scholarly journals Decametric Radio Bursts Associated with Coronal Loop Structures

1980 ◽  
Vol 86 ◽  
pp. 435-438
Author(s):  
T. E. Gergely ◽  
M. R. Kundu ◽  
L. Golub ◽  
D. Webb
Keyword(s):  
Active Region ◽  
Coronal Loop ◽  
Opposite Polarity ◽  
Small Scale ◽  
List Type ◽  
Radio Bursts ◽  
Type Number ◽  
X Ray ◽  
Decameter Wavelength ◽  
Different Types

The soft x-ray (2–54 Å) pictures obtained by the S-054 experiment aboard SKYLAB provide an excellent opportunity to study the association of x-ray loop structures with radio bursts. We report here on the properties of meter-decameter wavelength radio bursts which appear to be associated with two different types of loop structures: a)Relatively short lived small scale loops, which are observed to link magnetic fields of opposite polarity, called x-ray bright points (XBPs); andb)Longer lived loop systems which appear to connect opposite magnetic polarities of an active region and active region complexes as well.

Fluorescence effects in quantitative microprobe analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 188-189
Author(s):  
S.J.B. Reed
Keyword(s):  
Microprobe Analysis ◽  
Depth Distribution ◽  
Exciting Radiation ◽  
Primary Radiation ◽  
List Type ◽  
Type Number ◽  
Computing Power ◽  
X Ray ◽  
Fluorescent Radiation

Characteristic fluorescenceThe theory of characteristic fluorescence corrections was first developed by Castaing. The same approach, with an improved expression for the relative primary x-ray intensities of the exciting and excited elements, was used by Reed, who also introduced some simplifications, which may be summarized as follows (with reference to K-K fluorescence, i.e. K radiation of element ‘B’ exciting K radiation of ‘A’):1.The exciting radiation is assumed to be monochromatic, consisting of the Kα line only (neglecting the Kβ line).2.Various parameters are lumped together in a single tabulated function J(A), which is assumed to be independent of B.3.For calculating the absorption of the emerging fluorescent radiation, the depth distribution of the primary radiation B is represented by a simple exponential.These approximations may no longer be justifiable given the much greater computing power now available. For example, the contribution of the Kβ line can easily be calculated separately.

Interactive multiple area spectrum integration (MASI)

1994 ◽  
Vol 52 ◽  
pp. 942-943
Author(s):  
John A. Hunt ◽  
Richard D. Leapman ◽  
David B. Williams
Keyword(s):  
Image Processing ◽  
Low Dose ◽  
Routine Analysis ◽  
Reference Image ◽  
Area Spectrum ◽  
List Type ◽  
Type Number ◽  
Image Processor ◽  
X Ray ◽  
Scanning Path

Interactive MASI involves controlling the raster of a STEM or SEM probe to areas predefined byan integration mask which is formed by image processing, drawing or selecting regions manually. EELS, x-ray, or other spectra are then acquired while the probe is scanning over the areas defined by the integration mask. The technique has several advantages: (1) Low-dose spectra can be acquired by averaging the dose over a great many similar features. (2) MASI can eliminate the risks of spatial under- or over-sampling of multiple, complicated, and irregularly shaped objects. (3) MASI is an extremely rapid and convenient way to record spectra for routine analysis. The technique is performed as follows:Acquire reference imageOptionally blank beam for beam-sensitive specimensUse image processor to select integration mask from reference imageCalculate scanning path for probeUnblank probe (if blanked)Correct for specimen drift since reference image acquisition

scholarly journals Acceleration, Containment and Emission of High Energy Flare Particles: Radio Evidence

1974 ◽  
Vol 57 ◽  
pp. 423-435 ◽  
Author(s):  
A. Boischot
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Solar Atmosphere ◽  
Impulsive Phase ◽  
High Energy ◽  
Continuous Phase ◽  
List Type ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Number

The existence of non thermal radio bursts provide evidences for the acceleration of electrons in the solar atmosphere.It is shown, from the characteristics of the bursts, that the electrons are accelerated in at least four different phases: (1)An impulsive phase which gives μib and III bursts.(2)A gradual phase which gives μIV and S1IV bursts.(3)A quasi-continuous phase which gives S2IV bursts and noise storms.(4)An acceleration by shock waves gives type II bursts.(5)Eventually, another shock-wave acceleration giving the moIV burst.

