Types of Databases

These days, when you talk about databases in the wild, you are primarily talking about two types: analytical databases and operational databases.

Let's examine each type.

Analytic Databases

Analytic databases (a.k.a. OLAP- On Line Analytical Processing) are primarily static, read-only databases which store archived, historical data used for analysis. For example, a company might store sales records over the last ten years in an analytic database and use that database to analyze marketing strategies in relationship to demographics.

On the web, you will often see analytic databases in the form of inventory catalogs such as the one shown previously from Amazon.com. An inventory catalog analytical database usually holds descriptive information about all available products in the inventory.

Web pages are generated dynamically by querying the list of available products in the inventory against some search parameters. The dynamically-generated page will display the information about each item (such as title, author, ISBN) which is stored in the database.

Operational Databases

Operational databases (a.k.a. OLTP On Line Transaction Processing), on the other hand, are used to manage more dynamic bits of data. These types of databases allow you to do more than simply view archived data. Operational databases allow you to modify that data (add, change or delete data).

These types of databases are usually used to track real-time information. For example, a company might have an operational database used to track warehouse/stock quantities. As customers order products from an online web store, an operational database can be used to keep track of how many items have been sold and when the company will need to reorder stock.

Database Models

Besides differentiating databases according to function, databases can also be differentiated according to how they model the data.

What is a data model?

Well, essentially a data model is a "description" of both a container for data and a methodology for storing and retrieving data from that container. Actually, there isn't really a data model "thing". Data models are abstractions, oftentimes mathematical algorithms and concepts. You cannot really touch a data model. But nevertheless, they are very useful. The analysis and design of data models has been the cornerstone of the evolution of databases. As models have advanced so has database efficiency.

Before the 1980's, the two most commonly used Database Models were the hierarchical and network systems. Let's take a quick look at these two models and then move on to the more current models.

Hierarchical Databases

As its name implies, the Hierarchical Database Model defines hierarchically-arranged data.

Perhaps the most intuitive way to visualize this type of relationship is by visualizing an upside down tree of data. In this tree, a single table acts as the "root" of the database from which other tables "branch" out.

You will be instantly familiar with this relationship because that is how all windows-based directory management systems (like Windows Explorer) work these days.

Relationships in such a system are thought of in terms of children and parents such that a child may only have one parent but a parent can have multiple children. Parents and children are tied together by links called "pointers" (perhaps physical addresses inside the file system). A parent will have a list of pointers to each of their children.

This child/parent rule assures that data is systematically accessible. To get to a low-level table, you start at the root and work your way down through the tree until you reach your target. Of course, as you might imagine, one problem with this system is that the user must know how the tree is structured in order to find anything!

The hierarchical model however, is much more efficient than the flat-file model we discussed earlier because there is not as much need for redundant data. If a change in the data is necessary, the change might only need to be processed once. Consider the student flatfile database example from our discussion of what databases are:

Name	Address	Course	Grade
Mr. Eric Tachibana	123 Kensigton	Chemistry 102	C+
Mr. Eric Tachibana	123 Kensigton	Chinese 3	A
Mr. Eric Tachibana	122 Kensigton	Data Structures	B
Mr. Eric Tachibana	123 Kensigton	English 101	A
Ms. Tonya Lippert	88 West 1st St.	Psychology 101	A
Mrs. Tonya Ducovney	100 Capitol Ln.	Psychology 102	A
Ms. Tonya Lippert	88 West 1st St.	Human Cultures	A
Ms. Tonya Lippert	88 West 1st St.	European Governments	A

As we mentioned before, this flatfile database would store an excessive amount of redundant data. If we implemented this in a hierarchical database model, we would get much less redundant data. Consider the following hierarchical database scheme:

However, as you can imagine, the hierarchical database model has some serious problems. For one, you cannot add a record to a child table until it has already been incorporated into the parent table. This might be troublesome if, for example, you wanted to add a student who had not yet signed up for any courses.

Worse, yet, the hierarchical database model still creates repetition of data within the database. You might imagine that in the database system shown above, there may be a higher level that includes multiple course. In this case, there could be redundancy because students would be enrolled in several courses and thus each "course tree" would have redundant student information.

Redundancy would occur because hierarchical databases handle one-to-many relationships well but do not handle many-to-many relationships well. This is because a child may only have one parent. However, in many cases you will want to have the child be related to more than one parent. For instance, the relationship between student and class is a "many-to-many". Not only can a student take many subjects but a subject may also be taken by many students. How would you model this relationship simply and efficiently using a hierarchical database? The answer is that you wouldn't.

Though this problem can be solved with multiple databases creating logical links between children, the fix is very kludgy and awkward.

Faced with these serious problems, the computer brains of the world got together and came up with the network model.

Network Databases

In many ways, the Network Database model was designed to solve some of the more serious problems with the Hierarchical Database Model. Specifically, the Network model solves the problem of data redundancy by representing relationships in terms of sets rather than hierarchy. The model had its origins in the Conference on Data Systems Languages (CODASYL) which had created the Data Base Task Group to explore and design a method to replace the hierarchical model.

The network model is very similar to the hierarchical model actually. In fact, the hierarchical model is a subset of the network model. However, instead of using a single-parent tree hierarchy, the network model uses set theory to provide a tree-like hierarchy with the exception that child tables were allowed to have more than one parent. This allowed the network model to support many-to-many relationships.

Visually, a Network Database looks like a hierarchical Database in that you can see it as a type of tree. However, in the case of a Network Database, the look is more like several trees which share branches. Thus, children can have multiple parents and parents can have multiple children.

Nevertheless, though it was a dramatic improvement, the network model was far from perfect. Most profoundly, the model was difficult to implement and maintain. Most implementations of the network model were used by computer programmers rather than real users. What was needed was a simple model which could be used by real end users to solve real problems.

MANET (Mobile Ad Hoc Network)

MANET stands for "Mobile Ad Hoc Network." A MANET is a type of ad hoc network that can change locations and configure itself on the fly. Because MANETS are mobile, they use wireless connections to connect to various networks. This can be a standard Wi-Fi connection, or another medium, such as a cellular or satellite transmission.
                  
                                            (Or)


A MANET (Mobile Ad Hoc Network) consists of a collection of mobile nodes communicating in a multi-hop way without any fixed infrastructure such as access points or base stations. 
Some MANETs are restricted to a local area of wireless devices (such as a group of laptop computers), while others may be connected to the Internet. For example, A VANET (Vehicular Ad Hoc Network), is a type of MANET that allows vehicles to communicate with roadside equipment. While the vehicles may not have a direct Internet connection, the wireless roadside equipment may be connected to the Internet, allowing data from the vehicles to be sent over the Internet. The vehicle data may be used to measure traffic conditions or keep track of trucking fleets. Because of the dynamic nature of MANETs, they are typically not very secure, so it is important to be cautious what data is sent over a MANET.



Characteristics of MANET 

• No centralized control & administration
• Self-organizing and self-restoring
• Transmission through multiple hops
• Frequent link breakage and change of network topology

Applications of MANET 

• Battlefield communication 
• Sensor networks 
• Personal area networking using PDAs, laptops and handphones, etc 
• Search-and-rescue 
• Cellular network and wireless Hot Spot extension 

Alexander Graham Bell Biography

Alexander Graham Bell first invented the telephone at the age of 29, in 1877. The following year, the Bell Telephone Company was established, during which time he married Mabel Hubbard and setting off on a honeymoon across Europe for an entire year.

Alexander Graham Bell's fame is attached to the success of the telephone, but in fact bell embarked upon several other projects. He remained an ambitious and creative man throughout his life, during which he would continue to learn, create and challenge himself to improve the modern world. Bell engaged in many different scientific studies including kites, airplanes, tetrahedral structures, sheep-breeding, desalinization, water distillation, hydrofoils and artificial respiration, as documented in his various journals and logbooks.

The Invention of the telephone empowered Bell, in terms of financial security, which allowed him to devote himself to developing his other ideas and interests. In 1881, Bell won France's Volta prize of $10,000 which he used to et up the Volta Laboratory in Washington, D.C. This is where Bell teamed up with Chichester Bell and Charles Sumner Tainter, to produce a marketable version of the Phonograph, first thought up by Thomas Edison. A secondary laboratory was set up in 1885, at Beinn Bhreagh, near Baddeck, where he brought together an intelligent young team to follow new ideas and concepts.

The photophone was the first invention created by Bell after the telephone, which allowed sound to be transmitted via a beam of light. Charles Sumner Tainter and Bell himself developed the photophone using sensitive selenium crystal and a mirror which vibrated in reply to sound. The first successfully transmitted photophone message was sent in 1881 over a distance of 200 yards. Bell hailed the photophone as "the greatest invention I have ever made; greater than the telephone." This invention is the fundamental principle which modern day lasers and fiber optics rely on, although many other principles had to be recognised before these were brought into effect.

Alexander Graham Bell's interest in heredity, led him to explore, first of all the deaf followed by sheep born with genetic abnormalities. He conducted various sheep-breeding experiments in which he strived to increase the number of twin and triplet births. Bell also created an electromagnetic device to detect a bullet. following President Garfield being shot by an assassin and having the bullet lodged inside him. He continued to work on this and thus invented the telephone probe, which would make a telephone receiver click when it connected with metal.

Bell's son, Edward, died due to respiratory problems which inspired Bell to invent a metal vacuum jacket which assists breathing. He also invented an audiometer which detected small hearing problems, conduced various experiments relating to energy recycling and substitute fuels, and attempts of separating salt from seawater.

The bulk of Bell's time was then spent exclusively on flight, as Bell enjoyed a challenge. The 1890's saw Bell develop a keen interest in propellers and kites, which led him to create a new kite design, based on a tetrahedron. In 1907, Bell established the Aerial Experiment Association with Glenn Curtiss, William "Casey" Baldwin, Thomas Selfridge and J.A.D. McCurdy, four young engineers with a passion for creating airborne transport. It took the group 2 years to create four powered aircraft, the Silver Dart being the stand-out project which made it's first flight in Canada on February 23rd, 1909.

Bell ended his career by concentrating on hydrofoils, looking to improve their performance, and in 1919, himself and Casey Baldwin built a hydrofoil which set a water-speed record which would not be beat for 44 years.

Shortly before Bell died, he told a reporter, "There cannot be mental atrophy in any person who continues to observe, to remember what he observes, and to seek answers for his unceasing how's and why's about things."

Clooney, an Irish Setter, Captures Best in Show at 2010 National Dog Show

In Thursday’s National Dog Show competition, a Boxer named Scarlett had impressive credentials, but it was Clooney, an Irish Setter, who won Best in Show.

Clooney and his handler, Peter Kubacz, summed up the day's events with an interview at the end of the dog show. When Kubacz was asked if Clooney knew he was the top dog, Clooney nodded yes with the enthusiasm of a true winner.

Clooney was one of more than 2,000 dogs representing 179 different breeds that took to the ring on Thanksgiving Day to compete in The National Dog Show presented by Purina. Hosted by the Kennel Club of Philadelphia, the show is one of the oldest benched conformation dog shows in the country and has been held annually since 1933. A conformation dog show shows off breeding stock and a benched show allows those attending to mingle with the dogs behind the scenes.

To pick the winning dog, the judge has to know the breed standard of each dog.

