What is the difference between the "Internet" and the "World Wide Web" ?

 

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Question: What Is the Difference Between the Internet and the Web?

People commonly use the words "Internet" and "Web" interchangeably. This usage is technically incorrect.

Answer: The Internet and the World Wide Web have a whole-to-part relationship. The Internet is the large container, and the Web is a part within the container. It is common in daily conversation to abbreviate them as the "Net" and the "Web", and then swap the words interchangeably. But to be technically precise, the Net is the restaurant, and the Web is the most popular dish on the menu.
Here is the detailed explanation:
1: The Internet is a Big Collection of Computers and Cables.
The Internet is named for "interconnection of computer networks". It is a massive hardware combination of millions of personal, business, and governmental computers, all connected like roads and highways. The Internet started in the 1960's under the original name "ARPAnet". ARPAnet was originally an experiment in how the US military could maintain communications in case of a possible nuclear strike. With time, ARPAnet became a civilian experiment, connecting university mainframe computers for academic purposes. As personal computers became more mainstream in the 1980's and 1990's, the Internet grew exponentially as more users plugged their computers into the massive network. Today, the Internet has grown into a public spiderweb of millions of personal, government, and commercial computers, all connected by cables and by wireless signals.
No single person owns the Internet. No single government has authority over its operations. Some technical rules and hardware/software standards enforce how people plug into the Internet, but for the most part, the Internet is a free and open broadcast medium of hardware networking.
Here is a conceptual diagram of the Internet and how it contains many forms of online communications
2: The Web Is a Big Collection of HTML Pages on the Internet.
The World Wide Web, or "Web" for short, is a massive collection of digital pages: that large software subset of the Internet dedicated to broadcasting content in the form of HTML pages. The Web is viewed by using free software called web browsers. Born in 1989, the Web is based on hypertext transfer protocol, the language which allows you and me to "jump" (hyperlink) to any other public web page. There are over 65 billion public web pages on the Web today.

Can physical therapy before hip, knee replacement surgery improve outcomes?

 

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Physical therapy after total hip (THR) or total knee replacement (TKR) surgery is standard care for all patients. A new study, appearing in the October 1 issue of the Journal of Bone & Joint Surgery (JBJS), also found that physical therapy before joint replacement surgery, or "prehabilitation," can diminish the need for postoperative care by nearly 30 percent, saving an average of $1,215 per patient in skilled nursing facility, home health agency or other postoperative care.

Many adults in the world, mainly in the USA have physician-diagnosed arthritis. As the condition progresses, arthritis patients often require THR and/or TKR to maintain mobility and life quality. The number of THRs is expected to grow by 174 percent (572,000 patients) between 2005 and 2030, and TKRs by 673 percent (3.48 million). In recent years, the length of hospital stay following surgeries has decreased from an average of 9.1 days in 1990 to 3.7 days in 2008, while the cost of post-acute care, primarily in skilled nursing facilities and home health agencies, has "skyrocketed."

Utilizing Medicare claims data, researchers were able to identify both preoperative physical therapy and postoperative care usage patterns for 4,733 THR and TKR patients. Postoperative, or "post-acute" care, was defined as the use of a skilled nursing facility, home health agency or inpatient rehabilitation center within 90 days after hospital discharge. Home health agency services included skilled nursing care, home health aides, physical therapy, speech therapy, occupational therapy and medical social services.

Approximately 77 percent of patients utilized care services following surgery. After adjusting for demographic characteristics and comorbidities (other conditions), patients receiving preoperative physical therapy showed a 29 percent reduction in postoperative care use. In addition:

• 54.2 percent of the preoperative physical therapy group required postoperative care services, compared to 79.7 percent of the patients who did not have preoperative therapy.
• The decline in postoperative care services resulted in an adjusted cost reduction of $1,215 per patient, due largely to lower costs for skilled nursing facility and home health agency care.
• Preoperative physical therapy cost an average of $100 per patient, and was generally limited to one or two sessions.

"This study demonstrated an important opportunity to pre-empt postoperative outcome variances by implementing preoperative physical therapy along with management of comorbidities before and during surgery," said orthopaedic surgeon Ray Wasielewski, MD, co-author of the study.

