Thursday, March 06, 2014

Facebook Reveals Who You Love

Facebook graph reveals who you love

The friends of a Facebook user's friends and the links between them. Two heavily linked clusters are obvious at 12 and 3 o'clock - perhaps the user's workplace and college pals. But notice the somewhat isolated person down around 7 o'clock, who shares links to many smaller clusters of the central user's friends. Computer analysis points to this person as the romantic partner.

From a map of Facebook friends, a computer algorithm developed by Jon Kleinberg, the Tisch University Professor of Computer Science, and Lars Backstrom '04, Ph.D. '09, now at Facebook, will correctly identify a person's spouse, fiancĂ© or other romantic partner about 70 percent of the time.
"We are trying to build up a sort of chemistry kit for finding different elements of a network," Kleinberg said. The team will present their results at the ACM Conference on Computer Supported Cooperative Work and Social Computing, Feb. 15-19 in Baltimore.
As you might guess, the method works best when the couple is married, and works better the longer the relationship has been in force. On the dark side, if the algorithm does not select the person who is the relationship partner, there is a significantly increased chance that in a month or two the couple will break up.
The researchers tested their methods on anonymized data from 1.3 million randomly selected Facebook users aged 20 or older who listed their status as "married," "engaged" or "in a relationship." Along with a list of a Facebook user's friends, the data also show how those friends are linked to one another.
The first guess was that the romantic partner would be "embedded" – that the couple would have many . That works, the researchers found, but not very well, finding the partner about 25 percent of the time. So they introduced a concept they call "dispersion," where the couple's mutual friends are not highly connected among themselves, but rather are scattered over many aspects of the central user's life. In real-world terms, your spouse goes where you go, and knows the people in your office, your church, your bridge club and so on, although those people seldom meet one another across group lines.
"You have to ask, 'How did the relationship get that way?'" Kleinberg said. "Your spouse acts as a sort of time traveler in your life, who went back and met all those people."
Combining embededness with dispersion boosted performance. The researchers then factored in the dispersiveness of the dispersed  – whether the person your romantic partner knows at your office is also connected to some people in your church and your bridge club.
Finally, they added measures of interaction, such as how often people look at each other's profiles, attend the same events or appear together in photos. Ultimately they were able to identify the partner 70.5 percent of the time. Others who might be chosen by the algorithm are most often family members or their partners.
As a spinoff, the researchers were able to determine, 68.3 percent of the time, whether a given user was or was not in a relationship at all, and with 79 percent accuracy if the relationship was a marriage.
There may be other applications for analysis based on dispersion, the researchers said, including grouping people into categories or, for social scientists, finding the person who just doesn't fit a category. Backstrom, who developed Facebook's friend recommender, is looking at ways to evaluate incoming messages to a Facebook user based on the user's relationship with the source.
And identifying people with strong ties to one another may also show where to go to influence a group. "If you're someone who bridges between groups it can be a source of power," Kleinberg explained.
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Sunday, February 23, 2014

HP Next-Generation Workstation

HP's Next-Generation Workstation

Hewlett-Packard’s new Z620 workstation is as screamingly fast as it is easy to service. It is completely redesigned with a two-socket motherboard in a rackable mini-tower. Its top configuration delivers 24 cores across two Intel Xeon E5 2697v2 3.0 GHz CPUs. Its 12 DIMM slots can handle as much as 192 GB of 1,866 MHz eight-channel ECC DDR3 memory with four memory channels per CPU. A six-channel SATA controller can address as much as 12 TB of internal storage and manage RAID 0, 1, 5 or 10 arrays.
There is more to report on the latest workstation, including a reconfigured interior and a Thunderbolt option. Read on for details and performance results from CRN Test Center benchmarks.

Storage

HP has boosted the Z620’s storage-controller options, adding an 8 port LSI 9717 4i4e SAS controller and LSI 9212 4i4 port SAS RAID card. That is on top of the motherboard’s Marvell SATA controller with six channels for RAID 0, 1, 5 and 10, two of which can handle 6.0 Gb/s. For system and booting, the company this year uses Seagate Pro series SSDs instead of Micron.
The test system also sported a pair of Hitachi 7200K 6.0 Gbps spinning drives in a RAID 5 array controlled by a LSI MegaRAID 9260 8i. Against this array, the Z620 turned in a sustained data transfer rate for sequential reads of almost 370 MB/s.
Transaction and throughput performance were measured with IOmeter. For this test, peak performance was found with sequential 4K reads and a queue size of 48.

Thunderbolt too

HP is among just a handful of vendors to fully embrace Intel’s new Thunderbolt spec, which defines a high-speed bus for video and storage. It included a sample of its Thunderbolt 2.0 PCIe card in the test system, and its performance was pretty good. The card delivered a sustained transfer rate of 280 MB/s with sequential reads of 32K, but its IOps was just 8K. By reducing packet size to 4K, testers were able to boost IOps to 70K and still achieve 275 MB/s, or 2.2 Gb/s. In drag-and-drop tests of file transfers, the drive delivered a transfer rate in excess of 3 Gb/s. HP’s Thunderbolt card is scheduled to begin shipping early next year.

IO chops
To measure transaction processing, testers reconfigured IOmeter’s access specifications to use 512 byte packets. A peak sustained transaction performance of 153K IOps was observed with a transaction queue size of 64.
Other I/O gear included in the base Z620 configuration includes dual gigabit Ethernet ports, four USB 3.0 ports—two front and two rear—and FireWire. Options include a 10 GbE NIC. For graphics, HP offers the Z620 equipped with an Nvidia Quadro K4000, K5000, 6000, Tesla C2075 and K20c models, or AMD’s FirePro W7000.

Geekbench

This score was a bit of a head scratcher. Using the 64 bit version of Primate Labs’ Geekbench 2.3, the Z620 turned in a top score of 35,040. That is an extremely high score in its own right, but it falls well short of the 41,348 turned in by last year’s Z620 workstation, the fastest PC we have ever tested.
That machine had slower processors (2.9 GHz) and slower memory (1,600 MHz), yet delivered a far higher Geekbench score.

The bottomline

HP has kept much of what the CRN Test Center liked about prior versions of its venerable workstation, namely its ease of service. The lockable side panel is removed with the flip of a lever to expose processors, DIMM slots, storage, expansion cards, power supply and many other internal components that can be serviced without tools. As before, the second processor slot is implemented as a daughtercard—complete with memory and fan—but it is now far easier to remove and more precise to reinstall. The Z620’s internals truly are a masterpiece of engineering.
Despite its anomalous Geekbench results, the latest Z620 workstation delivers outstanding performance benchmarks overall. This machine is built to be easy to service and upgrade and delivers consistent performance for video production, computer-aided design and any application that demands ultra-high performance from a small footprint PC. List prices start at $1,689 with a three-year warranty.


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