Some days ago, I was in one of these modern wagons of the new Brussels’ metro heading to the station, standing up near the door when a strange individual entered the place.
I have to say, these days the metro is not the happiest place in the world: think of a fastly moving, silent long and closed oven (30°C average), filled with exotic scents reminding us of the multi-cultural, cosmopolitan nature of Europe’s capital social tissue, for the pleasure of the senses and full of either highly communicative, red-faced, boozed people commenting the latest world cup goal in every possible language (reminding us again of the Brussels multiculturalism for the pleasure of our other senses) and second, half-closed-eyed, opium-dreaming folks in profound introspection.  I would think many of the second class specimens reached this state after being in the first one.

The fact is, I was myself in a vague zen self-contemplating state, waiting to reach my final destination to get out of this unhealthy sauna, when this chap entered and parked himself at my right.

I didn’t really notice him as I was in standby, energy-saving mode.

A station later, however, when my right foot reached an obstacle, I peeked down by reflex just to notice a small black wallet lying on the floor.  As it apparently had slipped out the newly arrived chap, I looked up just to face a strange hairy creature very close to Uncle Itt, a tad taller.

“Scuse me”, I said to him, friendly
(no answer)
“Hey”, I exclaimed, on a 20 db higher pitch
(still no answer)
I then moved my hand in front of his face, though it was difficult to locate the exact position of the eyes behind that solid curtain of hairs, to obtain a rather awkward 15° head twist to the left followed by the same movement the opposite sense.
At this point I was considering to just forget about it, give Itt a friendly kick in the ribs or pull off some of these abundant hair (very tempting) or even recollected some of my old sign-language communication skills when I noticed a rythmical, almost imperceptible shaking of the hairstack.

I glanced attentively at the subject, since it wasn’t quite clear if it was due to parkinson, some mild form of Tourette’s syndrome or just autism.

At this moment, Itt’s hand, just like Napoleon, slipped into his jacket and stayed there some seconds, apparently doing some sort of scratching.

To my surprise, the autist now entered a frantically faster rythmical movement, something like a jump from allegro to scherzo furioso.

And the light was.

So I heartly gave the music lover an elbow kick in the ribs, to which, to my satisfaction, I obtained a quick reaction this time, and saw Itt move apart the left side of the hairstack, freeing his furious left teen eye and
uncover a white cable which he plugged off his left ear.

My right cochlea was assaulted by what I immediately recognized as the latest riffs of Let There Be Rock.  The sound was so powerful, going out of this tiny plug that I just stood there in awe and was only able to point my finger to the black wallet in the floor, to which Itt quickly reached and headed off the wagon at the next stop.

I made a quick estimate.  The volume off this earplug inside the ear would almost certainly be delivering more than 90db.  At this rate, I thought, this guy will be deaf in 15 to 20 years, starting at a high-frequency loss to degenerate to a disabling mild-to-severe loss after 45 years age, with just some years of frequent exposure to
loud music over 80db.

I was furious and apalled at the same time.  As an ex-profoundly deaf person now using a cochlear implant, I know what deafness is about.
I am totally against the proliferation of these super-powerful headphones plugged into the ears used indiscriminately.  I see often people of all ages wearing headphones in public places, but you never know at which volume they’re playing music at.  That reminded me of a Wired article I read long ago.

It is widely known that long exposure to loud noise (over 85db) can cause first tinnitus and progressively, deafness.
The human cochlea contains, in the organ of Corti, a number of sensory cells called hair cells.  There are approximately 10000 “inner hair cells” and 30000 “outer hair cells”.  The hair cells are located in rows along the organ or Corti and are functionally different.  The vibrations transmitted from the stapes to the perilymph, then to the endolymph, will cause the vibration of the hair cells which, in the end, will cause electrical potentials which we perceive as “sounds”.

Long, strong vibrations of the endolymph cause hair cell damage and death.
Think about it. 

More information:

The Cochlea http://en.wikipedia.org/wiki/Cochlea
Noise-induced hearing loss: http://www.nidcd.nih.gov/health/hearing/noise.asp

I was looking for some information on Europalia, an annual cultural event having China on the spotlight this year. I found an interesting exhibition called the orchid pavillon, covering the origin and development of chinese writing, which I’ll try to attend this year.

How curious, however, is the fact that some of the oldest chinese writings are oracle scripts. eg divinatory scripts carved in animal bones, often turtle shields and other animal bones. I found lots of references to the so-called jiaguwen .

Funny enough, Oracle founders Larry Ellison, Bob Miner and Ed Oates didn’t think about divinatory rituals or ancient scriptum when baptising their flagship software, that complicated piece of software full of surprises and power, but rather an obscure CIA project code name they all worked on.
No doubt every Oracle dba or developer who’s been around for a while knows where the pythian group takes its name from (and I’m not mentioning all the ethymologies and the hypothetical presence of ethylene in Delphi’s temple)… That made me build a little list of possible similar group names.

- The shamans
- The sybilians
- The dogonian mazes
- The buzian sounds
- The baulé mickeys
- The ayahuasca drinkers
- …

To be continued…

It just strikes my mind to see how some topics come back in cycles. I remember an interesting conversation
on correlation/causation and predictive models back in 2005. Yes, I’m an old man and quite silent, but I’m working on it.

Jonathan Lewis’ post on correlation puts me in a fuzzy state of over-stimulative reminiscences. This is why I often find Jonathan’s posts so stimulating: they are not only very informative but are food for thought and propose new exploratory possibilities.

