David's World

US Airways

2010-01-08T14:17:10Z

This winter's itinerary: Pittburgh-Charlotte,NC-Frankfurt,Germany, and Munich,Philly-PA,Pittsburgh, at a whopping $900+ price tag. Results: Not flying with US Airways again if I can avoid it. My First flight was cancelled due to some software problem with an onboard computer on their Embraer jet, after we've been on board for an hour. Rerouted - next flight 4 hours late due to a failed hydraulic pump. Then a fully booked overnight flight in the wrong kind of seat. Arrival: 7 hours late on the other side of the Atlantic in the end, no compensation from US (only EU airlines are required to reimburse/make happy their customers). I've learned a lesson about redundancy: when you fly aircraft that have 12 hydraulic pumps (not all redundant), you don't just increase safety while in the air - you also increase the likelihood that the aircraft is going to be grounded because one of them fails. (Note to self: compile list of airlines that charge for infants.) Return flight: East Coast in the winter chaos; plane running one hour late as it is being de-iced. Is ice in January such a surprise that this couldn't have been anticipated? No more US Airways flying for me. It does not suffice that their cabin staff has always been super-friendly, and that they have a pilot who can fly very big gliders on staff. The getting-me-there-on-time bit has to work. Rant finished.

Building small, big and fast aircraft: The power of startups

2009-12-17T17:18:01Z

Just saw a video (see below) of the newly-built SpaceShipTwo aircraft, a plane that will take a small number of super well-off to the end of the universe as we know it, or just above the atmosphere, to be precise. It's a fascinating design, but what's much more fascinating is the enterpreneurship story behind this. Since 2004, two small companies managed to develop two spacecraft and two carrier aircraft (jets); the first combination winning the 10M$ X-Prize in 2005, the second in the process of achieving FAA approval. Second, take the gliders (sailplanes) that I enjoy flying. All of them are developed and built at affordable prizes by small companies such as the German companies Grob, Schempp-Hirth, or Schleicher. They are built to withstand much higher G-forces than those airliners and reach amazing efficiency and high speeds. (Great powered aircraft are similarly built by small and medium-size aviation companies such as the American Cirrus.) Those gliders have been made from composite materials (fiberglass+gel coat) since the late 70's. I'm just mentioning this because I'm now introducing the herculanean efforts building the Boeing 787, the first composite airliner, taking the dedication of thousands of engineers and mechanics over a decade to build. The Airbus A380, the world's largest airliner, wasn't different. Of course, the comparison is ridiculous, even in the case of the pressurized, jet-propelled space craft+carrier planes that fly faster and higher than airliners, and that are built to comparable safety standards. Is the technical challenge that different when scaling up a pressurized jet from a dozen to a few hundred passengers? It seems clear: aircraft development doesn't scale well. I bet that very similar cases can be made for software development - compare the behemoth that is Windows (maintained by thousands of programmers at Micrsoft) to the Mac operating system that was initially developed by far fewer people at NeXT. Why is that so? It's a fascinating and unanswered question from the point of view of research into emerging collaboration in teams and of communication networks to explain the apparent loss in efficiency.

Are we better off without religion?

2009-12-09T02:53:45Z

Christmas is coming up, and just in time the Guardian goes over some recent research in the social sciences asking the question: are we better off without religion? Sociologist Gregory Paul's view is that religion is a sign of dysfunctional societies. Generally, societies with higher "popular religiosity" also fare worse when it comes to measures of community success, such as the number of jailed people, sexually transmitted diseases, corruption, and the like (Paul, 2005, 2009). The causality of this is not clear, but Paul argues that religiosity is the result rather than the cause. One should note that such correlations depend on a subjective, albeit wide-ranging Successful Societies Scale: if socio-economic factors would be weighted heavily, the most-religious country (US) would end up close to the the least-zealous societies (Sweden, Japan). One may wonder how much of the originally intended "good" is left in the world's religions - the good that stabilized societies through more or less arbitrary rule systems. The good that kept people healthy ("no pork!") and made communities stronger ("Love thy neighbor!"). The good that allowed some preachers and some movements out of many to evolve and develop into world religions. Note Pope Benedict II's (Joseph Ratzinger's) views on liturgy, which argue that the "new" forms have made church-goers self-indulgent and ignorant of views from outside (the priest turning to the congregation, preaching in their language - his conclusion: back to the Latin mass, is, of course, ridiculous). Christmas traditions are a good example of a combination of religious and pagan traditions that have lost their meanings. I for one am glad to avoid Santa Clauses, Christmas shopping in stores, and I greatly enjoyed my department's "non-denominational Holiday party". Paul, Gregory S., Cross-national correlations of quantifiable societal health with popular religiosity and secularism in the prosperous democracies: a first look. Journal of Religion & Society. 7, 2005. Paul, Gregory S., The Chronic Dependence of Popular Religiosity upon Dysfunctional Psychosociological Conditions. Evolutionary Psychology 7(3). 2009.

