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Topic: Clusters

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In the News (Mon 27 May 19)

  Open cluster - Wikipedia, the free encyclopedia
While most clusters become dispersed before a large proportion of their members have reached the white dwarf stage, the number of white dwarfs in open clusters is still generally much lower than would be expected, given the age of the cluster and the expected initial mass distribution of the stars.
Because the stars in an open cluster are all at roughly the same distance from Earth, and were born at roughly the same time from the same raw material, the differences in apparent brightness among cluster members is due only to their mass.
The radial velocity of cluster members can be determined from Doppler shift measurements of their spectra, and once the radial velocity, proper motion and angular distance from the cluster to its vanishing point are known, simple trigonometry will reveal the distance to the cluster.
en.wikipedia.org /wiki/Open_cluster   (3164 words)

 Cancer Clusters, Cancer Facts 3.58   (Site not responding. Last check: 2007-11-06)
Cancer clusters may be suspected when people report that several family members, friends, neighbors, or coworkers have been diagnosed with the same or related cancers (see Defining Disease Clusters section).
Another difficulty epidemiologists face when investigating a possible cancer cluster is accurately defining the group of people who should be considered “at risk.” One of the greatest pitfalls of defining clusters is the tendency to extend the geographic borders of the cluster to include additional cases of the suspected disease as they are discovered.
A cancer cluster could be the result of chance, miscalculation of the expected number of cancer cases, or differences in the case definition (the criteria that determine whether or not the cases being investigated are related to the cluster) between observed cases and expected cases.
cis.nci.nih.gov /fact/3_58.htm   (2444 words)

 Clusters   (Site not responding. Last check: 2007-11-06)
In 1996 the Northeast Ohio Clusters Project was launched by the region's four leading economic development organizations: the Greater Akron Chamber, the Cleveland-Cuyahoga County Port Authority, Cleveland Tomorrow, and the Greater Cleveland Growth Association.
The project was initiated on the premise that the region's economic performance, in terms of the quality of jobs, quantity of out-of-region exports, and generation of wealth and income, is based on a portfolio of industries whose competitive strength is reinforced by a network of customers, suppliers and resources.
This "clustering" concept had been recognized in several regions, including Silicon Valley in California, The Research Triangle in North Carolina, and the Optics Valley in Arizona.
www.clevelandgrowth.com /Market_Data/Clusters/About/index.asp   (202 words)

 Sea and Sky: Star Clusters
Open clusters are formed when several stars are formed at the same time from the same cloud of dust and gas.
Unlike open clusters, globular clusters are much older and usually contain between ten thousand to a million stars which are gravitationally bound in a tight concentration.
Star cluster are among the easiest objects to observe in the night sky.
www.seasky.org /cosmic/sky7a06.html   (775 words)

 Harvard Business School - Institute for Strategy and Competitiveness
Clusters are geographic concentrations of interconnected companies, specialized suppliers, service providers, and associated institutions in a particular field that are present in a nation or region.
Cluster development initiatives are an important new direction in economic policy, building on earlier efforts in macroeconomic stabilization, privatization, market opening, and reducing the costs of doing business.
Clusters are a prominent feature on the landscape of every advanced economy, and cluster formation is an essential ingredient of economic development.
www.isc.hbs.edu /econ-clusters.htm   (1582 words)

 Open or Galactic Clusters   (Site not responding. Last check: 2007-11-06)
Open clusters are preferentially found in the plane of the galaxy (thus they are also called galactic clusters); in contrast, the globular clusters are concentrated in the halo of the galaxy and can be very far out of the plane.
In images of open clusters such as this one, not all stars in the field of view are members of the cluster; some are stars between us and the cluster and some are stars beyond the cluster.
The stars in the cluster must all have approximately the same proper motion or the cluster would have dissipated over time, but stars not associated with the cluster would be expected to have more random motions.
csep10.phys.utk.edu /astr162/lect/clusters/open.html   (314 words)

