Opendap linked servers

The purpose of the OPULS project is to adapt the OPeNDAP and Unidata server systems (Hyrax and TDS, respectively) for greater conformance, linkage, and eventual integration. Over the course of the project, we also hope to demonstrate how each group can capitalize on advances achieved by the other.

In the initial stages of the project, we will focus on data-model and protocol specifications, along with server conformance testing. Although these activities only set the stage for a common server framework, the resulting tests and specifications will immediately enhance the interoperability of the two server systems. We also anticipate that other OPeNDAP-related systems (such as PyDAP) will be adapted by their authors to pass conformance tests put forward jointly by OPeNDAP and Unidata.

via unidata.ucar.edu

This is great news. I've been working a lot on Pydap lately, mostly on tools that extend its functionality — like geospatial search, and more recently an Opendap-aware caching frontend.

ReaderSharer Brings Sharing Options Back to Google Reader in Firefox and Chrome

Chrome/Firefox (Greasemonkey): If you're not a fan of the Google+ integration in Google Reader or you simply wish you could still use the old sharing system, ReaderSharer is an extension that restores those functions.

The extension brings back the Shared Items, share button, and Trends options from the old version of Reader, while still retaining all the new options like +1's. Currently the Firefox implementation is through a Greasemonkey userscript, but in Chrome it's a standard extension. There are conflicts with Adblock at the moment, so if you're using it, you'll need to disable it for the Reader page to get it to work.

via lifehacker.com

This is cool, I was working on a similar extension. But I've been thinking if this is really the best solution; I think we should go back with to a decentralized social network using blogs, RSS, and the Comment/MetaWeblog APIs.

Behind Intel's New Random-Number Generator

Today I read for the second time about a simple random-number generator developed by Intel, based on a simple digital circuit:

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The idea is that initially both inverters leave the circuit in the same state. When the clock pulses both inverters fall into an undeterminate state, and then random noise makes one of the node to switch to a 1, and the other, to 0. One thing that caught my attention on the article was this part:

This digitized approach to random-bit generation would work fine if all inverter circuits were absolutely identical. But the messiness of the physical world never really allows that. In reality, no two inverters are exactly the same. Having subtle differences in the speed or strength of their responses might seem like a mild offense, but in this application, such differences could easily compromise the randomness we were trying to extract from the circuit.
 
To keep the inverters in balance, we built a feedback loop into the new hardware. The circuitry in that loop performs some targeted fiddling until the two possible output values, 0 and 1, each occur roughly half the time. This helps our design satisfy one of the rules for statistical randomness: In a long stream of numbers, there should be roughly the same number of all possible digits. By adjusting the internal workings of each inverter on the fly, we can defend against the predictability that cryptologists so dread.

I wonder if it wouldn't be feasible to use von Neumann's method of tossing a biased coin?

Skeptic finds he now agrees global warming is real - Yahoo! News

A prominent physicist and skeptic of global warming spent two years trying to find out if mainstream climate scientists were wrong. In the end, he determined they were right: Temperatures really are rising rapidly.

The study of the world's surface temperatures by Richard Muller was partially bankrolled by a foundation connected to global warming deniers. He pursued long-held skeptic theories in analyzing the data. He was spurred to action because of "Climategate," a British scandal involving hacked emails of scientists.

via old.news.yahoo.com

The best part is when he says, "The skeptics raised valid points and everybody should have been a skeptic two years ago,". This is how science works, and I was always a bit worried about all the negative reaction to skeptics — even though I thought mainstream thought was correct.

Nature's laws may vary across the Universe

One of the most cherished principles in science - the constancy of physics - may not be true, according to research carried out at the University of New South Wales (UNSW), Swinburne University of Technology and the University of Cambridge.

The study found that one of the four known fundamental forces, - measured by the so-called fine-structure constant and denoted by the symbol ‘alpha' - seems to vary across the Universe.

via physorg.com

I wonder if the rules propagate in space — maybe one day our region of the universe will be unfavorable for life? This would be similar to what happens in Asimov's "The Gods Themselves", where two universes were connected and the leaking of the nuclear interaction constant would create a supernova on our side, generating free energy for the other universe.

Flowers on my garden and humidity

I was having a problem with my virtual garden, and my flowers were all dying. I decided to check the equations that I use to calculate the efficiency of different flowers to see if I had made a mistake; looks like everything is ok and the flowers are dying just because of temperature changes. Maybe I should increase the rate of mutations to allow for a greater range of colors.

Anyway, one thing I did different from my first weather garden was that while the first version was based only on the relation between flower albedo and local temperature, this one also takes into account the local humidity. The way I came up to incorporate humidity was relating it to the "spikiness" of the flowers. Usually in deserts leaves tend to be thinner and spikier, in order to avoid loss of water (or so I recall learning). So my model takes into account the spikiness of the flowers, favoring rounder flowers in less dry weather.

Each flower on the garden is represented by a cosine wave of the form y = cos(x*k) * L + O, where k is a wave-number that defines the number of petals, L is the length of each petal, and O is an offset parameter related to the spikiness of the flower. Here's a simple example of a flower with k=5, L=10, O=5, first in cartesian coordinates and then in polar coordinates:

The (completely non-scientifical) way in which I measure spikiness is by taking O-L. Here's how it looks like when we relate this variable to the humidity. On the graph below I plotted several flowers. The x axis shows humidity percentage, going from 0 to 100. On the y axis we have O-L: spikier flowers appear on small values of O-L. The size of each flower shows its efficiency for the corresponding humidity. We can see that for lower values of humidity the spikier flowers fare better (they appear bigger), while the opposite is true for moister weather: