quarterwave

The probabilities discussed in this paper seem to have an L1 flavour (Manhattan distance) while those in quantum mechanics come from L2 functions (Pythagorean distance).

Interesting stuff, reminds me of the analog circuit optimizer a few weeks back. Compared with (say) the evolution of a flying squirrel, are there aspects to this method that might be called 'genetic'?

Also, is the design method extensible to control surfaces? Say, self-adjusting flaps that can handle a sudden cross-draft?

Good point. It comes down to how well the analog cancellation will attenuate the in-band blocker (cf. IIP3 spec of the RF LNA).

After my family started buying dresses online (average $20 per item), I started paying more attention. Online shopping in India not only provides a vast range across vendors, it also saves the cost and hassle of travelling to a big store - especially for singleton purchases. When discerning dress buyers are happy to buy online that must signal some kind of shift.

The analogy with license plate detection appears quite accurate.

At first glance this scheme appeared akin to gathering wifi MAC address broadcasts, but the picture of the box shown in the article has a Tx antenna co-ax connector (looks like SMA). Then there is the question of SIM authentication for service. I don't suppose the cops are going to provide 4G service for free (there is also the issue of service collision and spectrum allocation) so probably what happens is that the SIM data is handshaked using some duplex protocol (hence the need for Tx in the base station), but no connection is made.

A bandgap circuit subtracts log(A.x) and log(B.x) to get a ratio log(A/B) that is independent of x (x>0), and to achieve this topology by evolution is a striking result. The question is whether one would trust the resultant topology in the absence of a known pattern. This is not casting a doubt on the evolutionary algorithm, it is more about the quality of the device compact models and the ability of the circuit equation solver to capture subtle instabilities and starting problems.

My guess is that today's compact models and solvers are both good enough for us to contemplate a 'Turing test' for analog circuit design.

In II-1-5 [1] we learn that magnetism is a relativistic effect whose strength is v^2/c^2. This ratio is a very small number for the electron drift velocities associated with typical currents in copper wires, yet we perceive magnetic forces because positive and negative electric charges in the wire are balanced to better than v^2/c^2.

Can anyone indicate how + and - charges are distributed in a CME? Are there strong electric fields due to local charge imbalances? For the magnetic field, it's tempting to say that the drift velocity of charges in a CME is high (as much as 0.001c) but then wouldn't charges of both polarities be moving with that (average) speed? Perhaps there is some initial motion when the charges are ejected from the sun?

[1] http://www.feynmanlectures.caltech.edu/II_01.html#Ch1-S5

Looks like multi-core asynchronous with load balancer wins even in the laser world.

'Enigma' the novel by Robert Harris on which that movie was based, is superb though. Definitely makes 1943 seem like 1943.

Another book worth reading is David Kahn's historical account 'Seizing the Enigma.'

Growing up in the early 70's (1970's, that is) I got a small book as birthday present: 'Let's go to the moon'. It was about a bunch of racoons that build a lunar rocket, and a sly fox named Reynard up to no good. Wonderfully illustrated with racoons drawing up plans, wearing goggles, and welding away. Does anyone else remember this masterpiece?

You know my methods Watson, what can you deduce?

Well, Holmes, from the range, it appears to be a point-to-point radio rather than an ad-hoc network. The length (6 inches) favours the 40MHz ISM band, with a low-gain integrated antenna & low data rate. I daresay the device casing itself could serve as the radiator. Perhaps some proprietary signal encoding for the (very) low signal power & to handle multiple access. Hardware is probably FPGA-based DSP + ARM processor. Most of the communication smarts would be at the TCP/IP level (e.g; retransmission) rather than in the radio per se, enabling low power operation.

It's nice to see a small start-up build something like this.

How quickly does a model's accuracy and precision improve with increasing sample size? Indeed, there are counter examples (like the periodogram estimator for psd) where variance does not decrease with window length.

We often don't know which model to use. Occam's Razor [1] can be effective in favouring simpler models, but I tend toward the view that a good data scientist is invariably needed to build good models. Hence I view Big Data more as a consulting business than SaaS.

[1] For an excellent Bayesian discussion on why Occam's Razor actually works, see Chapter 28 of David J.C. MacKay's book 'Information Theory, Inference and Learning Algorithms'.

The 2008 crisis showed that systemic risk in the repackaging business far outweighs the fine print in retail investment products. If people are upset it's not due to their ignorance but because of the feigned ignorance of those experts whose job is to study and understand risk, especially at government regulatory offices. The sporting equivalent would be for a commissioner to wax eloquent about the 'glorious uncertainties of the game' when the reality is a less-than-glorious certainty of match-fixing scandals.

