Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Re:Abstractions -WTF? (Score 1) 109

As I said, this was a long time ago, so maybe I'm not remembering the exact performance problem we hit. My larger point still stands: we were burned by an abstraction, possibly made worse by our own lack of expertise. In our defense, we weren't there to build a website. Or research was in a totally unrelated area, not even really within the realm of computer science, and none of us had expertise building websites that scaled. The website was just the thing we used to collect data and do experiments. We built it because we couldn't get someone wide to do it for us. Someone before my time picked Ruby on Rails because it was supposed to be something people like us could use.

Comment Abstractions (Score 3, Informative) 109

I worked on a project around 2007 that used Ruby on Rails. That was my first experience with Ruby and my first experience with a real web product. I liked Ruby and Rails, but it was easy to get bitten by some of the abstractions. I remember the site bogged down really bad whenever we searched for a record in a large database table. The problem was that the database was hidden behind ActiveRecord, so it was easy to forget we were using a database at all. Writing a for loop to search for a record that matched some criteria felt natural, because our interface was with objects, not the underlying tables. However, behind the scenes, each iteration was a separate query. The result was thousands and thousands of queries, instead of just a single query with a simple WHERE clause. We were essentially doing in Ruby what we could have done much more efficiently in SQL. Once we realized the problem, we rewrote that kind of code so it used more or less raw SQL. The result was much faster, but we lost the readability of the abstraction. Everyone on the team was new to Ruby and Rails (grad students who shuffled in and out each semester), so it's possible that we were just doing things completely wrong. Still, it feels like it shouldn't have been that easy to shoot ourselves in the foot. Have things improved since then? How do you balance nice abstractions like ActiveRecord with performance? How do you make it clear to novices what's going on internally, so they can avoid the mistakes that we made?

Comment Re: Gun Free Zone (Score 3, Informative) 1165

The point of gun-free zones is not to deter bad guys. It is to help prevent good guys bringing guns to places where they aren't needed, getting involved in an argument or whatever, and escalating things to the point where someone is shot. Another reason is to prevent unintentional shootings, either from a malfunction or a dumb accident.

You can argue that it is still not a good idea, but at least be honest enough to acknowledge the real reasons behind the policy.

Comment Re:Don't fall for that one... (Score 1) 190

Assert your rights. For example:

"I am disputing this debt. You must verify this debt as required by the Fair Debt Collection Practices Act. Because I am disputing this debt, you must not report it to the credit reporting agencies. If you have already reported it, contact the credit reporting agencies, inform them that the debt is disputed, and request that they delete it from my credit report. Reporting information that you know to be inaccurate, or failing to report information correctly, violates the Fair Credit Reporting Act. Aside from verification of the debt, do not contact me about this debt. The Fair Debt Collection Practices Act, 15 USC Section 1692c requires that you honor this request."

Comment Re:Lock-em down (Score 1) 698

Forget the fire codes. If you lock the shooter in a room, you might also lock a lot of potential victims in the room with him. Say someone enters a packed cafeteria and fires some shots. No matter what, people will instinctively run to the exits once they realize what's going on. If the doors are open, they'll have a chance to get away. But, if the doors locked, everyone will pile up near the exits and be trapped. Now, the shooter has a lot of targets clumped together.

Comment Re:The 4th of December? (Score 2) 340

You can't be American, because you're apparently unaware...

Let me stop you right there. You must not know Americans, because unawareness, of our own history and so many other things, is one of our hallmarks. The fact that the signing of the Declaration of Independence wasn't promptly followed by the "shot heard round the world," or that the war dragged on for years and wasn't particularly popular while it was raging, or that our Constitution was our second attempt at self government is not something people know. The details of our history just aren't taught, or aren't taught well at least, so we end with people having a weak grasp of the highlights and not understanding or even being aware of the rest.

Comment ZigBee (Score 1) 176

Hue bulbs speak ZigBee, not Wi-Fi. Communication between the bridge and the lights is done with a mix of the ZigBee Home Automation and ZigBee Light Link application profiles on a ZigBee PRO mesh network using an IEEE 802.15.4 MAC layer. The bridge is an IP-to-ZigBee gateway, but there's no direct IP connectively to the bulbs.

