Cosmic y-ray bursts

1981 ◽  
Vol 301 (1462) ◽  
pp. 645-658 ◽  
Keyword(s):  
Temporal Structure ◽  
Considerable Progress ◽  
Large Network ◽  
Exact Location ◽  
Made In ◽  
Arrival Directions

Although y-ray bursts were discovered over ten years ago, the study of their temporal structure, their spectrum and their lg N against lg S distribution have still not enabled scientists to determine their origin. Since 1978, however, considerable progress has been made in the accuracy of locating bursts by triangulation methods, by using a large network of observations made by the Helios B solar-orbiting satellite, the interplanetary spacecraft Pioneer Venus and Venera 11 and 12, ISEE-C and Earth-orbiting satellites. With the great distances between these various measuring points, it can be hoped that an accuracy of the order of one minute of arc will be attained for many events observed in 1979 and 1980. This accuracy has already been surpassed for the March 5, 1979 event. In this paper an analysis of the latest observations, and results on the exact location of the arrival directions of several bursts will be presented, along with the evidence they provide about the origin of this radiation.

Biological Production of (S)-acetoin: A State-of-the-Art Review

2019 ◽  
Vol 19 (25) ◽  
pp. 2348-2356 ◽  
Author(s):  
Neng-Zhong Xie ◽  
Jian-Xiu Li ◽  
Ri-Bo Huang
Keyword(s):  
Side Effects ◽  
Chemical Synthesis ◽  
State Of The Art ◽  
Optically Active ◽  
Considerable Progress ◽  
Future Prospects ◽  
Chiral Compound ◽  
Biological Production ◽  
Acetoin Production ◽  
Made In

Acetoin is an important four-carbon compound that has many applications in foods, chemical synthesis, cosmetics, cigarettes, soaps, and detergents. Its stereoisomer (S)-acetoin, a high-value chiral compound, can also be used to synthesize optically active drugs, which could enhance targeting properties and reduce side effects. Recently, considerable progress has been made in the development of biotechnological routes for (S)-acetoin production. In this review, various strategies for biological (S)- acetoin production are summarized, and their constraints and possible solutions are described. Furthermore, future prospects of biological production of (S)-acetoin are discussed.

scholarly journals III. On the nature and construction of the sun and fixed stars

1795 ◽  
Vol 85 ◽  
pp. 46-72 ◽  
Keyword(s):  
Central Body ◽  
Planetary System ◽  
Considerable Progress ◽  
The Sun ◽  
Great Satisfaction ◽  
The Earth ◽  
The World ◽  
Celestial Bodies ◽  
The Universe ◽  
Made In

Among the celestial bodies the sun is certainly the first which should attract our notice. It is a fountain of light that illuminates the world! it is the cause of that heat which main­tains the productive power of nature, and makes the earth a fit habitation for man! it is the central body of the planetary system; and what renders a knowledge of its nature still more interesting to us is, that the numberless stars which compose the universe, appear, by the strictest analogy, to be similar bodies. Their innate light is so intense, that it reaches the eye of the observer from the remotest regions of space, and forcibly claims his notice. Now, if we are convinced that an inquiry into the nature and properties of the sun is highly worthy of our notice, we may also with great satisfaction reflect on the considerable progress that has already been made in our knowledge of this eminent body. It would require a long detail to enumerate all the various discoveries which have been made on this subject; I shall, therefore, content myself with giving only the most capital of them.

Depressive Illnesses in Children and Adolescents: A Review of Current Concepts

1985 ◽  
Vol 30 (2) ◽  
pp. 119-129 ◽  
Author(s):  
B.J. Mcconville ◽  
R.T. Bruce
Keyword(s):  
Children And Adolescents ◽  
Current Knowledge ◽  
Considerable Progress ◽  
Childhood And Adolescence ◽  
Age Related ◽  
Developmental Age ◽  
The Subject ◽  
Made In

Considerable progress has been made in our understanding of depressive illnesses in childhood and adolescence, especially over the last several years. A number of major books on the subject have now appeared, along with a large number of individual papers. This paper attempts to summarize current knowledge, and indicates developmental, age-related and other issues which still require further study.

scholarly journals CONSTITUENT TRANSPORT IN ESTUARIES

1968 ◽  
Vol 1 (11) ◽  
pp. 86 ◽  
Author(s):  
Bard Glenne
Keyword(s):  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Considerable Progress ◽  
Diffusion Method ◽  
Common Application ◽  
Made In ◽  
Mixing And Transport

During the last two decades considerable progress has been made in analyzing the diffusion process in estuaries. Unfortunately, certain difficulties (e g prediction of diffusion coefficients) still prevent common application of the diffusion method An old technique, related to the diffusion concept, can however, frequently give useful information regarding constituent mixing and transport velocities in natural estuaries.

