Installing OpenFVM on Darwin (Mac OS X)
Yes. After many, many years I went back to GNU compilers and linkers
Let’s say you want to simulate a fluid, and how it is heated by a hot cylinder.
What do you do? You take a hot cylinder and measure the lost of heat. But if you don’t want to mess around with hot cylinders and water, and you have a Mac (or even better Linux) you can install a simulation software and reproduce your experiment in the computer.
OpenFVM is such an application, and is opensource. It is easy to use, but must be compiled to be installed. That’s pretty easy on Linux, no idea about Windows, and decently easy on Mac. Here are some advices for Mac users.
Developers’ tool
First of all, you must install either Apple developer tools or fink. Apple’s tools have a huge amount of useless stuff (like XCode), where fink is fantastic, because it creates a similar environment of a debian machine. For example, you can search if there is a package ready to be used with:
apt-cache search package_name
and then install it with
apt-get install package_name
NB as root, you have to add the following line to your .profile file:
test -r /sw/bin/init.sh && ./sw/bin/init.sh
Installation of GMSH
You could download the GMSH libraries from http://www.geuz.org/gmsh, but you would not have the possibility to use (easily) the command line. Then, it is much better to build them.
Download the source code. Untar it and go into the directory gmsh-version_number. Run ./configure. You’ll probably get an error:
configure: error: Could not find GSL, aborting.
If so, you have to install the Gnu Scientific Libraries. Then:
apt-get install gsl
If the linker (ld) shows some problem, you probably also have to add the directory where fink put all libraries to the LDFLAFS environment variable. Add in the makefile:
export LDFLAFS=-L/sw/lib/
or in your .profile
export DYLD_LIBRARY_PATH=/sw/lib/
But this might be not enough. If you receive an error message about a missing libjpeg library you have to create a link in /sw/lib:ln -s /sw/lib/libjpeg.62.dylib /sw/lib/libjpeg.dylib
Compiling OpenFVM
Before following the instruction you find on the OpenFVM page on how to compile all the stuff, go into Flow/serial/laspack and edit eigenval.c. Comment out the line #ifdef __linux__ like that:
//#ifdef __linux__
#define max(x, y) ((x) > (y) ? (x) : (y))
#define min(x, y) ((x) < (y) ? (x) : (y))
//#endif
After having built the laspack libraries, run make in the Flow/serial directory.You will get the following error:
source/main.c:24:20: error: malloc.h: No such file or directory
Here, you have to edit main.c, setup.c, reorder.c and change#include <malloc.h> in#include <sys/malloc.h>.
Now compile. If you get the following error:
Undefined symbols:
"_max", referenced from:_EstimEigenvals in liblaspack.a(eigenval.o)
"_min", referenced from: _EstimEigenvals in liblaspack.a(eigenval.o)
it means you have not edited eigenval.c in the Flow/serial/laspack directory.
Google Friends etc….
With Google Friends, you “add social features to your site”. Whatever that means!
GF is an application based on Opensocial . Opensocial is a standard for having the same application working on different social network sites. The simplest feature, for instance, is that you can log in with your Yahoo/Google/MySpace/LinkedIn (and others) account. You could build a stupid application showing all your friends. If you put this application on MySpace or visualab.org, well, it will work the same!
If you “join” visualab.org (the button on the right) (yes, just underneath “Google Friends”), you won’t get anything because I have no time to set up a social network website, but well, that could be a terrific investment. It is like if you bought one IBM share in the 1960s… for free.
And I’m not going to ask Bill Gates to write an operating system!
Making money with water –Quantum of solace
Finally, an enlightened and perverse mind has found the way to become shamefully rich in the water industry. After three months in the US, interviewing executives and analysts from the water industry, I begun wondering if there was anybody out there happy with what so many people call “the blue gold”.
Really, is there anybody getting rich, shamefully rich, with water? YES!
Dominic Greene, CEO of Greene & Co., will apparently provide water to the whole country of Bolivia, after having negotiated an increase of 100% in tariffs.
With water tariffs in Bolivia ranging between 2.01 and 7.28 Bolivianos/m3 (0.25 and 0.95 USD/m3, 2005 data) and average water use for domestic consumption of 55 litres/day (1987 data), Mr Green will rake up more than $55m, before tax, as we can assume he will not invest a single Boliviano in new infrastructures.