Submission + - Advice for Recording Interviews with Family Member

almeida writes: My grandfather passed away when I was in my early twenties, around the time that I was just learning to appreciate his humor, stories, history, and perspective. All four of my nine-month-old daughter's grandparents and one of her great grandparents are currently alive and well, but I'm afraid that they'll pass away before she has the same chance to really know them, interact with them as an adult, and learn from them. To help preserve part of our family history and to give her a chance to hear about them in their own words with their own voice, I have decided to record a series of interviews with some of the older members of our family. I want to ask about their childhoods, their relationships with their families, how they met their spouses, what my wife and I were like as children, how the world has changed in their lives, what they might have done differently in their lives, what advice they have for her, etc. After listening to many hours of NPR, I have come to really enjoy audio-only interviews and would like to take this approach with my interviews. So my questions for Slashdot are what type of recording equipment should I use? What type of environment will give the best quality? I want to balance audio quality with content quality. I think sitting around the kitchen table would make people more comfortable and more willing to talk than sitting in some kind of recording studio. How can I minimize background noises, echos, and static? I only want to hear the voices, the laughter and the sighs, and maybe some crying. What media should I use to store the recordings? I realize I'll have to do some editing to separate the good stuff from the boring parts. If anyone has done something like this before, what kind of ratio can I expect? What's the best way to edit something like this? What other questions should I ask? What would you want to know from your grandparents?

Comment Re:Sure there are more blackberries (Score 5, Informative) 207

I develop applications for BlackBerry and I've talked to RIM about what restrictions corporate users will see. According to RIM, only 40% of BlackBerry users are on BlackBerry Enterprise Networks (BES) and over 90% of BES installations use the default settings. The default BES settings do not impose any restrictions on the device.


Teacher Sells Ads On Tests 532

Tom Farber, a calculus teacher at Rancho Bernardo high school in San Diego, has come up with a unique way of covering district cuts to his supplies budget. He sells ads on his tests. "Tough times call for tough actions," Tom says. The price of an ad on a Mr. Farber Calc test is as follows: $10 for a quiz, $20 for a chapter test, and $30 for a semester final. Most of the ads are messages from parents but about a third of them come from local businesses. Principal Paul Robinson says reaction has been "mixed," but adds, "It's not like, 'This test is brought to you by McDonald's or Nike.'" I see his point. Being a local business whore is much better than being a multinational conglomerate whore.

Submission + - How a Pulsar gets its Spin

brian0918 writes: "Until now, the assumption has been that the rapid spin of a pulsar comes from the spin of the original star. The problem was that this only explained the fastest observed pulsars. Now, researchers at Oak Ridge have shown that the spin of a pulsar is determined by the shock wave created when the star's massive iron core collapses. From the article: 'That shock wave is inherently unstable, and eventually becomes cigar-shaped instead of spherical. The instability creates two rotating flows — one in one direction directly below the shock wave and another, inner flow, that travels in the opposite direction and spins up the core. The asymmetrical flows establish a 'sloshing' motion that accounts for the pulsars' observed spin velocities from once every 15 to 300 milliseconds.'"
United States

Submission + - Military to forecast global wars with new computer

John Keller writes: "Scientists at the U.S. Defense Advanced Research Projects Agency (DARPA) in Arlington, Va., are asking industry for ideas on how to develop an advanced computer system called the Integrated Crisis Early Warning System (ICEWS) that is able to predict global wars and other political instability. The goal is to develop a system to monitor, assess, and forecast crises throughout the world to support decisions on how to allocate resources to mitigate them, officials say. The ICEWS will provide military commanders with a powerful capability to anticipate and respond to worldwide political crises and track their success in near-real time.

URL of this story is: EWS/none/none/DARPA-kicks-off-program-to-develop-a dvanced-computer-system-to-forecast-global-wars-an d-other-political-instability/"

Slashdot Top Deals

"With molasses you catch flies, with vinegar you catch nobody." -- Baltimore City Councilman Dominic DiPietro