Technology news update!

NASA's robotic sub readies for dive into Earth's deepest sinkhole

2007-03-25T03:32:00.000-07:00

NASA's robotic sub readies for dive into Earth's deepest sinkhole

Credit: DEPTHXCarnegie Mellon University
Credit: DEPTHX/Carnegie Mellon University

An underwater robot, shaped like a flattened orange, maneuvered untethered and autonomously within a 115-meter-deep sinkhole during tests this month in Mexico, a prelude to its mission to probe the mysterious nether reaches of the world's deepest sinkhole.

Bill Stone, leader of the NASA-funded Deep Phreatic Thermal Explorer (DEPTHX) mission, said the 2.5-meter-diameter vehicle performed "phenomenally well" during early February tests in the geothermal sinkhole, or cenote, known as La Pilita. Carnegie Mellon University researchers developed the software that guided the DEPTHX craft.

"The fact that it ran untethered in a complicated, unexplored three-dimensional space is very impressive," said Stone, an engineer and expert cave diver who heads Stone Aerospace Inc. of Austin, Texas. That's a fundamentally new capability never before demonstrated in autonomous underwater vehicles (AUVs), he added.

The autonomous navigation and mapping software that enabled DEPTHX to safely and precisely operate in the close confines of cenote La Pilita was developed by a team of Carnegie Mellon researchers led by David Wettergreen, associate research professor in the Robotics Institute. "These experiments give us confidence that DEPTHX will be able to meet the challenge of its ultimate goal, the cenote El Zacatón," Wettergreen said.

Like La Pilita, Zacatón is in the Mexican state of Tamaulipas and was formed by the collapse of a limestone chamber dissolved by warm, acidic groundwater that originated in a nearby volcanic region. The current theory is that the cenote formed under a vast travertine bed like that of Mammoth Hot Springs in Yellowstone National Park. But no one knows how deep Zacatón goes. Human divers, descending far below safe depths, have made it to 282 meters without reaching bottom. Sonar doesn't work over long distances in the confines of the cenote, and current measurements peter out at around 270 meters.

NASA has funded the mission to develop and test technologies that might someday be used to explore the oceans hidden under the icy crust of Europa, one of Jupiter's moons. Team members, including scientists from the Southwest Research Institute, the University of Texas and the Colorado School of Mines, also want to learn more about the cenote, including its physical dimensions, the geothermal vents that feed it and whatever life exists at various depths.

Because a tether could become tangled or snagged at great depths, DEPTHX is designed to operate autonomously — independent of human control once it is under way. In areas that are well-mapped, the AUV can operate by dead reckoning, using depth, velocity and inertial guidance sensors to estimate its position. It is also equipped with an array of 56 sonar sensors — 32 with a range of 100 meters and 24 with a range of 200 meters — that send sonar beams out in all directions. DEPTHX uses the sonar data to detect obstacles and locate itself on a map, providing precise navigation in the pitch-black deep water.

In unexplored areas, the sonar is combined with a software technology known as simultaneous localization and mapping (SLAM) to produce maps of the cenote. In previous applications, Carnegie Mellon roboticists have used a two-dimensional version of SLAM to map environments such as building hallways and mine corridors. Because DEPTHX won't just maneuver side to side, but also up and down, one of Wettergreen's Ph.D. students, Nathaniel Fairfield, has adapted SLAM for more complicated 3-D operation.

The DEPTHX researchers, including Project Scientist George Kantor and Senior Research Programmer Dominic Jonak of Carnegie Mellon, traveled five hours south of the border town of Brownsville, Texas, to reach La Pilita. From the surface, the cenote looks like an ordinary duck pond, perhaps 30 meters across. "You can swim across it in a minute and it is warm, too," Wettergreen said. "But the top is like the neck of a vase. As you get deeper, the cenote widens until it's more than 100 meters across. It is a duck pond that is 115 meters [375 feet] deep."

The overhang created by the narrowing at the top of La Pilita made the cenote a challenging environment. Researchers made certain that, in event of emergency, DEPTHX could find its way to the surface, even if it had been operating underneath the overhang. Kantor has developed vehicle models and sensor filters for highly accurate dead reckoning. Repeated tests showed that DEPTHX could estimate its position even after hours of underwater operation, determining its location within one meter using dead reckoning and within 15 centimeters using sonar localization.