Bilingualism and cognition: A focus on mechanisms

2014 ◽  
Vol 18 (1) ◽  
pp. 47-50 ◽  
Author(s):  
VIRGINIA VALIAN
Keyword(s):  
Young Adults ◽  
Executive Function ◽  
Executive Functions ◽  
List Type ◽  
Type Number ◽  
Old People ◽  
Daily Lives ◽  
Different Types ◽  
Children And Young Adults ◽  
Underlying Mechanisms

The goal of my keynote article, “Bilingualism and Cognition” (Valian, 2014), was to resolve the inconsistencies in effects of bilingualism on executive functions, whether the individuals were children, young adults, or old people. To summarize (and sharpen) my argument: 1.Especially in children and young adults, benefits of bilingualism for executive functions are not reliable. In old people, there are benefits for executive functions but contradictory results on delay of cognitive impairment, depending on whether studies are retrospective or prospective.2.All experiences that have benefits for executive functions and aging – and there are many – yield inconsistent effects. Bilingualism is not alone.3.Three reasons for inconsistencies in bilingualism and other experiences are: a.Executive function and cognitive reserve are broad cover terms for a variety of mechanisms, most of which are ill-understood. Because we mean different things by ‘executive function’ from one experiment to the next, we can both think we don't have an effect when we do and think we have an effect when we don’t.b.Tasks are impure: apparently similar tasks measure different aspects of executive function and measure other aspects of cognition as well. Because we lack a good analysis of tasks, we too often do not know what we are measuring. I encourage readers to examine the demos in the supplementary materials of the keynote article to see for themselves what the tasks are like.c.Individuals engage in many different activities that may be on a par with bilingualism in their benefits.4.Different types of bilingual experience are unlikely to explain the variability of findings, given the inconsistencies in extant data on varieties of bilingualism.5.There is a benefit of bilingualism, but bilingualism competes with other sources of benefits. Especially for children and young adults, whose daily lives are full of cognitively enriching and challenging experiences, we should expect variability in effects of being bilingual.6.The way forward is to focus on underlying mechanisms.

scholarly journals Solar X radiation

1965 ◽  
Vol 23 ◽  
pp. 45-52 ◽  
Author(s):  
C. de Jager
Keyword(s):  
Electromagnetic Radiation ◽  
Gamma Rays ◽  
Electronic Transitions ◽  
List Type ◽  
X Rays ◽  
Type Number ◽  
X Ray ◽  
Image Position ◽  
Electron Shells

X-ray bursts are defined as electromagnetic radiation originating from electronic transitions involving the lowest electron shells; gamma rays are of nuclear origin. Solar gamma rays have not yet been discovered.According to the origin we have : 1.Quasi thermal X-rays, emitted by (a) the quiet corona, (b) the activity centers without flares, and (c) the X-ray flares.2.Non-thermal X-ray bursts; these are always associated with flares.The following subdivision is suggested for flare-associated bursts :

scholarly journals Proton Flare Project: Introduction and Summary

1968 ◽  
Vol 35 ◽  
pp. 511-534
Author(s):  
Z. Švestka
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Active Region ◽  
Interplanetary Space ◽  
Practical Experience ◽  
Morning Session ◽  
List Type ◽  
Type Number ◽  
Friday Morning ◽  
The Individual

All contributions presented at the Friday morning session concerned results of the Proton Flare Project (PFP), which was organized by the IAU Commission 10 under the sponsorship of the IQSY Committee, from May 1 to September 30, 1966. As explained by Z. Švestka in his introductory talk, this project had four main aims: (1)To observe proton flares shortly after the minimum of the solar activity, when, on the rising part of the solar cycle, some proton flares already appear, but not too many of them, so that the individual proton flare phenomena are fairly isolated. This makes it easy to study all the effects of such a proton flare in the interplanetary space and in the Earth's surroundings, and particularly, it allows a detailed study of the isolated active region, in which the proton flare appears.(2)To get some practical experience in the forecasts of proton flares and verify the reliability and the practical use of them.(3)With the aid of these forecasts, to give to the solar and geophysical observatories and to the launching sites the possibility to get prepared for the coming event. It was hoped that in this way one might get very detailed observations of the proton-flare active region, of the proton flare itself, and of its effects in the interplanetary space and in the Earth's magnetosphere and ionosphere.

scholarly journals A new catalogue of quasi-stellar objects

1986 ◽  
Vol 119 ◽  
pp. 51-52
Author(s):  
A. Hewitt ◽  
G. Burbidge
Keyword(s):  
Seyfert Galaxies ◽  
List Type ◽  
Type Number ◽  
Stellar Objects ◽  
Bl Lac Objects ◽  
X Ray ◽  
Bl Lac ◽  
Similar Information ◽  
Quasi Stellar Objects ◽  
Objective Prism

