Cover photo
Claude St-Louis
Worked at Jeffery Hale-Saint Brigid's
Lives in Québec, QC Canada
799 followers|19,707 views


Claude St-Louis

Shared publicly  - 

Here's my layman's understanding.

Fill a tube with glass frit,  run salty water through it between membranes and induce a little electric current... this  causes clumping of salty sections and less salty sections throughout the running water as it goes through the tube. not all that useful as it's kinda dispersed. and hard to get at.

Then they figured out something awesome.  If you hit that tube with a shockwave, all the heavy clumps (the salty ones) wind up on one side, and the less heavy (clean water)  winds up on the other, easy to split off into two new pipes.

Much cheaper than boiling all the water, and collecting condensation. Much easier than pushing the water through membranes that tend to clog a lot, and need constant repair/replacement.  Much faster as you do it with running water, not batches in vats, and it  looks like it can probably scale.
MIT team invents efficient shockwave-based process for desalination of water.
5 comments on original post
Add a comment...

Claude St-Louis

Shared publicly  - 
La unión hace la fuerza 👍👍👍
 ·  Translate
13 comments on original post
Add a comment...

Claude St-Louis

Shared publicly  - 
A magnificent opera! The video =3h15mns
 ·  Translate
Don Giovanni Viena 2015 desde la Wiener Staatsoper, vídeo de la representación de junio de la obra maestra de Mozart ComparteFacebookTwitterGoogleCorreo electrónicoPocket
Add a comment...

Claude St-Louis

Shared publicly  - 
thank you +Refurio Anachro !
What do mathematicians want from their #notations ? Why are they so hard to learn? And why is it cool if you do? Mathematical writing is a couple of millenia(!) old. Almost all of that time it relied on hand drawn formula.

In this post I will be arguing for hand drawn notations. It has been inspired by +Xah Lee​​​​​​​​​​​​'s critique of TeX for mathematical publishing, a
very much different opinion:

I'm linking the above 2-year old post first, because it has some discussion, the latest is this one:

(1) - First and before all, the notation should reflect what is going on. To the point that everything that can be said about a structure, can also be written down. Uhm, that sounds weird... But it's not, let my try again:

What i'm demanding here is that the language has to be powerful enough to capture what you intend to say with it.

Say, you have an idea, followed by cognition, a little enlightenment so to speak, and you now want to share it with your friends. So you make up a story to convice them. Better yet, start writing it down so you can be sure it doesn't change after you fiddled it to your satisfaction.

Your story might contain nouns for all objects of interests, verbs that allow to relate them in each of the important ways, or be structured in a very different way. If your language is one of the better ones, it'll allow others to reason in interesting directions you haven't thought of before.

(2) - All notation should be concise. People working with results (to apply them, do research, or teach them) are expected to fill loads of blank space with scribbles in that notation.

I find it interesting that that often makes reading math books hard. Sure, finding answers often took one or many researchers's life-long dedication, but learning notation is no piece of cake either! Some areas easily require you to invest a year of studying to get a decent insight from scratch.

Still, it is much more economic to read those pesky books than to find out all by yourself! You know, there are lots of beginner's introductions for almost any topic, but they are fashionable, ephemeral after a while, whereas the original writings often stay popular for decades, centuries, or even longer!

Maybe mathematicians like TeX because it feels more like drawing pictures. And that one guy, Donald, felt that he should be holding the pen, because he couldn't trust people who'd typeset for him to make the best decisions. And that that'd be worth the effort!

(3) - Make it look similar to everyone else's. You do want to lean on the plenty of natural language or existing math notation to communicate with your readers. Ideally one would use the same symbols, but if there is something to describe that could be really new, that might not be the best choice:

(4) - Make it subtely differ from everyone else's. Yes, I know, I just stated the opposite opinion. It is just impossible to tell beforehand which other notation will appear next to our favorite kind of hieroglyphs:

For one, you don't know about relations to other areas that haven't been discovered yet, and in mathematical reasoning that tends to be the case more often than not!

And secondly, still, people will want to try and look if they can find such connections, even if that turns out not to be the case.

All of these reasons only make sense if we understand written mathematics as a form of communication between human beings. To make these ideas do something in the physical world, for example, tell a computer to perform a computation, is the job of engineers. Like typesetters they are better at their job than mathematicians... Oh wait, I'm contradicting myself again!

(5) - Nowadays we have another fascinating development: Proof assistants. Simple programming languages, like S R, Mathlab octave, or Mathematica Sage, that do computations (even symbolic ones, reading and printing equations) don't count here!

Well, mathematicians do compute, but their top notch results are theorems. Sometimes that means presenting the outcome of large computations, but not too many researchers end up publishing tables with numbers (or symbols) in mathematics.

