Nokia Lumia 900 Review: Bigger Is Not Always Better

The sequel to the best Windows Phone we've ever used is...not the best Windows Phone we've ever used

By Dan Nosowitz

Lumia 900 and iPhone The Lumia is the bigger one. Dan Nosowitz

If you want to buy a phone right now, and you're shopping based on quality rather than price, you have two choices in terms of size. You can get the iPhone, with its 3.5-inch screen, or you can choose from a handful of top-tier Android and Windows phones, all of which will have, at the bare minimum, a four-inch screen. Most of them will be bigger--4.3 inches is much more common right now, and an increasing number are even larger, including the Samsung Galaxy Nexus(4.65 in), HTC Titan (4.7 in), and the Samsung Galaxy Note (which, at 5.3 inches, is more lunchtray than phone).

The Nokia Lumia 900 is essentially a 4.3-inch version of the Lumia 800, a phone I absolutely loved in its 3.7-inch iteration (a Europe-only model). So reviewing the Lumia 900 presents an interesting question: with most other specs remaining constant, how does the experience of using a phone change when it grows to the size most phone manufacturers insist we really want?

WHAT'S NEW

The Lumia 900 is Nokia's first "flagship" Windows Phone that's available in North America (the Lumia 710, a cheapie, has been available on T-Mobile for a little while already). It's the sequel to the much-admired Lumia 800 and its changes are mostly in size (of various sorts). It's got a 4.3-inch screen, compared to the Lumia 800's 3.7-inch screen; it has 4G LTE (on AT&T), compared to the Lumia 800's 3G; it has a bigger battery and a front-facing camera.

Nokia Lumia 900 and Plaid Sheets:  Dan Nosowitz

WHAT'S GOOD

This is mostly a good phone. Windows Phone is a great operating system; it's still maturing, but it's very usable, and it's an interesting and distinctly different approach to a smartphone than iOS or Android. (More on that here.) The physical design is pretty good; it's inoffensive, at worst, and is weighty enough to feel sturdy rather than cheap and plasticky, as many Windows Phones do (especially those made by Samsung). It's also nicely thin, only a millimeter or two thicker than the iPhone. The screen, though not thrilling in its resolution, has great deep blacks, which is important when using an OS with a predominantly black interface by default.

AT&T'S 4G LTE continues to be great. This is the first phone using AT&T's LTE I've personally used, and it feels just as screamingly fast as Verizon's. It's startling how quickly things load--LTE is as fast or faster than many people's home internet connections, so apps download instantly, web pages load instantly, music and podcasts sync instantly. I was impressed with AT&T's coverage too--I used the Lumia 900 all over New York City and it never dropped out on me. And the giant 1830mAh battery will get you through a full day with normal use, which is not always the case with the current crop of LTE-capable phones.

WHAT'S BAD

Bigger is not better. Gadget makers will tell you I'm wrong--they'll point to sales numbers, saying that people have embraced big phones by the millions. But you could just as easily point to the iPhone, the most successful phone line in the country by a long shot, and say that it proves that people love smaller phones. Or you could remember that if you want a good Android or Windows phone, you are basically forced to buy a giant one. There are no longer any top-tier 3.7-inch phones. There are a rapidly decreasing number of 4-inch phones (the Motorola Droid 4, an above-average but not particularly special phone, is the only high-end 4-incher released in the past six months). If you're shopping Android or Windows, your choices are limited to big or bigger. And that's not necessarily for the better.

Most gadgets need to be of a particular size to fulfill their particular roles. A phone has to fit in your pocket or purse. An ebook reader has to display a page of text. A tablet has to provide a full web experience. You can't just stretch it out, like it's a Gumby made of silicon and glass and metal and plastic, and say it's a better device because of it. And that's exactly what the Lumia 900 is. The phone is big--not as big as a Galaxy Note, but big. It's actually wider and thicker than the Samsung Galaxy Nexus, a phone with a substantially bigger screen.

Nokia Lumia 900: Back and Sides: Clockwise from top left: right edge (buttons are a volume rocker, power/hold button, and camera shutter), top edge (with a headphone jack, microphone, and microUSB port, and SIM card slot), back, and bottom edge (speaker grille). Click here to get a bigger view of the other sides of the Lumia 900.  Dan Nosowitz

I have small hands (we all have our hurdles in life), and for me, any phone with a screen bigger than four inches is more difficult to use than it's worth. In regular use, I find myself constantly readjusting my grip--I can't hold the phone and reach all parts of the screen with my thumb. Beyond the overall size increase, I don't think the bigger screen has any real benefits in this case. The Windows Phone keyboard is excellent; I never found it awkward to type on the smaller Lumia 800, so unless you have the sausage fingers of Billy Joel (YouTube it, the dude has ten kielbasas attached to his palms), I can't imagine this being a striking improvement. The screen is also mathematically worse than the Lumia 800's. It's the same exact screen--a PenTile AMOLED screen with 800 x 480 resolution and Nokia's ClearBlack tech, which, if you don't understand that, congratulations for not having so much nonsense rattling around in your head. What matters is that it's the same number of pixels stretched across a larger canvas—the opposite of Apple's approach with its Retina Display—which means a visible downgrade in image quality.

So on the Lumia 900, the picture is worse. It creates a bigger bulge in my pocket. What's the point?

All the buttons are on the right edge of the phone, even the power/hold button, which is often found on the top edge. That's essential, because it's not really possible for anyone besides Hakeem Olajuwon to reach the top edge of the phone while holding it with one hand. But with it placed on the side, I found myself accidentally hitting the hold switch often, since it falls directly under your right thumb.

