Fault tolerant computing-II
So the basics are there, with full recovery from 23 failures over 1000 timesteps on 32 processes: context: https://cosmicrays.wordpress.com/2011/07/06/fault-tolerant-computing/
Author: Christine Corbett Moran
Fault tolerant computing
As a first step to writing my own simulation code while attempting to do something useful, a few days ago I started writing a code to explore failure and recovery from failure in a distributed computation. By failure in this case, I mean when one of the computation units goes down. My test system is N harmonic oscillators on N nodes (or processes on a shared memory machine). Read More …
The Intersection of Productivity and Joy (over the past months)
Since last we spoke a couple of months ago, I had a hell of a time personally: I moved house, went from one location to another too often, had a major and very stressful financial crisis and had some rough times with friends which rocked the emotional boat. Although there are many things which didn’t Read More …
Probing the dark matter issue in f(R)-gravity via gravitational lensing
A few days ago in gr-qc journal club we discussed an interesting paper by a member of our own institute, Probing the dark matter issue in f(R)-gravity via gravitational lensing.1. Background Dark Matter We theoretically expect dark matter to exist based largely on extensive observations of both dynamics (rotation curves and objects such as the Read More …
Halos gone MAD
I have previously blogged about Structure finding in cosmological simulations and the Haloes Going Mad conference in Madrid this past spring–there you will find the basic background if you are unfamiliar with the subject and I’ll skip that in this post. The result of this conference was a Halo-finder comparison project and its findings were recent posted on the physics arxiv in the paper Haloes gone MAD: The Halo-Finder Comparison Project. I’ll summarize them here.
The paper concentrates on comparing codes on given test data, not comparing the results of various codes to observations, provides a standard test suite and proposes a standard methodology of comparison, both on test, isolated, halos and on a simulation of cosmological volume. Read More …
Kliq Soft Launch
Kliq soft launched this weekend. You can schedule a meetup (dinner, drinks, you name it) in just a few thumb taps with your local facebook friends or be adventurous and be introduced to a friend of a friend. This is just a taste of what’s to come. Get Kliq on the iPhone App Store at http://itunes.apple.com/lt/app/kliq/id412169676 or visit http://kliq.in. Read More …
Locally Cold Flows from Large-Scale Structure
Walls, filaments and voids: it is thought that the large scale distribution of matter is a complex network of galaxies and galaxy clusters connected by elongated filaments and sheetlike walls, outlining vast underdense regions known as voids and meeting at dense and compact regions known as haloes. Aragon-Calvo et. al. in [1] build upon the SpineWeb framework outlined in [2] , which has the capability of identifying these walls, filaments and clusters in cosmological simulations to examine the effect of environment (namely whether a galaxy is “living” in a wall or a void) on the dispersion of the Hubble flow around the Milky, which is significantly lower than theoretical expectations. They show that the measured dispersion could be a result of the fact that Milky Way resides inside a wall of radius around 10Mpc, which is supported by data. Read More …
YouTube – Creating a Hubble Galaxy in Two Minutes
YouTube – Creating a Hubble Galaxy in Two Minutes.
The Pioneer Anomaly
A few weeks ago, Astrophysics Master’s student Tina Wentz gave a great overview of the phenomenon known as the Pioneer Anomaly in our gr-qc journal club. I’m indebted to her for that overview as well as pointing me to relevant papers in the preparation of this post. Background Launched in 1972 and 1973 respectively, the Read More …
Green's functions
Some of the most important equations in physics can be solved by constructing a beast with a curious set of properties, called a Green’s function. This post contains some interesting nuggets from a lecture I gave on St. Patrick’s day about Green’s functions to the course I assist, Mathematical Methods in the Physical Sciences II. I’ll Read More …