scholarly journals Corrections to the Hipparcos proper motions in declination for 807 stars

2008 ◽  
pp. 109-113 ◽  
Author(s):  
G. Damljanovic ◽  
N. Pejovic
Keyword(s):  
Accurate Determination ◽  
Annual Number ◽  
Time Interval ◽  
Proper Motions ◽  
Hipparcos Catalogue ◽  
Time Variations ◽  
Better Than ◽  
Good Agreement

We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations ?? for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years) much longer than that of the Hipparcos mission (less than 4 years). In addition, the annual number of observations for every PZT programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2), aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our ?? and the EOC-2 ones for the star sample used in the present paper.

scholarly journals Astrometric star catalogues as combination of Hipparcos/Tycho catalogues with ground-based observations

2004 ◽  
pp. 1-8 ◽  
Author(s):  
J. Vondrák
Keyword(s):  
Universal Time ◽  
Optical Observations ◽  
Proper Motions ◽  
Earth Orientation ◽  
Optical Wavelength ◽  
Primary Representation ◽  
Hipparcos Catalogue ◽  
Time Variations ◽  
Celestial Reference System ◽  
Better Than

The successful ESA mission Hipparcos provided very precise parallaxes positions and proper motions of many stars in optical wavelength. Therefore it is a primary representation of International Celestial Reference System in this wavelength. However, the shortness of the mission (less than four years) causes some problems with proper motions of the stars that are double or multiple. Therefore, a combination of the positions measured by Hipparcos satellite with ground-based observations with much longer history provides a better reference frame that is more stable in time. Several examples of such combinations are presented (ACT, TYCHO-2, FK6, GC+HIP, TYC2+HIP, ARIHIP) and briefly described. The stress is put on the most recent Earth Orientation Catalogue (EOC) that uses about 4.4 million optical observations of latitude/universal time variations (made during the twentieth century at 33 observatories in Earth orientation programmes), in combination with some of the above mentioned combined catalogues. The second version of the new catalogue EOC-2 contains 4418 objects, and the precision of their proper motions is far better than that of Hipparcos Catalogue.

scholarly journals Using MoS2/Fe3O4 as Ion-Electron Transduction Layer to Manufacture All-Solid-State Ion-Selective Electrode for Determination of Serum Potassium

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 155
Author(s):  
Yan Su ◽  
Ting Liu ◽  
Caiqiao Song ◽  
Aiqiao Fan ◽  
Nan Zhu ◽  
...  
Keyword(s):  
High Performance ◽  
Accurate Determination ◽  
Water Layer ◽  
Ion Selective Electrode ◽  
Potential Response ◽  
Selective Electrode ◽  
Response Measurement ◽  
Long Term Stability

As an essential electrolyte for the human body, the potassium ion (K+) plays many physiological roles in living cells, so the rapid and accurate determination of serum K+ is of great significance. In this work, we developed a solid-contact ion-selective electrode (SC-ISE) using MoS2/Fe3O4 composites as the ion-to-electron transducer to determine serum K+. The potential response measurement of MoS2/Fe3O4/K+-ISE shows a Nernst response by a slope of 55.2 ± 0.1 mV/decade and a low detection limit of 6.3 × 10−6 M. The proposed electrode exhibits outstanding resistance to the interference of O2, CO2, light, and water layer formation. Remarkably, it also presents a high performance in potential reproducibility and long-term stability.

scholarly journals Visualizing the Bohr effect in hemoglobin: neutron structure of equine cyanomethemoglobin in the R state and comparison with human deoxyhemoglobin in the T state

2016 ◽  
Vol 72 (7) ◽  
pp. 892-903 ◽  
Author(s):  
Steven Dajnowicz ◽  
Sean Seaver ◽  
B. Leif Hanson ◽  
S. Zoë Fisher ◽  
Paul Langan ◽  
...  
Keyword(s):  
Structural Changes ◽  
Accurate Determination ◽  
Bohr Effect ◽  
Salt Bridges ◽  
Histidine Residues ◽  
Regions Of Stability ◽  
The Individual ◽  
T State

Neutron crystallography provides direct visual evidence of the atomic positions of deuterium-exchanged H atoms, enabling the accurate determination of the protonation/deuteration state of hydrated biomolecules. Comparison of two neutron structures of hemoglobins, human deoxyhemoglobin (T state) and equine cyanomethemoglobin (R state), offers a direct observation of histidine residues that are likely to contribute to the Bohr effect. Previous studies have shown that the T-state N-terminal and C-terminal salt bridges appear to have a partial instead of a primary overall contribution. Four conserved histidine residues [αHis72(EF1), αHis103(G10), αHis89(FG1), αHis112(G19) and βHis97(FG4)] can become protonated/deuterated from the R to the T state, while two histidine residues [αHis20(B1) and βHis117(G19)] can lose a proton/deuteron. αHis103(G10), located in the α1:β1dimer interface, appears to be a Bohr group that undergoes structural changes: in the R state it is singly protonated/deuterated and hydrogen-bonded through a water network to βAsn108(G10) and in the T state it is doubly protonated/deuterated with the network uncoupled. The very long-term H/D exchange of the amide protons identifies regions that are accessible to exchange as well as regions that are impermeable to exchange. The liganded relaxed state (R state) has comparable levels of exchange (17.1% non-exchanged) compared with the deoxy tense state (T state; 11.8% non-exchanged). Interestingly, the regions of non-exchanged protons shift from the tetramer interfaces in the T-state interface (α1:β2and α2:β1) to the cores of the individual monomers and to the dimer interfaces (α1:β1and α2:β2) in the R state. The comparison of regions of stability in the two states allows a visualization of the conservation of fold energy necessary for ligand binding and release.