The design is also somehow not quite as enthralling as the sleek Lumia 800, even though it's nearly identical. It's the little things, which add up to a different impression when you're dealing with a very simple design presentation. Example: the 800's screen was curved, with the screen seeming to melt off into the sides of the phone like an infinity pool. The 900 has a typical flat screen, with a more definitive bezel between the screen and the sides of the phone, and a weird raise ridge around the edges. It's a very minimalist design, which worked for the 800, because it had nice little touches and felt compact and sharp. The Lumia 900 isn't bad-looking, and it's certainly well-crafted, but it's also not that interesting.

The camera remains not very good. I was surprised at this with the Lumia 800, and I'm still surprised--the Nokia N8, probably the worst phone I've ever reviewed, had a stellar camera, and Nokia is well-known for their phone cameras. The Lumia 900's is average at best--I love that it has a dedicated shutter button, and shutter speed is pretty good, but I wasn't impressed with image quality. The Lumia often came up with very dark shots, and color reproduction was sometimes off. And in lower-light situations, photos were extremely noisy.

Nokia Lumia 900 vs. iPhone 4S: Near and Far: A couple more comparisons: the Lumia 900 took the two photos on the left, while the iPhone 4S took the two on the right. You can see that the Lumia works okay in full sunlight, but still has troubles with shadows and differences in light (look at the slanted shadow on the building to the right of the Empire State Building, or how the daffodils blend into the brighter sidewalk in the upper left corner). Click here to get a bigger view.  Dan Nosowitz

The hardware handles the Windows Phone operating system pretty nicely; it's responsive and fast, for the most part. The way it scrolls still feels not quite as organic as iOS--there's a little lag, and sometime the "flick" motion results not in a super-fast scroll, like you wanted, but a slow trudge downwards through a list. Otherwise the software has the same ups and downs (and it's mostly ups, to be clear) as any other Windows Phone, plus a few Nokia-specific apps (Nokia Drive, a free turn-by-turn GPS app; yet another mapping app, Nokia Maps; and a little Nokia-curated section of the App Marketplace).

THE PRICE

It's available on AT&T for $100 with a two-year contract. That's half the price of other 16GB phones like the iPhone, and probably a good way for Microsoft and Nokia to worm their way back into the public consciousness. It's a good deal, though given the fact that you're signing a two-year contract that'll cost you several thousand dollars in voice and data plans, it doesn't really make sense to care much about an extra $100 up front.

Nokia Lumia 900 Email App:  Dan Nosowitz

THE VERDICT

The Lumia 900 is a pretty good phone--I still think the iPhone is a smarter buy on AT&T, due to its gigantic and thriving App Store, sleeker hardware, and more polished software, but the Lumia 900 is very nice. And yet I don't think it's as good a phone as the Lumia 800 (though the LTE speeds are delightful). It's a weird feeling to be disappointed while still recommending a product, but that's how it goes--the 900 doesn't live up to my expectations, but it's still the best Windows Phone in America. Still, it feels a little dull, where the Lumia 800 felt fresh and new and stylish. But most of all, I'm turned off by the size. Dear phone manufacturers: I know it's an easy sell to say that your phone is bigger and therefore better--but for some of us, it's simply not the case.

First Bedside Genetic Test Could Prevent Heart Complications

A genotyping test from a Canadian biotech company enables timely personalized drug treatment.

• WEDNESDAY,

Audio »

For some cardiac patients, recovery from a common heart procedure can be complicated by a single gene responsible for drug processing. The risk could be lowered with the first bedside genetic test of its kind. The test shows promise for quickly and easily identifying patients who need a different medication.

Quick test: This shoebox-sized device from Spartan Bioscience supports the first bedside genetic test.
Spartan Bioscience

After a patient receives a heart stent—a small scaffold that props open an artery—his or her doctor will prescribe a blood thinner to prevent platelets from building up inside the device. However, for some 70 percent of patients with Asian ancestry and 30 percent of patients with African or European ancestry, a single genetic variant will prevent one of the most commonly prescribed blood thinners from working. Alternatives exist, but they are more expensive, so hospitals could use an easy way to identify who does and does not need the more expensive drug.

Canada's Spartan Bioscience has developed a near "plug-and-play" genotyping device that allows nurses and others to quickly screen patients at the bedside, perhaps while they are undergoing the stent placement procedure. Users take a DNA sample from a patient's cheek with a specialized swab, add the sample to a disposable tube, and then place the tube and sample in a proprietary shoebox-sized machine and hit a button. Shortly thereafter, the user receives a printout of the patient's genetic status for the drug-processing variant. The whole procedure takes about an hour. Most clinicians currently have to wait several days for similar information to come from off-site genetics testing companies.

"For six years we've been plugging away at this, and we finally broke through about a year and a half ago," says Spartan Bioscience founder Paul Lem. He says the simple test came to life with innovations at every step—from the special swab that collects the right amount of DNA, to the chemicals in the disposable reaction tube, to the software that automates the DNA reading—and a team with diverse backgrounds including his in medicine and molecular biology and others' in optical hardware.

Lem has kept an eye on other companies trying to create a bedside genetic test, some going after the same variant, and calculates that over $1 billion in capital has been spent over the last five years in this area.

The University of Ottawa Heart Instituteresearchers conducted a proof-of-principle trial for the device and found that the bedside test is effective at quickly identifying carriers of the drug-processing variant and can be performed by nurses with minimal training. The findings were published in The Lancetlast week.