Wettergreen said the use of SLAM was limited during this initial test, but Stone noted that the 3-D mapping capability was demonstrated Feb. 5 when DEPTHX made a descent to the cenote floor. DEPTHX spun slowly as it descended, helping the sonar beams cover as much of the walls as possible. The resulting map revealed a tunnel on the western wall and a bulging of the northwest wall at a depth of about 30 meters.

DEPTHX was able to maneuver close to the walls so it could extend a mechanical arm with a coring mechanism and obtain wall samples. The AUV also conducted water-sampling experiments, though the full science instrumentation package won't be tested until the second week of March, when the researchers will return to La Pilita for a science investigation and complete rehearsal of their mission to Zacatón. The researchers plan to begin their exploration of Zacatón in May.

Source: Carnegie Mellon University

Enter 'Junior': Stanford team's next-generation robot joins DARPA Challenge

2007-03-25T03:22:00.000-07:00

By David Orenstein

Mike Montemerlo of the Stanford Racing Team works on a robotic 2006 Passat, whose software must understand concepts that befuddle many humans, such as right of way. 'Junior' is Stanford's entry in DARPA's Urban Challenge on Nov. 3. Credit: Stanford University

When five autonomous vehicles, including the Stanford Racing Team's winning entry "Stanley," finished the 2005 Grand Challenge in the still Nevada desert, they passed a milestone of artificial intelligence. The robots in the 2007 Urban Challenge, however, will have to handle traffic. It is a tougher test that calls for a new generation of technology. Enter "Junior," the Stanford Racing Team's new brainchild.

"In the last Grand Challenge, it didn't really matter whether an obstacle was a rock or a bush because either way you'd just drive around it," says Sebastian Thrun, an associate professor of computer science and electrical engineering. "The current challenge is to move from just sensing the environment to understanding the environment."

That's because in the Urban Challenge, sponsored by the Defense Advanced Research Projects Agency (DARPA), the competing robots will have to accomplish missions in a simulated city environment, which includes the traffic of the other robots and traffic laws. This means that on race day, Nov. 3, the robots not only will have to avoid collisions, but also they will have to master concepts that befuddle many humans, such as right of way.

"This has a component of prediction," says Mike Montemerlo, a senior research engineer in the Stanford Artificial Intelligence Lab (SAIL). "There are other intelligent robot drivers out in the world. They are all making decisions. Predicting what they are going to do in the future is a hard problem that is important to driving. Is it my turn at the intersection? Do I have time to get across the intersection before somebody hits me?"

Racing team leaders Thrun and Montemerlo discussed Junior for the first time Feb. 17 at the annual conference of the American Association for the Advancement of Science in San Francisco. Thrun joined fellow roboticists in a panel discussion, "Robots—Our Future's Sustainable Partner." He spoke about autonomous guidance systems and machine vision. Afterward, he and Montemerlo participated in a press conference.

The racing team, based in the School of Engineering, is supported by returning industry team members Intel, MDV-Mohr Davidow Ventures, Red Bull and Volkswagen of America and joined this year by new supporters Applanix, Google and NXP Semiconductors. DARPA also has provided $1 million of funding.

Introducing Junior

Junior is a 2006 Passat wagon whose steering, throttle and brakes all have been modified by engineers at the Volkswagen of America Electronics Research Lab in Palo Alto to be completely computer-controllable. The engineers also have created custom mountings for a bevy of sophisticated sensors.

An important difference between Junior and Stanley is that Junior must be aware of fast- moving objects all around it, while Stanley only had to grapple with still objects in front of it. Junior's sensors are therefore much more sophisticated, Thrun says. They include a range-finding laser array that spins to provide a 360-degree, three-dimensional view of the surrounding environment in near real-time. The laser array is accompanied by a device with six video cameras that "see" all around the car. Junior also uses bumper-mounted lasers, radar, Global Positioning System receivers and inertial navigation hardware to collect data about where it is and what is around.

Because Junior collects much more data than Stanley did, its computational hardware must be commensurately more powerful, says Montemerlo. Using Core 2 Duo processors—each chip includes multiple processing units—Junior's "brain" is about four times more powerful than Stanley's.

