Artificial Cornea Offers Long-Term Vision

Patients with impaired vision because of a damaged cornea could soon regain their sight without need of a human donor transplant. Instead, such patients could be aided by an artificial but biosynthetic implant. One such implant has now been tested in patients over two years, and the results are as good as, or even better than, those achieved with donor corneas.

The transparent tissue that covers the surface of the eyes, the cornea, can be damaged by injury, infection, or inflammation, causing the eye to lose much of its ability to refract light and focus images on the retina. Such damage has caused loss of vision in millions of people around the world. The best treatment for cornea damage remains a transplant, but donor corneas are in chronically short supply.

Plastic replacements have been available for decades, but their implantation is still plagued by side effects such as infection and glaucoma. "They remain a last resort option for patients where all other options have failed, including donor transplants," says Joachim Storsberg at the Fraunhofer Institute for Applied Polymer Research in Potsdam, Germany. Storsberg is developing plastic implants but was not involved with the current work.

ABS

An anti lock breaking system(ABS) prevents the vechile wheels from locking up while breaking.
ABS ComponentsMain components to an ABS system:

Speed sensors
Pump
Valves
Controller
Speed SensorsThe ABS needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.PumpSince the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.ValvesThere is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions:


In position one, the valve is open; pressure from the master cylinder is passed right through to the brake.
In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder.
In position three, the valve releases some of the pressure from the brake.ControllerThe controller is a computer in the car. It watches the speed sensors and controls the valves.ABS at WorkThere are many different variations and control algorithms for ABS systems. We will discuss how one of the simpler systems works.
The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 kph) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.
The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.
When the ABS system is in operation you will feel a pulsing in the brake pedal; this comes from the rapid opening and closing of the valves. Some ABS systems can cycle up to 15 times per second

Google-certified ad networks in AdSense

Google-certified ad networks in AdSense

VIOP

Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VOIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.






Internet telephony refers to communications services — voice, facsimile, and/or voice-messaging applications — that are transported via the Internet, rather than the public switched telephone network (PSTN). The basic steps involved in originating an Internet telephone call are conversion of the analog voice signal to digital format and compression/translation of the signal into Internet protocol (IP) packets for transmission over the Internet; the process is reversed at the receiving end.[1]






VOIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations of VOIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs

uav

An unmanned aerial vehicle (UAV; also known as a remotely piloted vehicle or RPV, or Unmanned Aircraft System (UAS)) is an aircraft that flies without a human crew on board the aircraft. Their largest uses are in military applications. To distinguish UAVs from missiles, a UAV is defined as a reusable, uncrewed vehicle capable of controlled, sustained, level flight and powered by a jet or reciprocating engine. Therefore, cruise missiles are not considered UAVs, because, like many other guided missiles, the vehicle itself is a weapon that is not reused, even though it is also unmanned and in some cases remotely guided.

There are a wide variety of UAV shapes, sizes, configurations, and characteristics. Historically, UAVs were simple drones^[1] (remotely piloted aircraft), but autonomous control is increasingly being employed in UAVs. UAVs come in two varieties: some are controlled from a remote location, and others fly autonomously based on pre-programmed flight plans using more complex dynamic automation systems.

Currently, military UAVs perform reconnaissance as well as attack missions.^[2] While many successful drone attacks on militants have been reported, they are also prone to collateral damage and/or erroneous targeting, as with many other weapon types.^[1] UAVs are also used in a small but growing number of civil applications, such as firefighting or nonmilitary security work, such as surveillance of pipelines. UAVs are often preferred for missions that are too "dull, dirty, or dangerous" for manned aircraft.

iPad from Apple

The iPad from Apple Inc. (AAPL-Q235.970.970.41%) scored very well in terms of ease of use and battery life in its first reviews, but it won't obliterate the laptop computer market just yet, according to the New York Times and Wall Street Journal.







Reviewers at both papers said that while the tablet computer, which goes on sale on Saturday, works nicely for Web surfing or consuming media like video and books, it may appeal less to people who need laptops for more heavy duty chores.
The Journal's Walt Mossberg said he prefers the iPad as an e-reader to the popular Kindle e-reader from Amazon.com Inc. (AMZN-Q131.81-3.96-2.92%)


But David Pogue from the New York Times said the device's 1.5 pound weight is too heavy for reading compared to Kindle's 10 ounces. He also griped that “You can't read well in direct sunlight” and “You can't read books from the Apple bookstore on any other machine, not even a Mac or iPhone.”
Both reviewers said they were very impressed with the gadget's battery life as it lasted longer than Apple's impressive claim of 10 hours battery life.

4G MobileTechnology

4G refers to the fourth generation of cellular wireless standards. It is a successor to 3G and 2G standards. The nomenclature of the generations generally refers to a change in the fundamental nature of the service. The first was the move from analogue (1G) to digital (2G) transmission. This was followed by multi-media support, spread spectrum transmission and at least 200 kbit/s (3G) and now 4G, which refers to all IP packet switched networks, mobile ultra-broadband (gigabit speed) access and multi-carrier transmission.




A 4G system is expected to provide a comprehensive and secure all-IP based solution where facilities such as IP telephony, ultra-broadband Internet access, gaming services and streamed multimedia may be provided to users.






The remainder of this article uses 4G to refer to IMT Advanced (International Mobile Telecommunications Advanced), as defined by ITU-R.






An IMT Advanced cellular system must have target peak data rates of up to approximately 100 Mbit/s for high mobility such as mobile access and up to approximately 1 Gbit/s for low mobility such as nomadic/local wireless access, according to the ITU requirements. Scalable bandwidths up to at least 40 MHz should be provided. [1][2]






The pre-4G technology 3GPP Long Term Evolution (LTE) is often branded "4G", but the first LTE release does not fully comply with the IMT-Advanced requirements. LTE has a theoretical net bitrate capacity of up to 100 Mbit/s in the downlink and 50 Mbit/s in the uplink if a 20 MHz channel is used - and more if Multiple-input multiple-output (MIMO), i.e. antenna arrays, are used. Most major mobile carriers in the United States and several worldwide carriers have announced plans to convert their networks to LTE beginning in 2009. The world's first publicly available LTE-service was opened in the two Scandinavian capitals Stockholm and Oslo on the 14 December 2009, and branded 4G. The physical radio interface was at an early stage named High Speed OFDM Packet Access (HSOPA), now named Evolved UMTS Terrestrial Radio Access (E-UTRA).