Six new dog breeds were among the breeds showcased in this year's National Dog Show. New breeds are recognized by the American Kennel Club when the breed has a good following spread across the country with a parent club to oversee them. The six new breeds introduced this year were the Boykin Spaniel in the sporting group, the Cane Corso and the Leonberger in the working group, the Bluetick Coonhound and Redbone Coonhound in the hound group and the Icelandic Sheepdog in the herding group.

This year's National Dog Show was a wide open field with no particular favorite. The breeds competing in the finals for the coveted title of Best in Show were:

* in the sporting group, Clooney, a 3-year-old male Irish Setter;

* in the working group, Scarlett, a 3-year-old female Boxer with 52 all-breed Best in Show victories under her collar;

* in the herding group, Beyonce, a 3-year-old female Australian Shepherd;

* in the hound group, Hickory, a 4-year-old female Scottish Deerhound;

* in the terrier group, Maddy, a 2-year-old female American Staffordshire Terrier with nine Best in Show wins to her credit;

* in the non-sporting group, a 6-year-old male Schipperke, Johnny Be Good, who was aptly named because, as a puppy, he wasn't good;

* and in the toy group, Joe, a 3-year-old male Affenpinscher.

Interesting facts and bits of trivia learned the National Dog Show:

* The Chinese Crest is a breed that, unlike other dog breeds, has sweat glands on its body.

* Responsible breeders do recognize that some dogs are smaller than their breed standard, but there is no such thing as a teacup dog and they will not breed any dog for a smaller size.

* A conformation dog show is meant to show off breeding stock and a dog is disqualified if they have been altered.

* Redbone Coonhounds can bark 125 times in one minute.

* The Doberman Pincher was named after the man who first bred them for man's protection. He apparently had good reason for wanting protection: His last name was Doberman and he was a tax collector.

* Most of the breeds from the terrier group evolved in Britain.

* Helen Keller brought the first Akitas to the United States in the 1930s.

* The Rottweiler was bred to be a drover dog for butchers. Once the railroads became popular and the butchers no longer needed the Rottweiler as a drover, the dog was used to protect the butcher's coin purse. They hung their purse around the dog's neck.

* The Boxer got its name from standing on back legs and boxing to get attention.

* The Schipperke has no tail.

Click image below to see photos of the National Dog Show

Youth Rules at the American Music Awards

Miley Cyrus celebrated her 18th birthday two days early by hitting the stage at the American Music Awards barefoot and belting out "Forgiveness and Love," but it was a true teenager who swept the fan count on Sunday, Nov. 21, at the Nokia Theater in downtown Los Angeles.

Sixteen-year-old Justin Bieber trounced the competition at the 37th annual popularity contest, that is voted on by the general public and sponsored by ABC-TV, becoming the youngest person ever to win Artist of the Year. And as the show aired live, screams echoed for him from the upper tiers all night long. As one teen fan shrieked in a quiet moment, "Justin, I love you!"

You could barely hear Bieber sing as those adoring fans went crazy as he took to the stage midway through the show, following Rihanna's exuberant opening number, Cyrus' heartfelt ballad, Diddy-Dirty Money's rapping romp and the Black Eyed Peas' cool techno riff on their new single "The Time." Perhaps it was a sign that today's music business belongs to the young, as screams and cheers also met Taylor Swift as she sang her new single "Back to December" and accepted the favorite country female award.

"I want to thanks my fans," said the often-maligned Swift, one of America's most popular recording artists of the moment. "It's wonderful and rare to be understood, and you guys really get me."

Other top acts who performed included Kid Rock, Bon Jovi, Enrique Iglesias, Train, Pink, Ke$ha, Katy Perry, Santana, Ne-Yo, Christina Aguilera and Usher, who took home two awards of his own. But the finale was the thing that kept stars like Heidi Klum, Jessica Alba, Christina Milian, Samuel L. Jackson, Jenny McCarthy, Mandy Moore and Sheryl Crow in their seats to the end. For when the combined "boy bands" of New Kids on the Block and the Backstreet Boys bounded onto the stage, not a person had left the three-hour-long show. Promoting their combined tour that launches in 2011, the not-so-young nine reminded many of the older set of their own youth, singing a medley of their hits from 15 years ago.

