scholarly journals Gravitational Lenses Among Highly Luminous Quasars: Large Optical Surveys

1996 ◽  
Vol 173 ◽  
pp. 13-20
Author(s):  
J.-F. Claeskens ◽  
A.O. Jaunsen ◽  
J. Surdej
Keyword(s):  
World Wide ◽  
Total Sample ◽  
Gravitational Lenses ◽  
Web Page ◽  
Optical Telescope ◽  
Fundamental Parameters ◽  
Observational Status ◽  
Number Counts ◽  
Optical Surveys ◽  
The Universe

The search for multiply imaged quasars among highly luminous quasars (HLQs) is a very good strategy to determine the fundamental parameters of the Universe. We report on the present observational status of a combined sample of HLQs, including new observations obtained with the Nordic Optical Telescope (NOT) and at ESO. This combined sample of HLQs now contains 1178 distinct HLQs. A complete list of the total sample will be soon made available, through a World-Wide-Web page. Preliminary maximum likelihood results are also presented, using a simple statistical model to constrain the values of galactic parameters, of the number counts of QSOs, and of the cosmological constant.

Allan Rex Sandage. 18 June 1926 — 13 November 2010

2012 ◽  
Vol 58 ◽  
pp. 245-264 ◽  
Author(s):  
Donald Lynden-Bell ◽  
François Schweizer
Keyword(s):  
Stellar Evolution ◽  
Star Clusters ◽  
Optical Telescope ◽  
Elemental Abundances ◽  
Mount Wilson Observatory ◽  
History Of ◽  
Expansion Of The Universe ◽  
Edwin Hubble ◽  
Number Counts ◽  
The Universe

Allan Sandage was an observational astronomer who was happiest at a telescope. On the sudden death of Edwin Hubble, Sandage inherited the programmes using the world’s largest optical telescope at Palomar to determine the distances and number counts of galaxies. Over many years he greatly revised the distance scale and, on reworking Hubble’s analysis, discovered the error that had led Hubble to doubt the interpretation of the galaxies’ redshifts as an expansion of the Universe. Sandage showed that there was a consistent age of creation for the stars, the elements and the cosmos. Through work with Baade and Schwarzschild he discovered the key to the interpretation of the colour–magnitude diagrams of star clusters in terms of stellar evolution. With others he founded galactic archaeology, interpreting the motions and elemental abundances of the oldest stars in terms of a model for the Galaxy’s formation. He published several fine atlases and catalogues of galaxies and a definitive history of the Mount Wilson Observatory.

scholarly journals Searching for cross-correlation between stochastic gravitational-wave background and galaxy number counts

2020 ◽  
Vol 500 (2) ◽  
pp. 1666-1672
Author(s):  
Kate Z Yang ◽  
Vuk Mandic ◽  
Claudia Scarlata ◽  
Sharan Banagiri
Keyword(s):  
Gravitational Wave ◽  
Cross Correlation ◽  
Sloan Digital Sky Survey ◽  
Number Count ◽  
Frequency Bands ◽  
Galaxy Count ◽  
Harmonic Decomposition ◽  
Number Counts ◽  
Gravitational Wave Background ◽  
The Universe

ABSTRACT Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo have recently published the upper limit measurement of persistent directional stochastic gravitational-wave background (SGWB) based on data from their first and second observing runs. In this paper, we investigate whether a correlation exists between this maximal likelihood SGWB map and the electromagnetic (EM) tracers of matter structure in the Universe, such as galaxy number counts. The method we develop will improve the sensitivity of future searches for anisotropy in the SGWB and expand the use of SGWB anisotropy to probe the formation of structure in the Universe. In order to compute the cross-correlation, we used the spherical harmonic decomposition of SGWB in multiple frequency bands and converted them into pixel-based sky maps in healpix basis. For the EM part, we use the Sloan Digital Sky Survey alaxy catalogue and form healpix sky maps of galaxy number counts at the same angular resolution as the SGWB maps. We compute the pixel-based coherence between these SGWB and galaxy count maps. After evaluating our results in different SGWB frequency bands and in different galaxy redshift bins, we conclude that the coherence between the SGWB and galaxy number count maps is dominated by the null measurement noise in the SGWB maps, and therefore not statistically significant. We expect the results of this analysis to be significantly improved by using the more sensitive upcoming SGWB measurements based on the third observing run of Advanced LIGO and Advanced Virgo.

scholarly journals A Simulation of the Structure of the World-Wide Web

2002 ◽  
Vol 7 (1) ◽  
pp. 9-25 ◽  
Author(s):  
Moses Boudourides ◽  
Gerasimos Antypas
Keyword(s):  
World Wide Web ◽  
Power Law ◽  
Web Sites ◽  
World Wide ◽  
The Internet ◽  
Web Pages ◽  
Small Worlds ◽  
Web Page ◽  
Simple Simulation ◽  
The World

In this paper we are presenting a simple simulation of the Internet World-Wide Web, where one observes the appearance of web pages belonging to different web sites, covering a number of different thematic topics and possessing links to other web pages. The goal of our simulation is to reproduce the form of the observed World-Wide Web and of its growth, using a small number of simple assumptions. In our simulation, existing web pages may generate new ones as follows: First, each web page is equipped with a topic concerning its contents. Second, links between web pages are established according to common topics. Next, new web pages may be randomly generated and subsequently they might be equipped with a topic and be assigned to web sites. By repeated iterations of these rules, our simulation appears to exhibit the observed structure of the World-Wide Web and, in particular, a power law type of growth. In order to visualise the network of web pages, we have followed N. Gilbert's (1997) methodology of scientometric simulation, assuming that web pages can be represented by points in the plane. Furthermore, the simulated graph is found to possess the property of small worlds, as it is the case with a large number of other complex networks.