Unfortunately for him, after having bribed the newly installed dictator with an aluminium case full of dollar bills, he will eventually be left, alone and without water, in the Andean highlands by an agent on Her Majesty’s Secret Service, James Bond. Mr Green will eventually be executed by his former partners.
PS James Bond may be a fictional character, but Bolivian tariffs and consumption data I used are not. Cfr. www.earthtrends.org/gsearch.php?va=cp&kw=bolivia&theme=0 and www.sisab.gov.bo/sisab2/sisab/documentos/INDICADORES2005.pdf
Non sani lo straniero
Sulla proposta di abolire diritto del medico di non segnalare la presenza di uno straniero "illegale".
Il diritto romano distingueva tra Ius Gentium e Ius Civile –e altri ancora. Il primo, il diritto dei popoli, all’inizio venne identificato come “the law common to all nations” (Ancient Law, by Henry Sumner Maine, Theodore William Dwight, versione integrale su Google books). In un secondo periodo venne identificato come “a great though as yet imperfectly developed model to which all law ought as far as possible to conform,” un modello ottimo, sia pur non perfettamente sviluppato, al quale tutte le leggi dovrebbero conformarsi.
Quest’idea di super-modello, secondo Maine e Dwight, derivava dall’ideale greco di una legge di Natura, verso la quale la razza umana (human race, scrivono M&D) si sarebbe naturalmente evoluta. Ora, non c’è bisogno di tirare in ballo la teoria dei giochi, collaborazione e proprietà emergenti, buddismo, cristianesimo, stoici greci e romani e chissà quant’altro per immaginare che una legge come:
non fare agli altri quello che non vorresti fosse fatto a te
è un buon punto di partenza per una legge di natura.
Siccome alcune leggi italiane si basano su principi sani come uguaglianza o umanità (nel senso fantozziano di come è umano Lei) in Italia vige una legge (Dlgs 286/1998) che recita:
Art 35 […] 3. Ai cittadini stranieri presenti sul territorio nazionale, non in regola con le norme relative all’ingresso ed al soggiorno, sono assicurate, nei presidi pubblici ed accreditati, le cure ambulatoriali ed ospedaliere urgenti o comunque essenziali, ancorché continuative, per malattia ed infortunio e sono estesi i programmi di medicina preventiva a salvaguardia della salute individuale e collettiva. Sono, in particolare, garantiti:
a) la tutela sociale della gravidanza e della maternità, a parità di trattamento con le cittadine italiane, ai sensi delle leggi 29 luglio 1975, n. 405, e 22 maggio 1978, n. 194, e del decreto del Ministro della sanità 6 marzo 1995, pubblicato nella Gazzetta Ufficiale n. 87 del 13 aprile 1995, a parità di trattamento con i cittadini italiani;
b) la tutela della salute del minore in esecuzione della Convenzione sui diritti del fanciullo del 20 novembre 1989, ratificata e resa esecutiva ai sensi della legge 27 maggio 1991, n. 176;
c) le vaccinazioni secondo la normativa e nell’ambito di interventi di campagne di prevenzione collettiva autorizzati dalle regioni;
d) gli interventi di profilassi internazionale;
e) la profilassi, la diagnosi e la cura delle malattie infettive ed eventuale bonifica dei relativi focolai.
4. Le prestazioni di cui al comma 3 sono erogate senza oneri a carico dei richiedenti qualora privi di risorse economiche sufficienti, fatte salve le quote di partecipazione alla spesa a parita’ con i cittadini italiani.
5. L’accesso alle strutture sanitarie da parte dello straniero non in regola con le norme sul soggiorno non puo’ comportare alcun tipo di segnalazione all’autorità, salvo i casi in cui sia obbligatorio il referto, a parità di condizioni con il cittadino italiano.
Il problema arriva quando io sono convinto che non mi troverò mai nella posizione dell’altro. Tipo io sono un leghista italiano e l’altro è un immigrato illegale, ossia un essere umano illegale.
