scholarly journals Errors of Observation in Double-Star Work

1971 ◽  
Vol 5 ◽  
pp. 133-135
Author(s):  
W. D. Heintz
Keyword(s):  
Noise Level ◽  
Double Star ◽  
Astronomical Observation ◽  
Time Interval ◽  
The Past ◽  
Visual Binary ◽  
Long Time ◽  
Observational Errors ◽  
Long Term Variations

Astronomical observation frequently is focused on minute quantities, and on digging information even from below the 'noise level'. In all cases of long-term variations, such as visual binary motions, measurements over a long time interval have to be combined. All of this requires a knowledge of the observational errors in the past and present. We usually are not at liberty to discard old observations since we cannot repeat them at any later time desired. Visual observations leave no re-measurable records, so we have to take the word of the observer, and make the best of it.

Errors of Observation in Double-Star Work

1965 ◽  
Vol 5 ◽  
pp. 132-135
Author(s):  
W. D. Heintz
Keyword(s):  
Noise Level ◽  
Double Star ◽  
Astronomical Observation ◽  
Time Interval ◽  
The Past ◽  
Visual Binary ◽  
Long Time ◽  
Observational Errors ◽  
Long Term Variations

Astronomical observation frequently is focused on minute quantities, and on digging information even from below the ‘noise level’. In all cases of long-term variations, such as visual binary motions, measurements over a long time interval have to be combined. All of this requires a knowledge of the observational errors in the past and present. We usually are not at liberty to discard old observations since we cannot repeat them at any later time desired. Visual observations leave no re-measurable records, so we have to take the word of the observer, and make the best of it.

Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles

1994 ◽  
Vol 12 (10/11) ◽  
pp. 1065-1070 ◽  
Author(s):  
V. Mussino ◽  
O. Borello Filisetti ◽  
M. Storini ◽  
H. Nevanlinna
Keyword(s):  
Correlation Coefficient ◽  
Geomagnetic Activity ◽  
Activity Level ◽  
Activity Levels ◽  
Data Set ◽  
The Past ◽  
Long Term Trends ◽  
A Minor ◽  
Long Term Variations

Abstract. Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (r) between geomagnetic indices and sunspot numbers for the ascending phases of sunspot cycles 9 to 22, confirming previous findings based on a minor number of sunspot cycles. The result is useful to researchers in topics related to solar-terrestrial physics, particularly for the interpretation of long-term trends in geomagnetic activity during the past, and to forecast geomagnetic activity levels in the future.

scholarly journals Flare Stars in the ETA Tauri Fields Significant Long-Term Variations of their Flaring Activity

1989 ◽  
Vol 104 (2) ◽  
pp. 143-146
Author(s):  
G. Szécsényi-Nagy
Keyword(s):  
New Method ◽  
The Past ◽  
Flare Stars ◽  
Frequency Variations ◽  
Flare Frequency ◽  
Long Term Variations

Photographic surveys completed during the past 30 years yielded data of about 600 flare stars in these fields. Although their average flare number is very low 17 of the stars produced 10… 120 flare ups. In order to investigate the possible long-term activity changes of these objects a new method - which is described below -was developed. Making use of it significant flare frequency variations were found at two out of three ‘active’ flare stars.

scholarly journals A Transient Shock-Wave in the Shell of the Be Star HD 184279

1987 ◽  
Vol 92 ◽  
pp. 95-98
Author(s):  
D. Ballereau ◽  
J. Chauville
Keyword(s):  
Shock Wave ◽  
Radial Velocity ◽  
Emission Spectrum ◽  
Short Term ◽  
Balmer Series ◽  
Spectroscopic Observations ◽  
The Past ◽  
Be Star ◽  
Long Term Variations

HD 184279 (V1294 Aql) has presented in the past an emission spectrum on the first terms of the Balmer series, and shell absorptions on the hydrogen and neutral helium lines. Their variations have been reported by Merrill (1952), Merrill and Lowen (1953) and Svolopoulos (1975). Ballereau and Hubert-Delplace (1982) evidenced long-term V/R variations with an amplitude of ∼100 km s-1. Short-term photometric variations are irregular (Tempesti and Patriarca, 1976), while long-term variations are correlated with radial velocity (RV) of shell lines (Horn et al., 1982). Ballereau and Chauville (in preparation) extended the spectroscopic observations until 1984 and confirmed the pseudo-periodic variations, the last half-period ranging over 3.4 years (April 1, 1980-August 1, 1983).