But what makes Junior truly autonomous will be its software, which is the focus of about a dozen students, faculty and researchers at SAIL. Modules for tasks such as perception, mapping and planning give Junior the machine-learning ability to improve its driving and to convert raw sensor data into a cohesive understanding of its situation.

New software development began last fall. Montemerlo has been testing some of the team's software modules in simulated traffic situations since the beginning of the year. The team expects to move into full-time testing and iterative improvement by the end of March.

Junior's name is not only an implicit homage to its predecessor, but also to Stanford University's namesake, Leland Stanford Jr. Carrying this sense of history, Junior will set out to make technology history of its own and pave the way to a future where autonomous cars can make driving safer, more accessible and more efficient. Self-driving cars could give drivers newfound free time.

"You could claim that moving from pixelated perception, where the robot looks at sensor data, to understanding and predicting the environment is a Holy Grail of artificial intelligence," says Thrun.

Source: Stanford University

How to Sketch a Polynomial

2007-03-24T23:31:00.000-07:00

How to Sketch a Polynomial

I've been swapping cute math tricks with my coworker Paul Pedersen, and recently he showed me this beautiful method for sketching polynomials:

As an example let's pick a random polynomial:

y⁴ + x³ - y² + x - 1 = 0.

Plot on the x axis of a graph a point for every x power. For example for x³ plot the point (3,0). For x¹ plot the point (1,0).

Now label "+" the positive coefficient's points and "-" the negative coefficient's points. Do the same for the y axis.

Now connect the lines.

Now reflect across both axis. If you have an even exponent flip the sign.

Now draw a line between every positive and negative sign.

Now connect the lines. My freehand splines are a little sloppy, but you get the idea...

And there it is. Compare with an actual graph:

Let's try with some simpler curves where we know the answer: take x² + y² = 1 or x²

+ y² - 1 = 0:

Connect the lines:

Circle!

Just for fun, try x² - y² - 1 = 0:

Connect the lines:

Wow. Why don't they teach this as part of the high school math cannon? These kinds of simple inexplicable patterns remind me why I loved math in the first place. Can anyone figure out why it works? I've been thinking about it for a while but I don't think I have the right training and tools. I can't even come up with a rough sketch. Please let me know if you can figure it out!

Earth Hurtles Toward 6.5 Billion

2006-02-21T19:19:00.000-08:00

By Joanna Glasner | Also by this reporter
02:00 AM Feb, 21, 2006 EST

The planet's population is projected to reach 6.5 billion at 7:16 p.m. EST Saturday, according to the U.S. Census Bureau and its World Population Clock.

Thomas Malthus, the 18th-century thinker who famously predicted the human population would outrun its food supply, would be astounded.

Back in 1798, when Malthus penned his classic An Essay on the Principle of Population, barely a billion Homo sapiens roamed the planet. Today, Earth's population teeters on the brink of a new milestone: 6.5 billion living, breathing humans.

"Malthus would be astonished not only at the numbers of people, but at the real prosperity of about a fifth of them and the average prosperity of most of them," said demographer Joel Cohen, a professor of populations at Rockefeller and Columbia universities. "He wouldn't be surprised at the abject poverty of the lowest quarter or third."

The clock, which operates continuously, estimates that each second 4.1 people are born and 1.8 people die. The clock figures are estimates, subject to error, given the difficulties of maintaining an accurate global population count.

However, the key concept -- that population levels are growing, but at a slower rate than in the past few decades -- reflects the consensus view of demographers. The current growth of world population, estimated by Cohen at 1.1 percent a year, has slowed significantly from its peak of 2.1 percent annual growth between 1965 and 1970.

"That's a phenomenal decline," said Cohen, who probed the question of whether population growth is sustainable in his book, How Many People Can Earth Support?. (The short answer: It depends.)

Today, a large portion of the world's population lives in nations that are at sub-replacement fertility, meaning the average woman has fewer than two children in her lifetime. Countries in this camp include former members of the Soviet Union, Japan and most of Europe.

Demographers attribute the slowing rate of global population growth in part to more-widespread availability of birth control and to people in developed nations choosing to have fewer children. But low-birthrate countries are counterbalanced by nations like Yemen, where the average woman has seven children in her lifetime.

The highest population growth rates emanate disproportionately from the poorest regions of Africa, the Middle East and the Indian subcontinent.

