jignasa

Friday, 5 April 2013

322. Web 2.0

Web 2.0

The term Web 2.0 was coined in 1999

Web 2.0
Web 2.0 was first introduced in the market by O’Reilly at the brainstorming discussion at media live International in 1999. The information available through Web 2.0 empowered the new generation to develop new concepts like Wiki, Widgets and Video streaming. It also allowed many users to publish their own content through few basic steps, which was not possible in the Web 1.0 or The Internet. Web 2.0 was responsible for the development of various sites that we commonly use today like Twitter, Flickr and Facebook.

Web 2.0 can be described in three parts:

Rich Internet application (RIA)

Web-oriented architecture (WOA)

Social Web

defines how Web 2.0 tends to interact much more with the end user and make the end-user an integral part.

As such, Web 2.0 draws together the capabilities of

client- and server-side software,

content syndication and

the use of network protocols.

Standards-oriented web browsers may use plug-ins and software extensions to handle the content and the user interactions.
Key features of Web 2.0 include

Folksonomy: Free Classification of Information
Rich User Experience
User as a Contributor
Long Tail
User Participation
Basic Trust
Dispersion

Web 2.0 sites provide users with

Information storage,

Creation, and

Dissemination capabilities

that were not possible in the environment now known as "Web 1.0".

Web 2.0 websites include the following features and techniques, referred to as the acronym SLATES by Andrew McAfee:

Finding information through keyword search.

Links

Connects information together into a meaningful information ecosystem using the model of the Web, and provides low-barrier social tools.

Authoring

The ability to create and update content leads to the collaborative work of many rather than just a few web authors. In wikis, users may extend, undo and redo each other's work. In blogs, posts and the comments of individuals build up over time.

Web 2.0 and philanthropy

Web 2.0 in social work

Web-based applications and desktops

According to Best, the characteristics of Web 2.0 are:

1. Rich user experience,

2. User participation,

3. Dynamic content,

4. metadata,

5. Web standards and

6. scalability.

Web 2.0 applications tend to interact much more with the end user. As such, the end user is not only a user of the application but also a participant by:

1. Podcasting

2. Blogging

3. Tagging

4. Curating with RSS

5. Social bookmarking

6. Social networking

7. Web content voting

Web 2.0, The popularity of the term, along with the increasing use of

1. blogs,

2. wikis, and

3. social networking technologies,

has led many in academia and business to append a flurry of 2.0's

To existing Web 2.0 concepts and fields of study, including

1. Library 2.0,

2. Social Work 2.0,

3. Enterprise 2.0,

4. PR 2.0,

5. Classroom 2.0,

6. Publishing 2.0,

7. Medicine 2.0,

8. Telco 2.0,

9. Travel 2.0,

10. Government 2.0, and even

11. Porn 2.0.

What are the criticisms on Web 2.0?

The term Web 2.0 was never clearly defined and even today if one asks ten people what it means one will likely get ten different definitions.

Critics of the term claim that "Web 2.0" does not represent a new version of the World Wide Web at all, but merely continues to use so-called "Web 1.0" technologies and concepts.
First, techniques such as AJAX do not replace underlying protocols like HTTP, but add an additional layer of abstraction on top of them.
Second, many of the ideas of Web 2.0 were already featured in implementations on networked systems well before the term "Web 2.0" emerged.
Amazon.com, for instance, has allowed users to write reviews and consumer guides since its launch in 1995, in a form of self-publishing.
Amazon also opened its API to outside developers in 2002.
Previous developments also came from research in computer-supported collaborative learning and computer supported cooperative work (CSCW) and from established products like Lotus Notes and Lotus Domino, all phenomena that preceded Web 2.0.
"Nobody really knows what it means...If Web 2.0 for you is blogs and wikis, then that is people to people. But that was what the Web was supposed to be all along... Web 2.0, for some people, it means moving some of the thinking [to the] client side, so making it more immediate, but the idea of the Web as interaction between people is really what the Web is. That was what it was designed to be... a collaborative space where people can interact."
Other critics labeled Web 2.0 "a second bubble" (referring to the Dot-com bubble of circa 1995–2001), suggesting that too many Web 2.0 companies attempt to develop the same product with a lack of business models.
In terms of Web 2.0's social impact, critics such as Andrew Keen argue that Web 2.0 has created a cult of digital narcissism and amateurism, which undermines the notion of expertise by allowing anybody, anywhere to share and place undue value upon their own opinions about any subject and post any kind of content, regardless of their particular talents, knowledge, credentials, biases or possible hidden agendas.
Keen's 2007 book, Cult of the Amateur, argues that the core assumption of Web 2.0, that all opinions and user-generated content are equally valuable and relevant, is misguided.
Additionally, Sunday Times reviewer John Flintoff has characterized Web 2.0 as "creating an endless digital forest of mediocrity: uninformed political commentary, unseemly home videos, embarrassingly amateurish music, unreadable poems, essays and novels... [and that Wikipedia is full of] mistakes, half truths and misunderstandings".
Michael Gorman, former president of the American Library Association has been vocal about his opposition to Web 2.0 due to the lack of expertise that it outwardly claims, though he believes that there is hope for the future.
There is also a growing body of critique of Web 2.0 from the perspective of political economy.
As Tim O'Reilly and John Batelle put it, Web 2.0 is based on the "customers... building your business for you," critics have argued that sites such as Google, Facebook, YouTube, and Twitter are exploiting the "free labor" of user-created content.
Web 2.0 sites use Terms of Service agreements to claim perpetual licenses to user-generated content, and they use that content to create profiles of users to sell to marketers. This is part of increased surveillance of user activity happening within Web 2.0 sites.
Jonathan Zittrain of Harvard's Berkman Center for the Internet and Society argue that such data can be used by governments who want to monitor dissident citizens.