"The stakes are pretty high" for the risks associated with the variant in the test, says Euan Ashley, a cardiologist with Stanford's Center for Inherited Cardiovascular Disease. Patients who receive a stent implant after a heart attack or as a preventive measure are at risk for serious adverse events if their bodies cannot process a commonly prescribed anti-platelet drug into its active form. "There's a startling number of people who carry the variant, which leaves them at risk," says Ashley. "Being able to get an answer within an hour or two—when you are thinking of a patient's heart—is a pretty compelling case for [testing for it]."

Ashley notes that there may come a day when a patient's entire genome could be sequenced at the bedside, which may encourage a different model for bedside genotyping. "But we aren't there yet," he says. Genome-sequencing technologies capable of clinical diagnoses currently require days to identify all the base pairs in a human genome. "Sometimes, speed is of the essence," says Ashley. The technology is a good example of a real opportunity to do actual personalized medicine in real time, he says.
Spartan Bioscience got regulatory approval for the test in the European Union in December 2010, and hopes to have approval in the United States by the end of this year. The company gives away the devices for free, and charges $200 per test.
Spartan Bioscience is also looking for other applications for the technology, says Lem, from infectious diseases like MRSA, an antibiotic resistant strain of staph infections, to pharmacogenetic markers such as a hereditary resistance to standard hepatitis C treatment.
"Doctors from around the world have been pinging us with all the applications they've been saving up to the day when a bedside DNA test is finally available," says Lem.

Quantum Computer Built Inside a Diamond

Scientists have built a quantum computer in a diamond, the first of its kind. The chip in the image measures 3mm x 3mm, while the diamond in the center is 1mm x 1mm. (Credit: Courtesy of Delft University of Technology and UC Santa Barbara)

Science Daily— Diamonds are forever -- or, at least, the effects of this diamond on quantum computing may be. A team that includes scientists from USC has built a quantum computer in a diamond, the first of its kind to include protection against "decoherence" -- noise that prevents the computer from functioning properly.

The demonstration shows the viability of solid-state quantum computers, which -- unlike earlier gas- and liquid-state systems -- may represent the future of quantum computing because they can be easily scaled up in size. Current quantum computers are typically very small and -- though impressive -- cannot yet compete with the speed of larger, traditional computers.

The multinational team included USC Professor Daniel Lidar and USC postdoctoral researcher Zhihui Wang, as well as researchers from the Delft University of Technology in the Netherlands, Iowa State University and the University of California, Santa Barbara. Their findings will be published on April 5 in Nature.

The team's diamond quantum computer system featured two quantum bits (called "qubits"), made of subatomic particles.

As opposed to traditional computer bits, which can encode distinctly either a one or a zero, qubits can encode a one and a zero at the same time. This property, called superposition, along with the ability of quantum states to "tunnel" through energy barriers, will some day allow quantum computers to perform optimization calculations much faster than traditional computers.

Like all diamonds, the diamond used by the researchers has impurities -- things other than carbon. The more impurities in a diamond, the less attractive it is as a piece of jewelry, because it makes the crystal appear cloudy.

The team, however, utilized the impurities themselves.

A rogue nitrogen nucleus became the first qubit. In a second flaw sat an electron, which became the second qubit. (Though put more accurately, the "spin" of each of these subatomic particles was used as the qubit.)

Electrons are smaller than nuclei and perform computations much more quickly, but also fall victim more quickly to "decoherence." A qubit based on a nucleus, which is large, is much more stable but slower.

"A nucleus has a long decoherence time -- in the milliseconds. You can think of it as very sluggish," said Lidar, who holds a joint appointment with the USC Viterbi School of Engineering and the USC Dornsife College of Letters, Arts and Sciences.

Though solid-state computing systems have existed before, this was the first to incorporate decoherence protection -- using microwave pulses to continually switch the direction of the electron spin rotation.

"It's a little like time travel," Lidar said, because switching the direction of rotation time-reverses the inconsistencies in motion as the qubits move back to their original position.

The team was able to demonstrate that their diamond-encased system does indeed operate in a quantum fashion by seeing how closely it matched "Grover's algorithm."

The algorithm is not new -- Lov Grover of Bell Labs invented it in 1996 -- but it shows the promise of quantum computing.

The test is a search of an unsorted database, akin to being told to search for a name in a phone book when you've only been given the phone number.

Sometimes you'd miraculously find it on the first try, other times you might have to search through the entire book to find it. If you did the search countless times, on average, you'd find the name you were looking for after searching through half of the phone book.

Mathematically, this can be expressed by saying you'd find the correct choice in X/2 tries -- if X is the number of total choices you have to search through. So, with four choices total, you'll find the correct one after two tries on average.

A quantum computer, using the properties of superposition, can find the correct choice much more quickly. The mathematics behind it are complicated, but in practical terms, a quantum computer searching through an unsorted list of four choices will find the correct choice on the first try, every time.

Though not perfect, the new computer picked the correct choice on the first try about 95 percent of the time -- enough to demonstrate that it operates in a quantum fashion.

நுரையீரலைப் பாதுகாப்போம்..

 
 
ஒரு நிமிடத்திற்கு சராசரியாக 18 முதல் 20 சுவாசம் என சீராக வைப்பது மூளையில் உள்ள முகுளத்தின் வேலை.

