Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment Re:This should be a given.. (Score 3, Informative) 47

The base-pair sequence of DNA determines its biological function. As you say, this sequence determines what kinds of proteins get made, including their exact shape (and more broadly how they behave).

But TFA is talking about the conformation (shape) of the DNA strand itself, not the protein structures that the DNA strand is used to make.

In living organisms, the long DNA molecule always forms a double-helix, irrespective of the base-pair sequence within the DNA. DNA double helices do actually twist and wrap into larger-scale structures: specifically by wrapping around histones, and then twisting into larger helices that eventually form chromosomes. There are hints that the DNA sequence itself is actually important in controlling how this twisting/packing happens (with ongoing research about how (innapropriately-named) "junk DNA" plays a crucial role). However, despite this influence between sequence and super-structure, DNA strands essentially are just forming double-helices at the lowest level: i.e. two complementary DNA strands are pairing up to make a really-long double-helix.

What TFA is talking about is a field called "DNA nanotechnology", where researchers synthesize non-natural DNA sequences. If cleverly designed, these sequences will, when they do their usual base-pairing, form a structure more complex than the traditional "really-long double-helix". The structures that are designed do not occur naturally. People have created some really complex structures, made entirely using DNA. Again, these are structures made out of DNA (not structures that DNA generates). You can see some examples by searching for "DNA origami". E.g. one of the famous structures was to create a nano-sized smiley face; others have 3D geometric shapes, nano-boxes and bottles, gear-like constructs, and all kinds of other things.

The 'trick' is to violate the assumptions of DNA base-pairing that occur in nature. In living cells, DNA sequences are created as two long complementary strands, which pair up with each other. The idea in DNA nanotechnology is to create an assortment of strands. None of the strands are perfectly complementary to each other, but 'sub-regions' of some strands are complementary to 'sub-regions' on other strands. As they start pairing-up with each other, this creates cross-connections between all the various strands. The end result (if your design is done correctly) is that the strands spontaneously form a ver well-defined 3D structure, with nanoscale precision. The advantage of this "self-assembly" is that you get billions of copies of the intended structure forming spontaneously and rapidly. Very cool stuff.

This kind of thing has been ongoing since 2006 at least. TFA erroneously implies that this most recent publication invented the field. Actually, this most recent publication is some nice work about how the design process can be made more robust (and software-automated). So, it's a fine paper, but certainly not the first demonstration of artificial 3D DNA nano-objects.

Comment Non-deterministic sort (Score 4, Interesting) 195

Human sorting tends to be rather ad-hoc, and this isn't necessarily a bad thing. Yes, if someone is sorting a large number of objects/papers according to a simple criterion, then they are likely to be implementing a version of some sort of formal searching algorithm... But one of the interesting things about a human sorting things is that they can, and do, leverage some of their intellect to improve the sorting. Examples:
1. Change sorting algorithm partway through, or use different algorithms on different subsets of the task. E.g. if you are sorting documents in a random order and suddenly notice a run that are all roughly in order, you'll intuitively switch to a different algorithm for that bunch. In fact, humans very often sub-divide the problem at large into stacks, and sub-sort each stack using a different algorithm, before finally combining the result. This is also relevant since sometimes you actually need to change your sorting target halfway through a sort (when you discover a new category of document/item; or when you realize that a different sorting order will ultimately be more useful for the high-level purpose you're trying to achieve; ...).
2. Pattern matching. Humans are good at discerning patterns. So we may notice that the documents are not really random, but have some inherent order (e.g. the stack is somewhat temporally ordered, but items for each given day are reversed or semi-random). We can exploit this to minimizing the sorting effort.
3. Memory. Even though humans can't juggle too many different items in their head at once, we're smart enough that we encounter an item, we can recall having seen similar items. Our visual memory also allows us to home-in on the right part of a semi-sorted stack in order to group like items.

The end result is a sort that is rather non-deterministic, but ultimately successful. It isn't necessarily optimal for the given problem space, but conversely their human intellect is allowing them to generate lots of shortcuts during the sorting problem. (By which I mean, a machine limited to paper-pushing at human speed, but implementing a single formal algorithm, would take longer to finish the sort... Of course in reality mechanized/computerized sorting is faster because each machine operation is faster than the human equivalent.)

Submission + - Alternatives to Slashdot post beta? 8

An anonymous reader writes: Like many Slashdotters, I intend to stop visiting Slashdot after the beta changeover. After years of steady decline in the quality of discussions here, the beta will be the last straw. What sites alternative to Slashdot have others found? The best I have found has been arstechnica.com, but it has been a while since I've looked for tech discussion sites.

Submission + - Slashdot BETA Discussion (slashdot.org) 60

mugnyte writes: With Slashdot's recent restyled "BETA" slowly rolled to most users, there's been a lot of griping about the changes. This is nothing new, as past style changes have had similar effects. However, this pass there are significant usability changes: A narrower read pane, limited moderation filtering, and several color/size/font adjustments. BETA implies not yet complete, so taking that cue — please list your specific, detailed opinoins, one per comment, and let's use the best part of slashdot (the moderation system) to raise the attention to these. Change can be jarring, but let's focus on the true usability differences with the new style.

Submission + - Slashdot creates beta site users express theirs dislike (slashdot.org) 4

who_stole_my_kidneys writes: Slashdot started redirecting users in February to its newly revamped webpage and received a huge backlash from users. The majority of comments dislike the new site while some do offer solutions to make it better. The question is will Slashdot force the unwanted change on its users that clearly do not want change?

Submission + - Once Slashdot beta has been foisted upon me, what site should I use instead? 2

somenickname writes: As a long time Slashdot reader, I'm wondering what website to transition to once the beta goes live. The new beta interface seems very well suited to tablets/phones but, it ignores the fact that the user base is, as one would expect, nerds sitting in front of very large LCD monitors and wasting their employers time. It's entirely possible that the browser ID information gathered by the site has indicated that they get far more hits on mobile devices where the new interface is reasonable but, I feel that no one has analyzed the browser ID (and screen resolution) against comments modded +5. I think you will find that most +5 comments are coming from devices (real fucking computers) that the new interface does not support well. Without an interface that invites the kind of users that post +5 comments, Slashdot is just a ho-hum news aggregation site that allows comments. So, my question is, once the beta is the default, where should Slashdot users go to?

Submission + - Slashdot beta sucks 9

An anonymous reader writes: Maybe some of the slashdot team should start listening to its users, most of which hate the new user interface. Thanks for ruining something that wasn't broken.

Comment Re:Just in time too. (Score 1) 267

> 99% of the computing needs of 99% of the people can be met by the existing

You know, this phrase has been uttered so many times it became completely meaningless. Please define "Computing needs"?

If you had asked someone in the 50ies, they would have told you that the average person needs some help with adding the numbers for checkbook balancing. So a simple calculator should be enough, right? Nobody would have considered that people of 2000ies would deem it a worthwhile endeavour to use processing power that exceeds the computing power of the entire civilization in the 50ies by orders of magnitudes, simply for gaming.

Today people use a different frame of reference based on the applications they know today. The mistake is still the same.

Why do we need more of moores law?
- Right now everything is about the internet of things. Moores law is not only about transistor density, it is also about power. We need extremely low power computing. The trillion sensor revolution is not a joke. It is happening right now.
- We are still orders of magnitude away in computing power from anything required to make truely intelligent system. There are huge research projects right now, pushing the understanding of the human brain (the EU human brain project for example). If you want your fridge to be as intelligent as a dog, you may want it to have more computing power than your current pc or smartphone.

Slashdot Top Deals

No amount of careful planning will ever replace dumb luck.