Correlation implies cause

For a lot of people, this is intuitively right. For 2 measurements which are related with a third variable say time, having these measures changing over time in a very similar fashion looks like they share a common cause.
Constant change rates on both variables indicates linearity. Okay, let me be nit-picking and make some definitions:

The linear correlation coefficient r measures the strength and direction of a linear relationship (or association) between two variables (aka Pearson’s coefficient).

When r is close to 1, the relationship between both variables is strong. That means that when values for X go up, values for y also go up.
On the other hand, when r is close to -1, there is also a linear relationship, but now when x goes up, y goes down.
Finally when r is close to 0, there is no linear relationship, but random non-linear relationships can be found on these variables.

To tell how “strong” a correlation is depends on the kind of data. This is why scientific data generally need a higher correlation coefficient to call them “strong” (generally above 0.8) than medical/social/psychological data. It is well accepted today that the interpretation of a correlation coefficient depends on the context of data.

The determination coefficient R^2 gives the proportion of variance of one variable that is predictable from the other one. It will tell us how certain we can be of making a prediction from a certain model.

So, back to the original discussion, the sentence “correlation does not mean causation” doesn’t necessarily mean that correlation doesn’t indicate potential causal relations. It’s just saying that a strong correlation is not sufficient to establish a causal relationship. period.

Haven’t you seen Dr House ? The white board ? Yes, it’s fiction, but illustrative.

So far, I have found it useful to correlate some wait events from statspack measurements with other non-db measurements. In one particular case, many years ago, it helped me to find the root cause of a really odd performance issue. I found out the problem to be related to the NFS client configuration on a Solaris server while using NAS storage and Oracle 8.0.6.

Personally, I would be very careful on building predictive models for anything in Oracle. One thing I’ve learned over all these Oracle versions is that one size doesn’t fit all, and of course, the more I know, probably the more I miss. The only steady ground I have is the scientific method: hypothesis, test, prediction.
Working with test cases, with representative test data, with a well-known baseline state.

As Ian Anderson sings, “life is a song”…

A day like today, 409 years ago, died Giordano Bruno. Burnt alive by the italian Inquisition after 7 years of trial, in Campo de Fiori, Rome. The story of his capture in Venezia, extradition to Rome, and finally his sentence eloquently displays the Catholic Church’s fear upon the spread of Bruno’s ideas.

Yes, we have wikipedia and a plethora of qualified sources to know more about this astonishing man.

But still…

Bruno, who entered the Dominican order at age 14, had a prodigious memory (he was sent to show his gift to the pope at age 20 and was asked to teach mnemonics), obtained his PhD in Philosophy at age 25, traveled a great deal across Europe (a true Erasmian) and published his works mainly in Paris.

What I find remarkable in Bruno’s works and life, apart from his visionary theories on the universe and his unorthodox (for his time) religious views, is his constant quest for truth and wisdom, his explorations between science and occultism (some will say hermeticism), his uncomformism, his freedom.

I put here some links about Giordano Bruno that I particularly appreciate and that will serve me as a reminder of further readings.

Absolute astronomy:
Reviewing the reviews: Giordano Bruno and Marshall McLuhan
De immenso, de minimo and de infinito
On the infinite universe and Worlds

Frances Yates on Wikipedia

Everybody now seems to be either on Facebook or Twitter (or both). Oracle Corporation is
fully using web 2.0 technologies and social networks (they are on twitter and Faebook. This is not really surprising as this company has almost always been riding the waves of emerging technologies. See for example the usage of Social Networks and 2.0 technologies in Oracle’s CRM offering.

However, I wonder about the dangers of social networks when used (and abused) by poorly informed people.
Social engineering is also part of a hacker’s bag. Tools like Maltego allow you to search on multiple social networks and display this information in a graphical way.

Here’s a very good post on Twitter and information mining, by Lenny Zeltser.

I don’t know why, but Wittgenstein is on my mind these days.

On a recent exchenge between Don Burleson and Jonathan Lewis, I couldn’t help but add a comment.

Long ago, I saw an article on Pervasive Business Intelligence, from DMReview.com.
At the time of this article, in 2005, pervasive computing was out there for more than a decade (see Real-Time Pervasive Systems.
Ralph Kimball mentioned in his – now a classic book – The datawarehouse toolkit book, the potential of clickstream analysis: analyze every user’s action in an online store. Similarly, you could
analyze many actions of a customer in a physical store by using RFID tags.
The fact is that BI technology is now able to collect and analyze huge volumes of data in near real-time.
With the emergence of Business Performance Management systems, a complete performance management
cycle is put in place to guide enterprise’s strategy through reporting and analysis based on BI.
As John Kopecko, Hyperion’s CTO (before it was acquired by Oracle) wrote in his paper Pervasive BI – the next step in the evolution of Business Intelligence.

BI must evolve beyond its current status as a tool experts use to report performance to managers and executives
and become an everyday business tool for everyone in the enterprise. In short, BI must
become pervasive.

That reminded me of an old story about a newly hired Toyota executive who was told to work with production workers right from the start to find new ways of improving production quality. He didn’t start his new job going to meetings, presentations and all the classic workday of a med/senior executive.
He was told to watch the production lines and discover why disruptions happened and how to fix them. From the ground.

He was put in a Japanese team where nobody spoke English.

He discovered that all the workers had integrated quality and performance management practices, applying them in real-time, from the production lines up to the Board.

Now pervasive BI makes me wonder, what if everyone in the enterprise could access relevant data and analyze it to better achieve his/her tasks ?

Did you mean Hyperion ? It’s amazing what this piece of code can do with Essbase, MDX and XML/A.

I just decided to start this blog, and as an excuse I post a link to an excellent book I have recently read.

I though this book desserved a detailed review that I hope will help other people in choosing the right book for their needs.