321. Q. & A.s SCI. & TECH. – 19

Q. & A.s ‑‑‑ SCI. & TECH. – 19

500Q. Are all solar flares of the same intensity?

Solar flares are not all the same intensity. In fact, there are many more low-intensity flares than high-intensity flares. The number of flares increases with decreasing intensity right on down to the limit of the sensitivity of the instruments that have been used to detect them.

501Q. How often do solar flares occur at solar minimum and at solar maximum, on a day-to-day basis?

This depends upon the flare intensity.

At solar minimum, at an average rate of about one per day, the statistics of flares that were detected from 1980 through 1989 with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission show that flares occurred. There can be long periods of time at solar minimum when no detectable flares occur.

At solar maximum the average rate was as high as 20 per day (averaged over a 6 month interval). So the rate at solar maximum is roughly a factor of ten greater than at solar minimum. It is important to realize, however, that the flare rate is very irregular. Then a large active region can form and produce many flares in just a few days. The duration of a solar flare in the energetic hard x-rays is seconds to minutes This emission can last from minutes to hours.

502Q. What is the velocity of plasma from a solar flare as it heads toward Earth?

The electromagnetic radiation from flares travels at the speed of light and reaches the Earth in eight minutes. CMEs [Coronal mass ejections], on the other hand, travel at speeds from 100 to 1000 kilometers per second and take several days to reach the Earth.

503Q. One solar flare crippled the communications satellite Anik E1 permanently and temporarily interfered with other satellites - why weren't all affected equally?

The sensitive components on Anik E1 were presumably not shielded well enough to withstand the large storm that occurred.

The effects of the storm are not the same at all locations. It may be that Anik was damaged while other satellites were not because it just happened to be in a location where the effects of the storm were particularly intense.

The Anik satellites are in high, geosynchronous orbits that expose them to the Earth's radiation belts. But other satellites are in similar orbits.

504Q. Do you know of any Web site that supplies daily information about solar flares?

MIGRAINES AGGRAVATE.

The same has been reported to the number of patients in Intensive Care Units and in Emergency Rooms. So, there is a DIRECT CORRELATION.

There is something called, "Monthly Chronogram", where the patient reports during one month the date and the hour of the "aggravations" of her/his disease.

505Q. What's the lifespan profile of sunspots?

The lifespan of a sunspot can be anywhere from less than an hour for a small spot to as long as several months.

506Q. Can flares erupt on any star's surface, or just the Sun's?

Flares do erupt on the surface of other stars. Most stars are in fact too far away for flares having the brightness of those that occur on the Sun to be observed.

507Q. Do flares have a measured effect on the ionosphere?

Solar flares do have an effect on the ionosphere. The evolution of the x-ray emission from a flare is mimicked in the ionosphere as a Sudden Ionospheric Disturbance (SID). This particularly affects radio communications at frequencies below around 30 MHz that depend upon the reflection of the signal off the ionosphere for long distance communications.

508Q. I would greatly appreciate it if you would tell me which specific types of ions or particles are emitted from a solar flare.

The types of particles detected in space from solar flares reflect the composition of the solar corona.

The corona is mostly hydrogen, so a lot of energetic protons and electrons are observed. Since the protons are heavier and more energetic than the electrons, they are of particular concern because of the damage they can do to astronauts and to electronic equipment.

The next most abundant element is helium, which is observed along with its isotope helium-3.

Heavier ions such as carbon, oxygen, silicon, iron, and many others are present at a much lower level.

