Jun 11th, 2009| 03:52 pm | Posted by hlee

I was at the SUSY 09 public lecture given by a Nobel laureate, Frank Wilczek of QCD (quantum chromodynamics). As far as I know SUSY is the abbreviation of **SUperSYmetricity** in particle physics. Finding such antimatter(? I’m afraid I read “Angels and Demons” too quickly) will explain the unification theory among electromagnetic, weak, and strong forces and even the gravitation according to the speaker’s graph. I’ll not go into the details of particle physics and the standard model. The reason is too obvious. Instead, I’d like to show this image from wikipedia and to discuss my related questions.

Continue reading ‘how to trace?’ »

Tags:

cliche,

collion,

identifiability,

identification,

irony,

LHC,

Power,

reconstruction,

source detection,

subparticle,

supersymmetry,

SUSY,

TRACE,

type I error,

Type II error,

uncertainty principle,

unification,

youtube Category:

Cross-Cultural,

Data Processing,

High-Energy,

Misc,

Quotes,

Uncertainty |

Comment
Mar 5th, 2008| 04:46 pm | Posted by hlee

This is a quite long paper that I separated from [Arvix] 4th week, Feb. 2008:

[astro-ph:0802.3916] P. Carvalho, G. Rocha, & M.P.Hobso

**A fast Bayesian approach to discrete object detection in astronomical datasets – PowellSnakes I **

As the title suggests, it describes Bayesian source detection and provides me a chance to learn the foundation of source detection in astronomy. Continue reading ‘[ArXiv] A fast Bayesian object detection’ »

Tags:

Bayesian evidence,

coloured background,

CRLB,

decision theory,

filter,

Fisher informatoin,

likelihood,

PowellSnake,

prior,

simulated annealing,

SNR,

source detection,

state space,

Sunyaev-Zel'dovich effect,

symmetric loss,

templates Category:

Algorithms,

arXiv,

Bayesian,

Cross-Cultural,

Data Processing,

Fitting,

Frequentist,

MCMC,

Methods,

Objects |

Comment
Oct 21st, 2007| 03:59 pm | Posted by vlk

`wavdetect` is a wavelet-based source detection algorithm that is in wide use in X-ray data analysis, in particular to find sources in Chandra images. It came out of the Chicago “Beta Site” of the AXAF Science Center (what CXC used to be called before launch). Despite the fancy name, and the complicated mathematics and the devilish details, it is really not much more than a generalization of earlier local cell detect, where a local background is estimated around a putative source and the question is asked, is whatever signal that is being seen in this pixel significantly higher than expected? However, unlike previous methods that used a flux measurement as the criterion for detection (e.g., using signal-to-noise ratios as proxy for significance threshold), it tests the hypothesis that the observed signal can be obtained as a fluctuation from the background. Continue reading ‘The power of wavdetect’ »

Tags:

AXAF,

ChaMP,

Chandra,

ciao,

Power,

source detection,

Type II error,

wavdetect,

wavelet Category:

Algorithms,

Imaging,

X-ray |

1 Comment
Jan 29th, 2007| 01:59 am | Posted by hlee

In Spring 2006, SAMSI (Statistical and Applied Mathematical Sciences Institute) program on Astrostatistics began with tutorials, followed by workshops and regular meetings of working groups (Exoplanets, Surveys and Population Studies, Gravitational Lensing, Source Detection and Feature Detection, Particle Physics). Workshop speakers/participants and working group members brought up many statistical challenges in astronomy and physics and had extensive discussions. Summaries and relevant materials are available from the websites (click the links; some materials such as journal papers are password protected).