Archive for the ‘Cross-Cultural’ Category.

Sep 22nd, 2009| 12:03 pm | Posted by hlee

Thanks to a Korean solar physicist^{[1]} I was able to gather the following websites and some relevant information on Space Weather Forecast in action, not limited to literature nor toy data.

Continue reading ‘More on Space Weather’ »

Tags:

automatic,

CME,

computer vision,

data mining,

feature detection,

filament,

image processing,

machine learning,

manifold,

space weather,

statistical learning,

sunspot,

SVM Category:

Algorithms,

arXiv,

Cross-Cultural,

Data Processing,

Imaging,

Jargon |

Comment
Sep 10th, 2009| 11:20 pm | Posted by hlee

Soon it’ll not be qualified for [MADS] because I saw some abstracts with the phrase, **compressed sensing** from arxiv.org. Nonetheless, there’s one publication within refereed articles from ADS, so far.

http://adsabs.harvard.edu/abs/2009MNRAS.395.1733W.

*Title:***Compressed sensing imaging techniques for radio interferometry**

*Authors:* Wiaux, Y. et al. Continue reading ‘[MADS] compressed sensing’ »

Tags:

compressed sensing,

ill-posed,

image reconstruction,

interferometry,

inverse problem,

MADS,

Nyquist-Shannon sampling theorem Category:

Algorithms,

Cross-Cultural,

Data Processing,

Imaging,

Jargon,

Spectral |

Comment
Sep 8th, 2009| 10:17 am | Posted by hlee

I happened to observe a surge of principle component analysis (PCA) and independent component analysis (ICA) applications in astronomy. The PCA and ICA is used for separating mixed components with some assumptions. For the PCA, the decomposition happens by the assumption that original sources are orthogonal (uncorrelated) and mixed observations are approximated by multivariate normal distribution. For ICA, the assumptions is sources are independent and not gaussian (it grants one source component to be gaussian, though). Such assumptions allow to set dissimilarity measures and algorithms work toward maximize them. Continue reading ‘[ArXiv] component separation methods’ »

Sep 4th, 2009| 01:30 pm | Posted by hlee

ARCH (**autoregressive conditional heteroscedasticity**) is a statistical model that considers *the variance of the current error term to be a function of the variances of the previous time periods’ error terms*. I heard that this model made Prof. Engle a Nobel prize recipient. Continue reading ‘[MADS] ARCH’ »

Sep 1st, 2009| 07:43 pm | Posted by hlee

[arxiv:0906.3662] **The Statistical Analysis of fMRI Data** by Martin A. Lindquist

Statistical Science, Vol. 23(4), pp. 439-464

This review paper offers some information and guidance of statistical image analysis for fMRI data that can be expanded to astronomical image data. I think that fMRI data contain similar challenges of astronomical images. As Lindquist said, collaboration helps to find shortcuts. I hope that introducing this paper helps further networking and collaboration between statisticians and astronomers.

**List of similarities** Continue reading ‘[ArXiv] Statistical Analysis of fMRI Data’ »

Tags:

data aquisition,

experimental design,

fMRI,

ICA,

image analysis,

image processing,

localization,

modeling,

pipeline,

preprocessing,

similarities,

Spatial,

temporal,

time series,

voxel Category:

arXiv,

Cross-Cultural,

Data Processing,

Imaging,

Jargon,

Methods,

Stat |

Comment
Aug 13th, 2009| 09:52 am | Posted by hlee

Over the few years, at the heart of astronomical researches, I see astronomers treat statistics like a magic crystal. Continue reading ‘Magic Crystal’ »

Aug 12th, 2009| 06:03 pm | Posted by hlee

Statistical Resampling Methods are rather unfamiliar among astronomers. Bootstrapping can be an exception but I felt like it’s still unrepresented. Seeing an recent review paper on **cross validation** from [arXiv] which describes basic notions in theoretical statistics, I couldn’t resist mentioning it here. **Cross validation** has been used in various statistical fields such as classification, density estimation, model selection, regression, to name a few. Continue reading ‘[ArXiv] Cross Validation’ »

Tags:

ADS,

cross-validation,

machine learning,

Model Selection,

n-fold Category:

arXiv,

Astro,

Bayesian,

Cross-Cultural,

Data Processing,

Frequentist,

Jargon,

Methods,

Quotes,

Stat |

Comment
Jul 30th, 2009| 01:57 am | Posted by hlee

##### X={ primer, tutorial, cookbook, Introduction, guidebook, 101, for dummies, …}

#####

I’ve heard many times about ** the lack of documentation** of this extensive data analysis system, **ciao**. I saw people still using ciao 3.4 although the new version 4 has been available for many months. Although **ciao** is not the only tool for Chandra data analysis, it was specifically designed for it. Therefore, I expect it being used frequently with popularity. But the reality is against my expectation. Whatever (fierce) discussion I’ve heard, it has been irrelevant to me because **ciao** is not intended for statistical analysis. Then, out of sudden, after many months, a realization hit me. **ciao is different from other data analysis systems and softwares.** This difference has been a hampering factor of introducing ciao outside the Chandra scientist community and of gaining popularity. This difference was the reason I often got lost in finding suitable documentations. Continue reading ‘Where is ciao X ?’ »