U.S. population is also growing at a steady clip, augmented by high numbers of immigrants. It is projected to hit 300 million later this year. Earth's population is expected to reach 7 billion in 2012, according to the Census Bureau.

Carl Haub, a demographer with the Population Reference Bureau, sees urbanization contributing to slowing growth, because urban areas typically have lower birthrates than rural areas. In 1950, less than 30 percent of people lived in areas defined as urban. Next year, the United Nations projects that more than half the world's population will be urban.

As population growth marches forward, debate continues in academia -- as it has since Malthus' time -- over how many people the Earth can realistically support.

Certainly individual countries, such as Bangladesh or Rwanda, can be characterized as overpopulated, said Haub. But in other places, such as India, it's harder to determine the extent to which overpopulation -- rather than other social and economic factors -- contributes to poverty.

Some turn to mathematical models for estimating maximum sustainable population levels.

One metric modeled on the Census Bureau's population clock compares world population to the finite supply of arable land.

For his part, Cohen estimates that if we want to support individuals indefinitely -- allotting each person 3,500 calories per day from wheat and 247,000 gallons per year of fresh water -- the planet has room for only about 5 billion people.

But such formulas are subject to tinkering. Changes in agricultural practices, more efficient water-desalination technologies and a host of other factors can increase the number of people the planet can support. Shifts in behavior -- such as acceptance of new food sources that are cheap to produce -- can have a similar effect, noted Cohen.

"What most of this commentary neglects is the role of culture in defining wheat as food but not, let's say, cultured single-cell algae," he said.

Independent Search Engine & Directory Network Grows to 165+ Members

2006-02-21T19:16:00.000-08:00

Independent Search Engine & Directory Network continues rapid membership growth and expands international reseller network.

Las Vegas, NV (PRWeb) February 21, 2006 -- The Independent Search Engine & Directory Network (ISEDN.org) founded by ExactSeek.com in late June, 2005 continues to recruit members from around the world, surpassing a 165 members in the 8 months since its inception.

The organization whose stated purpose is to provide an affordable alternative to the pay-per-click offerings of the major search engines has not only rapidly expanded its membership but also recruited dozens of major resellers of its hybrid paid inclusion model, targeting small to medium-size online businesses that have become disillusioned with click fraud and escalating pay-per-click costs.

"We expect the ISEDN to continue its rapid growth in the coming months," said Mel Strocen, CEO of Jayde Online, Inc., ExactSeek's parent company. "We now have a membership thats truly international in scope and we plan to aggressively pursue partnerships with a broad range of related service providers in North America and abroad, including hosting, domain registrar and website submission companies. The ISEDN also plans to introduce a number of free services and applications that will be of interest to webmasters and site owners later this year."

Strocen went on to say that the ISEDN was well positioned to take advantage of the growing dissatisfaction among search engine advertisers with the pay-per-click industry leaders.

ABOUT ExactSeek & The ISEDN
ExactSeek.com is part of the Jayde Online Network which includes GoArticles.com | SiteProNews.com | SEO-News.com | Blog-Search.com and FreeWebSubmission.com. Jayde Online Inc. has been internet-focused from its inception in 1998 and primarily involved in the publication of email newsletters and the development of niche and general search engines.

The ISEDN was established in June, 2005 and is an outgrowth of ExactSeek's featured listing paid inclusion program which offers affordable, non-PPC search advertising to the online community. More information on the ISEDN, its mission statement and future plans can be found at ISEDN.org.

