scholarly journals Stellar distance and velocity (III)

2021 ◽  
Vol 19 ◽  
pp. 142-155
Author(s):  
Miloš Čojanović
Keyword(s):  
Real Data ◽  
The Sun ◽  
Standard Methods ◽  
The Third ◽  
Correct Method

The use of parallax angles is one of the standard methods for determining stellar distance. The problem that arises in using this method is how to measure that angle. In order for the measurement to be correct, it is necessary for the object we are observing to be stationary in relation to the sun. This is generally not true. One way to overcome this problem is to observe the object from two different places at the same time. This would be technically possible but will probably never be realized. Another way to determine the distance is given in [1]. With certain assumptions, this is a mathematically completely correct method. After the publication of the third Gaia's catalog [2], we are now able to test the proposed method using real data. Unfortunately, for the majority of stars it is not possible to obtain the distance directly, but with the help of some additional measurements we would be able to indirectly determine the distance of such stars.

scholarly journals Models for Chromatid Interference With Applications to Recombination Data

Genetics ◽  
2000 ◽  
Vol 156 (3) ◽  
pp. 1449-1460
Author(s):  
F Teuscher ◽  
G A Brockmann ◽  
P E Rudolph ◽  
H H Swalve ◽  
V Guiard
Keyword(s):  
Real Data ◽  
New Model ◽  
The Third ◽  
Genetic Interference ◽  
Three Components

Abstract Genetic interference means that the occurrence of one crossover affects the occurrence and/or location of other crossovers in its neighborhood. Of the three components of genetic interference, two are well modeled: the distribution of the number and the locations of chiasmata. For the third component, chromatid interference, there exists only one model. Its application to real data has not yet been published. A further, new model for chromatid interference is presented here. In contrast to the existing model, it is assumed that chromatid interference acts only in the neighborhood of a chiasma. The appropriateness of this model is demonstrated by its application to three sets of recombination data. Both models for chromatid interference increased fit significantly compared to assuming no chromatid interference, at least for parts of the chromosomes. Interference does not necessarily act homogeneously. After extending both models to allow for heterogeneity of chromatid interference, a further improvement in fit was achieved.

The ‘Cycle’ of Arignota. Sappho’s frr. 95 and 96 V.

2020 ◽  
Vol 12 (2) ◽  
pp. 203-227
Author(s):  
Kyriakos Tsantsanoglou
Keyword(s):  
The Sun ◽  
Common Theme ◽  
The Third ◽  
Strong Feeling

AbstractAfter preparing a detailed new edition of Sappho’s frr. 95 and 96 V., continuously transmitted in the parchment codex P. Berol. 9722, the author proposes that they constitute a ‘cycle’ of three homometric poems with a common theme articulated in successive episodes (i. 95, ii. 96.1–20, iii. 96.21–36). In the first, Sappho conveys her despair for her separation from her beloved pupils, Arignota being one of them. In the second, Arignota is presented in Sardis, where she excels among the Lydian women. She expresses a strong feeling of nostalgia for her stay in Lesbos with Sappho and for her beloved friend there, Atthis. In the third, Sappho addresses Atthis and, employing the mythological exemplum of Aphrodite’s love to Adonis and their distant meetings, declares that they will sail to the port of Geraistion in Asia Minor’s Aegean coast, whence they will travel to Sardis for meeting their old friend. The author also meditates on the possibility that the name Ἀριγνώτα (= ‘One-easy-to-be-known, Easy-to-identify’), is a renaming by Sappho of Ἀρύηνιc, the daughter of the Lydian king Alyattes, who is yearning to see her old teacher and her childhood girlfriend before her marriage to Astyages, son of Kyaxares, king of the Medes. The marriage was negotiated for ending a many years war between the two nations, a peace that coincided with the eclipse of the sun, usually dated on May 28, 585 BC.

scholarly journals PHL 417: a zirconium-rich pulsating hot subdwarf (V366 Aquarid) discovered in K2 data

2020 ◽  
Vol 499 (3) ◽  
pp. 3738-3748
Author(s):  
R H Østensen ◽  
C S Jeffery ◽  
H Saio ◽  
J J Hermes ◽  
J H Telting ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Helium Abundance ◽  
The Sun ◽  
The Third ◽  
Short Period ◽  
Standard Models ◽  
Hot Subdwarfs ◽  
Amplitude Mode ◽  
Rare Group