Improvised Explosives in Iraq: Of makers, disarmers, and the dead.

2009-08-16T00:26:31Z

The Hurt Locker is a film about a US bomb squad dying and cheating death in the heat and dust of Iraq. It is fiction, shot and edited in documentary style. Creepy Realism. Coming out of the movie I am still wondering: why did the US decide to send soldiers to hell, and how could the US-UK coalition commit the arson that removed a dictatorship to create the Iraqi hell in the first place? Questions, not new. The Hurt Locker is out in US theaters now. It's worth seeing. This week, the New York Times ran a remarkable piece titled How Baida Wanted to Die about a Iraqi suicide bomber who did not manage to explode her bomb. It is wide-spread religion that brainwashed a young woman. But the horrors of war and her marriage triggered her decision to join those who carry their belt stuffed with explosives to a busy market. A police officer told the reporter before her interview with the young woman: "You're going to like Baida".

How people find a common language

2009-06-08T18:44:15Z

Humans carrying out a task together find a common language, sooner or later. Even communities of speakers do this, and in fact this how they may come up with natural languages over time. At Carnegie Mellon University, we have now simulated this process in a cognitive computer model, tracing the steps that humans take to learn the elements of a graphical language, to forget them, to re-learn, and to arrive at a common language in a small community. Psychological research provides a pretty precise picture of how human memory works. In this paper to be presented at the International Conference on Cognitive Modeling, we describe the combination of two worlds: multi-agent and evolutionary simulation on the one hand, and psychologically validated models of memory and cognition to simulate the evolution of a domain language. The model explains the empirical data pretty well, but also makes a prediction: that human communication between two partners needs to go both ways in order for us to learn and to converge. David Reitter and Christian Lebiere. Towards explaining the evolution of domain languages with cognitive simulation. In: Proceedings of the 9th International Conference on Cognitive Modeling (ICCM), Manchester, UK, 2009.

]]> Abstract

We simulate the evolution of a domain language in small speaker communities. Data from experiments (Garrod et al., 2007; Fay et al., 2008) show that human communicators can evolve graphical languages quickly in a constrained task (Pictionary), and that communities converge towards a common language even in the absence of feedback about the success of each communication. We postulate that simulations of such horizontal evolution have to take into account properties of human memory (cue-based retrieval, learning, decay). We implement a model that can draw abstract concepts through sets of non-abstract, related concepts, and recognize such drawings. The knowledge base is a network with association strengths randomly sampled from a natural distribution found in a text corpus; it is a mixture of knowledge shared between agents and individual knowledge. In three experiments, we show that the agent communities converge, but that initial convergence is stronger when communities are structured so that the same pairs of agents interact throughout. Convergence is weaker in communities when agents do not swap roles (between recognizing and drawing), predicting the necessity of bi-directional communication in domain language evolution. Average and ultimate recognition performance depends on how much of the knowledge agents share initially.

Recession Era Victory Garden in Oakland, Pittsburgh

2009-06-05T21:51:02Z

Here's a great little Recession Era Victory Garden providing seedlings for everyone who likes to take some and plant them in their yard. (Found on Forbes Ave, Oakland, Pittsburgh.)

Oh my, UI: Evolution of the dialog from hell

2009-05-20T22:04:30Z

Various friends have been pointing out that Aquamacs features in blogs these days, which is great. They're all pointing out our (rarely seen) dialog from hell, which has too many buttons in a not-so-logical arrangement. Luckily, we've already thought of something for this dialog that has been in Emacs for a long time. The current Aquamacs version (1.7) uses this one:
Still, this is a far cry from what it's supposed to look like. More improvements are on the way for Aquamacs 2.0, whose Cocoa-based framework will allow us to design an appropriate dialog much more easily.

