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Math

+ - Collatz proved - hailstone sequences end in 1. ->

Submitted by mikejuk
mikejuk (1801200) writes "A proof has been proposed for the Collatz conjecture about hailstone sequences. A hailstone sequence starts from any positive integer n the next number in the sequence is n/2 if n is even and 3n+1 if n is odd. The conjecture is that this simple sequence always ends in one.
Simple to state but very difficult to prove and it has taken more than 60 years to get close to a solution. Paul Erdos said "Mathematics is not yet ready for such problems" — so is it now?"

Link to Original Source

Comment: Re:Some idea (Score 1) 137

by Manywele (#35651982) Attached to: Fighting Fires With Beams of Electricity

Flames are ionised (i.e. charged) particles. If you have a strong enough electric field (which is really not the same as 'shooting electricity' as per the article) when the charged particles move through the electric field there will be a force on them perpendicular to their motion and to the field i.e. the flame will curve over into spiral.

That's for a magnetic field. Charged particles move along the direction of electric fields.

Earth

Lidar Finds Overgrown Maya Pyramids 169

Posted by kdawson
from the run-but-you-can't-hide dept.
AlejoHausner writes "A team of archaeologists scanned the jungle of Belize with lidar. Although most of the reflections came from the jungle canopy, some light reflected off the ground surface. Using this, suddenly hidden pyramids, agricultural terraces, and ancient roads are revealed, at 6-inch resolution. The data allowed the archaeologists to bolster their theory that the ancient city of Caracol covered more than 70 square miles of urban sprawl and supported a population of over 115,000."
Cellphones

Wi-Fi In a SIM Card 126

Posted by kdawson
from the personal-bubble dept.
gaijin_ writes "What if, rather than buying a MiFi or using a Wi-Fi router app like those on the Palm Pre Plus, you could stick a SIM in any device and have a shared 3G connection? That's what Sagem Orga and Telefonica are promising: they've developed the SIMFi, a USIM card with an embedded Wi-Fi radio that, when dropped into any standard handset, can share the 3G HSPA connection with various Wi-Fi clients as an instant access point."

Comment: Re:Developing Nations Crippled by Road Costs (Score 1) 239

by Manywele (#29850813) Attached to: Developing Nations Crippled By Broadband Costs
They're used to dealing with bad transportation and roads, no or spotty electricity, using pit latrines and poor medical care. Those problems are being worked on and are showing improvement. [Fermi problem: what would it cost to take say, Tanzania, and give it a complete first world infrastructure; highways, paved local roads, sewage treatment, electricity, water, trash pickup?] Does that mean you think that the rapid expansion of cell networks in Africa and the resulting connectivity is wasted or shouldn't have been done? Third world residents deserve access to the modern world and broadband is part of that.

As a Peace Corps volunteer in 1999 the internet (very slow shared connection) was 2 days away and cost 1$/hour. Now it's a couple of hours away from where I lived, half the price and 10x faster. That needs to keep expanding. I tried explaining what the internet was to a rural friend. He had *seen* a phone once 10 years ago. Now he has one. The internet needs to go that way. People deserve access to information. Hey, maybe they'll start to figure out some of the solutions to their problems themselves instead of relying on people to tell them what to do.

[5 years in the Peace Corps in rural West & East Africa.]

Comment: Re:goofy timeline; my experience (Score 1) 201

by Manywele (#27902337) Attached to: Open Source Textbooks For California
I see now it does cover thermo and does seem to be Cal state standards compliant. I've run into your books before and I like them more than the lesser-of-evils textbook I ended up with. I've thought about trying to use it in class but for the reasons outlined above it's just not going to (officially) happen. I'll probably steal some of your problems though :).

Comment: Re:goofy timeline; my experience (Score 3, Informative) 201

by Manywele (#27901999) Attached to: Open Source Textbooks For California
As a California high school physics teacher I agree that your text will never be adopted by a public California high school. You have a picture of a beer for one, obviously encouraging underaged drinking. Plus it's not aligned to the state standards (you're missing thermo). Also every physics teacher has to agree on a single textbook in case a physics student transfers mid-year. That hasn't happened in the 4 years I've been teaching here so why we're catering to the random data point is beyond me. But the standards are the main problem. You see, the school board has to ensure that the book meets the state standards. They're not going to actually read the standards and the book and see if they match up (and they're really not qualified to determine that). But the major publishers also publish helpful guides that link all the standards to specific pages in the text so all the board members have to do is look at the guide and say "Yup, it's standards complient" or more precisely verify the existence of such a guide and deem that necessary and sufficient. Since you don't have such a guide the board can not legally adopt your text. I'm pretty sure the picture of a beer would prevent me from even getting it approved as a supplementary text (were I to ask rather than just use it.)