Long Term Variations in Jupiter’s 11 cm Radio Emission

1975 ◽  
Vol 2 (6) ◽  
pp. 340-342
Author(s):  
P.M. McCulloch
Keyword(s):  
Radio Emission ◽  
Orbital Period ◽  
Full Range ◽  
Rotational Axis ◽  
The Past ◽  
Range Of Values ◽  
Long Term Variations

During the past twelve years five series of observations have been made of the polarization of Jupiter’s radio emission at a wavelength of 11 cm. This data shows characteristics which have been stable over a period of years as well as some unexplained variations. The observations were made during one complete orbital period of Jupiter and hence were obtained over the full range of values of DE, the angle between Jupiter’s rotational axis and the plane of the sky. These are summarized in Table 1. The 1967 observations have been reported previously (Komesaroff and McCulloch 1967) and the 1963 data is from Roberts and Komesaroff (1965).

Models of Neuronal Transient Synchrony During Propagation of Activity Through Neocortical Circuitry

1998 ◽  
Vol 79 (1) ◽  
pp. 1-12 ◽  
Author(s):  
David Golomb
Keyword(s):  
Correlation Function ◽  
Noise Level ◽  
Cross Correlation ◽  
Time Shift ◽  
Time Interval ◽  
Mutual Distance ◽  
Synaptic Noise ◽  
Transient Activity ◽  
Long Time ◽  
System Average

Golomb, David. Models of neuronal transient synchrony during propagation of activity through neorcortical circuitry. J. Neurophysiol. 79: 1–12, 1998. Stereotypic paroxysmal discharges that propagate in neocortical tissues after electrical stimulations are used as a probe for studying cortical circuitry. I use modeling to investigate the effects of sparse connectivity, heterogeneity of intrinsic neuronal properties, and synaptic noise on synchronization of evoked propagating neuronal discharges in a network of excitatory, regular spiking neurons with spatially decaying connectivity. The global coherence of the traveling discharge is characterized by the correlation function between spike trains of neurons, averaged over all the pairs of neurons in the system at the same distance. Local coherence of two neurons is characterized by their correlation function averaged over many trials or, for persistent activity, over a long time interval. Spike synchronization between neurons emerges as a result of the transient activity; if activity is persistent, there is no synchrony, and cross-correlation functions are flat. During discharge propagation, system-average cross-correlation between neurons does not depend on their mutual distance except for a time shift. Spike synchronization occurs only when the average number of synapses M a cell receives is large enough. As M increases, there is a cross-over from an asynchronized to a synchronized discharge. Synaptic depression appears to help synchrony; it reduces the M value at the cross-over. The strengths of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) conductances affect synchrony only weakly. Spike synchronization is robust even with large levels of heterogeneity. Synaptic noise reduces synchrony, but strong synchrony is observed at a noise level that cannot evoke spontaneous discharges. System-average spike synchronization is determined by the levels of sparseness, heterogeneity, and noise, whereas trial-average spike synchronization is determined only by the noise level. Therefore, I predict that experiments will reveal local, two-cell spike synchrony, but not global synchrony.

scholarly journals The Street Network Composition and the Evolution of Street Paving in the Lyudin End of Novgorod (according to the Troitsky Excavation Data)

2018 ◽  
pp. 157-171
Author(s):  
Н. Н. Фараджева ◽  
О. А. Тарабардина ◽  
П. Г. Гайдуков
Keyword(s):  
Structural Features ◽  
Primary Objective ◽  
Integrated Analysis ◽  
Time Interval ◽  
Archaeological Research ◽  
Street Network ◽  
The Past ◽  
Network Composition ◽  
Excavation Site