Tags:

ciao,

cookbook,

documentation,

guide,

introduction,

matlab,

primer,

Python,

R,

SAS,

software,

Tutorial Category:

Cross-Cultural,

Languages,

Misc |

1 Comment
Jul 29th, 2009| 01:02 am | Posted by hlee

Speaking of XAtlas from my previous post I tried another visualization tool called **Parallel Coordinates** on these Capella observations and two stars with multiple observations (AL Lac and IM Peg). As discussed in [MADS] Chernoff face, full description of the catalog is found from XAtlas website. The reason for choosing these stars is that among low mass stars, next to Capella (I showed 16), IM PEG (HD 21648, 8 times), and AR Lac (although different phases, 6 times) are most frequently observed. I was curious about which variation, within (statistical variation) and between (Capella, IM Peg, AL Lac), is dominant. How would they look like from the parametric space of High Resolution Grating Spectroscopy from Chandra? Continue reading ‘[MADS] Parallel Coordinates’ »

Tags:

Classification,

clustering,

display,

EDA,

eye catcher,

GGobi,

Inselberg,

parallel coordinates,

visualization Category:

Algorithms,

arXiv,

Cross-Cultural,

Data Processing,

High-Energy,

Jargon,

Methods,

Spectral,

X-ray |

3 Comments
Jul 27th, 2009| 07:37 am | Posted by hlee

I wish I could chase all rabbits. Another rabbit I missed came to a realization by a friend, who was sure that I already knew this “call for papers” notice for the special issue of the signal processing magazine (SPM). Although those due dates were mistaken (the white paper due was several months back), my friend thought it would be useful for me and my group just in case I didn’t know about it. Yes, I was very delighted such things were on going. No doubt that I was disappointed when the white paper due was long gone. Continue reading ‘Another exciting news (with no use)’ »

Jul 27th, 2009| 06:09 am | Posted by hlee

I’m getting behind these days because of chasing too many rabbits. One of those rabbits is hunting online lectures useful for everyone. **Prof. Feynman’s lectures** have great reputations but they have been hard to come by. I once listened to a pirate version of his lecture tape with horrible sound quality. Thanks to **Bill Gates** and **Microsoft Research**, although it is a belated news, I’m very delighted to say “Feynman lectures are online.” Continue reading ‘News and related stories’ »

Jul 12th, 2009| 07:33 pm | Posted by hlee

An email was forwarded with questions related to the data sets found in “Be an INTEGRAL astronomer”. Among the sets, the following scatter plot is based on the Crab data.

Continue reading ‘different views’ »

Tags:

ANOVA,

block design,

crab nebula,

F-test,

gaussinity,

integral,

light curve Category:

Astro,

Cross-Cultural,

gamma-ray,

High-Energy,

Jargon,

Objects,

Uncertainty |

Comment
Jul 12th, 2009| 07:21 pm | Posted by hlee

Approximately for a decade, there have been journals dedicated to **bioinformatics.** On the other hand, there is none in astronomy although astronomers have a long history of comprising a huge volume of catalogs and data archives. Prof. Bickel’s comment during his plenary lecture at the IMS-APRM particularly on **sparse matrix** and **philosophical issues on choosing principal components** led me to wonder why astronomers do not discuss **astroinformatics**. Continue reading ‘Astroinformatics’ »

Tags:

astroinformatics,

bioinformatics,

catalog,

dimension reduction,

journals,

penalize,

regularization,

sparse matrix,

variable selection Category:

Astro,

Cross-Cultural,

Data Processing,

Imaging,

Jargon,

Stat |

1 Comment
Jul 4th, 2009| 12:59 am | Posted by hlee

I was reading the June 2009 IMS bulletin on my way to Korea for the 1st IMS-APRM meeting. Then, I was in half shock and in half sadness. Something unlike than the Drake equation had happened. Continue reading ‘worse than the Drake eq.’ »

Tags:

bump hunting,

chain rule,

computational geometry,

Drake eq.,

IJ Good,

K Worsley,

obituary,

spectral analysis Category:

Astro,

Cross-Cultural,

Jargon,

Spectral,

Stat |

Comment
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