மொத்த நுரையீரலின் கொள்ளளவு சராசரியாக 6 லிட்டர் தான். மிகவும் இழுத்து மூச்சுவிடும் போது காற்றின் அளவு 5 லிட்டர்தான். எப்போதும் நுரையீரலுக்குள்ளே இருந்துகெண்டிருக்கும் காற்றின் அளவு 1 லிட்டர். பொதுவாக நுரையீரலில் சுரக்கும் சளி போன்ற நீர்மம் சில தூசிகளை அகற்றி வெளியேற்றும். 

இதுபோல் மூச்சுக் குழாய்களில் மேல் சிலியா என்ற பொருள் இருக்கும். இதுவும் மிக நுண்ணிய தூசியைக் கூட அகற்றிவிடும். இது மூச்சுக் குழாய்களில் வரும் தூசியை மேல்நோக்கி திருப்பி அனுப்பிவிடும்.

நாம் அறியாமலே சில சமயங்களினித உடலின் செயல்பாடுகளுக்கு ஒவ்வொரு உறுப்பும் இன்றியமையாததாகும். இதில் உடலுக்கு மெயின் சுவிட்சு போல் செயல்பட்டு, காற்றை உள்வாங்கி, வெளிவிட்டு உடலுக்கு உயிர் சக்தியைத் தரும் மோட்டார்தான் நுரையீரல்.

வாயுப் பரிமாற்றம் (Exchange of gas) நுரையீரலின் முக்கிய பணியாகும். மேலும் சில முக்கிய வேதிப் பொருட்களை உருவாக்குவதற்கும், வேறு சில வேதிப் பொருட்களை செயலிழக்கச் செய்வதும் இதன் மற்ற பணிகளாகும். நுரையீரலானது உடலியக்கத்திற்கு ஆற்றல் தரும் ஆக்ஸிஜனை உள் எடுத்துக் கொள்வதற்கும் கார்பன்-டை- ஆக்ஸைடை வெளியேற்றுவதற்கும் முக்கிய உறுப்பாக செயல்படுகிறது.

ஒரு நாளைக்கு சராசரியாக ஒரு மனிதன் 22,000 முறை மூச்சு விடுகி றான். கிட்டத்தட்ட 255 கன மீட்டர் (9000 கன அடி) காற்றை உள்ளிழுத்து வெளிவிடுகிறான்.

நுரையீரலின் செயல்பாடு.
மூக்கின் வழியாக நாம் உள்ளிழுக்கும் காற்று மூச்சுக் குழாய் (Trachea) வழியாக நுரையீரலுக்கு செல்கிறது. மூச்சுக் குழாய் மார்புப் பகுதியில் இரண்டாக பிரிந்து வலது, இடது நுரையீரலுக்குச் செல்கிறது. நுரையிரலுக்குள் நுழைந்தவுடன் மூச்சுக்குழல் ஒவ்வொன்றிலிருந்தும் கிளைகள் பிரியும். பின்னர் அவற்றிலிருந்து இன்னும் சிறு கிளைகள் என நிறைய பிரிவுகள் ஒரு மரத்தின் பெரிய கிளையிலிருந்து பரந்து பிரிந்து சின்னச்சின்ன தளிர்கள் வருவதுபோல் பிரிகின்றன.


அதனாலேயே இதனை மூச்சுமரம் (Respiratory tree) என்று அழைக்கின் றோம். முதல் நிலை மூச்சுக் குழல் (Primary bronchi), இரண்டாம் நிலை மூச்சுக் குழல் (secondry bronchi), மூன்றாம் நிலை மூச்சுக் குறுங்குழல் (bronchiole) என்று படிப்படியாகப் பிரிந்து கடைசியாக சின்னச் சின்ன பலூன்கள் மாதிரி தோன்றும் குட்டிக்குட்டி அறைகளுக்குள் இந்த குழல்கள் நீட்டிக் கொண்டிருக்கும். இவற்றை காற்று நுண்ணறைகள் (Alveoli) என்று அழைக்கிறோம்.

நாம் இழுக்கும் மூச்சுக்காற்று மூச்சு மரம் வழியாக காற்று நுண்ணறை களுக்குள் வந்துவிடும். உடலில் பல பாகங்களிலும் இருந்து பயன்படுத் தப்பட்ட ரத்தம் இதயத்தின் வலது வெண்டிரிக்கலை அடையும். அங்கிருந்து நுரையீரல், தமணி மூலம் நுரையீரலுக்கு கொண்டு செல்லப்படுகிறது.

நுரையீரல் தமணியும், வலது கிளை, இடது கிளை, என்று இரண்டாகப் பிரிந்து இரண்டு நுரையீரலுக்கும் செல்கிறது. இதுவும் பலமுறை கிளைகளாகப் பிரியும். இப்படிப் பிரியும்போது காற்று நுண்ணறைகளின் பக்கத்தில் தமணிகளின் மிக மிகச் சிறிய கிளைகள் அமைந்திருக்கும். இந்தச் சின்ன தமணிக் கிளைகள்தான் தந்துகிகள் (Capillaries) எனப்படுகிறது.

காற்று நுண்ணறை பக்கத்திலேயே தந்துகிகள் இரண்டின் சுவர்களும் மிக மிக நுண்ணியவையாக இருக்கும். அடுத்தடுத்து நுண்ணறைக்குள் காற்று நிறைந்திருக்கும் தந்துகிக்குள் ரத்தம் நிறைந்திருக்கும். வெளியிலிருந்து மூச்சுக்குழல் மூலம் உள்ளிழுக்கப்பட்ட காற்றில் நிறைய ஆக்ஸிஜன் இருக்கும். எனவே, நுண்ணறைக்குள்ளும் அதே அளவு ஆக்ஸிஜன் இருக்கும். தந்துகியில் உள்ள ரத்தத்தின் ஆக்ஸிஜன் அளவு குறைவு. கார்பன்டை ஆக்ஸைடின் அளவு அதிகம். உடலுக்கு வேண்டாத உடலிலிருந்து வெளியேற்றப்பட வேண்டிய மற்ற சில பொருட்களும் தந்துகியில் உண்டு.