Later on, the adults in the crowd headed to the hottest after party, the opening of the new Rolling Stone Restaurant and Lounge, where that magazine's publisher Jann Wenner held court in a private room. He greeted most of the night's stars from the earlier show, everyone from Bon Jovi, Iglesias and Kid Rock to Perry and her husband, Russell Brand, along with Jamie Foxx, Brandy, Brittany Snow and the "Glee" guys, Mark Salling and Matthew Morrison.

Obama, Hill leaders to meet: taxes, treaty on tap

The clock running, President Barack Obama and Republican and Democratic congressional leaders are sizing up each other as they struggle for common ground on taxes and nuclear arms before the end of the year.

The president and top congressional officials planned to meet Tuesday morning in the White House, the first such session since the midterm elections altered the political terrain and the government's balance of power.

Of immediate consequence is the fate of expiring Bush-era tax rates and a U.S.-Russia treaty to reduce nuclear weapons arsenals.

But Obama's meeting with House and Senate leaders from both parties — eight altogether — will also help define the interaction between the White House and a divided Congress for the next two years.

Obama said Monday he hopes the meeting "will mark a first step toward a new and productive working relationship, because we now have a shared responsibility to deliver for the American people on the issues that define not only these times but our future."

Despite their political gains, Republicans are approaching Tuesday's session with some apprehension. Presidents typically gain a public relations advantage by inviting leaders of the opposition party to the White House.

Many Republicans still bristle at the health care summit that Obama called last February. Democrats got more time to make their case than Republicans, and the session yielded no Democratic compromises.

"In the past, when we have private meetings with the president, he has rarely missed the opportunity to lecture us for our political or ideological beliefs," said House Republican Whip Eric Cantor of Virginia. "I'm hopeful that those days are gone."

In a double-bylined op-ed piece Tuesday in The Washington Post, House Speaker-to-be John Boehner, R-Ohio, and Senate Minority Leader Mitch McConnell, R-Ky., signaled that any compromises with the White House on spending and tax cuts would have to be on their terms.

"We can work together and accomplish these things, but the White House and Democratic leaders in Congress first will have to prioritize," they wrote. "It's time to choose struggling middle-class families and small businesses over the demands of the liberal base. It's time to get serious."

Cantor, who will become the House majority leader in January, accused the president of engaging in "class warfare." "This country is about making sure everyone has a fair shot," he said in an interview.

Republicans applauded Obama's announcement Monday to freeze the pay of all civilian federal employees for two years; traditional Democratic allies, including the AFL-CIO, denounced it as shortsighted.

The White House had initially scheduled the meeting for Nov. 18 but rescheduled at the request of McConnell and Boehner. That session was to have concluded with a private dinner. Tuesday's session was expected to last an hour and end before lunch.

"No doubt there are interesting dynamics," said chief White House political adviser David Axelrod. "There are people who say they want to take steps to deal with our long-term debt issues. We'll work with anyone who wants to work with us on that in a productive way."

Big East gets bigger, adds TCU for 2012 season

Texas – TCU is getting out of future debates about whether the Horned Frogs deserve to be in a BCS game. They are joining a league with automatic access.

The Frogs won't have to be a BCS buster when they move to the Big East Conference, starting with the 2012 season. Win their new league and they will be guaranteed a spot in one of the big-money games.

In the latest restructuring of the college football landscape, TCU's board of trustees unanimously approved an invitation Monday to join the Big East in football and all other sports. The move from the Mountain West Conference becomes official July 1, 2012.

TCU athletic director Chris Del Conte said gaining automatic-qualifying status "was a big factor" in the move and gives the Horned Frogs "the greatest opportunity to compete for the national championship."

