Monday, May 28, 2012

Going Beyond Search, Into Fetch

You whippersnappers might not remember, but libraries used to have something called card catalogs. Each book’s index card told you which shelf housed the corresponding volume. You had to go fetch it on foot.
Nowadays, you look up a book on a library computer screen, but you usually have to go fetch it on foot.
Until recently, we’ve had the same situation with searching the Web. You could look up a Web page using Google and Bing, but you still had to go fetch it.
But that’s about to change. In the last couple of weeks, both Google and Microsoft have added new features that try to spare you that last step. Now when you search at or, you don’t just get a list of Web pages that match your search. Off to the right, where the search results page used to be empty, you now see actual information about the subject of your search, carefully packed into a new, concise, attractive panel.
Microsoft calls this panel the Snapshot. Google calls it the Knowledge Graph, even though it doesn’t look or work anything like a graph. In both cases, you get this “Is this the information you desired, master?” panel only when you search for well-known people, places and things.
On Google, for example, the Graph panel displays a tiny dossier — usually drawn from Wikipedia — when you search for a well-known person like Martha Stewart, Benjamin Franklin, Barney the Dinosaur or James Cameron. You get a capsule description, birth and death dates, spouse and children, awards, education, best-known works (books or movies, for example) and latest Google Plus post, if the person has a Google Plus account. (Benjamin Franklin, Barney and James Cameron don’t.)
You get similar panels when you search a movie title (release date, director, composer, screenplay, awards, cast); book title (date, author, characters, genres, sequels); band (dates of activity, home state, members, record companies, song and album lists); city, state and country names (map, area, local time, population, points of interest); movie stars (the usual bio info plus net worth). Also landmarks, sports teams, art masterpieces and astronomical bodies.
The information is drawn from Wikipedia, the CIA World Factbook, Freebase and Google Books. Google says that in all, the Graph database contains summaries for 500 million entries.
That might seem like a lot. But Google is correct when it describes today’s Graph as a “baby step.” For example, the panel doesn’t appear when you search for hotels, restaurants, corporations, events or fictional characters like Odysseus and Santa Claus. (Oh dear — did I just ruin it for millions of children? It’s true, kids — there is no Odysseus.)
When it does appear, the Graph panel serves two other very useful purposes. First, it appears when you search for something that has multiple meanings, like “peanuts” (the nut or the cartoon?), “Chicago” (the town or band?) or “pogue” (iconoclastic technology columnist or Irish rock band?).
Second, the bottom of the panel reveals what other, similar searches might interest you, based on the search behavior of fellow Googlephiles. If you search for one snarky TV hit comedy, this feature might tip you off to others you might like.
Microsoft is scheduled to introduce its similar Snapshot feature on Thursday. It may take a couple of weeks before everybody sees it.
Here again, the Snapshot panel appears to the right of the standard results list. It’s like Google’s Graph, but with a different focus: it appears only when you’re trying to spend money. It pops up for restaurants (hours, ratings, reservation links); movies (trailer, length, rating, plot, links to reviews, director and cast); hotels, events, bands and so on.
Sometimes the Snapshot appears fully formed with the relevant details for your search. Other times, you have to point to the > mark that appears beside an item in the main search results list; the Snapshot changes to show the details of just that item.
Bing isn’t nearly as enthusiastic when you aren’t looking for information related to spending. For example, searching for a famous person might yield only the date of birth and (in the case of current online celebs) number of Twitter followers — but no photo, list of works and so on.

Thursday, May 3, 2012

Semiconductor device

Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide, as well as organic semiconductors. Semiconductor devices have replaced thermionic devices (vacuum tubes) in most applications. They use electronic conduction in the solid state as opposed to the gaseous state or thermionic emission in a high vacuum.

Semiconductor devices are manufactured both as single discrete devices and as integrated circuits (ICs), which consist of a number—from a few (as low as two) to billions—of devices manufactured and interconnected on a single semiconductor substrate, or wafer.

Semiconductor materials are so useful because their behavior can be easily manipulated by the addition of impurities, known as doping. Semiconductor conductivity can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid; thus, semiconductors can make excellent sensors. Current conduction in a semiconductor occurs via mobile or "free" electrons and holes, collectively known as charge carriers. Doping a semiconductor such as silicon with a small amount of impurity atoms, such as phosphorus or boron, greatly increases the number of free electrons or holes within the semiconductor. When a doped semiconductor contains excess holes it is called "p-type", and when it contains excess free electrons it is known as "n-type", where p (positive for holes) or n (negative for electrons) is the sign of the charge of the majority mobile charge carriers. The semiconductor material used in devices is doped under highly controlled conditions in a fabrication facility, or fab, to precisely control the location and concentration of p- and n-type dopants. The junctions which form where n-type and p-type semiconductors join together are called p-n junctions.