Contact Information:
Mel Strocen
Jayde Online, Inc.
702-361-2982

Teleport

2006-02-18T15:48:00.000-08:00

1.0 INTRODUCTION
1.1 Introduction
The concept of teleportation was originally developed during the Golden Age of 20th century science
fiction literature by writers in need of a form of instantaneous disembodied transportation technology to
support the plots of their stories. Teleportation has appeared in such SciFi literature classics as Algis
Budry’s Rogue Moon (Gold Medal Books, 1960), A. E. van Vogt’s World of Null-A (Astounding Science
Fiction, August 1945), and George Langelaan’s The Fly (Playboy Magazine, June 1957). The Playboy
Magazine short story led to a cottage industry of popular films decrying the horrors of scientific
technology that exceeded mankind’s wisdom: The Fly (1958), Return of the Fly (1959), Curse of the Fly
(1965), The Fly (a 1986 remake), and The Fly II (1989). The teleportation concept has also appeared in
episodes of popular television SciFi anthology series such as The Twilight Zone and The Outer Limits.
But the most widely recognized pop-culture awareness of the teleportation concept began with the
numerous Star Trek television and theatrical movie series of the past 39 years (beginning in 1964 with the
first TV series pilot episode, The Cage), which are now an international entertainment and product
franchise that was originally spawned by the late genius television writer-producer Gene Roddenberry.
Because of Star Trek everyone in the world is familiar with the “transporter” device, which is used to
teleport personnel and material from starship to starship or from ship to planet and vice versa at the speed
of light. People or inanimate objects would be positioned on the transporter pad and become completely
disintegrated by a beam with their atoms being patterned in a computer buffer and later converted into a
beam that is directed toward the destination, and then reintegrated back into their original form (all
without error!). “Beam me up, Scotty” is a familiar automobile bumper sticker or cry of exasperation that
were popularly adopted from the series.
However, the late Dr. Robert L. Forward (2001) stated that modern hard-core SciFi literature, with
the exception of the ongoing Star Trek franchise, has abandoned using the teleportation concept because
writers believe that it has more to do with the realms of parapsychology/paranormal (a.k.a. psychic) and
imaginative fantasy than with any realm of science. Beginning in the 1980s developments in quantum
theory and general relativity physics have succeeded in pushing the envelope in exploring the reality of
teleportation. A crescendo of scientific and popular literature appearing in the 1990s and as recently as
2003 has raised public awareness of the new technological possibilities offered by teleportation. As for
the psychic aspect of teleportation, it became known to Dr. Forward and myself, along with several
colleagues both inside and outside of government, that anomalous teleportation has been scientifically
investigated and separately documented by the Department of Defense.
It has been recognized that extending the present research in quantum teleportation and developing
alternative forms of teleportation physics would have a high payoff impact on communications and
transportation technologies in the civilian and military sectors. It is the purpose of this study to explore
the physics of teleportation and delineate its characteristics and performances, and to make
recommendations for further studies in support of Air Force Advanced Concepts programs.
1.2 The Definitions of Teleportation
Before proceeding, it is necessary to give a definition for each of the teleportation concepts I have
identified during the course of this study:
Approved for public release; distribution unlimited.
2
􀂾 Teleportation – SciFi: the disembodied transport of persons or inanimate objects across space by
advanced (futuristic) technological means (adapted from Vaidman, 2001). We will call this sf-
Teleportation, which will not be considered further in this study.
􀂾 Teleportation – psychic: the conveyance of persons or inanimate objects by psychic means. We
will call this p-Teleportation.
􀂾 Teleportation – engineering the vacuum or spacetime metric: the conveyance of persons or
inanimate objects across space by altering the properties of the spacetime vacuum, or by altering
the spacetime metric (geometry). We will call this vm-Teleportation.
􀂾 Teleportation – quantum entanglement: the disembodied transport of the quantum state of a
system and its correlations across space to another system, where system refers to any single or
collective particles of matter or energy such as baryons (protons, neutrons, etc.), leptons
(electrons, etc.), photons, atoms, ions, etc. We will call this q-Teleportation.
􀂾 Teleportation – exotic: the conveyance of persons or inanimate objects by transport through extra
space dimensions or parallel universes. We will call this e-Teleportation.
We will examine each of these in detail in the following chapters and determine whether any of the above
teleportation concepts encompass the instantaneous and or disembodied conveyance of objects through space.

continue...

Atom xda! Fav

2006-02-18T07:10:00.000-08:00

Atom xda! Fav

Specification:
Sorry unformatted!