ABSTRACT The Kepler spacecraft observed the hot subdwarf star PHL 417 during its extended K2 mission, and the high-precision photometric light curve reveals the presence of 17 pulsation modes with periods between 38 and 105 min. From follow-up ground-based spectroscopy, we find that the object has a relatively high temperature of 35 600 K, a surface gravity of $\log g / {\rm cm\, s^{-2}}\, =\, 5.75$ and a supersolar helium abundance. Remarkably, it also shows strong zirconium lines corresponding to an apparent +3.9 dex overabundance compared with the Sun. These properties clearly identify this object as the third member of the rare group of pulsating heavy-metal stars, the V366-Aquarii pulsators. These stars are intriguing in that the pulsations are inconsistent with the standard models for pulsations in hot subdwarfs, which predicts that they should display short-period pulsations rather than the observed longer periods. We perform a stability analysis of the pulsation modes based on data from two campaigns with K2. The highest amplitude mode is found to be stable with a period drift, $\dot{P}$, of less than 1.1 × 10−9 s s−1. This result rules out pulsations driven during the rapid stages of helium flash ignition.

Invasive Squamous Cell Carcinoma with Osteomyelitis of the Foot

2015 ◽  
Vol 105 (4) ◽  
pp. 374-376
Author(s):  
Morteza Khaladj ◽  
Rose-Mary Mbibong ◽  
Nisha Shah ◽  
Ayesha Mohiuddin ◽  
Aqsa Siddiqui
Keyword(s):  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Chronic Wounds ◽  
Squamous Cell Carcinomas ◽  
Initial Presentation ◽  
Invasive Squamous Cell Carcinoma ◽  
The Sun ◽  
The Third

Squamous cell carcinomas are often seen on the sun-exposed areas of the skin and are rarely observed on the digits of the foot. However, there have been incidences of squamous cell carcinoma developing in the presence of chronic wounds with osteomyelitis, thus complicating the treatment. We present a patient with osteomyelitis who developed invasive squamous cell carcinoma of the third digit. We conclude that wounds with osteomyelitis may have underlying pathologic abnormalities that are not obvious on initial presentation.

General

2017 ◽  
Vol 64 (2) ◽  
pp. 220-238
Author(s):  
Ivana Petrovic ◽  
Andrej Petrovic
Keyword(s):  
The Sun ◽  
Creation Myths ◽  
The Third ◽  
Greco Roman ◽  
Astronomical Instruments ◽  
Music Of The Spheres ◽  
Desert Island ◽  
Complete Translation

If you still haven't chosen a book to take with to the desert island, I have a suggestion: L'encyclopédie du ciel. At 1,202 pages, it will keep you occupied day and night: what you read as text by day will help you read by night in the sky. This wonderful and extremely useful book is as difficult to classify as it is to put down. Essentially, it is a compendium of Greco-Roman discourse on the stars and planets, divided into three parts. The first (‘Les images: histoire et mythologie: voir et raconter’) is about the constellations and the planets. It opens with a catalogue in which each constellation is illustrated, explained, and accompanied with appropriate quotations from Eratosthenes’ Catasterismoi and Hyginus’ Astronomica. There follow essays about the names of the constellations, on the Sun, Moon, and the planets, and one on Greek and Roman creation myths. All are accompanied by long passages of appropriate Greek and Latin texts in translation. The second part of the book (‘Les lois: l'astronomie: observer et calculer’) is about the ancient attempts to make sense of and explain the stars and planets as a system, about calendars, and about ancient astronomical instruments and objects. This part of the book also contains a complete translation of Hipparchus’ Commentary on the Phaenomena of Eudoxus and Aratus. It closes with an account of Greek star catalogues. The third part of the book is concerned with various attempts to interpret the celestial phenomena (‘Les messages: signes et influence: interpréter et prédire’). It includes, but is not restricted to, astrology; philosophical ideas are also discussed, such as astral apotheosis, the ascent of the soul through the sky, and the music of the spheres. There is a dictionary of astronomical and astrological terms and a dictionary of ancient astronomers and authors dealing with astronomy. The book closes with parallel star catalogues of Eratosthenes, Hipparchus, and Ptolemy.

scholarly journals THE LOCATION OF THE XANTHATE GROUPS IN PARTLY SUBSTITUTED CELLULOSE XANTHATES

1957 ◽  
Vol 35 (12) ◽  
pp. 1522-1533 ◽  
Author(s):  
E. P. Swan ◽  
C. B. Purves
Keyword(s):  
Cellulose Acetate ◽  
Chlorine Dioxide ◽  
Methyl Esters ◽  
Lead Tetraacetate ◽  
Degree Of Substitution ◽  
Hydroxyl Groups ◽  
Primary Position ◽  
Standard Methods ◽  
The Third ◽  
Almost All