Ossia, metti che io sono un cittadino italiano, sì, ma fatico ad esprimermi in un italiano corretto (non aulico –corretto), mi incazzo (termine corretto, anche se non aulico) perché un miliardo e trecento milioni di cinesi riescono a copiare i miei tessuti stampati con telai del dopoguerra, sono pronto a linciare un cittadino tunisino accusato di omicidio da un mio simile (che poi si scopre essere il vero colpevole), sono talmente abbietto da bruciare le tende dei campi nomadi di Opera dove dormono bambini, riesco a far leva sulla paura del diverso dei miei simili e diventare quindi senatore della Repubblica Italiana pagato più di quanto non riuscissi a raccimolare con la mia fabbrichetta a tecnologia celtica….. se io, insomma, sono qualcosa che è difficile da definire in maniera aulica, e sono dalla parte del più forte, che faccio?
Semplice: cerco di cancellare la legge che potrebbe elevarmi verso uno stato più umano, e rimango una bestia, e cerco di far sì che il mio mondo retroceda allo stato bestiale, hobbiano, di uomo lupo all’uomo. E propongo un cambiamento:
39.305 Bricolo, Rizzi, Mauro, Bodega, Mazzatorta, Vallardi
All’articolo 39, dopo la letto s) , inserire la seguente: « s -bis) all’articolo 35, il comma 4 e` sostituito dal seguente: “Le prestazioni di cui al comma 3 sono erogate previo pagamento della relativa tariffa ovvero delle quote di compartecipazione alla spesa a parita` con i cittadini italiani qualora i richiedenti risultino privi di risorse economiche. Nel caso in cui la prestazione da erogare sia classificata urgente e non differibile, il pagamento della tariffa o della quota di compartecipazione e` posticipato. In caso di rifiuto del richiedente alla corresponsione di quanto dovuto ai sensi del presente comma, le strutture sanitarie ne trasmettono segnalazione all’autorita` competente”».
39.306 Bricolo, Rizzi, Mauro, Bodega, Mazzatorta, Vallardi
Dopo la lettera s) , inserire la seguente: « s- bis) all’articolo 35, il comma 5 dell’articolo e` soppresso».
Il risultato? Anche solo da un punto di vista egoistico…. più gente malata in giro. Non esistono malattie illegali, che si sappia.
Una petizione qui: http://appelli.arcoiris.tv/salute
Info: http://www.simmweb.it
Tell me how you drink, I’ll tell you who you are
I have interviewed the CEO of a investment management firm. We were speaking about the need of investment in infrastructure (mainly water), and how good, or bad, the situation is around the world.
And then he made a more specific example:
The water systems, the utilities worldwide, are sort of a barbell. There’s roughly 25% of the world that has running water in their residence and something like 75% of the people alive today do not have water in their residence. And most of those folks are drinking raw unprocessed water. Now, as to the western industrialized nations, the U.S., Europe, et cetera, there’s a big difference. For example, the water system in Switzerland is- being Swiss is very, very efficient, very good, very high quality. The water system in other areas is quite the opposite: leaky, old, dilapidated. Italy is one, yes.
In some areas, Italian water infrastructure is of such poor quality, that many “developing” countries are in much better shape.
China, Brazil, Credit Risk Management and the BIG crisis
In 2005, I was volunteering in Brazil. I couldn’t buy the Economist every week, so each issue I could find was read carefully for more than a week. The issue about China had the honour to stay in my backpack for three weeks, while I was travelling around the country with the highest interest rates in the world (after Nigeria, if I remember well). As soon as I came back to Europe, seven months later, I found a job as a credit risk consultant.
Now –I am a former physicist without any economic training. But these three things (China, Brazil, Credit Risk Management) look to me three possible interpretation keys of what is happening now. Not the only ones, of course, but three possible ones.
That issue of the Economist said that inflation was low, notwithstanding the amazing growth, thanks to China, which was producing lots of goods at very low price. During a growth period, central banks would normally set high interest rates, increasing so the cost of money. Otherwise, if the cost of money is low, industries borrow more money, produce more goods and are willing to pay more. So everybody starts buying more, and prices increase, and we have inflation. That’s why in Brazil the interest rates were so high: the economy had a 4% annual growth, but the country suffered a 7% annual inflation. So the cure was an astonishing 19% interest rates.
But Brazil was more the exception than the rule, and no one else needed that cure –apart from Nigeria, apparently. Inflation was low everywhere. In the last decade, China has played the same role that technology had played 200 years ago. It made possible to produce the same good at a much lower cost. With one big difference. As technology improves, cost of goods will decrease. As the Chinese workers improve, cost of goods will increase.