Technical specifications | Applications

Platform
Processor
Memory
Display
Audio
Keyboard / Button / Switch
Camera
Interface
Notification

Language options available
Device-to-Device Connectivity
GSM / GPRS
Battery
Operation time
AC adapter
Regulatory
Minimum desktop requirements
Warranty
Dimensions

• Approx. 58(W) x 102(L) x 18.5(T) mm
• Weight with battery: 140g
Platform

• Microsoft Windows Mobile™ 5.0
• Integrated personal digital assistance, tri-band EDGE phone, FM radio, high-resolution camera, Bluetooth, and Wireless LAN
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Processor

• Intel PXA272 416MHz
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Memory

• Flash ROM: 128MB in total
• RAM: 64MB
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Display

• 2.7" TFT LCD display with touch panel
• 240 x 320 dots resolution
• Supports 262K colours (65,536 effective)
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Audio

• Stereo speaker
• Speaker with receiver
• Omni-directional mono microphone
• Support speaker phone operation
• Ringtone support: 64-chord MIDI, MP3, WMA, WAV
• Playback support: MIDI, MP3, WMA, WAV, AMR
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Keyboard / Button / Switch

• Power button
• Send and End phone button
• Start and O2 MediaPlus button
• Side buttons: Volume up, Volume down, Camera and Recorder
• 5-way navigation buttons: Right, Left, Up, Down and Action
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Camera

• Colour 2-mega-pixel CMOS camera
• Preview mirror for self portrait
• White LED strobe flash
• Support still image and video capture
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Interface

• Infrared IrDA 1.2 SIR (115kbps at 30cm)
• Mini-USB connector for USB 1.1 connection and power charging
• SIM card slot
• MiniSD memory card slot
• Audio jack (2.5mm ø)
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Notification

• Three-color LED (amber, green and blue)
• Notification by sound, message and vibration
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Language options available

• English
• Traditional Chinese (in separate SKU)
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Device-to-Device Connectivity

• Bluetooth
Bluetooth SIG version 1.2 compliant
Supported profiles: headset, hands-free, object push, serial port, dial-up network, advanced audio distribution (A2DP), Audio/Video Remote Control (AVRCP)
• Wireless LAN
IEEE 802.11b compliant
• Infrared
Infrared IrDA 1.2 SIR (115kbps at 30cm)
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GSM / GPRS

• Tri-band GSM/GPRS/EDGE:
GSM900
GSM1800
GSM1900
• GSM services
Speech services with EFR/FR/HR/AMR codec
Emergency call
DTMF tone generation
Call holding, waiting, forwarding, barring
SMS w/ MT/PP, MO/PP, text mode, PDU mode
• GPRS / EDGE functionality
EGPRS class 10
GPRS CS 1 to 4 coding scheme supported
EDGE MCS 1 to 9
• SIM function
3V SIM operation
SIM application toolkit
Over the air provisioning
• Internal antenna
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Battery

• Removable rechargeable Li-Ion battery, 1,500mAh
top Top
Operation time

• Standby: 150 hours
• Talk time up to 5.5 hours

Battery life may vary depending on RF conditions and actual usage
top Top
AC adapter

• AC input: 100~240 Vac, 50 / 60Hz
top Top
Regulatory

• R&TTE, EMC/EMI, Safety
• BQB certification
• USB v1.1 compliance test
top Top
Minimum desktop requirements

• Microsoft® Windows® XP (Service Pack 1 or later), Microsoft® Windows® 2000 (Service Pack 4 or later)
• Microsoft® Outlook® 98 or later required for synchronisation of email, calendar, contacts, tasks and notes (Microsoft® Outlook® 2002 recommended)
• Microsoft® Internet Explorer 4.01 or later
• Hard-disk drive with 65MB of available hard-disk space (actual requirements will vary based on the selection of features and user's current system configuration)
• Available Infrared or USB port
• One CD-ROM drive
• VGA graphics card or compatible video graphics adapter at 256 colour or higher
• Keyboard
• Microsoft® mouse or compatible input device
top Top
Warranty

• 12 months for main unit
• 6 months for supplied accessories
top Top

Specifications subject to change without notice.

O2 is a registered trademark of O2 Limited.

Microsoft, Windows Mobile, ActiveSync, Pocket Outlook, Windows NT and the Windows logo are trademarks of Microsoft Corporation in the United States and/or other countries.

Bluetooth is a registered trademark of Bluetooth SIG, Inc.

Firefox Users Quarrel Over Memory 'Leak'

2006-02-16T16:31:00.000-08:00

Firefox Users Quarrel Over Memory 'Leak'

Page 1 of 2

By Gregg Keizer, TechWeb News

Firefox's memory appetite has some users up in arms, but according to one of the open-source browser's developers, that's part of the plan.