scholarly journals Sulfur dioxide layer height retrieval from Sentinel-5 Precursor/TROPOMI using FP_ILM

2019 ◽  
Vol 12 (10) ◽  
pp. 5503-5517 ◽  
Author(s):  
Pascal Hedelt ◽  
Dmitry S. Efremenko ◽  
Diego G. Loyola ◽  
Robert Spurr ◽  
Lieven Clarisse
Keyword(s):  
Sulfur Dioxide ◽  
Accurate Determination ◽  
Volcanic Eruptions ◽  
Critical Parameters ◽  
Layer Height ◽  
Learning Machine ◽  
The Impact ◽  
First Time ◽  
Better Than

Abstract. The accurate determination of the location, height, and loading of sulfur dioxide (SO2) plumes emitted by volcanic eruptions is essential for aviation safety. The SO2 layer height is also one of the most critical parameters with respect to determining the impact on the climate. Retrievals of SO2 plume height have been carried out using satellite UV backscatter measurements, but, until now, such algorithms are very time-consuming. We have developed an extremely fast yet accurate SO2 layer height retrieval using the Full-Physics Inverse Learning Machine (FP_ILM) algorithm. This is the first time the algorithm has been applied to measurements from the TROPOMI instrument onboard the Sentinel-5 Precursor platform. In this paper, we demonstrate the ability of the FP_ILM algorithm to retrieve SO2 plume layer heights in near-real-time applications with an accuracy of better than 2 km for SO2 total columns larger than 20 DU. We present SO2 layer height results for the volcanic eruptions of Sinabung in February 2018, Sierra Negra in June 2018, and Raikoke in June 2019, observed by TROPOMI.

scholarly journals The Hipparcos Extragalactic Link

1995 ◽  
Vol 166 ◽  
pp. 127-132 ◽  
Author(s):  
Jean Kovalevsky
Keyword(s):  
Reference Frames ◽  
Hubble Space Telescope ◽  
Visible Spectrum ◽  
Proper Motions ◽  
Time Intervals ◽  
Hipparcos Catalogue ◽  
Celestial Reference System ◽  
Celestial Reference Frame ◽  
Galactic Radio ◽  
Better Than

In conformity with the IAU resolutions on reference frames adopted in 1991, the Hipparcos catalogue will represent, in the visible spectrum, the celestial reference system defined by fixed positions of extra-galactic radio-sources. This will be realized by the strongest possible link between the IERS celestial reference frame with positions and/or proper motions of the largest possible number of Hipparcos stars determined also with respect to extragalactic objects. The data which will be used must be available before April 1995. It will include the following: positions and proper motions of radio stars observed by VLBI, VLA and MERLIN; photographic positions in fields including quasars; proper motions with respect to galaxies of the Lick, Yale, and Kiev programs, proper motions derived from pairs of photographic plates taken at large time intervals; and possibly data acquired by Hubble Space Telescope and from Earth's rotation data. The organization of the tasks within the working group is briefly described. The final accuracy of the link is expected to be of the order of, or better than, half a milliarcsecond.

The Proton Magnetic Resonance Spectra of some Chlorinated Polycyclodiene Pesticide Metabolites. Rapid Assessment of Stereochemistry

1971 ◽  
Vol 49 (12) ◽  
pp. 1993-2003 ◽  
Author(s):  
J. D. McKinney ◽  
L. H. Keith ◽  
A. Alford ◽  
C. E. Fletcher
Keyword(s):  
Magnetic Resonance ◽  
Accurate Determination ◽  
Rapid Assessment ◽  
Shift Reagent ◽  
Coupling Constant ◽  
Pesticide Metabolites ◽  
Relative Stereochemistry ◽  
Superimposed Signals ◽  
Good Agreement

The rapid and accurate determination of the relative stereochemistry of some postulated chlorinated polycyclodiene pesticide metabolites without excessive dependence on chemical methods is described. Proton assignments were made employing the new nuclear magnetic resonance (n.m.r.) shift reagent, Eu(DPM)3, which effected the separation of superimposed signals in these systems. The assignments based on coupling constant information and requiring spin decoupling equipment are in good agreement with those obtained from the Eu(DPM)3 studies. The data presented establishes the relative stereochemistry of these biologically important compounds and demonstrates the utility of one or both approaches in elucidating their overall structures.