Comment: Re:Supply and Demand (Score 1) 1322

by Manywele (#27810129) Attached to: Why Is It So Difficult To Fire Bad Teachers?

Incredibly low? TFA quoted the median salary for a teacher in their mid 30s as $74,000 a year. I'm sure many people would be happy to trade their "incredibly low" salary for that incredibly low salary.

I don't know what article you're reading but the one linked in the summary says nothing about the median salary of a teacher. The number $74,000/yr, which I assume you pulled out of your ass, is about $30,000/yr inflated over the actual value. Sure, after 30 years of teaching I'd be making that much, but not in my mid-30s.

Input Devices

NYU Researchers Create Cheap, Flexible Pressure-Based Interface 55

Posted by timothy
from the where-would-you-put-it? dept.
Al writes "A super-cheap, thin and flexible touch interface developed by researchers at New York University and could be used to add touch sensing to all sorts of gadgets and devices. It measures a change in electrical resistance when a person or object applies different pressure. The "Inexpensive Multi-Touch Pressure Acquisition Devices (IMPAD)" consists of two sheets of plastic containing parallel lines of electrodes. The sheets are arranged so that the electrodes cross, creating a grid and each intersection acts as a pressure sensor. The sheets are also covered with a layer of force-sensitive resistor (FSR) ink, a type of ink that has microscopic bumps on its surface. So, when something coated in the ink is pressed, the bumps move together and touch, conducting electricity."
The Media

Should Google Be Forced To Pay For News? 322

Posted by timothy
from the according-to-his-need dept.
Barence writes "The Guardian Media group is asking the British government to investigate Google News and other aggregators, claiming they reap the benefit of content from news sites without contributing anything towards their costs. The Guardian claims the old argument that 'search engines and aggregators provide players like guardian.co.uk with traffic in return for the use of our content' doesn't hold water any more, and that it's 'heavily skewed' in Google's favour. It wants the government to explore new models that 'require fair acknowledgement of the value that our content creates, both on our own site (through advertising) and "at the edges" in the world of search and aggregation.'"

Comment: Re:You are teaching them science is boring. Stop i (Score 1) 314

by Manywele (#27250279) Attached to: How To Get High-Schoolers Involved In Real Science?
Could you provide a little more info on the Sterling engine from a bike wheel and rubber bands? I'm a high school physics teacher (done most of what you mention) and I've tried two different hand made Sterling engine models, including the one from Make magazine two years ago or so. Couldn't get either one even close to working.

Yeah, I realize 20 years makes the memory a little hazy.
Earth

+ - The Alps of the Antarctic

Submitted by CaroKann
CaroKann (795685) writes "Recently, scientists have been creating the first detailed maps of the Antarctic Gamburtsev mountains using radar and gravity sensors. As a result, scientists have discovered that the Gamburtsev mountains, which were originally discovered by Russian explorers fifty years ago, are similar in size and shape to the European Alps, with lofty peaks and valleys. This discovery suggests that the Antarctic ice sheet formed relatively quickly, covering the mountains before they could be ground down. In addition, liquid water has been discovered in valleys about 3 km below the ice surface. It is estimated that the Gamburtsev mountains are approximately 500 million years old. By comparison, the Alps are approximately 55 million years old. It is hoped that this new data can be used to better understand how the ice sheets work and how they may react to global warming."
Announcements

+ - Iranian Student proves P=NP-> 1

Submitted by Anonymous Coward
An anonymous reader writes "Iranian student Zohreh O. Akbari, a native of Tehran, and currently a graduate student at Payame Noor University, claims to have proven that P=NP in her recent paper entitled "A Deterministic Polynomial-time Algorithm for the Clique Problem and the Equality of P and NP Complexity Classes". Her paper was published in the Proceedings of the World Academy of Science, Engineering and Technology, and if true has some very serious consequences. It should be noted that most Computer Scientists have believed that P does not equal NP. This follows on the heels of a paper by Dr. Rafee Kamouna that SAT is not NP-Complete, another proof that shoved aside established belief in theoretical computer science."
Link to Original Source

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