In Western countries, most workers are paid more than they were 200 years ago. The industry needs much less workers to produce the same amount of a certain good, so it can afford higher salary –here in Europe and US.
The introduction of the Chinese labour meant cheaper goods both because Chinese workers are cheaper, both because Western workers agreed to be paid less, in order not to see their jobs exported to China. That is what happened in Germany, a country where the ratio of the salaries of executives and workers had been historically very low. Unions agreed for a cut in salaries.
So, the deflation caused by the introduction of new technologies 200 years ago was real and lasting. The deflation introduced by the opening to the Chinese labour market was not. It is not. When dstribution of wealth gets really bad, something has to change… But of course, we couldn’t care less about the global Gini index, and banks were all so happy: low inflation, low interest rates, high growth, high returns from investments. What the hell could they ask more for?
Answer: less capital requirement. If you want to invest, say, $100, the financial regulatory authority of your country could ask you to put in your safe at least $8. If you are able to prove, with “advanced financial engineering techniques”, that your investment is not that risky, the authority could ask you to put in the safe only $4.
These “advanced techniques”, roughly, measure the volatility of your investments and the rating of the companies you have invested in. If you invest in IBM bonds, and the rating agencies (Moody’s, Standard & Poor’s, Fitch and no one else) say that IBM is a good company, then you need less capital requirement. If your portfolio has given a steady return for the last six months and has not oscillated up and down, then, again, you need less capital requirement.
Now, both methods are far from being perfect. The rating agencies are normally the last ones to realise when a company is going bankrupt. Example: Parmalat in Italy was rated “very very good” by Standard & Poor’s few weeks before it went bankrupt and burnt 2% of the Italian GDP. And the fact that in the last six months your portfolio has not fluctuated, it does not mean it will not plunge in the future.
There was this faith –that because banks were using excel sheets or (my goodness!) Java and C++ libraries to compute the variance of their return over time, they could better manage their risk. In April 2005, Alan Greenspan was happily announcing that, “with these advances in technology, lenders have taken advantage of credit-scoring models and other techniques for efficiently extending credit to a broader spectrum of consumers”. Fannie and Freddie were invited by the US administration to give mortgages to people that, only few years before, had not been able to get any credit.
Theory of chaos is the best tool to describe the market behaviour. A small variation here, and you have a big variation there that could put the system outside the pattern of stability –the attractor. One year ago, we had a big variation when “very very very good” mortgages were not paid back. That shot the market far away from the attractor.
In addition to that, what a shame!, Chinese workers have begun to ask for more money. Not much, but enough to add another instability input.
No one knows what is going to happen now. But if you look at the past equilibrium as the attractor of the system, any attempt to put that system back on the same track might be doomed to fail. Non linear systems have this nice characteristics: when you try to put the system back, you don’t have the faintest idea of what is happening. You could easily worsen the situation.
What we have to understand, probably, is that the equilibrium was not an equilibrium, but a transition phase from a local economy, where Europe and US were the only financial economies in the world serving about 400m people, to a global economy, with Brazil, China, India and Russia in to the game, involving about 6 billion people. And we also have to understand that 6, 7 or 8 billion people cannot live the way we have lived in the last 50 years. We should start thinking seriously at new energy sources and higher efficiency–not because the ice on the Antarctic is melting and polar bears have lost their nuptial bed, but because there are not enough energy sources for all of us. Full stop.
And, that’s the bad news, in our market economy the only way to have less consumption will mean very expensive energy. Forget oil at $200 a barrel. It will cost $500 for us stopping travelling around the world with $400 flights (that is how much I paid for my eleven or more transatlantic flights this year). Unless, of course we want to fight for the inviolable right of cheap energy. In this case, we should remember that Iran is much more advanced then Iraq, and that China… well, China is really advanced, really big, really strong, and incredibly organised. We better share the resources with them.
~
Regarding the “advanced financial techniques”, here is a true anecdote told me by someone who was working for the same credit risk consultancy which was consulting Fannie & Freddie:
“Today, the senior manager has asked junior: ‘How much is 200% of 240%?’ Junior opens excel, types on the keyboard and says: ‘Four hundred…. four hundred eighty!’”
Junior was right, but if you need excel to multiply a number by two, you should not be allowed to give any advice to the biggest mortgage lenders in the most advanced economy of the world.