 LCI: HPC Revolution 2006
Clusters: the HPC Revolution 2006 Conference, organized by the Linux Clusters Institute (LCI), is the premier international forum for sharing information on management, administration, and scientific computing techniques on clustered systems for high-performance computing.
Clusters: The HPC Revolution 2006 will feature a broad range of presentations and papers from HPC and large-scale cluster computing professionals in industry, academia, and government.
The Linux Clusters Institute was founded by the National Center for Supercomputing Applications, the Center for High Performance Computing at the University of New Mexico, and the Advanced Computing Technology Center at the IBM Watson Research Center.
www.linuxclustersinstitute.org /Linux-HPC-Revolution   (280 words)

 Galaxy Clusters Evolution
The presence of the X-ray gas guarantees the cluster is bound, and the observations are only limited by the exposure time, and not by the number of galaxies visible in the cluster.
The main method of measuring cluster masses via their X-ray emission, the hydrostatic isothermal beta-model, requires both the average X-ray temperature (from the X-ray spectrum) and density profile (from a fit to the surface brightness distribution).
The easiest quantity to measure for clusters (and in many cases the only quantity which can be measured for distant clusters) is their X-ray luminosity.
imagine.gsfc.nasa.gov /docs/features/topics/clusters_group/evolution.html   (1404 words)

 Star Clusters
Spectroscopic study of globular clusters shows that they are much lower in heavy element abundance than stars such as the Sun that form in the disks of galaxies.
The age of globular clusters is determined by investigating their H-R diagrams, as discussed in our globular cluster page.
Open clusters populate about the same regions of the Milky Way and other galaxies as diffuse nebulae, notably spiral arms in disk galaxies, and irregular galaxies, and are thus found along the band of the Milky Way in the sky.
www.seds.org /messier/cluster.html   (574 words)

 Chandra :: Field Guide to X-ray Sources :: Groups & Clusters of Galaxies
Galaxy clusters are the largest gravitationally bound objects in the universe.
Astronomers think that galaxy clusters form as clumps of dark matter and their associated galaxies are pulled together by gravity to form groups of dozens of galaxies, which in turn merge to form clusters of hundreds, even thousands of galaxies.
The gas in galaxy clusters is heated as the cluster is formed.
chandra.harvard.edu /xray_sources/galaxy_clusters.html   (257 words)

 Star Clusters   (Site not responding. Last check: 2007-11-06)
Open clusters are collections of hot, recently formed stars that are found preferentially in the spiral arms of the galaxy.
There are methods to determine the age of globular clusters that depend on the relative numbers of stars in the cluster having particular relations between their color and their brightness.
The distribution of globular clusters in the galaxy is quite different from that of the stars in the galactic disk.
csep10.phys.utk.edu /guidry/violence/starclusters.html   (311 words)

 Industry Clusters, Empire State Development   (Site not responding. Last check: 2007-11-06)
Industry clusters are groups of related industries located in one or more regions of the state.
ESD uses industry clusters as a framework for understanding the state and regional economies, and guiding economic development policy and initiatives.
Each profile provides a formal definition of the cluster, a summary of national and international market trends affecting the cluster, trends in New York cluster employment, and a summary of the cluster's presence in the state's economic development regions.
www.nylovesbiz.com /NYS_Home_To_Business/Industry_Clusters   (198 words)

 Universe Today - Super Star Clusters Started Small
The tightly packed group of clusters was found in the core of the active star formation region NGC 5461, within an arm of the giant spiral galaxy M101.
Super-star clusters, with a total mass of up to 1 million times that of the sun, are five to 50 times more massive than the spectacular R136 cluster at the center of the Tarantula Nebula in the Large Magellanic Cloud.
The dynamical evolution of the clusters at the core of NGC 5461 is being simulated by astronomy professor Paul Ricker at Illinois.
www.universetoday.com /am/publish/super_star_clusters.html?1212005   (746 words)