The Big East, currently with eight football teams, has one of six automatic BCS slots.

"Access got easier, not the road," said Frogs coach Gary Patterson, whose third-ranked Frogs (12-0) wrapped up their second consecutive undefeated regular season and Mountain West title with a 66-17 win at New Mexico on Saturday.

TCU is third in the BCS standings — the highest-ranked non-automatic qualifying team — and is in line for a chance to play for the national championship if Auburn or Oregon lose next weekend. The Frogs likely will play in the Rose Bowl if Auburn and Oregon both win.

"Who would have thought five years ago that the guaranteed fallback position is, you're going to the Rose Bowl, and one loss you're in the national championship?" Del Conte told a room filled with supporters and staff. "We're going to Pasadena, let's get fired up. We're going to the Big East, let's get fired up. ... It's a great time to be a Frog."

The pending departure of TCU continues a big shuffle for the Mountain West, which last summer announced that Boise State was leaving the WAC to join its league in 2011. That was expected to bolster the strength of the MWC and put the league in better position for possibly gaining an automatic BCS berth in the future. But now so much has changed.

Utah is leaving the Mountain West for the expanded Pac-12 and BYU is going independent. Fresno State and Nevada, and maybe Hawaii, are going from the WAC to the MWC in 2012 after TCU leaves.

"Today's intercollegiate athletics environment is very fluid," Mountain West Conference commissioner Craig Thompson said in a statement. "Our board of directors and directors of athletics, as they have throughout the history of the MWC and with even more focus recently, will continue to analyze the landscape and chart our course in the context of ongoing changes."

Thompson said there were "conversations already under way with potential future members."

Del Conte said losing BYU and Utah was a "significant blow" to the Mountain West.

"It was not the same league that we joined," he said. "It's not the same home that we bought, it's not same home we were invited to, and things changed, the landscape changed."

Boise State president Bob Kustra called TCU's decision disappointing "but not entirely surprising given the stakes of automatic qualification in the BCS bowl system and relative lack of access for non-AQ conferences." He said the Mountain West was still a good fit for his school.

TCU could help the MWC land an automatic bid to the BCS after the Frogs are gone.

TCU's excellent 2010 (and it's 2011 performance) will count toward the MWC's resume when the conferences are evaluated after the 2011 season.

BCS officials have said a non-automatic qualifying conference could earn an automatic bid for the 2012 and '13 seasons.

And if the Big East's BCS bid comes under scrutiny when the next TV contract ends after the 2013 season, TCU's 2010 season will also count toward the Big East's resume.

"It's too soon to speculate about what the BCS thresholds will be for the 2015 and beyond, but it seems likely that TCU's move will enhance the Big East's position," BCS executive director Bill Hancock said in an e-mail.

The Big East has schools in nine of the nation's 35 largest media markets and will being adding Dallas/Fort Worth, the fifth largest.

"Located in one of the top five media markets in the country, TCU also enables the Big East to extend its media footprint, which already encompasses more than a quarter of the country," league commissioner John Marinatto said.

The only current Big East team ranked in the AP poll is No. 23 West Virginia (8-3, 4-2 Big East), which is 24th in the BCS standings. Connecticut (7-4, 4-2) could get the league's automatic BCS spot.

TCU might not be headed to a BCS game without Boise State's loss Friday night in overtime at Nevada. Had the Broncos remained undefeated, there was a real possibility that the Broncos could have passed the Frogs in the BCS standings and been the only non-AQ team to get into one of the top-level bowls.

"This is a great move," Patterson said. "I'll say this, we don't seem to get bored around this place. ... The one last mark people have held against in recruiting is that we were not an automatic qualifier. Now that's been erased."

TCU was a BCS buster for the first time last season, then lost to Boise State in the Fiesta Bowl.

The Frogs have won 25 consecutive regular-season games, and 38 of 41 overall. The only losses in that span were in the Fiesta Bowl, and games at Oklahoma and Utah.

