By contrast, the current ranking system leads to the popular becoming more popular — once you’re on the top charts, you have increased visibility, which leads to more reviews, which further cements your chart position (as long as you stay inside your semantic rating bucket).
Those of us who want to discover hidden gems really need the search functionality to work with us, not against us. We want a system where the top charts are self-correcting, rather than self-reinforcing. Otherwise we get a situation like Apple’s with frozen charts, shady tactics, and skyrocketing user acquisition costs.
Category Archives: STEM
Bayesian Prediction for The Winds of Winter
Predictions are made for the number of chapters told from the point of view of each character in the next two novels in George R. R. Martin’s \emph{A Song of Ice and Fire} series by fitting a random effects model to a matrix of point-of-view chapters in the earlier novels using Bayesian methods. {\textbf{SPOILER WARNING: readers who have not read all five existing novels in the series should not read further, as major plot points will be spoiled.}}
via [1409.5830] Bayesian Prediction for The Winds of Winter.
Why the Z-80’s data pins are scrambled
I have been reverse-engineering the Z-80 processor using images and data from the Visual 6502 team. The image below is a photograph of the Z-80 die. Around the outside of the chip are the pads that connect to the external pins. (The die photo is rotated 180° compared to the datasheet pinout, if you try to match up the pins.) At the right are the 8 data pins for the Z-80’s 8-bit data bus in a strange order.
via Ken Shirriff’s blog: Why the Z-80’s data pins are scrambled.
The motivation behind splitting the data bus is to allow the chip to perform activities in parallel. For instance an instruction can be read from the data pins into the instruction logic at the same time that data is being copied between the ALU and registers. The partitioned data bus is described briefly in the Z-80 oral history[3], but doesn’t appear in architecture diagrams.
The complex structure of the data buses is closely connected to the ordering of the data pins.
Newest ‘procedural-generation’ Questions
Often synonymous with “random generation”, procedural generation is the usage of calculations and algorithms to create content, rather than referring to preset data. The typical reason is to generate content mid-gameplay, which makes for a more unpredictable and unique experience in multiple playthroughs. Common elements that are subject to procedural generation in games include item attributes, enemy abilities, and level layouts.
Procedural generation specifically refers to the usage of algorithms to generate content, it is not necessary to be random. Pseudo-random generators with fixed seeds can be considered procedural generation despite producing identical results.
via Newest ‘procedural-generation’ Questions – Game Development Stack Exchange.
Zoom in to see the fine details in this Gigapan image
Chris Walker made the image above with a DSLR camera, using a GigaPan device to record a series of individual images over the course of 15 minutes. In the panoramas you see here, nearly 100 frames were stitched together to create the resulting single photographs. Chris used PTGui Pro software to minimize visual imperfections, such as people appearing twice because they moved during the course of the 15-minute session.
Via Bears kickoff — Chicago Tribune.
You can navigate and see almost every person at Soldier Field for last Sunday’s Bears game against the Buffalo Bills. Quite fascinating!
Can Tesla Power Its Gigafactory with Renewables Alone?
All of the calculations are for energy, not power. In other words, you might produce 2400 MWh per day, but that doesn’t mean you’ll always have 100 MW available at any given instant. Sometimes you’ll generate more, other times less. Obviously there will be no solar production at night and less wind production on calm days. To be fully off-grid, Tesla will need some form of storage. As I surmised in a previous article, Tesla is probably shooting for more than the EV market; it seems logical for them to be looking into grid-level storage as well. What better way to showcase that than to include Li-ion batteries for on-site storage?
via Can Tesla Power Its Gigafactory with Renewables Alone? > ENGINEERING.com.
Space Station Sharper Images of Earth at Night Crowdsourced For Science
The images are available to the public through The Gateway to Astronaut Photography of Earth, the most complete online collection of images of Earth taken by astronauts. This database contains photographs beginning with those taken during Mercury missions in the early 1960s up to recent images from the station, with more added daily. As of August 2014, the collection included a total of nearly 1.8 million images, more than 1.3 million of them from the space station. Approximately 30 percent of those were taken at night.
via Space Station Sharper Images of Earth at Night Crowdsourced For Science | NASA.
Lost at Night requires the most skill, seeking to identify cities in images encompassing a circle 310 miles around. “We don’t know which direction the astronaut pointed the camera, only where the station was at the time the image was taken,” explains Sanchez. “Some images are bright cities but others are small towns. It is like a puzzle with 300,000 pieces.”
‘Unparticles’ May Hold The Key To Superconductivity, Say Physicists
In very simple terms, when that happens, material properties such as resistance no longer depend on the length scales involved. So if electrons move without resistance on a tiny scale, they should also move without resistance on much larger scales too. Hence the phenomenon of superconductivity.
“We have described how it is possible for unparticles in strongly correlated matter to mediate superconductivity,” say LeBlanc and Grushin.
Rosetta arrives at comet destination
“After ten years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometres, we are delighted to announce finally ‘we are here’,” says Jean-Jacques Dordain, ESA’s Director General.
“Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start.”
via Rosetta arrives at comet destination / Rosetta / Space Science / Our Activities / ESA.
From: Re-Live the excitement
For those of you who couldn’t follow the live streamed event this morning, here’s a short summary of what happened here at ESA’s European Space Operations Centre in Darmstadt at the Rosetta Rendezvous event. A full replay of the livestream can be found here.
A couple of pics here.
Previous coverage of it waking up here and of it having its software upgraded here.
A Fictional Compression Metric Moves Into the Real World
It seems that someone would have come up with such a metric by now. But, says Weissman, “there are two communities: the practitioners, who care about running time, and the theoreticians, who care about how succinctly you can represent the data and don’t worry about the complexity of the implementation.” As a result of this split, he says, no one had yet combined, in a single number, a means of rating both how fast and how tightly an algorithm compresses.
Misra came up with a formula (photo above), incorporating both. Along with existing benchmarks the formula creates a metric that the show writers tagged the “Weissman Score.” It’s not a fictional metric: although it didn’t exist before Misra created it for the show, it works and may soon find use in the real world.
via A Fictional Compression Metric Moves Into the Real World – IEEE Spectrum.