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Rafael Ferreira
Works at EO2
Attended USP
Lives in São Paulo
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Rafael Ferreira

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Okay, this is awesome. A complete transistor level simulation of the 6502 processor, done via a process that involves melting the cover of the chip with 200°F hot sulfuric acid to expose the die, taking 72 microscope images, stitching then together to make a 342Mpixel image, and then finding polygons that represent wires and transistor to then emulate the whole thing in software.

The slides from the SIGGRAPH talk are great:
http://www.visual6502.org/docs/6502_in_action_14_web.pdf
Visual Transistor-level Simulation of the 6502 CPU and other chips! Welcome to Visual6502.org! Here we'll slowly but surely present our small team's effort to preserve, study, and document historic computers. We aim to present our work in a visual, intuitive manner for education and inspiration, ...
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Circle us for a 6502 post every week, +Rafael Ferreira!
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Train track laying machine 
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I'm working on it
About 18 months ago, reports indicating that the NSA spied on the private communications of Brazilian President Dilma Rouseff began to surface. Now comes word via Bloomberg that Brazil is working h...
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John von Neumann on how failure precautions shape systems.

"If you look at automata which have been built by men or which exist in nature you will very frequently notice that their structure is controlled to a much larger extent by the manner in which they might fail and by the (more or less effective) precautionary measures which have been taken against their failure. And to say that they are precautions against failure is to overstate the case, to use an optimistic terminology which is completely alien to the subject. Rather than precautions against failure, they are arrangements by which it is attempted to achieve a state where at least a majority of all failures will not be lethal. There can be no question of eliminating failures or of completely paralyzing the effects of failures. All we can try to do is to arrange an automaton so that in the vast majority of failures it can continue to operate. These arrangements give palliatives of failures, not cures. Most of the arrangements of artificial and natural automata and the principles involved therein are of this sort."

Quoted in General Systems Thinking by Gerald Weinberg
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Survivorship bias is when you only pay attention to the data points that "survived" and ignore the ones that failed. A classic example is when comparing financial funds. Funds that lose money will eventually get shut down, boosting the average performance for funds that survive. You can be sure that the people who run financial firms are aware of this.

Apparently survivorship bias is a problem when comparing schools using test scores. If a school is particularly strict and has a high drop-out rate, it will tend to have higher scores than a more lenient school that gives students more chances after they screw up. This will be true whether or not being strict is a good policy for students.

We don't have to assume that schools are intentionally gaming test scores. If charter schools with higher test scores tend to survive then this will have an evolutionary effect encouraging strictness. But you can be sure that many school administrators are smart and, even if they didn't know the effect of strictness on test scores going in, they will eventually figure it out.

(Of course, people don't have to act on incentives, and we can praise schools that try to do the right thing in spite of them. But knowing that leniency is against your interests probably doesn't help, particularly when stricter schools are getting a lot of positive publicity.)

The statistical solution is to make sure that dropouts are counted when evaluating performance. We might even consider taking the school's admission policies into account, since not letting poor-performing students into the school in the first place is another way to increase test scores.

But if schools can choose how to present statistics about test scores when promoting themselves and we naively believe what we read in the news, these adjustments won't be made. Furthermore, this will tend to convince parents that stricter schools are better for their children, whether or not it's really true.

Something to remember when thinking about how incentives work.
An experienced researcher saw a story in the Economist about charter schools. It was, as is typical among news stories, incredibly naive. The writer didn't ask the right questions. Maybe he already...
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The story of one man determined to teach third graders about binary by only asking them questions. The whole transcript of him asking questions and the third graders yelling back answers is great.
The following is a transcript of a teaching experiment, using the Socratic method, with a regular third grade class in a suburban elementary school. I present my perspective and views on the session, and on the Socratic method as a teaching tool, following the transcript.
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No, seriously. This.
We can’t ignore the composition of the Unicode Consortium’s members, directors, and officers -- the people who define the everyday writing systems of all languages across the globe.
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Maybe the most beautiful factory-tour video ever made.
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Not terribly surprising, but useful to know: "Now researchers have taken a more rigorous approach to evaluating peer review, by tracking the fate of more than 1,000 papers that were submitted ten years ago to the Annals of Internal Medicine, the British Medical Journal and The Lancet.  Using subsequent citations as a proxy for quality, the team found that the journals were good at weeding out dross and publishing solid research. But they failed — quite spectacularly — to pick up the papers that went to on to garner the most citations. The shocking thing to me was that the top 14 papers had all been rejected, one of them twice,” says Kyle Siler, a sociologist at the University of Toronto in Canada, who led the study"

(via many people)

CC +Joshua Gans 
Top medical journals filter out poor papers but often reject future citation champions.
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Another project out of MIT media lab. Fairly compelling UX with 3D interaction (above and behind) with a tablet. Would be a lot better without the glove, though I'm not sure any of the gesture recognition out there yet (using, eg, interference with WiFi/cell signal, cameras, or sonor) is up to the fine-grained requirements of the task. Paper (http://static.googleusercontent.com/media/research.google.com/en/us/pubs/archive/43152.pdf) and video (http://vimeo.com/42173010).
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Have him in circles
295 people
Mike Higgins's profile photo
marco correia's profile photo
Thadeu Russo's profile photo
Deno lemes's profile photo
Francisco Kurpiel's profile photo
Rodrigo Sposito's profile photo
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Work
Occupation
Programmer,
Employment
  • EO2
    Senior Software Engineer, 2013 - present
  • R7.com
    Systems Architect, 2011 - 2013
  • R7.com
    Specialist Software Engineer, 2010 - 2011
  • Caelum
    Programmer,, 2008 - 2010
  • Sun
    2006 - 2008
  • Twic
Places
Map of the places this user has livedMap of the places this user has livedMap of the places this user has lived
Currently
São Paulo
Previously
Curitiba
Links
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Tagline
http://rafaelferreira.net
Introduction
Programming language enthusiast and all-around loudmouth.
Education
  • USP
    2003
  • CEFET-PR
  • Jean Piaget
Basic Information
Gender
Male
Other names
Rafael de F. Ferreira, Rafael de França Ferreira