So to them, a calculator isn't the right tool to write up their kind of results, and to communicate those to others. Or even to make significant progress, because calculators can only yield the easy fruits. The ones hard to get require a creative thinker to find a new way to get where no one has gone before.

But a proof assistant just might provide a significant edge over doing mathematics in the traditional way. And that would get many people writing maths in a format a computer can handle semantically.

What mathematics is, and how it is practiced are subject to change. I bet there'll always be a place for people doing geometry with a stick on a beach. But there will also be new fields born out of traditional ones.

And sometimes the medium changes, too. I'd guess that TeX's availability as open source has also been an important step in the ongoing struggle to free math papers from publishers, who lock them up, and let you have a look only if you pay them.

For a piece about change in mathematics, have a look at John Von Neumann's short "The Mathematician":

Thanks to +Stefan Huber​​​​​​​​​​​​ for posting about it here:

The picture I found because +Richard Green​​​​​​​​​​​​ used it here:

"Continued fractions"

It's by Lucas Vieira Barbosa, read Richard's post to find out more about him.

Still reading? Are you ready for more on complex numbers? Look out for my upcoming post!

4 comments on original post
John Gambini's profile photoRefurio Anachro's profile photo
+John Gambini​​, you can read off equations for phi, since all subtowers are equal to phi:

phi = 1 + 1/phi

By the way, what about representing continued fractions recursively?
Add a comment...

Claude St-Louis

Shared publicly  - 
Add a comment...

Claude St-Louis changed his profile photo.

Shared publicly  - 
Add a comment...

Claude St-Louis

Shared publicly  - 
I need to know more about this.
Add a comment...

Claude St-Louis

Shared publicly  - 
The absence of state capacity – that is, of the services and protections that people in rich countries take for granted – is one of the major causes of poverty and deprivation around the world. Unfortunately, the world’s rich countries currently are making things worse.
Add a comment...

Claude St-Louis

Shared publicly  - 
Fascinating! I need to learn more about this...
Links of links, and higher structures

A Brunnian link is a collection of linked loops with the property that cutting any one of the loops frees all the others. This picture, which comes from a paper by Nils A. Baas, shows a second order Brunnian link. This consists of six linked loops in a circle, but each of the linked loops is itself a Brunnian link of four linked loops, coloured purple, orange, beige and cyan.

One of the reasons that Baas is interested in such linked structures is because of their connections with physics. The Efimov effect in quantum mechanics refers to a bound state of three bosons in which the attraction between any two bosons is too weak to form a pair. In other words, removing any one of the particles results in the other two falling apart, like the links in the Borromean rings, a famous example of a Brunnian link. The hope is that the study of more general Brunnian links will predict generalized versions of the Efimov effect.

Baas expands on these themes in the recent paper On Higher Structures ( which discusses the concept of hyperstructures in mathematics and their possible applications. The paper gives an intuitive outline of the notion of “hyperstructure”; the rigorous definition, which appears in some of Baas's earlier works, is given in terms of category theory. 

The basic idea is that a hyperstructure consists of a set of bonds at various levels: 0, 1, 2 and so on. The bonds at level 0 are objects with properties. A 1-bond binds together some of the properties of the level 0 objects. In turn, the 1-bonds have properties of their own, which are bound together by 2-bonds, and so on.

The paper elaborates the underlying philosophy as follows: 
Much of the intuition around hyperstructures comes from thinking of them as evolutionary structures. They are designed and defined in the same way as evolution works: collections interact forming new bonds of collections with new properties, these being selected for further interactions forming the next level of bonds, etc. In a sense, nature or the environment acts as a kind of observer (or “observation sheaf”). The success of evolutionary structures makes their theoretical counterparts — hyperstructures — a useful design model.

The paper explains in detail how hyperstructures can capture the essence of organized structures, and discusses how the theory might be applied to understanding biological systems (such as in genomics) and democratic structures, as well as to designing and synthesising new molecules and materials.

Relevant links 

The picture comes from the 2010 paper New States of Matter Suggested by New Topological Structures ( by Nils A. Baas. In the recent paper, Baas acknowledges A. Stacey and M. Thaule for helping with the diagrams.

Here's a 2010 popular article about Baas's paper of that year:

Brunnian links are named after the German mathematician Hermann Brunn (1862–1939). The Borromean rings ( are special case of Brunnian links (

Efimov states were predicted by Russian physicist V.N. Efimov in 1970:

Baas's recent paper appears in the General Mathematics section of the arXiv. This is remarkable because this section is typically used as a dumping ground for papers that the arXiv moderators don't like, such as this recent paper about the Riemann hypothesis whose authors don't understand what they're doing:

(Maybe I should have had a Relevant links of links section, with a link to a list of links?)

