystals are employed. The well known loss peaks due to Al-Na pairs are further explored and similar peaks due to Al-Li are sought after but not found. It is concluded that the Al-Li pair is oriented along the C2 -axis of the A104 distorted tetrahedron. After irradiation, large peaks are observed at very low temperatures both in Li+- and Na+-containing crystals. These peaks, which are distorted below ∼6 K due to the onset of quantum effects, may originate in alkali centers produced when alkali ions are liberated by the irradiation.

scholarly journals TOPOCLIMATIC EFFECTS ON SPRING FREEZE CHARACTERISTICS AND PEACH PHENOLOGY

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 751A-751
Author(s):  
Joanne Logan ◽  
Michael J. Searcy
Keyword(s):  
Low Temperatures ◽  
Weather Station ◽  
Bud Development ◽  
Preliminary Results ◽  
The Past ◽  
Weather Stations ◽  
East Tennessee ◽  
Peach Trees ◽  
Peach Orchard

Peach production in Tennessee has suffered a decline in the past decade due to late and severe spring freezes. East Tennessee is an area of diverse topography. It may be possible to use topoclimate exposure to ameliorate the low temperatures in spring and therefore lessen the damage to peach buds. Exposure also may also influence the accumulation of chill units and growing degrees, therefore affecting the stage of peach bud development when the freeze occurs. Five automated weather stations were located in topoclimatically different areas of a peach orchard in Dandridge, Tennessee, from September, 1990 to May, 1991. Hourly chill units (base 6.1 °C) and growing degrees (base4.4 °C) were calculated. Twigs from peach trees close to each weather station were forced every three days to determine the date of completion of rest. Hourly freeze data were collected from each weather station. Preliminary results on the effects of topoclimate on spring freeze characteristics, accumulation of chill units and growing degrees, and peach phenology will be presented.

Compaction of icy/rocky porous mixtures at low temperatures (from 262K TO 77K) - preliminary results

1990 ◽  
Vol 5 (1-6) ◽  
pp. 696-698 ◽  
Author(s):  
J. Leliwa-kopystynski ◽  
S. Murakami ◽  
Y. Mizuno ◽  
N. Maeno ◽  
N. Bakun-czubarow
Keyword(s):  
Low Temperatures ◽  
Preliminary Results

THE ELECTRICAL RESISTANCE OF DILUTE COPPER ALLOYS AT VERY LOW TEMPERATURES

1955 ◽  
Vol 33 (3-4) ◽  
pp. 119-124 ◽  
Author(s):  
Guy K. White
Keyword(s):  
Electrical Resistance ◽  
Low Temperatures ◽  
Copper Alloys ◽  
Preliminary Results ◽  
Adiabatic Demagnetization

An adiabatic demagnetization cryostat for the measurement of electrical resistance of metals is described. Some preliminary results on copper containing small amounts of iron and tin are reported. These indicate that the rise in electrical resistance below the minimum is essentially complete in these specimens by ~ 2° K.

scholarly journals MICROSPECTROPHOTOMETRY OF CYTOCHROMES IN THE SINGLE CELL AT ROOM AND LIQUID NITROGEN TEMPERATURES

1965 ◽  
Vol 26 (3) ◽  
pp. 741-746 ◽  
Author(s):  
B. Thorell ◽  
B. Chance ◽  
V. Legallais
Keyword(s):  
Low Temperature ◽  
Single Cell ◽  
Liquid Nitrogen ◽  
Low Temperatures ◽  
Room Temperature ◽  
Single Cells ◽  
Visible Region ◽  
Absorption Bands ◽  
Preliminary Results ◽  
Favorable Conditions

By increasing further the sensitivity of microspectrophotometry, it is now possible to measure, under favorable conditions, the smaller absorption bands of the respiratory pigments of single cells in the visible region of the spectrum. A considerable aid in the distinction between cytochromes is afforded by liquid nitrogen microspectrophotometry. Under favorable conditions, the height of the peaks is increased over 8-fold at low temperatures. In diploid yeast, characteristically sharpened components not resolvable at room temperature are observed at low temperature; and in pentaploid yeast, a hitherto unrecognized pigment is observed at 583 mµ. These preliminary results indicate the feasibility and the value of low temperature microspectrophotometry of biological materials.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

Cyclic Evolution of Sunspots: Gleaning New Results from Old Data

2000 ◽  
Vol 179 ◽  
pp. 163-165
Author(s):  
S. K. Solanki ◽  
M. Fligge ◽  
P. Pulkkinen ◽  
P. Hoyng
Keyword(s):  
Sunspot Number ◽  
Sunspot Cycle ◽  
Preliminary Results ◽  
Butterfly Diagram

AbstractThe records of sunspot number, sunspot areas and sunspot locations gathered over the centuries by various observatories are reanalysed with the aim of finding as yet undiscovered connections between the different parameters of the sunspot cycle and the butterfly diagram. Preliminary results of such interrelationships are presented.

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

Quantitative Measurements on the Ion Etching of TMV

1973 ◽  
Vol 31 ◽  
pp. 336-337
Author(s):  
Irwin Bendet ◽  
Nabil Rizk
Keyword(s):  
Electron Microscope ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Ion Current ◽  
Beam Diameter ◽  
Ion Etching ◽  
Preliminary Results ◽  
Quantitative Measurements ◽  
Monitoring Devices

Preliminary results reported last year on the ion etching of tobacco mosaic virus indicated that the diameter of the virus decreased more rapidly at 10KV than at 5KV, perhaps reaching a constant value before disappearing completely.In order to follow the effects of ion etching on TMV more quantitatively we have designed and built a second apparatus (Fig. 1), which incorporates monitoring devices for measuring ion current and vacuum as well as accelerating voltage. In addition, the beam diameter has been increased to approximately 1 cm., so that ten electron microscope grids can be exposed to the beam simultaneously.

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