 Advantage West Midlands   (Site not responding. Last check: 2007-11-06)
Clusters were once geographically concentrated, for example in the Jewelley Quarter in Birmingham.
Throughout the UK and in the rest of the world, Business Clusters are seen as the new approach to economic development.
An overview of the strategic priorities for each cluster can be obtained by viewing the relevant priority cluster, or by downloading the executive summaries.
www.advantagewm.co.uk /business-clusters.html   (148 words)

 What is cluster? - A Word Definition From the Webopedia Computer Dictionary   (Site not responding. Last check: 2007-11-06)
The operating system assigns a unique number to each cluster and then keeps track of files according to which clusters they use.
Occasionally, the operating system marks a cluster as being used even though it is not assigned to any file.
You can free up disk space by reassigning lost clusters, but you should first make sure that the clusters do not, in fact, contain valuable data.
www.webopedia.com /TERM/c/cluster.html   (314 words)

 Linux Parallel Processing Using Clusters   (Site not responding. Last check: 2007-11-06)
Clusters are currently both the most popular and the most varied approach, ranging from a conventional network of workstations (NOW) to essentially custom parallel machines that just happen to use Linux PCs as processor nodes.
Further savings come from the fact that only one video card, monitor, and keyboard are needed for each cluster (although you will have to swap these to each machine to perform the initial installation of Linux, once running, a typical Linux PC does not need a "console").
The fact that replacing a "bad machine" within a cluster is trivial compared to fixing a partly faulty SMP yields much higher availability for carefully designed cluster configurations.
yara.ecn.purdue.edu /~pplinux/ppcluster.html   (5272 words)

 Catalogue: VII/92A   (Site not responding. Last check: 2007-11-06)
VII/92A Open Cluster Data 5th Edition (Lynga 1987) ================================================================================ Catalogue of Open Cluster Data (5th Ed.) LYNGA G.: 1987 ================================================================================ ADC_Keywords: Clusters, open ; Bibliography ; Combined data Description: This is a computer readable catalogue of open cluster data compiled by Gosta Lynga, Lund Observatory, Box 43, S-221 00 Lund, Sweden.
Cluster diameter (2) 417-418 I2 --- ObsType.37 ?
Note (3): the survey may be SO, O, E, J, R, I or SR Note (4): the "C" cluster designation has the general "format" CHHMM+DDd, i.e.
cdsweb.u-strasbg.fr /cgi-bin/Cat?VII/92A   (1372 words)

 DevChannel: Resources for Enterprise Developers
More often than not clusters, which are generally from 32 to thousands of tightly coupled Intel processors, have become an option for high performance computing (HPC), and even in general purpose computing in the commercial sector, especially for search engines.
Clusters got a big boost from the need for distributed computing for Web searches in the 1990s and from the explosion of Linux.
As a programmer, you should know how cluster architectures and their hardware interconnects can affect applications and their communications requirements.
hpc.devchannel.org   (879 words)

 Beowulf cluster Mini-HowTo   (Site not responding. Last check: 2007-11-06)
For other types of Beowulf clusters similar tools may be used, but we presently cannot provide an overview of such tools.
Due to the amount of network traffic expected in a cluster, a network switch isolating the traffic of the cluster should probably be installed.
Only in cases where your cluster is used solely for debugging and development should you consider letting users grab cluster nodes by anarchistic methods.
dcwww.camp.dtu.dk /cluster-howto.html   (2250 words)

These clusters can be composed of just a few machines that handle Web serving, or of hundreds or thousands of nodes that perform high-performance computing tasks that once would have required a supercomputer.
Don Becker, who pioneered Beowulf clustering, wrote many of the earliest network device drivers, and is founder and chief technical officer of clustering company Scyld Computing, confirmed that today's commodity Linux clusters are up to most, but not all, computing tasks.
The Altix is a new approach to Linux clustering that puts up to 64 processors in each node -- a far cry from the one or two processors per node in typical cluster systems.
www.gridtoday.com /03/0303/101127.html   (1132 words)