#mathematics #scienceeveryday #spnetwork arXiv:1509.00403
36 comments on original post
Add a comment...

Claude St-Louis

Shared publicly  - 
I'm discovering this extraordinary poet and this is exactly what I needed right now. Hope you will like it too.
Thanks to +Michael Baker for the post.
Acquainted with the Night
by Robert Frost

I have been one acquainted with the night.
I have walked out in rain -- and back in rain.
I have outwalked the furthest city light.

I have looked down the saddest city lane.
I have passed by the watchman on his beat
And dropped my eyes, unwilling to explain.

I have stood still and stopped the sound of feet
When far away an interrupted cry
Came over houses from another street,

But not to call me back or say good-bye;
And further still at an unearthly height,
O luminary clock against the sky

Proclaimed the time was neither wrong nor right.
I have been one acquainted with the night.
Add a comment...
In his circles
3,795 people
Have him in circles
799 people
Lid Kelly K's profile photo
Sonia beuron's profile photo
Ethan Hubler's profile photo
Human History In Brief's profile photo
Spencer Ottley's profile photo
Mechanics of Solids's profile photo
Jean Luc Aubert's profile photo
TOUQEER SHAH's profile photo
Alex andra's profile photo
Basic Information
  • Jeffery Hale-Saint Brigid's
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Québec, QC Canada
Claude St-Louis's +1's are the things they like, agree with, or want to recommend.

Quora is your best source for knowledge. Ask any question, get real answers from people with first hand experience, and blog about what you

Harvard Business Review

Improving the practice of management and its impact in a changing world.


RCI c'est le service multilingue de CBC/Radio-Canada qui permet de découvrir et surtout de comprendre et de mettre en perspective la réalité

Dichloroacetate and cancer : Pharyngula

So many people have sent me this sensationalistic article, "Scientists cure cancer, but no one takes notice", that I guess I have to respond

Valencia – Astonishing City of Arts and Sciences

The City of Arts and Sciences is something of a Phoenix in nature. Its home is the old bed of the river Turia. In 1957 the city of Valencia

The Making of So Beautiful or So What | Paul Simon - Here's a Behind The Scenes video for Paul Simon's new album "So Beautiful or So What," in stores everywhere April 12t

Québec veut donner plus de mordant à la loi sur la protection des animau...

Le gouvernement du Québec annonce une série de mesures visant à mieux protéger les animaux domestiques.

Les Communes enterrent le registre des armes d'épaule | Politique | Radi...

Fort de sa majorité, le gouvernement conservateur a réussi à faire adopter son projet de loi abolissant le registre des armes d'épaule.


HD Quality here: A CG movie featuring the Frank Lloyd Wright masterpiece, by Cristóbal Vila. Go to for m

Sky actually falling, report scientists -

A study of clouds over the last 10 years has found that their altitude has been declining, perhaps offsetting some global warming.

Scarlatti K209

The great Scott Ross plays Scarlatti's sonate K209 in Le château de Maisons-Laffitte (1988). Harpsichord: David Ley

Jacques Duchesneau quitte l'UPAC | Politique |

Jacques Duchesneau quitte l'Unité permanente anticorruption (UPAC), que dirige le commissaire Robert Lafrenière.

Comment désactiver Java ? | Korben

Suite à cet article sur la faille 0day dans Java, on m'a posé la question sur comment désactiver le machin. J'allais faire un petit tuto qua

Empower Success by Helping Others to Succeed

Individuals need help from others with skills that can help us succeed. The best way to ensure success for ourselves is to ensure success fo

Google Accounts

Google has more to offer when you sign in to your Google Account. Sign in on the right or create an account for free. Gmail. Chat with frien

Fairly Simple Math Could Bridge Quantum Mechanics and General Relativity...

A framework that relies on college-level mathematics could describe what happens to particles in so-called spacetime rips, gravity fluctuati

Genie in a Bottle: The Case Against Cold Fusion | Cocktail Party Physics...

It's starting to look like Debunking Week at the cocktail party. A couple of weeks ago, my SciAm Scibling Joanne Manaster alerted me to a ne

Are the big banks winning?

The big banks pay lip-service to the goals of Dodd-Frank -- but they're mounting bitter, rearguard actions in federal courts to block meanin

Difference Engine: End of the electric car?

Still happy on hydrogen A COUPLE of dozen electric cars with fuel cells under the bonnet (in place of the more usual flat-pack of batteries

Model Thinking

Model Thinking is a free online class taught by Scott E Page.