Magnetic minerals in 15-million-year-old Nevada rocks appear to preserve a moment when the magnetic north pole was rapidly on its way to becoming the south pole, and vice versa. Such “geomagnetic field reversals” occur every couple hundred thousand years, normally taking about 4,000 years to make the change. The Nevada rocks suggest that this particular switch happened at a remarkably fast clip.
" Magnetic Flip-Flops
Considering that ships, planes and Boy Scouts steer by it, Earth's magnetic field is less reliable than you'd think. Rocks in an ancient lava flow in Oregon suggest that for a brief erratic span about 16 million years ago magnetic north shifted as much as 6 degrees per day. After little more than a week, a compass needle would have pointed toward Mexico City.
The lava catches Earth's magnetic field in the act of reversing itself. Magnetic north heads south, and -- over about 1,000 years -- the field does a complete flip-flop. While the Oregon data is controversial, Earth scientists agree that the geological evidence as a whole -- the "paleomagnetic" record -- proves such reversals happened many times over the past billion years.
"Some reversals occurred within a few 10,000 years of each other," says Los Alamos scientist Gary Glatzmaier, "and there are other periods where no reversals occurred for tens of millions of years." How do these flip-flops happen, and why at such irregular intervals? The geological data, invaluable to show what happened, registers only a mute shrug when it comes to the deeper questions.
For that matter, why is it that instead of quietly fading away, as magnetic fields do when left to their own devices, Earth's magnetic field is still going strong after billions of years? Einstein is said to have considered it one of the most important unsolved problems in physics. With a year of computing on Pittsburgh's CRAY C90, 2,000 hours of processing, Glatzmaier and collaborator Paul Roberts of UCLA took a big step toward some answers. Their numerical model of the electromagnetic, fluid dynamical processes of Earth's interior reproduced key features of the magnetic field over more than 40,000 years of simulated time. To top it off, the computer-generated field reversed itself.
"We weren't expecting it," says Roberts, "and were delighted. This gives us confidence we've built a credible bridge between theory and the paleomagnetic data." Their surprising results, reported as a cover story in Nature (Sept. 21, 1995), provide an inner-Earth view of geomagnetic phenomena that have not been observed or anticipated by theory. Furthermore, the Glatzmaier-Roberts model offers, for the first time, a coherent explanation of magnetic field reversal.....more here ..."
Anyone carrying a compass would have seen its measurements skew by about a degree a week — a flash in geologic time. A paper describing the discovery is slated to appear in Geophysical Research Letters.
It is only the second report of such a speedy change in geomagnetic direction. The first, described in 1995 based on rocks at Steens Mountain, Ore., has never gained widespread acceptance in the paleomagnetism community. A second example could bolster the theory that reversals really can happen quickly, over the course of years or centuries instead of millennia.
Researchers aren’t sure why the geomagnetic field reverses itself. Many think it must have something to do with what creates the field in the first place — convective motions of liquid iron in the planet’s spinning outer core. As each flow cooled, it preserved the orientation of the magnetic field at the time, frozen like a tiny compass needle in the rock’s magnetic crystals.
One particular flow caught the scientists’ attention because it seemed to carry a complex magnetic history. The lava, initially started to cool and then was heated again within a year as a fresh lava flow buried it. The fresh lava remagnetized the crystals within the rock below, causing them to reorient themselves a whopping 53 degrees. At the rate the lava would have cooled, that would mean the magnetic field was changing direction at approximately 1 degree per week.
The Steens Mountain rocks have been reported to preserve a change of 6 degrees per day. That rate was so high — imagine trying to navigate when a compass changes by multiple degrees per day — that many scientists challenged the report. One line of argument held that the liquid outer core simply can’t generate magnetic field changes that rapidly. Another held that, even if the changes were happening, they wouldn’t be observable at the surface because the Earth’s internal electrical conductivity would screen the signals out.
" Steens Mountain looms on the horizon like a giant stone battleship becalmed on a vast, placid sea. Sixteen million years ago, a series of immense flows of lava gushed forth across those plains. Erosion has since claimed most of the lava flows, but the mountain remains, stretching 60 miles from north to south. Massive lava flows are common historically, but Steens Mountain contains geologic oddities so unexpected that they may profoundly alter our perception of the inner workings of our planet.
In the center of the Earth sits a dense core of nickel and iron, roughly 2,000 miles in diameter. Geophysicists, who study the Earth's interior, believe the inner core to be solid and the outer core fluid. A layer of solid rock 1,800 miles thick called the mantle surrounds the outer core. Atop the mantle rests the Earth's crust, the thin layer where mountains form, and wind and water wear them down.