I was curious how feathers -> flight evolved, came across this article: http://dinosaurs.about.com/od/thedinobirdconnection/a/origin...

Reminded me of the discussion about "The 'underlying' unity of nature" in the Feynman Lectures on Physics: http://www.feynmanlectures.caltech.edu/II_12.html#Ch12-S7

“Can you give me a simple, concrete explanation of how quantum computers work?” http://michaelnielsen.org/blog/quantum-computing-for-everyon...

To estimate an answer for the first problem: consider two cylinders with zero volume, the one equatorial (r=R) and the other polar (r=0). Both correspond to zero volume. Hence the maximum volume occurs (hand wave) for a height somewhere between 0 and 2R. Not knowing better, the initial estimate for h is to bisect this interval, to give h_est = R (compare 1 with 2/sqrt(3) ~= 1.15).

It would be nice to construct a first order correction term. Any ideas?

This is indeed true.

However in quite a few places the practicality of prepaid metal gas cylinders beats installing electric utility lines & meters, ensuring efficient transformers, preventing pilfering/meter tampering, etc.

Several languages use compound nouns, proper and common. These cause pronunciation problems when the phrase is read atomically, instead of by parsing. For example, German armbunduhr is easily understood as arm+bund+uhr = clock around arm, or wrist watch. Since I speak languages that also build up compound nouns (e.g; chair = four+legs), I have no trouble recognizing the need to parse in other languages.

The 741 has quite a few current mirrors for bias/gain, so the bias points would be much more sensitive to transistor parameter mismatch than to wiring neatness. Also, discrete PNP transistors tend to be different from the lateral PNP's in a bipolar transistor IC process.

I suppose the value in ordering such a kit is that the devices shipped are pre-matched etc, so the hobbyist may reasonably expect a first-pass success.

The 741 is dominant-pole compensated, so even if there were wiring-related phase shifts at high frequencies there will be no loop gain in that region to cause instability.

In his autobiography 'Wings of Fire', A.P.J.Abdul Kalam, himself an ISRO rocket scientist & program director who later became a highly popular President of India (he draws crowds to this day, several years after office), quotes Gen. Patton: "A good plan violently executed right now is far better than a perfect plan executed next week." That could well summarize the ISRO style.

Kalam also highlights the leadership-by-open-discussion style of Vikram Sarabhai and Satish Dhawan who successively headed ISRO in its formative years. If that sounds commonplace, bear in mind this was in a civilian government organization of the 1960's. People like Sarabhai (a Cambridge Tripos and inheritor of a family business empire) and Dhawan (a double PhD in math and aerospace from Caltech) could have played the part and been overbearing - but they deliberately chose to build a "startup culture" where people were encouraged to speak up.

The first question to ask may well be "why does my problem need computation on a commodity cluster?". A massive multi-player spaceship battle may be best served by a HPC environment, using C++ and MPI. There's probably only a limited class of distributed problems that map nicely to a commodity cluster. Several worthy commentators have pointed out that even if the systems programming environment offered the same verbs for both, commodity network latency makes "distributed concurrency" very different from "in-box concurrency". To loosely borrow a term from physics, time delays can break the scaling symmetry of a renormalization group.

A systems architect with a sound background in mathematics may be able to reason out the cluster performance of a social algorithm operating on a Erdos-Renyi random graph. Plodders such as myself will try to prototype. I'll insist that a prototype has business value if only because otherwise I have no way of appearing to be busy.

For prototyping a distributed system on a commodity cluster, my personal preference would be Erlang. As rvirding commented with great insight in another post, Erlang has an OS feel to it. From my limited perspective, Erlang spares me the trouble of knowing Unix and networking (for example: I don't need to know what a TCP port is). Erlang gives me a minimal & consistent set of verbs, and that's all I need for prototyping.

Are Erlang-based start-ups more likely to be acquired because Erlang has gained a Jedi Knight reputation for "sorcerer's ways"?

The research paper referenced above indicates a 0.5/sec sampling rate. Would a battery-backed inverter be able to sufficiently attenuate the power signature on this time-scale?

Good point: "I may be more acceptant of sentences with weird grammar."

The Borg from Star Trek TNG?

Interestingly enough, organic LED (OLED) technology uses dyes instead of semiconductor materials. OLED display panels can be 'printed' like ink-jet printers. http://en.wikipedia.org/wiki/OLED

When (if at all) will it be feasible for a bunch of kids in a garage to make a feature-length realistic-cgi movie? Assume computing on the public cloud, movie budget $1M.

Very nice! I assume clicking inside the panel is like throwing a pebble in a pond? Is this correct?

A discussion of the Third Law and the Nernst unattainability principle can be found in: http://benthamscience.com/open/totherj/articles/V006/1TOTHER...