We have prepared a new catalogue of QSOs and BL Lac objects containing approximately 3400 entries. A complete update of the Hewitt-Burbidge (1980) catalogue has been made with approximately another 2000 objects with known redshifts added. The references to discovery, magnitudes, redshifts, color, spectra and polarimetry have been updated for the objects listed in 1980, and complete new references are included for the new objects. In addition to the basic optical information, the new catalogue also contains X-ray, radio and infrared information for all objects. Absorption redshifts are listed when they are available. A supplementary catalogue which is now in preparation will contain similar information for objects described variously as Seyfert galaxies, N systems and AGNs. In doubtful cases we have used the operational dividing line ƶ = 0.1. All objects with ƶ < 0.1 are put in the supplementary catalogue unless their discoverers have unambiguously defined them as QSOs. With approximately twice as many objects included it is interesting to note that: a)There are still very few genuine BL Lac objects, ∼100.b)The largest number of additions has come from identifications using the objective prism-grism techniques.

scholarly journals The K-Band Hubble Diagram for X-Ray Selected Brightest Cluster Galaxies

1998 ◽  
Vol 179 ◽  
pp. 339-341
Author(s):  
R.G. Mann ◽  
C.A. Collins
Keyword(s):  
Star Formation ◽  
List Type ◽  
Type Number ◽  
Hubble Diagram ◽  
Technical Problems ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Absolute ◽  
Small Dispersion

The Hubble (magnitude-redshift) diagram for brightest cluster galaxies (BCGs) is a classic cosmological tool, widely studied because of the remarkably small dispersion (∼ 0.3 mag) in the absolute optical magnitudes of low redshift BCGs (Postman and Lauer 1995). Extending the BCG Hubble diagram to higher redshifts would greatly enhance its role as a cosmological probe, but this has been frustrated by several technical problems: – the conventional means of cluster selection in the optical become increasingly compromised by projection effects at z > 0.1– at higher redshifts the interpretation of optical magnitudes becomes increasingly complicated by the effects of possible star formation.

scholarly journals 4 Years of Radio to X-ray Observations of 3C 273

1989 ◽  
Vol 134 ◽  
pp. 112-113
Author(s):  
T.J.-L. Courvoisier ◽  
E. I. Robson ◽  
A. Blecha ◽  
P. Bouchet
Keyword(s):  
Near Infrared ◽  
Optical Emission ◽  
Light Curves ◽  
Physical Parameters ◽  
List Type ◽  
Type Number ◽  
Rapid Variability ◽  
X Ray ◽  
Model Independent ◽  
Ir Emission

The quasar 3C273 has been repeatedly observed at radio, mm, IR, optical, UV and X-ray frequencies since December 1983. A complex pattern of continuum variations has been discovered, which can be used to provide model independent physical parameters, and to constrain different models. The main features revealed by our set of observations are: (i)A flux decrease by 40% in the 2–10 kev flux in 20 days in early 1984 (Courvoisier et al. 1987).(ii)Differences between the X-ray light curves at 0.5 keV and 2–10 keV.(iii)A drop in the mm to mid-IR emission by factors 2–4 in early 1986, while the near infrared flux remained stable (Robson et al. 1986).(iv)A decrease in the ultraviolet intensity of ∼40% in about 6 months in 1987 (Ulrich, Courvoisier and Wamsteker 1988).(v)Rapid variability in the infrared and optical emission on timescales as short as one day in 1988 (Courvoisier et al. 1988 and Robson, Courvoisier and Bouchet this conference).

Hitachi Model XMA-5 Electron Probe Microanalyzer

1968 ◽  
Vol 26 ◽  
pp. 308-309
Author(s):  
Tomura ◽  
Okano ◽  
Hara
Keyword(s):  
Electron Probe ◽  
High Performance ◽  
List Type ◽  
X Rays ◽  
Type Number ◽  
Fluorescence Excitation ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Scientific Instrumentation ◽  
Made In

The recent advancement in scientific instrumentation has been phenomenal. This is particularity true in the electron probe microanalyzer field. This paper describes the improvements made in the Hitachi Model XMA-5 Electron Probe Microanalyzer to achieve high performance.1.X-ray spectroscopy1-1.It is now possible to analyze a wide variety of elements including ultra light elements in minute concentrations with the advent of an increasing number of dispersing elements and high detectability.1-2.A linear crystal drive and direct wavelength read-out (with respect to the crystal) is employed in the spectrometer to assure simultaneous analyses of up to three elements by using three of the six crystals provided. For correction of absorbed X-rays and fluorescence excitation and with due consideration of the angular distribution of the characteristic X-rays, an X-ray take off angle of 38° (electron probe is incident vertically on the specimen surface) was adopted.

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