Calendar of Meetings and Courses

2005 ◽  
Vol 11 (3) ◽  
pp. 278-281 ◽  
Keyword(s):  
World Wide Web ◽  
World Wide ◽  
Web Page ◽  
Additional Information ◽  
Electronic Submission ◽  
Submission Form ◽  
The Web

Following is a list of microscopy-related meetings and courses. The editors would greatly appreciate input to this list via the electronic submission form found in the MSA World-Wide Web page at http://www.msa.microscopy.com. We will gladly add hypertext links to the notice on the web and insert a listing of the meeting in the next issue of the Journal. Send comments and questions to JoAn Hudson, [email protected] or Nestor Zaluzec, [email protected]. Please furnish the following information (any additional information provided will be edited as required and printed on a space-available basis):

Stigmergic Hyperlink

2012 ◽  
pp. 260-272
Author(s):  
Artur Sancho Marques ◽  
José Figueiredo
Keyword(s):  
Social Networks ◽  
Social Change ◽  
World Wide Web ◽  
World Wide ◽  
Service Providers ◽  
Information Service ◽  
Web Page ◽  
The World ◽  
Patterns Of Behavior ◽  
Ecological Treatment

Inspired by patterns of behavior generated in social networks, a prototype of a new object was designed and developed for the World Wide Web – the stigmergic hyperlink or “stigh”. In a system of stighs, like a Web page, the objects that users do use grow “healthier”, while the unused “weaken”, eventually to the extreme of their “death”, being autopoieticaly replaced by new destinations. At the single Web page scale, these systems perform like recommendation systems and embody an “ecological” treatment to unappreciated links. On the much wider scale of generalized usage, because each stigh has a method to retrieve information about its destination, Web agents in general and search engines in particular, would have the option to delegate the crawling and/or the parsing of the destination. This would be an interesting social change: after becoming not only consumers, but also content producers, Web users would, just by hosting (automatic) stighs, become information service providers too.

Hybrid 2D/3D Development of Interactive Simulations

2011 ◽  
pp. 736-751
Author(s):  
Penny deByl
Keyword(s):  
Learning Environments ◽  
World Wide ◽  
Three Dimensional ◽  
Learning Context ◽  
Web Page ◽  
Effective Learning ◽  
Simulated Environments ◽  
The World ◽  
E Learning ◽  
Interactive Simulations

Three-dimensional virtual learning environments provide students with pedagogic experiences beyond traditional two-dimensional textbook and Web page content. When delivered via the World Wide Web, this technology is known as Web3D. Such immersive learning experiences are available to a wider audience of student and when coupled with existing 2D content make effective learning applications. In this chapter a method for delivering a 2D/3D hybrid Web page will be demonstrated, which illustrates a best of both worlds approach to including both traditional text-based content and 3D simulated environments in an e-Learning context.

Semi-Structured Data Extraction from Heterogenous Sources

2000 ◽  
pp. 83-102 ◽  
Author(s):  
Xiaoying Gao ◽  
Leon Sterling
Keyword(s):  
Knowledge Management ◽  
World Wide ◽  
Data Extraction ◽  
Research Problem ◽  
The Internet ◽  
Web Pages ◽  
Accessible Information ◽  
The World ◽  
Machine Readable ◽  
The Universe

The World Wide Web is known as the “universe of network-accessible information, the embodiment of human knowledge” (W3C, 1999). Internet-based knowledge management aims to use the Internet as the world wide environment for knowledge publishing, searching, sharing, reusing, and integration, and to support collaboration and decision making. However, knowledge on the Internet is buried in documents. Most of the documents are written in languages for human readers. The knowledge contained therein cannot be easily accessed by computer programs such as knowledge management systems. In order to make the Internet “machine readable,” information extraction from Web pages becomes a crucial research problem.

Calendar of Meetings and Courses

1998 ◽  
Vol 4 (1) ◽  
pp. 86-91
Author(s):  
Barbara Reine ◽  
Nestor Zaluzec
Keyword(s):  
World Wide Web ◽  
World Wide ◽  
Web Page ◽  
Electronic Submission ◽  
Submission Form ◽  
The Web

Following is a list of microscopy-related meetings and courses. The editors would greatly appreciate input to this list via the electronic submission form found in the MSA World-Wide Web page at http://www.msa.microscopy.com/. We will gladly add hypertext links to the notice on the Web and insert a listing of the meeting in the next issue of the Journal.

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