Complaints about Firefox's memory use, particularly charges that it "leaks" memory -- that it doesn't release memory once it's done using it -- had been circulating for some time before Ben Goodger, now employed by Google, but still a lead engineer on the browser project, posted an explanation on his blog Tuesday.

"What I think many people are talking about however with Firefox 1.5 is not really a memory leak at all. It is in fact a feature," wrote Goodger.

Goodger went on to describe how Firefox 1.5's Back-Forward feature caches recently-viewed pages so that they're immediately available when users click the Back or Forward navigational buttons.

"This can be a lot of data," Goodger said. "It's a trade-off. What you get out of it is faster performance as you navigate."

Firefox, said, Goodger, will cache up to 8 previous pages, depending on how much memory the machine has. A PC with 1GB or more will cache as many as 8 pages, while a computer with just 256MB or memory will cache only 3.

Goodger's explanation didn't sit well with every Firefox user. As of Thursday morning, more than 200 comments had been left on this blog, while at Slashdot, twice as many have opined.

Most of those complaints centered on Firefox's refusal to free up memory once tabs had been closed. "I have closed tabs down to a single tab and seen no improvement in memory usage," said one example comment to Goodger's blog.

As other writers rose to Firefox's defense, tempers flared. "Users don't want to hear it's because of a 'poorly coded webpage' or 'it's your flash plugin'. They just want to use a browser that doesn't leak memory like there is no tomorrow," wrote another user.

"In general, Firefox should release memory when tabs are closed," said Mike Schroepfer, Mozilla's director of engineering, on Thursday. "There are actually several different caches, which makes this a complicated issue.

"But there are cases where they're leaks," he acknowledged.

Goodger had admitted the same in his post. "All versions of Firefox no doubt leak memory -- it is a common problem with software this complicated."

Although the issue is unresolved -- commentators continued to argue over such practices as garbage collection and memory compaction -- Schroepfer said that Mozilla's goal was to "balance memory usage and performance."

"It's hard to set an exact target" for memory usage, he continued, which is why Firefox employs techniques like that used by the Back-Forward cache, where more memory is available to the browser when the PC has more system RAM.

Users can also manually tweak the Back-Forward cache setting, said Schroepfer, to reduce the amount of memory the feature consumes.

Within Firefox, enter "about:config" (minus the quotation marks) in the address bar to access the program's configuration file. Scroll down to the entry "browser.sessionhistory.max_total_viewers" (again, minus quotes), and double-click it.

In the ensuing "Enter integer value" field, type:

"0" to disable the cache "1" through "8" to set the maximum cache as 1 through 8 previously-viewed pages "-1" to return the cache to its default

'Robot Tarzan' helps forest work

2006-02-14T16:12:00.000-08:00

'Robot Tarzan' helps forest work
By Jo Twist
BBC News Online technology reporter

Researchers with the Treebot (Image: CENS)
The Treebot is the first of its kind
A fearless mobile robot is helping scientists monitor environmental changes in forests.

The hi-tech Tarzan of the robot world, nicknamed Treebot, is the first of its kind to combine networked sensors, a webcam, and a wireless net link.

It is solar-powered and moves up and down special cables to take samples and measurements for vital analysis.

Treebot has been developed by scientists at the US Centre for Embedded Network Sensing in California.

Pinpoint precision

Programmed with open-source computer code, Linux, the Treebot is a vital addition to researchers' environmental monitoring kit, according to one of the project leaders, Professor William Kaiser.

"One of our objectives is to make use of distributed sensors to acquire information about the environment," he said.

"It is very important in the biology community to understand the interaction between the atmosphere and the forest environment."

Understanding subtle changes in light, humidity, and carbon dioxide levels give scientists crucial indications and predictions about environmental change.

But 90% of all interaction between the environment and atmospheric conditions happens high up in the forest canopy, and it is a challenge taking detailed measurements and monitoring conditions over a period of time.

We are very excited about this and feel it really is a significant breakthrough in allowing us to have a variety of fixed and mobile sensors
Professor William Kaiser, CENS
The Treebot, which in scientific terms is a node in a Networked Infomechanical System (Nims), helps by being stealthy enough to travel through the forest canopy along specially-constructed cabling, night and day.