Airbus A320: what does this sign mean?

2009-05-17T03:19:11Z

I found this signage in a US airways A320 EOW, at the emergency exit door. I imagine some French and German designers must have pondered for days about how to come up with a drawing for what they wanted to convey, but somehow the message got lost on the way. Suggestions appreciated.

Mad bike skills in Edinburgh

2009-04-30T03:40:31Z

Friends from the other Burgh (Edin-) will recognize the locations - real bike skillz to see. On a related note: my trick bike, stolen four years ago in Edinburgh, has now been offered back to me in a reader (thief) comment on this blog. Not for real, I guess. To my regrets, requests for an interview with the bike thief were turned down. (Thanks to Gregor for the link.)

On slow Mac OS X Time Machine backups

2009-04-27T16:22:00Z

I do regular backups using Time Machine of my Macbook Pro laptop. Lately, I found that Time Machine on my MacBook Pro was horribly slow. Backing up well-filled 150GB internal drive onto an external 500GB WD MyBook (Studio) and another drive I keep at home, it could take an hour to do a backup. An initial backup would take more than a workday. Not good. What's worse was that my machine would slow down substantially while the backup was being done. Given that my backups saved me twice in the past six months from total data loss, I think it's important to keep the backups running smoothly. I've been doing the obvious, so far: the external drive is connected via FireWire (not USB), and I have excluded large DMGs and virtual machine harddisk files that change often in order to speed up backups. But here's three things that I did to speed up my backups.

I deleted the "inProgress" folder in my backup directory. It had accumulated a lot of abandoned backups. This takes a long time, so just erasing the whole volume may be the better option.
Analysis of the backup process (using "sudo fs_usage | grep backupd") revealed that Time Machine didn't actually spend time transferring data. It just wasted a lot of time recreating files in large directories. Time Machine can share whole directories with prior backups using hard links realized transparently in the file system. That's very neat and allows it to quickly copy (link to) directory structures. However, recreating directories with many files, where some files have changed, is a slow process. The culprit here are Mail.app's unstructured directories where thousands of messages are stored, one per file. That's a huge issue for the backup. Excluding these directories (in ~/Library/Mail) resulted in a great speedup. Of course, I only excluded IMAP directories that could be recreated easily from the server, and primarily Junk / Trash directories that don't need to be backed up. A further hint may be to download messages of the server and stick them into separate archival folders. I believe this creates separate directories that won't change, so they can be backed up easily. A final note concerns GMail and IMAP. Here, the "All Mail" directories may create a double archive that is not desirable, neither for storage (local cache), searching (double results) nor for TimeMachine backups. An option in GMail lets you switch IMAP off for these folders (enable the appropriate "Labs" feature first, then go to "Labels").
For little money, I bought an ExpressCard/34 for my Macbook Pro for little money off ebay, giving me an eSATA port. This appeared to speed up pure data transfer to 1.5GB/min by around 50% in unscientific testing with just a few samples. (For a problem like #2, it won't help.)

There are further hints regarding a slow Time Machine elsewhere, which didn't help me.

Our open social future

2009-04-22T15:32:06Z

When I started this blog in late 2004, it was a way to make me feel alive and productive. An interesting Slashdotting followed, and a few entries about a boring cellphone driver program that I made attracted hundreds of user comments, mostly reporting straight from the dumps of human intellect. A Scottish sports club that I am a member of soon gave me the semi-official nick-name "World", following this blog's name. 235 entries and 800 comments later, the blog now looks neglected. A common phenomenon among blogs: at least I lasted a bit longer than most. Most of the things I have to say turn out to be ones I'd like to communicate to my friends, so they end up on Facebook. Most of the work things (scientific stuff, Aquamacs) rightfully end up in publications or on mailing lists. And sometimes it's better to do the work rather than to talk about it. Finally, a few things are best said anonymously. (And just those things are often better not said at all.) The lack of control over who I'm talking to here and how this is archived led me to Facebook. However, I feel that the lack of openness and portability, the "lock-in" will ultimately bring me back to blogging. Perhaps we need a form of "open social network": a multi-function blog/twitter/event organizer/forum with open, public network interfaces and portable databases, installable on central server farms (like Facebook) as well as on private servers (like mine). Can it work? How are those making the software going to benefit from it? The idea is difficult to sell to venture capital firms, so perhaps it is best realized by the free software community. The components are already out there. Lock-in platforms like Facebook aren't the future - they're just the beginning.

