AERA Aiming High

AERA Aiming High

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  • cours - matière potentielle : context
  • cours - matière potentielle : year
  • cours - matière potentielle : objectives
  • leçon - matière potentielle : class
  • fiche de synthèse - matière potentielle : the distribution of observers
  • leçon - matière potentielle : achievement
  • expression écrite
  • cours - matière potentielle : sessions
  • cours - matière potentielle : content
  • cours - matière potentielle : plans
  • revision
  • leçon - matière potentielle : on the itbs
  • leçon - matière potentielle : than students of teachers
1 Aiming High: Implementation Fidelity, Cognitive Demand, and Struggling Readers' Literacy Outcomes Jill Feldman, Kelly Feighan, and Elizabeth Heeren Researchers studying a multi-year, federally funded Striving Readers project built upon previous analyses to investigate which components of an intensive two-year professional development intervention contributed most strongly to the academic achievement of students taught by teachers in four urban, economically disadvantaged middle schools in Memphis, Tennessee. After collaborating with literacy coaches to rate teachers' fidelity of implementation (FOI), authors analyzed the associations among FOI, observed literacy strategy use and cognitive demand level, and students' performance on a nationally normed reading test
  • proportion of teachers with full licensure
  • 41.2 teaching licensure
  • use of literacy strategies
  • rbs classroom observations
  • state test
  • literacy strategies
  • scores
  • teachers
  • 2 teachers

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CS161: Operating Systems
Matt Welsh
mdw@eecs.harvard.edu
Lecture 24: Distributed Operating Systems and Amoeba
May 3, 2007
© 2007 Matt Welsh – Harvard University 1Distributed Operating Systems
So far we have been talking about an OS that runs on a single
machine
What about an OS that runs across many machines,
distributed on a network?
Why might such a thing be useful?



© 2007 Matt Welsh – Harvard University 2Distributed Operating Systems
So far we have been talking about an OS that runs on a single
machine
What about an OS that runs across many machines,
distributed on a network?
Why might such a thing be useful?
● Transparent access to remote resources
● Support parallel computing – running programs across many machines simultaneously
● Provide a single system image across many different machines
Today: The Amoeba Distributed Operating System
● One of the first and most influential distributed OS projects
© 2007 Matt Welsh – Harvard University 3The rise of distributed computing
Mid-70's: Ethernet developed
● Developed by Bob Metcalfe while at Xerox PARC in 1973, went on to found 3Com
Allows machines to be connected into a local area network
User on one machine can access services and data on other machines
© 2007 Matt Welsh – Harvard University 4Internetworking
Routing allows multiple local networks to communicate:
140.247.62.xxx
140.247.60.xxx
140.247.62.1
140.247.60.1
Router (or “gateway”)
140.247.2.1
140.247.2.xxx
© 2007 Matt Welsh – Harvard University 5Internetworking
OK, but how do we communicate over long distances?
Harvard MIT
Autonomous system
(AS)
Cogent
Backbone router
Sprint
BUVerizon
● Long-distance (WAN) links between multiple sites
● So now, a user at Harvard can use services or data anywhere on the network!
© 2007 Matt Welsh – Harvard University 6Example Applications
Remote access to supercomputing resources
● User at University A can run jobs on supercomputer at University B
● e.g., Simulations of galaxy formation, biomedical data processing, etc.
Remote access to large data sets
● e.g., Archived scientific data, satellite images, genomic data, etc.
© 2007 Matt Welsh – Harvard University 7Grid Computing
Modern concept: Tie all of the world's high-end computers together
into a massive computing grid
© 2007 Matt Welsh – Harvard University 8http://tg-monitor.ncsa.teragrid.org/
© 2007 Matt Welsh – Harvard University 9Cluster Computing
Network of (generally identical) computers
Provide many fast CPUs for parallel
computing applications
Generally uses very fast local area network
● Asynchronous Transfer Mode (ATM)
● FiberChannel
● InfiniBand
● Myrinet
● These days: 10 Gbit Ethernet
Amoeba cluster at Vrije Universitat
© 2007 Matt Welsh – Harvard University 10