Cellulose sodium xanthates of degree of substitution (D.S.) 0.4 to 0.66 were methylated to xanthate S-methyl esters which were then acetylated completely, the final xanthate D.S. remaining close to the original value. Dexanthation with aqueous chlorine dioxide near pH 4.5 and −5° removed almost all of the S-methyl xanthate groups, but the loss of a few acetyl groups from, and the retention of 1 to 2% of sulphur in, the resulting cellulose acetate could not be avoided. The original xanthate groups were presumably represented in this acetate as unsubstituted hydroxyl groups, and these were located by standard methods involving tosylation–iodination, tritylation, and oxidations with lead tetraacetate. Xanthate groups appeared to occupy the third and sixth, but not the second, position in the cellulose, and 53 to 61% of the substituent was in the sixth or primary position; one sample of viscose was "ripened" before the cellulose sodium xanthate was isolated, and the value was 81%. The results were of a preliminary nature, because severe technical difficulties reduced their reliability.

scholarly journals Mixture Based Outlier Filtration

10.14311/816 ◽  
2006 ◽  
Vol 46 (2) ◽  
Author(s):  
P. Pecherková ◽  
I. Nagy
Keyword(s):  
Model Identification ◽  
Real Data ◽  
Control Algorithms ◽  
Linear Quadratic ◽  
Process Data ◽  
Linear Quadratic Gaussian ◽  
Standard Methods ◽  
Two Component ◽  
Reconstruction Filter

Success/failure of adaptive control algorithms – especially those designed using the Linear Quadratic Gaussian criterion – depends on the quality of the process data used for model identification. One of the most harmful types of process data corruptions are outliers, i.e. ‘wrong data’ lying far away from the range of real data. The presence of outliers in the data negatively affects an estimation of the dynamics of the system. This effect is magnified when the outliers are grouped into blocks. In this paper, we propose an algorithm for outlier detection and removal. It is based on modelling the corrupted data by a two-component probabilistic mixture. The first component of the mixture models uncorrupted process data, while the second models outliers. When the outlier component is detected to be active, a prediction from the uncorrupted data component is computed and used as a reconstruction of the observed data. The resulting reconstruction filter is compared to standard methods on simulated and real data. The filter exhibits excellent properties, especially in the case of blocks of outliers. 

scholarly journals A Symplectic Mapping Model as a Tool to Understand The Dynamics of 2/1 Resonant Asteroid Motion

1999 ◽  
Vol 172 ◽  
pp. 65-76
Author(s):  
John D. Hadjidemetriou
Keyword(s):  
Chaotic Motion ◽  
The Sun ◽  
Symplectic Mapping ◽  
Mapping Model ◽  
The Third ◽  
Secondary Resonances ◽  
Mean Motion ◽  
Slow Diffusion ◽  
Third Dimension ◽  
Asteroid Orbit

AbstractWe present a 3-D symplectic mapping model that is valid at the 2:1 mean motion resonance in the asteroid motion, in the Sun-Jupiter-asteroid model. This model is used to study the dynamics inside this resonance and several features of the system have been made clear. The introduction of the third dimension, through the inclination of the asteroid orbit, plays an important role in the evolution of the asteroid and the appearance of chaotic motion. Also, the existence of the secondary resonances is clearly shown and their role in the appearance of chaotic motion and the slow diffusion of the elements of the orbit is demonstrated.

scholarly journals The Ursa Major Cluster Redefined as a ‘Supergroup’

2016 ◽  
Vol 33 ◽  
Author(s):  
K. Wolfinger ◽  
V. A. Kilborn ◽  
E. V. Ryan-Weber ◽  
B. S. Koribalski
Keyword(s):  
Real Data ◽  
Virgo Cluster ◽  
Sloan Digital Sky Survey ◽  
Galaxy Groups ◽  
The Third ◽  
Evolutionary State ◽  
Sky Survey ◽  
Major Cluster ◽  
The Galaxy ◽  
Major Region

AbstractWe identify gravitationally bound structures in the Ursa Major region using positions, velocities and photometry from the Sloan Digital Sky Survey (SDSS DR7) and the Third Reference Catalogue of Bright Galaxies (RC3). A friends-of-friends algorithm is extensively tested on mock galaxy lightcones and then implemented on the real data to determine galaxy groups whose members are likely to be physically and dynamically associated with one another. We find several galaxy groups within the region that are likely bound to one another and in the process of merging. We classify 6 galaxy groups as the Ursa Major ‘supergroup’, which are likely to merge and form a poor cluster with a mass of ~ 8 × 1013 M⊙. Furthermore, the Ursa Major supergroup as a whole is likely bound to the Virgo cluster, which will eventually form an even larger system in the context of hierarchical structure formation. We investigate the evolutionary state of the galaxy groups in the Ursa Major region and conclude that these groups are in an early evolutionary state and the properties of their member galaxies are similar to those in the field.

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