Geophysicists think the fluid in the outer core circulates, with currents driven by gravitational and thermal forces interacting with the Earth's rotation. The currents are thought to travel roughly six to twenty miles per year.
This circulation in the iron-rich outer core generates the global magnetic field, the helpful force that guides not only compass needles but also, as biologists are finding, a wide variety of animals, from bacteria to seagoing turtles.
Yet the Earth's magnetic field is not as reliable as one might expect. Paleomagnetists, scientists studying the history of the magnetic field, learned 30 years ago that the polarity of the field occasionally reverses. If the field were reversed now, compasses would point south instead of north. Many scientists believed that these reversals happened slowly, in a series of short steps, taking roughly 5,500 years. But the rocks in Steens Mountain record episodes when the field was moving up to six degrees in a single day, a burst of speed over 1,000 times faster than expected. How the relatively slow-moving fluid in the outer core can generate such rapid changes is a mystery. .... more ..."
The last stable reversal occurred 780,000 years ago. Some geologists argue the Earth is overdue for a reversal and might even be entering one now, as the geomagnetic field has been getting weaker over the past 150 years or more.
But apocalyptic SyFy channel movies to the contrary, nobody should worry about waking up one morning to geomagnetic havoc. To geologists a polarity reversal is a nearly instantaneous thing that changes a global feature of the Earth — it’s really a spectacular phenomenon.
" Strictly speaking there are two types of polar reversal. One is the reversal of the planets magnetic poles and the other is a full geographical tilt of the Earth on its axis. While it is uncertain whether both would occur in tandem, some experts believe that the two are intricately linked. The last known reversal of the magnetic poles occurred around three quarters of a million years ago. Scientists point out that since there were no mass extinction's at that time the effects on existing life must have been relatively benign. Even so a magnetic polar reversal would result in a lessening of the planets magnetic field allowing harmful solar rays to penetrate to the surface of the planet.
It goes without saying that a full polar reversal, involving the geographic poles of the planet would be a much different proposition to the relatively tame magnetic reversal. A full polar reversal would be a highly catastrophic event, capable of destroying all life on Earth. It would also fall into that category of event over which we have absolutely no control whatsoever. In fact there are those who believe that full polar reversals are no more than a routine - if catastrophic event which happen according to regular cycles built-in to the Earth’s rotational mechanism.
Repeating cycle.
In many ways the ancient world understood this cycle of events far more intimately than we do today. They understood that as one day gives way to the next, there were periods when the Earth quite literally convulsed in a huge fit of turbulence that was no more than a routine element of the planet we live on. A destructive cycle that was repeated again and again.
Plato.
The ancient Greek philosopher Plato in his dialogue The Statesman adds further to the mystery saying: “At periods the universe has its present circular motion, and at other periods it revolves in the reverse direction.....Of all the changes which take place in the heavens this reversal is the greatest and most complete.” Plato warns this period of reversal is far from orderly: “There is at that time great destruction of animals in general, and only a
Unbalanced Earth.
The exact reasons behind polar reversals are not fully understood. What we do know is that they tend to happen when there is a wide divergence between the magnetic poles and their geographic equivalent, as is currently the case. Another possible reason is that the Earth is grossly unbalanced. The greatest north/south ( see here for pic) area of landmass is immediately opposite the greatest body of unbroken Ocean, stretching from pole to pole. Since land weighs more than water, this makes one side of the world very much heavier than the other. It also means that given the force of some unsettling influence - possibly an asteroid strike, the planet could quite literally topple over on its axis.
Magma tides.
Another plausible reason for a polar reversal are the effects of vast streams of magma that flow beneath the Earth’s crust. It is thought that when these undergo drastic changes to their rate of flow the resulting surge is enough to topple an already stressed planet on its axis. This could happen when melting polar ice lessens pressure at the poles leading to a surge of magma into the resulting cavity, with catastrophic results.
Few survivors.
From ancient and scientific sources we can accurately predict that the next polar reversal is solely a matter of time. When it does happen it will be a catastrophe of epic proportions that will leave few if any survivors. We must therefore hope that its onset continues to delay itself for as long as possible...more... "
Extra Lives - Why Video Games Matter by Tom Bissell (Pantheon). You're going to think very differently of your kids if all they do all day long is play xBox. After reading this book, you may wind up joining them. It turns out some our greatest leaders in the future may well be the hardcore gamers of today.
The Future Arrived Yesterday - The Rise of the Protean Corporation and What it Means for You by Michael Malone (Crown Business). The virtualization of the corporation is a reality. In other words, you may not be working from a cubicle for much longer, as wireless technology and more portable computing devices flood the marketplace. What does this mean for business? Read this book and find out, because, trust me, you don't want to be the last person standing without a chair in this very real game of musical chairs.