The Future of TV and the Italian cusine
I was wondering –why all Italian men in their 30s (or beginning 40s) are so familiar with cleaning products, food products, different kinds of brooms (il mocio vileda!), toilette paper and so on?
Then I understood why: we have to thank Silvio Berlusconi and the introduction of private TV channels in Italy in the late 1970s.
Movies started to be broadcasted and paid through commercials. Alberto Sordi’s fanatics, or Paul Newman afficionados, could watch their movie for free, but had to “pay” buying certain products in the supermarket. We children had less purchasing power than our mothers, so we both watched the same movies, but the commercials were targeting them.
It will all change now. First of all, children are already rarely watching TV with their parents. But increasingly more, each person has his/her computer, and can watch his/her favorite movie or video clip alone. Cinema is still a social activity, but has less commercials.
When I watch a movie on YouTube, the system knows quite well who I am. I shop around using Google CheckOut or Amazon (which oddly enough has not yet developed anything like Amazon CheckOut, or am I wrong?). So, in theory, YouTube can insert the right commercial for me, for each movie I want to watch.
Sites like hulu.com provide movies thanks to commercials, but they are still shooting in the dark. I just saw a commercial of a certain car insurance policy –I have no car and my only motorbike was stohlen two years ago. A waste of my and their time (and the insurance company’s money).
In the future, I’ll only watch commercials about magazines, books, movies, computer gadgets, cheap flight and local restaurant (Google knows where I am, scaring!).
And we will remain the only generation with a deep knowledge of the difference between Cif and Mr Clean (I have always preferred Cif, and still do).
Una cartolina da Los Angeles
Finalmente a Hollywood… basta con i video podcast, youtube, adesso il gioco si fa duro.
Ho scoperto che il centro vecchio di LA è molto carino, solo che ha 5 case, tra cui la più vecchia esistente in citta`, del 1818. La Union Station è un gioiellino di architettura coloniale, e anche la piazzetta antistante, con le orchestrine e i banchetti di cianfrusaglie turistiche. Da lì inizia Sunset Boulevard! Non sapevo neanche esistesse un viale con questo nome, pensavo solo al film. Sunset diventa poi Hollywood Boulevard. L’ho percorso (in macchina) sperando di beccare la gigantesca scritta sulle colline, ma un’ora dopo ero in mezzo a delle casette fighe in collina, e non c’era l’ombra di una scritta.
Il giorno dopo, per una emozionante intervista su un’impianto di trattamento delle acque reflue, mi è passato a prendere John, pubbliche relazioni di una società. Tranquillo. Durante le tre ore di viaggio ho scoperto che nonostante l’aspetto 100% caucasico (caucasico e` l’equivalente politically correct di WASP o gente biancoa anglosassone) ce l’ha a morte coi Bush, Hillary e compagnia, ed è spaventato all’idea che gli Stati Uniti possano invadere l’Iran. È anche convinto che lo invaderanno, e che Obama non vincerà se non lascerà cadere questo veto.
Il suo –se non pacifismo– rispetto per gli altri stati sovrani deriva dal fatto che ha fatto 5 anni di militare. Quattro a Vicenza e uno in Iraq, durante la prima guerra del 1991. Di notte doveva entrare a Baghdad col suo plotone (squadra? non ho fatto il militare) e mettere dispositivi radio all’interno di determinati edifici, in modo da permettere ai caccia di colpire il giusto bersaglio. Durante una di queste operazioni l’edificio antistante, con un intero plotone inglese dentro, è saltato in aria. Forse era stato minato, forse era stato bombardato dai caccia americani, nessuno lo sa o lo sapra`.
Potevano entrare nella città con mezzi corazzati ed elicotteri, nessuna resistenza da parte della popolazione o dell’esercito. Ma alla fine da una parte e dall’altra i morti ci sono stati, sia pur non centinaia di migliaia come nell’ultima guerra/invasione. “Inizi a fare il militare senza pensare che ti può capitare di ammazzare o di essere ammazzato. I miei due figli non potranno avvicinarsi ad una caserma finché io sarò in grado di impedirlo”.
