Less marriage makes women slaves

An article on The Economist about marriage in Asia inspired me to plot the situation in a graph that I consider interesting.
Women are getting married less and less. This is a fact. Moreover, if they get married, this happens later, with respect to the past (in a timeline of about 20 years). This is another fact.
With this said, I think that the situation is not that far from what this (causality) graph is saying.

More educated women normally find a job, which increases financial independence. Women busy with their jobs have less time for relations and, of course, marriage. Fewer marriages lead to fewer babies, since women prefer to have babies when the good old requirements of a family are present. Less babies make the society older. Which leads to increase social protection (pensions, health, etc…).
Less babies also mean that women now have more spare time to spend on their hobbies or working even more.
Fewer marriage is also related to the increase of men testosterone, which leads to more male crime.
This fact leads to increase social security measures.

What is going to happen?

Women will work harder and harder to support social protection and social security in order to be protected from old men crimes.
Is it better than just marrying?


Finally a break

Hello Everyone!
I am finally having a break for the next seven days. My flatmate and I definitely deserve it after the hard work we’ve been doing so far. Eating sandwiches left from official meetings is really a big deal. Sometimes I have to eat stuff I really don’t like. Hard to be a pig…

So here is the plan. This year we go to northern Europe: Germany, Denmark, Sweden. The whole trip is by car and we’re going to sleep in hostels on the way.
I stuffed the car with panini, biscuits, drinks, fruit and, of course, lots of sweets. Moreover, since I will be the DJ I provided some very good podcasts for science lovers like me (you can find a list here ) for a super smart driving experience.

Seatbelts are fastened. Ready to go.
Au revoir!


Probability can save your life (with a good degree of belief)

I’ve been running with my flatmate (who, by the way, is becoming a very good runner) last week and tried to support him during his training. Unfortunately, after 1 min I had to stop because we were crossing the main road in order to access the path towards the country side where air is much cleaner and fresh (refer to the picture above).
Since my flatmate always optimizes things, he pretends to minimize the effort by watching his right side and crossing the road as easier as I was eating a sandwich. Then I stopped him because I realised that approaching the road in that way may have been a terrible mistake.

The road is a one-way main road with an average traffic of 10 cars per minute, driving from right to left.
The safest approach should be walking on the zebra crossing, of course. But my flatmate is a little crazy and just crosses the road to the shortest path. There are actually three other ways to approach that road:

1) look at your left then cross
2) look at your left and right; then cross.
3) look at your right then cross

The first option seems to be the most dangerous one. On a one-way road cars are very likely to drive from the right side. Looking at your left does not provide any information about the safety of the crossing.

While the second option sounds safer than the others, my flatmate regularly crosses the street with the 3rd approach. He looks the same direction cars are likely to drive from and then crosses, ignoring the left side. He says that “watching left is useless on a one-way road where cars are expected to drive from the right side”…

My sandwich was almost over when subjective probability came to my mind. Unfortunately, I have no experience on the topic and I would like to convince my flatmate that he should also look to his left when crossing a one-way road (or that the probability that a crazy driver comes from his left is not zero).

Will you help me?

If you can formalize this problem with uncertain probability drop me a line worldofpiggy@gmail.com (or just leave a comment).


Strange food attractor

A paper written by my flatmate has been accepted and he will present it in China, next October.  To celebrate this wonderful event he decided to have a long weekend in Berlin.
I was busy working on another project and ordering some food from the internet (had to take advantage of the happy moment and ask some money to buy me drinks and junk food (oo)
But after two days I decided to meet him in Berlin, also because I finished all the food I bought in less than 24 hours…Hey! I was a hungry Pig, and I was super happy for him. This feeling normally makes me eat more.
I was so tired of going around Berlin, from one sightseeing bus to the other that I had to sit on a bench near Alexander Platz. I liked it there also because the people in the picture gave me food when I insisted that I was a bird too.

While they were concentrated into giving seeds and pieces of bread I realised something amazing. Those birds moved following trajectories I’ve been already seeing somewhere. It clearly was a strange attractor. They were attracted by seeds, but also scared by humans (and how they couldn’t! Sometimes I am scared t(oo)
It was very difficult to study the trajectories of those birds, also because I had no paper and no pen for some notes. By the way I remembered about a strange attractor which generates chaotic trajectories in a very similar way.
Otto Rössler came to my mind! Rossler, who – btw – was born in Berlin, is known for his contribution in chaos theory.
Attractors describe how a dynamical system “moves” in the plane (in our case it’s the xyz plane). Attractors are normally considered to explain very complex systems. Chaos is related to attractors for the reason you might understand.
He studied an attractor which follows an outward spiral on the (x,y) plane where an unstable fixed point is and when the system is “tired” to stay there, it follows another fixed point and rises to the z dimension.

Those birds were doing exactly the same: a fixed point on the (x,y) plane and another fixed point (the hands of the guy next to me and that tasty sandwich in the hands of the girl on the other bench) on the z dimension.

The Rossler’s attractor is defined by this set of non-linear differential equations

I simulated it on my computer with the parameters that Rossler studied at that time. So I set a=0.2, b=0.2, c=5.7 and started the computations.
Guess what I had? The birds’ trajectories (almost) (oo)
For those who feel curious like me Rossler’s attractor is amazing because it is formed by two out of three linear equations.
This looks weird. But it seems much more interesting if you think that a chaotic trajectory comes from such a simple system of equations. Moreover, those two linear equations can be studied in the (x,y) plane by setting the z coordinate to zero.
The resulting system will be:

For those who know a bit of dynamical systems, this is super easy. For those who are not into this topic just follow me (or quit reading with a “ooooh”)
The Jacobian matrix is a nice way to study the stability of a system. It basically takes into account the partial derivatives

which give an idea of how the system moves on the x and y coordinate. Theory says that if we have complex eigenvalues with positive real part, the equilibrium point will be an unstable spiral. There we go.
The eigenvalues of the system are  
If parameter a is in the range (0,2), these eigenvalues are complex and the origin is indeed an unstable spiral.

In the (x,y) plane (where z=0) this will lead to a spiral which gets bigger and bigger. But in the original system, z gets bigger and that will affect x too, which will decrease because of the negative contribute (look at the first equation). This makes the system going up and down in a weird way. Like the birds.

PS. (which clearly stands for Pig Scriptum)
Ok the birds here were just attracted by food. But it was cool to assume that they knew about the Rossler’s attractor

Digital Signal Processing and the 515$ issue

As every pig on earth I am not regular at writing. 
In the last few days I am reading very interesting articles about sociology and I think I will post something by next week. In the meantime I wanted to develop a pure DSP-based application, since I needed to manipulate some audio in realtime. But I am missing something required: a DSP Starter Kit to work with in Matlab.
I found this the Texas Instrument TMS320C6416 DSK amazing! This board has a 1Ghz DSP processor, 3 expansion connectors, 4 audio jacks (mic in, line in, speaker, line out), 4 leds (user definable), Spectrum Digital DSK and Code Composer to interface with Matlab.

I just have to borrow 515$ from my flatmate… That I don’t have :(
Any hint?