Confirmation of the new technique for measuring the linear thermal expansion of silicon

1993 ◽  
Vol 8 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Liu Fengchao
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Accurate Determination ◽  
Linear Thermal Expansion ◽  
Linear Expansion Coefficient ◽  
X Ray ◽  
High Purity Silicon ◽  
Different Temperatures ◽  
Better Than

This paper further confirms that the direct measurement of diffraction angles at different temperatures by using the X-ray diffractometer is better than measurement of the lattice parameters for the rapid and accurate determination of the linear thermal expansion of silicon. High purity silicon has the linear expansion coefficient, α= (2.45±0.05) × 10−6/°C at room temperature. This value does not change for doped P-type and N-type silicon.

Determination of the flexural stiffness of thin plates from small deflection measurements using optical holography

1982 ◽  
Vol 17 (1) ◽  
pp. 53-61 ◽  
Author(s):  
M J Marchant ◽  
M B Snell
Keyword(s):  
Numerical Method ◽  
Accurate Determination ◽  
Metal Plate ◽  
Thin Plates ◽  
Flexural Stiffness ◽  
Interference Fringes ◽  
Small Deflection ◽  
Stiffness Properties ◽  
Good Agreement

A technique is presented for accurate determination of the flexural stiffness of thin plates using optical holography. Measurements of the interference fringes on thin rhombic plates in anticlastic bending are used to calculate the components of curvature by a simple numerical method Control experiments on a metal plate give good agreement with the results of small deflection bending theory. The method appears ideally suited to the measurement of anisotropic flexural stiffness properties.

The study of regularities of changes in acoustic characteristics depending on microstructure parameters and development of acoustic limit state criterion

2020 ◽  
pp. 32-42
Author(s):  
V. N. Gadalov ◽  
S. V. Safonov ◽  
E. A. Filatov ◽  
O. N. Boldyreva ◽  
I. A. Makarova
Keyword(s):  
Structural Damage ◽  
Limit State ◽  
Acoustic Characteristics ◽  
Term Operation ◽  
Long Run ◽  
Microstructure Parameters ◽  
State Criterion ◽  
Good Agreement

The studies of the dependence of acoustic characteristics on the microstructure of chromium-molybdenum-vanadium steels in various structural states after long term operation are presented. The meaning of the acoustic limit state criterion, which represents a relative assessment of accumulated structural damage of the long run metal for the time delay of ultrasonic Rayleigh waves and determination of the limit state of the material, is revealed. It is established that at the acoustic criterion of the limit state of ≥0.7, the metal is in the state of avalanche creep and reaches the limit state. Measurements of acoustic characteristics gave a good agreement with the results of metallographic studies conducted on sections of metal cuttings. In addition, the criterion was tested when diagnosing technical devices made of steel 15X1M1F, 12X2MFSR, 17GS, 09G2S.

Long-term observations of the strongest inflow branch of warm water to the Arctic Mediterranean

2020 ◽  
Author(s):  
Bogi Hansen ◽  
Karin M. H. Larsen ◽  
Hjálmar Hátún ◽  
Svein Østerhus
Keyword(s):  
Satellite Altimetry ◽  
Saline Water ◽  
Accurate Determination ◽  
Volume Transport ◽  
High Accuracy ◽  
The Arctic ◽  
Boundary Current ◽  
Data Set

<p>Warm and saline water from the North Atlantic enters the Arctic Mediterranean through three gaps. The strongest of these three flows is the inflow between Iceland and Faroes, which is focused into a narrow boundary current north of the Faroes. This boundary current, the Faroe Current, has been observed with regular CTD cruises since 1988 and with moored ADCPs since 1997, as well as satellite altimetry since 1993. Once calibrated by the long-term ADCP measurements, the satellite altimetry is found to yield high-accuracy determination of the velocity field and volume transport down to fixed depth. Due to geostrophic adjustment, satellite altimetry combined with CTD data also allow fairly accurate determination of the depth of the Atlantic layer. From the combined data set, monthly transport time series have been generated for the period Jan 1993 to April 2019. Over the period, the annually averaged volume transport of Atlantic water in the Faroe Current seems to have increased slightly, while the heat transport relative to an outflow temperature of 0°C increased by 13%, significant at the 95% level. The salinity increased from the mid-1990s to around 2010, after which it has decreased, especially after 2016, leading to the lowest salinities in the whole period since 1988. To stay updated on a possible inflow reduction due to reduced thermohaline ventilation caused by this freshening, the future monitoring system of the Faroe Current is planned to be expanded with moored PIES (Pressure Inverted Echo Sounders). An experiment with two PIES in 2017-2019 has documented that these instruments allow high-accuracy monitoring of the depth of the Atlantic layer on the section, which combined with satellite altimetry and CTD observations should give more accurate transport estimates.</p>

Sign in / Sign up

Export Citation Format

Share Document