இந்த நிலையில் நுண்ணறை – தந்துகி சுவர்களின் வழியாக ஒரு பரிமாற் றம் நடக்கிறது. நுண்ணறையில் அடர்த்தியாக இருக்கும் ஆக்ஸிஜன் தந்துகிக்குள் பாயும். தந்துகியில் அடர்த்தியாக இருக்கும் கார்பன்டை ஆக்ஸைடு நுண்ணறைக்குள் பாயும். இதுதான் வாயுப் பரிமாற்றம் (Exchange & gases). இதைத்தான் ரத்த சுத்திகரிப்பு என்று அழைக்கிறோம்.

ஆக்ஸிஜன் ஊட்டப்பட்ட ரத்தம் நுரையீரலிலிருந்து சிரைகள் மூலமாக இதயத்தின் இடது வெண்டிரிக்கிளுக்குள் எடுத்துச் செல்லப் படுகிறது. அங்கிருந்து மீண்டும் உடலின் பல பாகங்களுக்கு தமனிகள் மூலம் இந்த சுத்த ரத்தம் எடுத்துச் செல்லப்படுகிறது.

நுரையீரலைச் சுற்றி இரண்டு உறைகள் உள்ளன. 1. வெளிப்படலம் (Outer pleura) 2. உள்படலம் (Inner pleura) இந்த இரண்டு படலங்களுக்கும் இடையே ஒரு இடம் உண்டு. அதற்கு ஃப்ளூரல் இடம் என்று பெயர். இதனுள் மிகச் சிறிய அளவு ஃப்ளூரல் திரவம் இருக்கும். இந்தத் திரவம்தான் சுவாசத்தின் போது நுரையீரல்களின் அசைவினால் உராய்வு ஏற்படாமல் தடுக்கிறது. சுவாசத்தைக் கட்டுப்படுத்தி சீராக வைப்பதே முகுளப்பகுதி. அதால் அதை விழுங்கிவிடுவோம். உடல் நலம் சரியில்லாமல் போனால் மட்டுமே அவை சளியாக மூக்கின் வழியாக வெளியேறும். இதையும் தாண்டி ஏதேனும் தூசு உள்ளே நுழைந்தால் இருமல், தும்மல் முதலியவற்றால் வெளியேற்றப் பட்டுவிடும். நுரையீரலின் பணிகள் காற்றில் உள்ள ஆக்ஸிஜனை (ஆக்ஸிஜன்= உயிர்வளி, பிராணவாயு) இரத்தத்தில் சேர்ப்பதும், இரத்ததில் உள்ள கார்பன்-டை ஆக்ஸைடை (கரியமில வாயு) பிரித்து உடலிலிருந்து வெளியேற்றுவதும் நுரையீரலின் முக்கிய பணியாகும்.

இதயத்திற்கு இரு புறமும் பாதுகாப்பாக இருந்து இதயத்தை அதிர்வுகளிலிருந்து காப்பாற்றுகிறது. சில முக்கிய வேதிப் பொருட்களை உற்பத்தி செய்வது, வேறு சில வேதிப் பொருட்களை செயலிழக்கச் செய்வது போன்ற உடலுக்கு உயிர்தரும் வேலைகளை நுரையீரல் செய்து வருகிறது. நுரையீரல் பாதிப்பு உலகில் இலச்சக்கணக்கான மக்கள் ஒவ்வொரு வருடமும் நுரையீரல் சம்பந்தப்பட்ட நோயின் தாக்குதலுக்கு ஆளாகின்றனர். காற்று மாசுபாடு காற்று மாசுபாடு அதாவது சிலிகா, ஆஸ்பெட்டாஸ், கந்தகம், போன்றவற்றைப் பயன்படுத்தும் தொழிற் சாலைகளில் பணி புரிபவர்களின் நுரையீரல்கள் அதிகம் பாதிக்கப்படுவதாக தகவல்கள் தெரிவிக்கின்றன. புகை பிடிப்பது உடல் நலத்துக்கு கேடு என்ற செய்தி அனைவரும் அறிந்ததே


புகைபிடிப்பது:
புகை பிடிக்கும்போது நிறைய கரித் துகள்கள் (Carbon particles) நுரையீரலுக்குள் சென்று அங்கேயே படிந்து விடுகின்றன. இதனால் ஆக்ஸிஜன்- கார்பன்டை ஆக்ஸைடு பரிமாற்றம் தடைபடுகிறது. மற்றும் சிகரெட், சுருட்டு, இவற்றிலுள்ள நிகோடின் என்ற வேதிப்பொருள் ரத்தத்தில் உள்ள ஆக்ஸிஜன் அளவைக் குறைத்து கனிமப் பொருள்களின் அளவுகளில் மாற்றத்தை ஏற்படுத்தி, ரத்தக் குழாய்களின் அடைப்பை உண்டாக்குகிறது. புகைப் பழக்கத்தால் மூச்சுக்குழல் அலர்ஜி, காற்றறைகளின் சுவர்கள் சிதைந்துபோதல், எம்ஃபசிமா, நுரையீரல் புற்றுநோய் ஆகியவை உண்டாகின்றன. புகைப் பிடிப்பவர்களுக்கு மட்டுமல்ல, பக்கத்தில் இருப்பவர்களுக்கும் (Passive smoking) இதே தீங்குகள் நேரிடும்.