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Story Source:

The above story is based on materials provided by American Academy of Orthopaedic Surgeons. Note: Materials may be edited for content and length.

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Journal Reference:

1. R. Snow, J. Granata, A. V. S. Ruhil, K. Vogel, M. McShane, R. Wasielewski. Associations Between Preoperative Physical Therapy and Post-Acute Care Utilization Patterns and Cost in Total Joint Replacement. The Journal of Bone & Joint Surgery, 2014; 96 (19): e165 DOI: 10.2106/JBJS.M.01285

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Colorful Butterfly Wings Inspire Counterfeit-Proof Tech

 

The butterfly Pierella luna appears to change color because of the microstructure of its wings, which feature slightly curved scales.
Credit: Mathias Kolle/Harvard

To stop identity thieves and counterfeiters, a group of researchers is looking for inspiration from an unlikely source: butterflies.

In order to attract a mate, the male Pierella luna butterfly of Latin America uses its wings to perform an advanced optical trick known as reverse color diffraction. Thanks to the microstructure of its wings — made up of tiny scales curled slightly upward at the end to diffract light — the butterfly appears to change color when it's viewed from different angles.

Now, researchers at Harvard University have figured out a way to use artificial photonic materials to mimic the Pierella luna's attractive light show. They've created what's known as a diffraction grating, a surface that splits white light into its individual wavelengths of color and sends those colors traveling in different directions. When the photonic material is viewed from one angle, it looks to be one color, but from a different angle, the color appears to change, according to study co-author Mathias Kolle, a member of the Harvard research team and an assistant professor of mechanical at the Massachusetts Institute of Technology (MIT). [Butterfly Gallery: Beautiful Wings Take Flight]

If you've ever owned a CD, then you've probably witnessed reverse color diffraction in action, Kolle told Live Science. Imagine putting a CD shiny side up on a table and then shining a light on it. Different colors appear on the CD's shimmery surface, depending on how you move your head.

This happens because the tiny data tracks that make it possible for you to listen to the CD also serve as a diffraction grating, splitting white light into its different wavelengths of color.

But this optical trick is more than just something to stare at; it can also be put to good use, the researchers said.

"We thought there could be some benefit for such a unique [material] in security printing," Kolle said. "Or, potentially, we could tailor the output of light-emitting devices by putting such a structure on top of them. The material could also coat the solar panels, to manipulate how light enters the individual cells, he added.

It's the new photonic material's microstructure that could make it valuable for a range of applications. The superthin, transparent material consists of an array of microscopic plates, or scales, that mimic those that make up the Pierella luna's wing. Each plate is about 18 micrometers tall — about one-fifth the diameter of a human hair — and each features a scalloped, or ridged, edge. The ridges on each plate look like tiny lines running through the material and are spaced about 500 nanometers apart.

"It's like if you take a notebook and put it on its side standing up, and then you put many notebooks the same distance from each other. That's the fundamental structure," Kolle said.

All of these features — both the plates themselves and the ridges running through them — can be manipulated to create different optical effects, Kolle said. By changing the height size and spacing between the plates or the ridges, the researchers can change how the material diffracts light — a feature that Kolle calls "tunability."

The material is also fairly difficult to recreate, Kolle said, which is why he thinks it could be used to make more secure banknotes or passports. If used for such purposes, it would lend these printed objects a so-called "optical signature," he said.

The ability to tune the material to specific wavelengths could also make it valuable for producers of solar cells or light-emitting diodes (LEDs) used inside consumer electronic devices. Both of these products need to be as efficient as possible in the ways they absorb or release light, the researchers said.

"We're also hoping we can tailor these structures to increase the capping efficiency of light into a solar cell," Kolle said. "And it's the inverse problem with light-emitting devices: Light has to come out of the LED, and we think that we can improve the out-capping efficiencies from LEDs."

The study was published online today (Oct. 6) in the journal Proceedings of the National Academy of Sciences.

Follow Elizabeth Palermo @techEpalermo. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.