"Using new Nims technology, provides us with a means to place instruments anywhere, moving horizontally and vertically," said Professor Kaiser.

"At the same time, we can monitor plants and even individual leaves over time using spectrographic imaging."

Eighteen months in development, the main difference between Treebot and other fixed sensors is its autonomous nature and its ability to communicate with other devices and sensors.

It has its own server and, using its wireless net link, sends sample information and other data back to scientists based at the University of California (UCLA).

They, in turn, can tell it go to specific points of interest and take samples or analyse particular areas.

The robot can also lower another sensor deep into the forest to pick up detailed data about conditions, and it talks to other fixed sensors on the ground around the forest.

"We need to understand carbon dioxide effects and light - to what extent it makes its way to lower canopy," said Professor Kaiser.

Treebot can pinpoint and analyse foliage to see if carbon dioxide has resulted from photosynthesis or from the upper atmosphere.

'Significant breakthrough'

The next stage of the project includes building a website from which schoolchildren can access images and information from Treebot, as well as help with experiments.

The Treebot in the forest canopy (Image: CENS)
It can move where it likes, night and day
The team also hope to introduce more Treebots and portable towers so that the entire Nims system can be moved, set up and launched at any location.

"We are very excited about this and feel it really is a significant breakthrough in allowing us to have a variety of fixed and mobile sensors, and it gives us a new understanding of our environment," Professor Kaiser said.

"We won't be surprised if we uncover an entirely new phenomenon with it."

The Treebot, part of wider research funded by the National Science Foundation Science and Technology Center, is set to swing into three forests by early 2004 and has already been successfully used at the Wind River Canopy Crane Research Facility in Washington state.

TextPayMe: Eliminating the IOU

2006-02-13T17:10:00.000-08:00

By Rachel Metz | Also by this reporter
02:00 AM Feb, 10, 2006 EST

When a group of people dine out together, someone always lacks cash. They forgot to go to the ATM, but they'll pay you back ASAP. Right.

Funny, though, how people rarely forget their cell phones. Philip Yuen put these two observations together and came up with TextPayMe to let people send money using text messaging.

TextPayMe seems like a logical second act for PayPal, but Yuen sees the services as complimentary.

"We just want to take over the world in all face-to-face transactions," he said.

TextPayMe doesn't have much competition in the United States so far, but PayPal may be hot on its heels. Ironically, PayPal began as a service for beaming money between PDAs. While people can now use PayPal through web-enabled cell phones, the company doesn't have an SMS function.

But a recent Craigslist job posting for a business manager for "PayPal Mobile," described as "a dynamic, young 'start-up' business unit within PayPal dedicated to bringing value-added mobile payment services to consumers and merchants," has launched rumors that such an offering may be forthcoming.

"We haven't made any announcements in the mobile payments world," the PayPal spokesperson said.

Yuen, a former Microsoft program manager, teamed up with his Lockheed systems analyst brother, Gerald, and another Microsoft employee, CJ Huang, to get TextPayMe rolling. The trio secured funding from startup seed company Y Combinator and launched the TextPayMe beta in mid-December.

TextPayMe works much like PayPal -- users create an online account and link it to a credit card or bank account. They can use SMS to send up to $500 a month. The service is now free, but the company might eventually charge fees for certain transactions, Yuen said. Beta adopters might have permanent free use, he said.

Combining text messaging and payment sounds like a pretty good idea when you consider 203 million people in the United States use cell phones, according to the CTIA, and 96 million people use PayPal.

Russ Jones, a payment industry consultant with Glenbrook Partners, said the move toward using cell phones for payment is inevitable.

He noticed, however, that TextPayMe's user agreement explicitly gives the company permission to pull users' credit report. That might scare some people away, and it's a deterrent TextPayMe doesn't need with PayPal potentially nipping at its heels. So far, about 900 people are signed up and about a third have completed transactions, according to Yuen.

Mark Toews, a technical recruiter in Seattle, said he signed up for TextPayMe about a month ago, but only used it once because his friends won't sign up. They're not willing to give up bank information to a new company. Toews hopes TextPayMe will become more popular.

"I think it's a great service," he said, "it just needs more time to mature and more people to get signed up with it before it will really blossom."

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2006-02-13T08:50:00.000-08:00

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