நுரையீரல் பாதிப்பின் அறிகுறிகள் இருமல் மூச்சு வாங்குதல் மூச்சு இழுப்பு நெஞ்சுவலிஹீமாப்டிஸிஸ் (இருமும்போது ரத்தம் வெளியேறுதல்) நுரையீரலைத் தாக்கும் சில முக்கிய நோய்கள் மூச்சுக்குழாய் அலர்ஜி(Bronchitis), நுரையீரல் அலர்ஜி (Pneumonia), காற்றறைகள் சிதைந்து போதல்(Emphysema), மூச்சுக்குழல்கள் சுருங்கிக் கொள்ளுதல் (Asthma).

நுரையீரலை பாதுகாக்க சில எளிய வழிகள்

தூசு நிறைந்த பகுதிகளுக்கு செல்லும் போது மூக்கில் துணியைக் கட்டிக்கொள்வது (Mask) நல்லது. பிராணயாமம், நாடி சுத்தி, ஆழ்ந்த மூச்சுப் பயிற்சி போன்றவற்றை தினமும் கடைப்பிடிப்பது. புகைப் பிடிப்பதை தவிர்ப்பது உடலில் நோய் எதிர்ப்பு சக்தியை அதிகரிக்கும் உணவு வகைகளை சாப்பிடுவது இன்றைய சூழ்நிலையில் மாசடைந்த காற்று அதிகம் இருப்பதால் நுரையீரல் சம்பந்தப்பட்ட நோய்களின் தாக்குதலும் அதிகம் இருக்கிறது.

இதனால் எதிர்காலத்தில் மினரல் வாட்டர் பாட்டிலைப் போல் ஆக்ஸிஜனை பாக்கெட்டுகளில் வாங்க வேண்டிய நிலை ஏற்படலாம். இந்நிலை மாற சுற்றுப்புறத்தை தூய்மையாகவும், பசுமை நிறைந்த பகுதிகளாகவும் மாற்றினாலே போதும்.. ஆரோக்கிய வாழ்வைப் பெற்றிட முடியும்.

Exploring the antidepressant effects of testosterone

Testosterone, the primary male sex hormone, appears to have antidepressant properties, but the exact mechanisms underlying its effects have remained unclear. Nicole Carrier and Mohamed Kabbaj, scientists at Florida State University, are actively working to elucidate these mechanisms.

They've discovered that a specific pathway in the hippocampus, a brain region involved in memory formation and regulation of stress responses, plays a major role in mediating testosterone's effects, according to their new report in Biological Psychiatry.

Compared to men, women are twice as likely to suffer from an affective disorder like depression. Men with hypogonadism, a condition where the body produces no or low testosterone, also suffer increased levels of depression and anxiety. Testosterone replacement therapy has been shown to effectively improve mood.

Although it may seem that much is already known, it is of vital importance to fully characterize how and where these effects are occurring so that scientists can better target the development of future antidepressant therapies.

To advance this goal, the scientists performed multiple experiments in neutered adult male rats. The rats developed depressive-like behaviors that were reversed with testosterone replacement.

They also "identified a molecular pathway called MAPK/ERK2 (mitogen activated protein kinase/ extracellular regulated kinase 2) in the hippocampus that plays a major role in mediating the protective effects of testosterone," said Kabbaj.

This suggests that the proper functioning of ERK2 is necessary before the antidepressant effects of testosterone can occur. It also suggests that this pathway may be a promising target for antidepressant therapies.

Kabbaj added, "Interestingly, the beneficial effects of testosterone were not associated with changes in neurogenesis (generation of new neurons) in the hippocampus as it is the case with other classical antidepressants like imipramine (Tofranil) and fluoxetine (Prozac)."

In results published elsewhere by the same group, testosterone has shown beneficial effects only in male rats, not in female rats.

More information: The article is "Extracellular Signal-Regulated Kinase 2 Signaling in the Hippocampal Dentate Gyrus Mediates the Antidepressant Effects of Testosterone" by Nicole Carrier and Mohamed Kabbaj (doi: 10.1016/j.biopsych.2011.11.028). The article appears in Biological Psychiatry, Volume 71, Issue 7 (April 1, 2012)

Provided by Elsevier

"Exploring the antidepressant effects of testosterone." April 2nd, 2012. http://medicalxpress.com/news/2012-04-exploring-antidepressant-effects-testosterone.html

Posted by
Robert Karl Stonjek

Photos by Rajkumar II

Brain imaging: fMRI 2.0

Functional magnetic resonance imaging is growing from showy adolescence into a workhorse of brain imaging.

Kerri Smith

 

PADDY MILLS

The blobs appeared 20 years ago. Two teams, one led by Seiji Ogawa at Bell Laboratories in Murray Hill, New Jersey, the other by Kenneth Kwong at Massachusetts General Hospital in Charlestown, slid a handful of volunteers into giant magnets. With their heads held still, the volunteers watched flashing lights or tensed their hands, while the research teams built the data flowing from the machines into grainy images showing parts of the brain illuminated as multicoloured blobs.