Siccome non si può parlare per 3 ore di Iraq, abbiamo parlato anche di Cultura con la C maiuscola. Prima di tutto i CHiPs, California Highway Patrols, gli Eroi dell’Autostrada: Poncharello e…. nessuno dei due si ricordava il nome dell’altro. Nessuno si ricorda il nome dell’altro, provate a chiedere. Non ne abbiamo beccato nemmeno uno di quelli veri, benché si sia passati da Santa Monica, dove i prodi Eroi salvavano bambini che volevano attraversare le autostrade a 5 corsie. Io che all’epoca andavo a scuola in bici, e l’autostrada del sole mi sembrava bella larga, mi chiedevo che cazzo facevano i californiani, a migliaia e migliaia in macchina dalla mattina alla sera. E ogni santo giorno c’era quello ubriaco, il camion che iniziava a perdere pomodori (grandi come meloni), il truzzo che sputava fuoco dal tubo di scappamento, e spatapum, 200 macchine una sull’altra –ma nemmeno un morto. Imbranati ma fortunati, i californiani.
E con grande disappunto ho scoperto che molto probabilmente Happy Days non è stato girato a Milwaukee, ma qui a Elei, LA. Vergogna.
Water Fuel Car Scam –again?!
If you (as I did) thought that only Fox news reached the lowest level of journalism in claiming that a car can use “just” water as a fuel…. well, you (we) were wrong. Even REUTERS has decided to spread the scam –sorry, the news. “It sounds too good to be true,” says Michelle Carlile-Alkhouri in her report. Ms Carlile: it sounded too good to be true because it is false. Did you really need another reporter, Siddhartha Dubey always from Reuter, to call a Professor from Queen Mary University, to tell the audience that “water is not a fuel?” in a new, different video-reportage. Where did you think these people take the energy for separating Hydrogen from Oxygen from? Santa Klaus?
I also used to believe that Santa Klaus brought my presents, but I did not wait for my sister to call a university professor to tell me the truth. Next time, Ms Carlile, do call yourself any physicist you might know and try to convince your editor that publishing scam –sorry, news –is not healthy both for Reuter itself and for the audience.
That is not flat-earth journalism. That is ignorance less professionality equals misinformation. Here is the video-scam.
PS I just discovered that I’m late…. thanks god.
Fox News and Water Fuel Cars
And someone says Physics is not important. And someone thinks journalists should be competent. Please note, the video below is something like a scam.
Nowadays, there is a silly competition in offering green solutions. General Motors, just before dying (yes it is dying: I just discovered the company’s three-year bonds are traded at half their value), says its SUVs are green because are the greenest of their kind –and then you discover they use 1 liter of fuel every 6 km (14 mpg). That is slightly less than a Ferrari! If you want to be green, you better don’t even buy a car. Whatever the car-makers try to show in their ads, cars are not green. They are big and heavy –an electric bicycle is green, not a one-ton car.
If GM is acting like a Far West charlatan, real charlatans have to scream even louder, possibly with the help of established media, like Fox News (same group as The Times of London and The Wall Street Journal, by the way).
In the video above, Fox News breaks the news: a revolutionary attempt to separate Hydrogen and Oxygen in water, with the use of electricity. Electrolysis is actually 200 years old (see my beloved wikipedia), but ok, at that time there was no Internet, and Fox’ editors are just coming a bit late.
What is amazing is that they say you can use electrolysis to get Hydrogen, and put the Hydrogen back in your car, and be green!
Now, the reality is that if you use Hydrogen, extracted through electrolysis, in an internal combustion engine, you actually waste energy. [The maximum (ideal) efficiency of an engine is given by the gap between the temperature of the environment and the temperature of the combustion chamber. The higher the gap, the higher the efficiency.] In today’s engines, if you produce 5 HP of heat power burning fuel (let it be gasoline or hydrogen) you can only use 1 HP of power for moving the car.
That is why Hydrogen cars are good only when they use fuel cells: the Hydrogen is “burnt” at low temperature, and the electrons moving from it to the Oxygen are used as electric power source. Something like a reverse electrolysis, nothing to do with internal combustion engines. Here the efficiency is extremely high, almost 90%. Only an incompetent would then use electricity to separate Hydrogen and Oxygen, and then burn them in a combustion engine: much better to use the electricity directly to move an electric engine.
In the video above, they say that the American congress and the Army are examining the invention. There are many studies showing that education in the US is not as good as it used to be. Let’s hope congress-people and army-people are from the old good school.
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