Credit or Debit?

2009-02-13T16:44:44Z

When senior US bankers had to answer to public concerns about their multi-million-dollar salaries and bonuses, their corporate jets and the bonuses paid to staff just before the taxpayer had to bail them out, Congresswoman Maxine Waters asked a few loaded questions: Did you increase your credit card interest rate?, and also Did any of you reduce the amount of credit that was available to credit card holders because they shopped at certain stores? The idea here is that the Bush administration rescued those banks in order to boost not just their liquidity, but to i>unfreeze credit. It appears they didn't put strong enough stipulations in place to ensure that banks would actually lend out that money. What's wrong with this picture? Isn't the idea of unfreezing credit a euphemism for increasing consumer debt? The credit obtained via credit cards is unsecured. Typically, purchases made with them decrease one's equity, and they're usually not an investment that promises returns. People use them to pay for things they can't really afford, given that they can't pay cash for them: a new TV, a family holiday, groceries. None of these enables them to profit. Credit card debt is a huge problem for consumers, especially in times of rising unemplyment. The right consequence of the crash must be to make such credit harder to obtain. There is hardly a need for credit card purchases: if you can't pay for it right away, don't buy it. Credit cards make sense where a deposit needs to guaranteed, e.g., when renting a car. But that's about it. Very similarly, it was the unsecured portion of debt that is typically secured against property that caused the price decline in the housing market: Lenders were giving out 105% mortgages, with cash-back deals and very little checks. (Casey Serin was a notorious case of someone who misunderstood the system, got scammed by get-rich schemes and is now in debt.) Investment is the key. Obama's stimulus package tried to do it: education, science, health, infrastructure. This aspect got cut out by Senate republicans, in favor of short-term solutions and tax breaks that typically benefit those who have jobs: the rich get richer.

The end of W, the end of an error.

2009-01-18T19:31:35Z

The headline is an understatement. When I saw Bush junior win the election eight years ago and disappointment prevailed at the Berlin election party I was at, hardly did we expect such wide-ranging consequences. The end of an error (quoting the Guardian's Oliver Burkeman)? An understatement. Watch Keith Olberman's summary of eight years, from how Bush "politicized the truth of science", to a war based on cherry-picked intelligence that led to an estimated 1.3 million deaths.

Banking 2008: Punch the Pig!

2008-12-29T15:20:24Z

Banking is becoming cute. I signed up for a free "Virtual Wallet" with my new bank, PNC. The wallet finally introduces a bit of sanity into banking: bank attach arbitrary rules to different types of accounts - you can write checks only with a checking account, and earn interest only with a savings account. If some merchant makes a mistake, overcharges your debit card and you overstep your carelessly determined overdraft boundaries, the bank will try to hit you with a $30 overdraft fine. Never mind that you may have $250k sitting in a savings account or a stock depot. Come in the virtual wallet. Granted, they still have some ridiculous government-made rules: but at least they're adding some extra functionality to make things more manageable. If you end up in the red in your checking account, the system automatically takes some money from your savings. Finally, 15 years after e-mail addresses became a common sight on business cards, my bank is now willing to send you a simple e-mail if you exceed some limits, or when your paycheck is paid. That said: money is money is money is equity, whatever the account. Some is liquid, some is not. Banking could be so simple, if it wasn't for the "psych factor" involved in consumer banking. PNC found a cute way to make us happy savers: on occasion, a pink pig appears on top the screen after you've logged in to your account. You punch the pig, and voila, $50 or whatever you've set will be transferred to your savings. Complete with sound effects. Did I mention you can have a green pig, too?

Pittsburgh at night

2008-12-06T04:18:57Z

The Skyline of Pittsburgh, PA, as seen from the South (Mount Washington).