The results showed that a technique called functional magnetic resonance imaging (fMRI) could use blood as a proxy for measuring the activity of neurons — without the injection of a signal-boosting compound^{1, 2}. It was the first demonstration of fMRI as it is commonly used today, and came just months after the technique debuted — using a contrast agent — in humans³. Sensitive to the distinctive magnetic properties of blood that is rich in oxygen, the method shows oxygenated blood flowing to active brain regions. Unlike scanning techniques such as electroencephalography (EEG), which detects electrical activity at the skull's surface, fMRI produces measurements from deep inside the brain. It is also non-invasive, which makes it safer and more comfortable than positron emission tomography (PET), in which radioactive compounds are injected and traced as they flow around the body.

fMRI has been applied to almost every aspect of brain science since. It has shown that the brain is highly compartmentalized, with specific regions responsible for tasks such as perceiving faces⁴ and weighing up moral responsibility⁵; that the resting brain is in fact humming with activity⁶; and that it may be possible to communicate with patients in a vegetative state by monitoring their brain activity⁷. In 2010, neuroscientists used fMRI in more than 1,500 published articles (see 'The rise of fMRI').

But researchers readily admit that the technique has flaws. It doesn't measure neuronal activity directly and it is blind to details such as how many neurons are firing, or whether firing in one region amplifies or dampens activity in neighbouring areas. The signal — a boost in blood flow in response to a stimulus — can be difficult to extract from the 'noise' of routine changes in blood flow, and the statistical techniques involved are easy to misunderstand and misuse. “I'm surprised that fMRI has kept going for 20 years,” says Karl Friston, scientific director of University College London's neuroimaging centre. Friston says he thought all the interesting questions would have been “cherry-picked within the first two or three years”.

But fMRI has kept going, in part because no other technique has bettered its ability to see what the human brain is doing. It has turned psychology “into a biological science”, says Richard Frackowiak, who works with Friston. Now, scientists are intent on finding ways around some of the limitations and pushing the technique into the next 20 years. Nature takes a look at four futures for fMRI.

 

Direct measures

Perhaps the biggest conundrum in fMRI is what, exactly, the technique is measuring. Researchers know that it measures the oxygen carried in blood by haemoglobin, and they assume that a stronger signal reflects a greater demand for oxygenated blood when neurons become electrically active in response to a task. But several papers have called this assumption into question, suggesting that blood oxygen levels could rise in preparation for neuronal activity as well as during it⁸; or, worse, that they could be undulating for reasons other than neuronal activity⁹.

Most researchers in the fMRI community are comfortable enough with the proxy to carry on doing experiments, even if not all the details have been ironed out. “We have a pretty good handle that it's measuring something that neurons are doing that's relevant to mental function,” says Russell Poldrack, director of the Imaging Research Center at the University of Texas at Austin. But some teams want to do better, by getting a more direct measure of neuronal activity. “The thing that we're most interested in is not where blood flow is but where the brain is electrically active,” says John George, an MRI physicist at the Los Alamos National Laboratory in New Mexico. The only ways in which electrical activity can be measured directly, however, are by placing electrodes into the brain, or by picking up electrical signals from outside the skull, a method that lacks the depth and spatial resolution of fMRI.

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Kerri Smith takes a look at what the future holds for fMRI

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One solution might be to use a type of MRI that can measure the magnetic field of each neuron as it conducts electrical signals. But these perturbations are an order of magnitude smaller than those produced by changes in blood oxygen level. George's team is therefore developing a technique that uses ultrasensitive magnetometers called SQUIDs (superconducting quantum interference devices) to pick up such perturbations¹⁰. “We detect currents close to the levels we anticipate neurons would produce,” he says. But the obstacles are huge. “It's very much like the early days of fMRI,” says George. The next steps are to make the detection methods faster — neural signals are much quicker than those from blood — and to win over sceptics with a clear demonstration of the measurements in a tissue sample or an animal. “There are hints that signals are there, but most people don't believe it,” says George. “Once they believe you can do it, they'll show you how to do it better.”

More than a pretty picture

The multicoloured splodges that correspond to active brain areas have helped fMRI to earn the disparaging nickname 'blobology', reflecting some neuroscientists' frustration with the limited information that a blob conveys. It can show that a language task, for example, correlates with activity in the left hemisphere's frontal lobe, but not whether the activity is actually the result of language processing — or simply of paying attention to a screen. “You can't just infer causality from looking at where a task is happening,” says Peter Bandettini, who heads the functional imaging methods section at the US National Institute of Mental Health's Laboratory of Brain and Cognition in Bethesda, Maryland. That is why the use of fMRI to show that a region is correlated with a task, “is starting to slow down”, he says. “No one's getting tenure based on that any more.”

Neuroscientists are now seeking ways to build a more detailed model of the brain's organization, networks and function, so that they can interpret the patterns of activation with more confidence. A good model of brain networks might provide more detail about what happens when a person looks at a familiar face, for example, including which regions are involved in visual processing, memories and emotion; the order in which the regions respond; and how important each area is to the overall task. “The major shift is towards networks,” says Stephen Smith, associate director of the Oxford University Centre for Functional MRI of the Brain, UK, whose team is working on such models. “What we're trying to get is the true underlying connectivity,” he says, “rather than make a superficial comment about everything being connected to everything because they're all correlated.”

A sophisticated picture of brain networks is also the goal of the Human Connectome Project¹¹, a 5-year, US$40-million effort funded by the US National Institutes of Health (NIH) in Bethesda, Maryland, that got under way in 2010. The project aims to map the human brain's wiring using a variety of techniques, including fMRI. Such a 'reference' connectome could help in interpreting individuals' fMRI scans and could reveal how variations in connectomes affect behaviour or contribute to disease.