Мостовые трех средневековых улиц (Пробойной, Черницыной и Яры-шевой), раскрытых в ходе многолетних археологических исследований на территории Людина конца, являются ценным источником для изучения формирования и развития уличной сети средневекового Новгорода. Поскольку средневековые улицы, исследованные на Троицком раскопе, были раскрыты в виде отдельных отрезков на площади девяти самостоятельных раскопов на протяжении 23 полевых сезонов (1976-1998), первостепенная задача работы состояла в выполнении сводной ярусо-логии уличных мостовых. Предпринятое исследование базируется на комплексном анализе стратиграфических, планиграфических и дендрохронологических данных. Результатом работ явились выводы, касающиеся сложения и эволюции уличной сети Людина конца средневекового Новгорода на протяжении значительного временного отрезка, начиная с 30-х гг. X и до середины XV в. The pavements of three medieval streets (Proboynaya, Chernitsyna and Yarysheva) disclosed in the course of long-term archaeological research on the territory of the Lyudin End, are a valuable source for the study of the street network of the medieval Novgorod formation and development. As far as medieval streets, studied on the Troitsky excavation site, were disclosed as separate segments on the square of nine independent excavations for the past 23 field seasons (1976-1998), the primary objective of the work was the implementation of the consolidated aromalogy of street pavement. The undertaken study is based on an integrated analysis of stratigraphic, planigraphic and dendrochronological data. The information obtained on planigraphy and chronology of each street pavement resulted in their comparative analysis, which highlights common and independent phases of street paving, their chronological and structural features were also mapped. The work resulted in the conclusion related to the composition and evolution of the street network of Lyudin End in medieval Novgorod for a substantial time interval from the 30ies of the 10 century to the mid 15 century

Tyrannosaurus rex it is not a prehistoric animal: roaring in a semantic prehistoric jungle

2020 ◽  
Vol 1 (3) ◽  
pp. 96-101
Author(s):  
Marco Romano ◽  
Raffaele Sardella
Keyword(s):  
Biological Evolution ◽  
Time Interval ◽  
Human History ◽  
Deep Time ◽  
Earth History ◽  
The Past ◽  
Center Stage ◽  
Large Audience ◽  
Long Time ◽  
Absolute Dating

The word “prehistory” has been used for a long time to indicate all extinct organisms of the past, with dinosaurs occupying a center stage stimulating the imagination of a very large audience. Such erroneous use of the term prehistory is widespread even today, a word and concept originally referred to the period of human history which preceded writing, i.e. prior to documented history and embracing a time interval from about 2.6 million years ago to 4000 BC. Keeping in mind the crucial milestone of 'deep time' concept in geology the division of the extensive Earth history into only two sections of respectively 4.5429 billion years and 4000 years in our opinion is a misleading oversimplification. Over the past few centuries much effort has gone into the development of a hyper-detailed chronostratigraphic scale, substantiated by absolute dating, detailed biostratigraphy, and documentation of biological evolution. All this generation of knowledge, conducted by thousands of researchers over many years, is completely lost when, in a simplistic way the anthropocentric dichotomy is accepted.

scholarly journals Properties of Circumstellar Dust in Symbiotic Miras

2006 ◽  
Vol 2 (S240) ◽  
pp. 596-604
Author(s):  
D. Kotnik-Karuza ◽  
T. Jurkic ◽  
M. Friedjung
Keyword(s):  
Temperature Distribution ◽  
Systematic Study ◽  
Light Curves ◽  
Circumstellar Dust ◽  
Symbiotic Stars ◽  
Time Intervals ◽  
Dust Temperature ◽  
Long Time ◽  
Long Term Variations

AbstractWe present a study of the properties of circumstellar dust in symbiotic Miras during sufficiently long time intervals of minimal obscuration. The publishedJHKLmagnitudes of o Ceti, RX Pup, KM Vel, V366 Car, V835 Cen, RR Tel and R Aqr have been collected. In order to investigate their long-term variations, we removed the Mira pulsations to correct their light curves. Assuming spherical temperature distribution of the dust in the close neighbourhood of the Mira, the DUSTY code was used to solve the radiative transfer in order to determine the dust temperature and its properties in each particular case.The preliminary results of this systematic study of dust envelopes in symbiotic stars with Miras as cool components provide information on nature of dust in these objects.

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