Become a fan of Slashdot on Facebook


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

Comment Correlation between Antibiotics and Obesity? (Score 3, Interesting) 256

On a hunch I decided to see if there's a correlation between obesity and antibiotics (which are known to kill both the good and bad types of gut bacteria)

Here's a map showing antibiotic prescribing rates.

Here's a map showing obesity rates:

Correlation is not causation, but in my unprofessional opinion, these maps look eerily similar.

Comment Re:Useless Change (Score 3, Informative) 383

One more MAJOR advantage of a camless design (if not the single greatest advantage) would be the ability to have extremely canted valve angles. Retrofitting an existing cylinder head design with camless engine technology is only scratching the surface. The biggest benefits would be gained by designing the cylinder head ports around the capabilities of the valve actuators. With cylinder head differences like this, we're literally talking about the difference between NASCAR horsepower levels and streetcar horsepower because cylinder head designs are the undisputed most important factor in making horsepower.

With traditional cylinder heads (on OHV engines), valve angles are limited by the rocker arms. Rocker arm rotation about one axis is trivial, but when the valve is canted it makes the valvetrain design exponentially more complex and prone to wear due to lateral loads as the angle is increased. A camless engine design wouldn't have this limitation. That being said, the camless designs have their own challenges, namely soft valve seat landings due to a nearly perfect square-wave lift profile.

Comment Re:Don't understand engines, eh? (Score 4, Informative) 383

They call it a "Digital Cam" because when you graph valve lift vs time it literally looks like a square wave. The ramps really are that steep!

This compares to a conventional cam with a sudo-sinusoidal shaped wave lift profile (neglecting the effects of high RPM valve float).

Criticize as much as you want, but a truly functional electronically controlled camless engine would be the holy grail of internal combustion engine design. You can easily pick up 20 horsepower on many engines just by swapping to a performance cam, but you often compromise efficiency. But with a camless engine, in theory, you could have cylinder deactivation, low compression starts, the elimination of throttle plates (lower pumping losses), "full race-cam" profiles for performance, a cam profile for smooth idling, low emissions, etc....
Truly the best of both worlds!! That being said, there are disadvantages....


I read an interesting SAE paper 20+ years ago describing a working prototype camless engine. The performance gains were impressive, but as I recall, there were two main obstacles:

1) Noise, Vibration, and Harshness. (NVH)

2) The valves landed harshly leading to valve seat wear. The SAE paper suggested using a method for softer valve landings.

Comment Too ambitious (Score 2) 75

3D printing hype is getting out of hand.

Why would anyone buy an unfinished looking $53,000 3D-printed car like THIS, when you could buy a 500+ horsepower 2016 Shelby GT350 for about the same price? The resale value alone would make the 3D printed choice foolish.

If 3D printing was as promising as this article makes it sound, then why can't I buy individual parts like custom 3D printed hoods? It's certainly more realistic to buy individual parts than 3d printing an "entire" car. It's just not anywhere close to being cost effective.

Submission + - Microsoft's 1TB Surface Book will cost you a hefty $3,199 (

logaecology writes: Microsoft talked about the Surface Book having up to a 1TB solid-state drive when it announced the laptop/tablet hybrid, but you couldnt actually buy it on launch — 512GB was as good as it got. Well, that extra-capacious model is now available fo...

Comment Re:Everything (Score 1) 889

^^^ THIS

I logged in just to mention Everything.
It's my favorite free program for Windows and and I don't care what the zealots say. There is NO comparable alternative for Linux.

One nice feature on Everything is the ability to add text files containing file lists to your search.
I use it to search multiple computers simultaneously and this way they can even be powered off.
The external file lists can be stored and synced on Google-Drive or an equivalent cloud storage.

I haven't tried it yet, but I might try creating a daily cron job that generates a text file list of all of my linux files and then try to use Everything via Wine as a viewer. It's a very clumsy alternative, but that's the best alternative I can think of.

Slashdot Top Deals

If I'd known computer science was going to be like this, I'd never have given up being a rock 'n' roll star. -- G. Hirst