Macrowikinomics - Rebooting Business and the World by Don Tapscott and Anthony D. Williams (Portfolio). Even though this book is slated to come out only next month, the buzz is high for the follow-up to the best-selling Wikinomics. In Macrowikinomics, Tapscott and Williams look at the new business models and social innovations from companies that are leveraging our new digital tools, channels and platforms to make the world a more prosperous and sustainable place.
Open Leadership - How Social Technology Can Transform the Way You Lead by Charlene Li (Jossey-Bass). Li's first book, Groundswell, put hard data against the power of online social networks and social media. In her second book, she looks at what it takes for a corporation to maintain control of the brand (both internally and externally) by leveraging social technologies to open up and transform the organization from within.
The Referral Engine - Teaching Your Business to Market Itself by John Jantsch (Portfolio). Jantsch is the champion of small businesses. His first book (named after his successful blog and podcast, Duct Tape Marketing) helped companies enjoy a champagne marketing experience on a beer budget. In his latest, he helps us understand that importance of referrals and word of mouth as the primary business driver before mass media advertising and PR.
PNP sensor:- This is a sensor whose output pulls up to the positive supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between zero volts & the output of the sensor to operate. This type of sensor is very vulnerable to short circuits to earth ( zero volts), a common fault if the wiring chafes/ becomes damaged. Often it will fry under this type of fault.
NPN sensor: - This is a sensor whose output pulls down to the negative ( 0 volts) supply rail when it senses a metal target. Thus any attached load to the sensor output must be connected between the Positive supply rail & the output of the sensor to operate. This type of sensor cannot survive a short up to the positive supply rail ( a very rare occurrence!). Shorts to the negative rail (zero volts) will not damage it at all & it can tolerate this indefinitely. NPN sensors are current sinking devices and PNP sensors are current sourcing devices. You can't connect a current sourcing sensor to another current sourcing input (like TTL for example), it just won't work unless you provide a path to ground. Likewise a current sinking sensor must be connected to a current sourcing input. So you have to know something about the input circuitry of the device you're trying to read the things with.
Sensor Connection with PLC:
Other factors affecting choice :- If there is a PLC attached then :-
a ] If the input device of the PLC registers a logic high/true state when left open circuit then this type of input is best served by an NPN sensor. This will pull the PLC input low when a target is sensed.
b ] If the input device of the PLC registers a logic low/false state when left open circuit, then this type of input is best served by a PNP sensor. This will pull the PLC input high when a target is sensed.
Internal circuit of sensor
** How to find sensor is NPN or PNP : 1) Power the sensor from (usually) 24VDC.
2) Connect one end of a (say) 10kohm resistor to the sensor output.
3) Connect the other end of the resistor to either 24Vdc or 24 VDC common.
4) Actuate the sensor.
5) If switching at the sensor output happens when the resistor is connected to 24 VDC, the sensor is NPN.
6) If the sensor output switches when the resistor is connected to 24 VDC common, the sensor is PNP.
One way to find out would be to look at the load the sensor is currently driving. If it is a relay, for example, the sensor output will go to one coil terminal and the other coil terminal will go to one of the power rails. If it is the low side, your sensor is PNP; if the other side of the relay is the low side, you sensor is NPN. If it is presently not connected, you will need to connect two resistors in series across the DC power rails. 3.3k, 1/4w should do if your supply is around 24VDC. Now hook the sensor output to the point between the resistors and activate the sensor. If the sensor is PNP, the sensor output point between the resistors will go high, if it's NPN, it will go low.
** How to test NPN and PNP sensor
Things You’ll Need:
• 3 wire sensor (DC voltage)
• digital multimeter
Step1
Set the multi meter to DC voltage. This is indicated by either the letters "VDC" or "DCV" or by a symbol which looks like 3 dashed lines over a solid line. There are usually several levels within the DC voltage setting. Choose the "600" level.
Step2
The power will need to be ON to perform this test, so use caution when attempting the following. Connect two of the sensor wires to the power supply. If the color combination of the wires is blue, black, and brown, then normally, the blue wire connects to 0v and the brown wire connects to positive volts. Touch the black meter probe to the 0V wire of the sensor. Connect the red meter probe to the signal output wire of the sensor. This wire is normally black. The meter should read "0."
Step3
Force the sensor to output. If it is a photoelectric sensor, block the photoelectric beam. If it is an inductive proximity switch, introduce a small piece of metal in front of the sensor. For an ultrasonic sensor or a capacitive sensor, you can just use your hand to make the sensor output. Be sure that the sensor is detecting the object. Many sensors have a small LED that illuminates when the sensor detects it's target.