 Windows File System clusters explained
The way FAT works is that it keeps a record at the start of the drive of all the files, and to point to the files, it points to the clusters that contain the files.
The main rule of clusters is that there cannot be more than 1 file per cluster, otherwise pointing to that cluster would cause problems, as it would be pointing and doing read/write operations on two files at once, which would crash more than you ever seen Windows crash before.
The number of maximum clusters is calculated by doing 2^X where X is the number of FAT (ex: FAT12).
www.iamnotageek.com /a/24-p1.php   (641 words)

 HP OpenVMS systems - Clusters   (Site not responding. Last check: 2007-11-06)
The cluster also allows you to connect systems of all sizes and capacities and achieve an easy-to-manage, single virtual system.
Using a Votes and Quorum mechanism, the Connection Manager ensures that cluster nodes are admitted to the cluster correctly and that resources are reallocated across the cluster when nodes shut down.
CI clusters offer the highest levels of availability and throughput since systems and storage devices are dual pathed.
h71000.www7.hp.com /openvms/products/clusters/Clusters_Overview.html   (3043 words)

 Crash test penguin? Chrysler meets Linux | CNET News.com
These "cluster" supercomputers made of low-cost Linux computers are chiefly an academic phenomenon, where researchers have tight budgets along with the expertise to assemble their own supercomputers.
Beowulf clusters are good for brute-force tasks, but some users have begun applying the systems to jobs that require more finesse, such as chip design and financial analysis.
Mainstream computing companies such as IBM, Dell Computer and Hewlett-Packard started selling clusters as early as 1999, but the products now are regular items on a price list rather than more customized products built on a case-by-case basis.
news.com.com /2100-1001-962661.html   (726 words)

 HPC - Linux Clusters   (Site not responding. Last check: 2007-11-06)
Compute clusters are fast replacing the legacy shared memory parallel systems that have been the traditional technology used in many high performance applications.
Clusters can lower total cost of ownership and time to market by performing simulations even faster than giant supercomputers.
This commitment, coupled with HP's experience and leadership in the HPC market and Linux, is reflected in the Unified Cluster Portfolio, our simple and cost-effective solution for high performance clusters.
www.hp.com /techservers/clusters/linux_clusters.html   (399 words)

 APOD Index - Galaxies: Clusters of Galaxies
Most galaxies in Coma and other clusters are ellipticals, while most galaxies outside of clusters are spirals.
Virgo cluster of galaxies reveals a hot X-ray emitting plasma or gas with a temperature of 10-100 million degrees pervading the cluster.
of the cluster, is centered in that area while other cluster members are scattered around it.
antwrp.gsfc.nasa.gov /apod/clusters_of_galaxies.html   (385 words)

 Cluster Headaches Worldwide Support Group
If they were to witness my nightly cluster ritual, they would never see me the same way again.
I reach a point of distraction from the cluster, and then I start the whole process over; roll and squeeze, crawl and bang, find the telephone.
Eventually, the cluster, whatever it is, drains from me. I can feel it passing through my temple, and behind my ear where it seems to run out of my skull like water passing down a pipe.
clusterheadaches.com   (1487 words)

 Globular Star Clusters
Charles Messier was the first to resolve one globular cluster, M4, but still referred to the other 28 of these objects in his catalog as "round nebulae." Thus, in summer 1782, before William Herschel started his comprehensive deep sky survey with large telescopes, there were 33 globular clusters known.
Globular clusters typically contain a number of variable stars, in particular RR Lyrae stars which were once called "Cluster Variables" because of their abundance in globulars.
It is perhaps a bit surprising that almost all globular clusters seem to be of about the same age; there seems to be a physical reason that they all formed in a short period of time in the history of the universe, and this period was apparently long ago when the galaxies were young.
www.seds.org /messier/glob.html   (1933 words)

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