Applying lessons learnt from deficiencies in the basel accords to Solvency II

2013 ◽  
Vol 6 (2) ◽  
pp. 309-328
Author(s):  
Johann Jacobs ◽  
Gary Van Vuuren
Keyword(s):  
European Union ◽  
Financial Crisis ◽  
Banking Sector ◽  
Insurance Industry ◽  
Solvency Ii ◽  
Capital Adequacy ◽  
Considerable Progress ◽  
Eu Legislation ◽  
Basel Accords ◽  
Made In

Solvency II is the new European Union (EU) legislation that will review the capital adequacy regime for the insurance industry. Considerable progress has been made in the banking sector with the implementation of the Basel Accords (Basel). The implementation of Solvency II, therefore, brings with it an opportunity for the insurance industry to assess the successes, weaknesses and shortcomings experienced by the banking sector's implementation of Basel so as to learn from them and ensure that Solvency II's implementation duplicates the successes and avoids the failures of Basel's. This article critically explores weaknesses and failures of Basel which were exacerbated and/or exploited by the financial crisis of 2007-2010 and provides advice on how these might be mitigated or avoided in the implementation of Solvency II.

scholarly journals Vitiligo: A Review

Dermatology ◽  
2020 ◽  
Vol 236 (6) ◽  
pp. 571-592 ◽  
Author(s):  
Christina Bergqvist ◽  
Khaled Ezzedine
Keyword(s):  
Autoimmune Disease ◽  
Skin Disorder ◽  
Current Knowledge ◽  
Daily Life ◽  
Considerable Progress ◽  
International Consensus ◽  
Selective Loss ◽  
The Future ◽  
Cosmetic Problem ◽  
Made In

Vitiligo, a common depigmenting skin disorder, has an estimated prevalence of 0.5–2% of the population worldwide. The disease is characterized by the selective loss of melanocytes which results in typical nonscaly, chalky-white macules. In recent years, considerable progress has been made in our understanding of the pathogenesis of vitiligo which is now clearly classified as an autoimmune disease. Vitiligo is often dismissed as a cosmetic problem, although its effects can be psychologically devastating, often with a considerable burden on daily life. In 2011, an international consensus classified segmental vitiligo separately from all other forms of vitiligo, and the term vitiligo was defined to designate all forms of nonsegmental vitiligo. This review summarizes the current knowledge on vitiligo and attempts to give an overview of the future in vitiligo treatment.

scholarly journals Titans of the early Universe: The Prato statement on the origin of the first supermassive black holes

2019 ◽  
Vol 36 ◽  
Author(s):  
Tyrone E. Woods ◽  
Bhaskar Agarwal ◽  
Volker Bromm ◽  
Andrew Bunker ◽  
Ke-Jung Chen ◽  
...  
Keyword(s):  
Black Holes ◽  
Early Universe ◽  
Supermassive Black Holes ◽  
Considerable Progress ◽  
Next Generation ◽  
Theoretical Understanding ◽  
Theoretical Evidence ◽  
Present Understanding ◽  
Insight Into ◽  
Made In

Abstract In recent years, the discovery of massive quasars at $z\sim7$ has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.

scholarly journals The IAU Strategic Plan

2015 ◽  
Vol 11 (A29A) ◽  
pp. 380-381
Author(s):  
George Miley
Keyword(s):  
Strategic Plan ◽  
Considerable Progress ◽  
General Assembly ◽  
Made In

AbstractI shall review the content of the IAU Strategic Plan (SP) to use astronomy as a tool for stimulating development globally during the decade 2010 - 2020. Considerable progress has been made in its implementation since the last General Assembly.

scholarly journals Spark spectra of bismuth, Bi II and Bi III. Evidence of hyperfine structure

1930 ◽  
Vol 129 (811) ◽  
pp. 579-588 ◽  
Keyword(s):  
Hyperfine Structure ◽  
Term Structure ◽  
Optical System ◽  
Spectral Region ◽  
Considerable Progress ◽  
Condensed Discharge ◽  
Made In

Wave-lengths in the spectrum of a condensed discharge in heated bismuth vapour have been measured from λ 7050 A. to λ 2000 A. and those in the spectrum of a condensed spark between metallic terminals in hydrogen from λ 2000 A. to λ 1340 A. Hilger E 1 spectrographs, one with a glass and one with a quartz optical system, were used to study the first-mentioned spectral region and a Hilger vacuum fluorite instrument for the latter range. Light from a hot spark between metallic terminals in vacuo was photographed with a 1-metre vacuum grating spectrograph in order to investigate the spectrum below λ 1340 A. By a study of the frequencies of the wave-lengths thus obtained, considerable progress has been made in the identification of the multiplet term structure of bismuth II and of bismuth III. Confirmation of the correctness of assignment of wave-lengths to one or other of these spectra was obtained readily in most cases by varying the excitation of the sources of light by means of inductance in the secondary spark circuit.

scholarly journals Space Astrometry - Its Impact on Astronomy and Astrophysics-Introductory Comments

1980 ◽  
Vol 5 ◽  
pp. 779-781
Author(s):  
Gart Westerhout
Keyword(s):  
Considerable Progress ◽  
Coordinate Systems ◽  
Technological Revolution ◽  
Space Astrometry ◽  
Astronomy And Astrophysics ◽  
Average User ◽  
Magnitude Improvement ◽  
Made In

Astrometry - the determination of positions, motions, and coordinate systems and the entirety of the products of these observations- was the first specialty in astronomy. The value of astrometry for all of the fields of astronomy does not have to be emphasized here; it is clear that the foundation of astronomy and astrophysics is provided by astrometry. What is perhaps not so clear is the fact that, although considerable progress has been made in the seventies, the numerical estimates for many of the basic quantities are much less certain than the average user realizes. Fortunately, astrometry stands at the brink of a technological revolution, involving both ground-based and space techniques. Once completed, this will lead to one or more orders of magnitude improvement in both the precision and quantity of most astrometric observations, with enormous implications for other fields of astronomy.

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