Step4
Watch the meter display as you force the sensor to output. If the readout changes to a number between 10 and 30, then the sensor output is a PNP type, also known as "sourcing." If the meter display remains at "0", then the sensor output is an NPN type, also known as "sinking."
Step5
If you believe that the sensor is NPN, there is an additional test that may be done to confirm. Remove the meter probes from the wires. Now place the red meter probe on the positive voltage sensor wire, normally a brown wire. Touch the black meter probe to the signal output wire of the sensor, normally black. When the sensor does not detect it's target, the meter display should read between 10 and 30. When the sensor senses an object, the display should drop to "0." This will confirm that the sensor has an NPN type output.
Tips & Warnings • Be sure to make solid contact between the meter probes and the wires.
• Do not handle the bare wires!
• Always use caution when working with any electrical device!
A massive scan of tumor samples from a Phoenix lab has revealed new genetic clues about an aggressive form of brain cancer, which could open the door to new treatments and explain why some patients don't respond to a common chemotherapy drug.
Scientists say the brain-cancer study, based on an analysis of genetic samples from 206 patients, is important because it suggests new targets to fight the disease. All its findings will be available to university researchers or drug companies that want to take a crack at investigating new drugs.
Cancer researchers increasingly are seeking to uncover genetic links that lead to cancer and tumor growth with the idea that smarter, targeted drugs have the potential to slow or halt the disease.
IGC's tissue bank is the core of the federal government's three-year pilot project, which now will continue a study of lung and ovarian cancers.
Fast-growing tumor
The federal government expects about 21,000 new cases of brain cancer this year. Glioblastoma is the most common form of brain cancer found in adults and typically involves fast tumor growth. People diagnosed with this type of aggressive brain cancer typically die within 14 months of diagnosis.
The study's findings include identifying three new genetic mutations tied to glioblastoma and discovering clues that may help alter existing drug treatment.
Barrow, located at St. Joseph's Hospital and Medical Center in Phoenix, treats 175 to 200 new patients each year with this type of brain cancer.
Shapiro said the life expectancy of patients with this disease was typically no more than four or five months in 1980. Now, many patients live two to three years or even longer with a standard treatment regimen that includes surgery to remove the tumor, followed by radiation and chemotherapy.
Still, doctors have been frustrated that some patients who take a common chemotherapy drug, known as Temodar (temozolomide), respond better than others. Doctors already know that the patients with an inactive MGMT gene seem to respond better to the chemotherapy drug.
The Cancer Genome Atlas team identified genetic mutations that may be linked to recurring tumors in such patients. That could give scientists more clues about how to use the drug Temodar in tandem with other drugs with greater success.
The other significant finding from the Cancer Genome Atlas team found three new genetic mutations that occur frequently with glioblastoma patients. The team also identified pathways, or clusters of genes, that are interrupted with great frequency in such patients.
Systematic approach
The National Cancer Institute and National Human Genome Research Institute launched the Cancer Genome Atlas project in 2006 in an attempt to bring a systematic genetic approach to cancer research. The goal: to yield fast-track therapies.
IGC was selected as the tissue bank from a field of 370 applicants that included many of the nation's top research universities. Scientists from the Harvard Medical School were part of the cancer genome team and were the lead authors on the glioblastoma study.
The Kano Model is a theory of product development and customer satisfaction developed by Professor Noriaki Kano in the 80’s. The concept is to classify and recognize the importance of different “types” of customer needs.
He concluded that performance on product and service attributes is not equal in the eyes of the customers and performance on certain categories attributes produces higher levels of satisfaction than others. Then it provides a simple ranking scheme which distinguishes between essential and differentiating attributes. The model is a powerful way of visualizing product characteristics and produced a rigorous methodology for mapping consumer responses into the graphic model.
The classification guidance on product characteristics can be seen as follow:
Basic attributes (Threshold) Attributes that must be exist in a product, seen as competitiveness when entry, to get awareness and successful in the market. This basic attributes will evolve but customer will neutral with the updated improvement.
Performance attributes (One dimensional) Customer satisfactions are positive correlated with additional value that they get, either in form of features, functionality, quality, price, etc. This attributes depends also on the targeted market and its positioning.
Excitement attributes (Delighters / Attractive) A contentment feeling from an additional value serves customers’ latent needs. It is not a main need that will degrade their satisfaction to below neutral if these features unavailable.
Sample of Kano Model
Then we organize this customer needs into a Critical-To-Quality (CTQ) tree.