509Q. What special precautions are taken aboard the space shuttle to prevent damage to their electronic components and how are the astronauts protected?

The primary protection is the Shuttle orbit.

The altitude of the Shuttle is typically 300-500 km above sea level. This is well within the Earth's magnetic field and below the Earth's radiation belts (the van Allen belts).

This magnetic field protects us from most of the charged particles from space, including from the Sun.

Since these charged particles can travel along the Earth's magnetic field to lower altitudes at the poles, however, the Shuttle orbit also avoids the regions around the north and south poles.

Manned missions to the Moon or Mars are much more dangerous, since these require leaving the protection of the Earth's magnetic field.
Some high-energy charged particles ("cosmic rays") do penetrate down to the Shuttle orbit and to the surface of the Earth.

Therefore, the risk of damage is higher at the Shuttle orbit than at the surface of the Earth. The Shuttle shroud does provide protection, but not from the highest energy particles.

The Shuttle astronauts have in fact seen flashes resulting from the interaction of high-energy protons with their eyes. Nevertheless, the increased health risk is not unacceptably high.

510Q. How does the sun burn? Is there oxygen in space? Isn't that needed for fire?

The burning in a fire is a chemical reaction, requiring oxygen. If such a chemical reaction were responsible for the heat of the Sun, the Sun would have lasted for less than 100 million years. We know, however, that the Sun must be several billion years old. Therefore, a greater source of energy is required.

511Q. Do all of the stars have names?

No, only about 250 of the brighter stars have names.

512Q. How did the stars get their names?

The Babylonians were probably the first historical people to name the stars. Most of the names which have come down to us are Arabic, with some Persian, Greek, Latin and Babylonian names. Most of the Latin names are modern. The names of the stars came to us about 2,000 years ago. Some of them came 500 years ago.

513Q. What star is nearest the Earth?

The Sun is the nearest the Earth. The mean distance of the Sun from the Earth is 150 million kilometres. The distance from the Earth to the second nearest star, Proxima Centauri, is about 4.2 light years from the Sun. That distance translates into 40 billion (40,000,000,000,000) kilometres.

514Q. What is a parsec?

The word "parsec" is made up of the parts of the words "parallax" and "second". It means the distance from the Earth to a star whose parallax is one second of arc. There is no star as near as one parsec, for the parallax of the nearest star is 0.75". A parsec is 3.26 light years.

515Q. How many stars can we see on a clear night?

A man can see between 3,500 and 4,000 stars.

516Q. Why are some stars brighter than others?

In general, a star's brightness depends upon its distance from us, its temperature and its size. With stars of the same size and temperature, the nearer stars will appear to be the brighter. With stars at the same distance and of the same size, the hotter stars will be the brighter. With stars at the same distance and the same temperature, the larger stars will appear brighter.

517Q. What does magnitude mean?

Magnitude is the measure of the brightness of a star or of any luminous body in the heavens.

518Q. Do the stars have colour?

Yes. The colours most often seen in the stars are red, orange, yellow, white and blue. There are some violet stars and a few green stars.

519Q. Do the colours of the stars have any significance?

Yes. Colours indicate star temperatures; they also tell which of the elements make up the stars. As a rule, the blue and the white stars are the hottest, while the red stars are cooler stars.

520Q. How hot are stars?

The hottest stars have a surface temperature about 45,000°C. The coolest visible stars are about 200°C at their surfaces. The inside temperatures of all stars must be measured in the millions of degrees.

521Q. How do we know the temperature of a star?

An instrument called a thermocouple indicates the amount of radiation we receive from a star. If the star's distance is known, its temperature can be calculated. The spectroscope will tell us of the behavior of the atoms that make up a star, and the laboratory gives us a criterion for the behavior of atoms of various elements at various temperatures. It is possible to estimate very closely the temperature of any star whose spectrum can be studied.

522. How big are stars?

The smallest known stars are about the size of planets. The largest stars are hundreds of times the diameter of the Sun.

523Q. Are the giants massive stars?

A giant star is one whose diameter is between 10 times the diameter of the Sun and 100 times its diameter.

The largest star masses known are only 100 times the mass of the Sun, and such stars are very rare. The giants are large, cool stars, whose masses are about the mass of the Sun and go from 10 and sometimes 20 times of the Sun's mass.

524Q. Are the giant stars hot stars?

Not as a rule, at least at their surface. There are very few hot stars that are larger than 10 times the diameter of the Sun.

525Q. What is a supergiant star?

Stars which are larger than giants are supergiant stars. A supergiant star is one whose diameter is more than 100 times the diameter of the Sun.