Other researchers are using sophisticated statistical techniques to pick out detailed patterns from fMRI scans. One, called multivariate analysis, charts the behaviour of many units — or voxels — of brain activity in parallel, rather than averaging them together into a blob. Blobs can identify large, active brain areas, but might miss clumps of inactive neurons within it or small islands of active neurons in quiet areas. “The more you look, the more you get meaningful information,” says Bandettini. “What previously was noise is now suddenly signal.” These techniques are even allowing researchers to work out what stimuli are present just by looking at brain activity patterns. Last year, Jack Gallant from the University of California, Berkeley, recorded the fMRI activity of three members of his lab as they watched hours of film clips. The team then developed a computational model that used fMRI scans to reconstruct a movie approximating what the people had been watching — a person wearing blue, for example, or a red bird¹².

Dampening the noise

fMRI tends to generate small signals and a lot of noise. “You need quite a lot of neurons firing in synchrony with each other to see a change in blood oxygenation,” says Smith. The noise means that many changes — a small group of neurons firing together, or subtle or quick variations in oxygenated blood flow — might not be picked up. The low signal-to-noise ratio forces fMRI researchers to use statistical approaches to pick out what is significant in their scans — and that means that there are numerous ways to interpret a data set. “If you try them all, you're going to find something,” says Poldrack.

Some groups are managing to boost the signal by using stronger magnets. In an MRI machine, a high magnetic field aligns the spins of the protons in hydrogen atoms; then radio waves knock the spins out of alignment. As the spins gradually realign, they send out a signal — or resonate — and those in areas of oxygenated blood resonate at a different frequency from those in deoxygenated blood. But only a tiny proportion of the protons react to the field and radio waves. Stronger magnets line up a greater proportion of the proton spins, which then generate a stronger signal as they realign.

“What was previously noise is now suddenly signal.”

The scanners used in neuroscience today typically have magnet strengths of 3 tesla, which is many thousand times stronger than Earth's magnetic field, and have a resolution of 3 cubic millimetres. But stronger magnets are creeping into practice. In 2010, for example, scientists at the University of Nottingham, UK, used a 7-tesla magnet to build a map of the human somatosensory cortex¹³ — which is responsible for processing touch and some aspects of movement — at a resolution of 1 cubic millimetre. The NeuroSpin facility near Paris is building an 11.7-tesla whole-body system, the strongest yet for human studies. Magnets much stronger than this cannot be used on humans, because they increase artefacts in the images and can trigger dizziness and other side effects.

Another way to increase the signal is to inject molecules that are easier to detect than oxygenated blood, in a method more akin to PET. Gary Green, director of the York Neuroimaging Centre at the University of York, UK, is working with parahydrogen, a 'hyperpolarized' molecule in which the proton spins are more aligned than in many other molecules, and which generates a strong signal during MRI. In 2009, Green and his colleagues showed that they could transfer spins from parahydrogen to an organic molecule without changing the latter's chemical structure¹⁴ — the first step towards preparing hyperpolarized drugs or other molecules that bind to receptors, and then track how these substances are taken up, or how they interact.

Finding better statistical ways to remove noise will also be a big help. Poldrack runs a 'best practice' wiki (www.fmrimethods.org) that covers how fMRI data should be analysed, and has published guidelines for how the work should be reported, recommending, for example, that researchers include all the experimental detail necessary to reproduce an analysis, such as “what your subjects were asked to do and what they actually did”¹⁵. “We need to enforce more rigour,” he says.

Which way to the clinic?

Getting fMRI to the clinic is, for some, the most pressing challenge the field will face in the next few years. “It hasn't really been used clinically yet, on individual subjects,” says Bandettini. Clinicians want to be able to ask, for example, whether a drug is working to relieve schizophrenia, or whether a person with depression is in danger of committing suicide. The difficulty lies in making sense of an individual's scan. Most fMRI data are averages of results from many people doing the same task. This method has a higher chance of seeing a true difference between two groups or two tasks than those from an individual.

Researchers are now developing statistical methods to pull meaningful information out of a single scan. In one study¹⁶ published in 2010, a team trained a computer to pick out patterns in brain-scan data collected when participants were resting. They did this for nearly 240 people aged 7–30 years to build up maps of brain connectivity at different ages. They then showed that they could take a single brain scan from a different person and, by comparing it with their reference set, work out the owner's brain maturity. Such techniques might eventually be used to diagnose a developmental delay or psychiatric disorder, and there are hints that they can identify teenagers genetically at risk for depression¹⁷.

Having a good reference set will form the backbone of clinical fMRI, says Arthur Toga, a neurologist at the University of California, Los Angeles. Toga is a principal investigator on an effort to build such a reference, called the Alzheimer's Disease Neuroimaging Initiative, a longitudinal study of around 800 people looking at the onset and progression of Alzheimer's disease through genetic analyses, brain structure and function and blood biomarkers. Toga hopes that the information will form a database against which future individual scans can be compared.

With new ways both to examine the data and to boost the technology, many neuroscientists see a future filled with multicoloured blobs — albeit sharper and better-understood ones. “People will be very busy easily for the next 20 years,” says Bandettini. “I would say that fMRI in many aspects hasn't really even begun.”

Nature 484, 24–26

( 05 April 2012 )

doi :10.1038/484024a

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Source: Nature
http://www.nature.com/news/brain-imaging-fmri-2-0-1.10365

Posted by
Robert Karl Stonjek