"Coach Patterson's done a great job there and has brought an awful lot of exposure to themselves just because of the success that they've had," South Florida coach Skip Holtz said. "Probably over the last five years, (they) have been one of the leaders in this whole BCS busters thing, and they've done it on a consistent basis. They've proven that they can compete at that level, that they're deserving of having the opportunity to be in a BCS conference."

Louisville athletic director Tom Jurich believes TCU is "a great addition" to the Big East, and has no problem with the league expanding so far west.

"Hey, the Big 12's got 10, the Big 10's got 12," Jurich said. "Why should we be any different?"

With all TCU sports moving to the Big East, it will create a 17-team basketball league.

Marinatto said the league was aware of the logistical issues associated with having 17 basketball teams and nine football teams and that those issues would be addressed. He wouldn't discuss the possibility of even more schools being added to the league outside of what the league previously stated.

Villanova, which won the FCS national championship last season, has been considering moving up in classification in football and joining the league in which their basketball teams and other sports are already a member.

"We are excited about the addition of TCU, as they bring a great deal of value to the Big East," Villanova AD Vince Nicastro said Monday. "However, our timeframe has not changed. We are continuing to move forward with our comprehensive evaluation of FBS level football, and are still targeting a decision by the spring of 2011."

The Big East will be the fourth conference for TCU since the Southwest Conference broke apart after the 1995 season and the Frogs weren't among the Texas schools that became part of the Big 12.

TCU was in the WAC from 1996-2000 before going to Conference USA for four seasons and then joining the Mountain West in 2005.

Watch out, PC: The tablet cometh

Tablets like the iPad and Samsung's Galaxy Tab are the gotta-have gadgets of the year, no doubt — but could they eventually replace the PC as your platform of choice?

Make no mistake: PCs are still big business, with consumers and companies expected to snap up more than 352 million systems this year alone, and more than 409 million in 2011. But tech analysts are cutting their forecasts in the face of surging tablet sales, and the trend is expected to continue in the coming months and years.

Gartner research director Ranjit Atwal announced Monday that he now believes consumers and businesses will have bought about 352.4 million PCs in 2010 by the end of December, a figure that represents a 14.3 increase from 2009.

Not bad, but Atwal adds that he's revised his latest projections downward from just two months ago, when he predicted that PC sales would see a 17.9 percent increase over 2009's total.

Naturally, Atwal blames slowing PC sales in part on the poor economy, with consumers and enterprise customers alike saving money by holding off on replacing their current systems.

Other factors to consider include the rise of cloud-based services, like Google Apps and Microsoft's new in-the-cloud Office applications, as well as the fact that PC makers aren't offering much in the way of jaw-dropping, gotta-have innovations these days.

That said, the "weaker consumer demand" for PCs in the coming years is also "due in no small part to growing user interest in media tablets such as the iPad," Atwal says, adding that by about 2014 or so, tablets will "displace" an eye-opening 10 percent of all PC sales.

Why are tablets like the iPad, the Samsung Galaxy (click here for my hands-on review), and other forthcoming examples taking off with consumers? Because they "enable better on-the-go content consumption" and boast "instant-on" functionality, according to Atwal — and as the years go by, media tablets will only become more powerful and "PC-like," to the point where users may increasingly think of their tablets as their "primary computing platform."

So, is it time to declare the PC dead? Of course not, Atwal says, arguing that PCs are "still seen as necessities" by most consumers and business folk.

But gone are the days when people are replacing their PCs every year, or even every couple of years, with users instead seeing smartphones and especially tablets as "complements, if not substitutes, for PCs," particularly "where voice and light data consumption are desired," Atwal says.

One needn't look any further than the latest sales figures for the iPad to see that users are embracing tablets on a large scale. For instance, according to one estimate quoted by Fortune magazine from an analyst with investment bank Piper Jaffray, consumers bought about 8.8 iPads an hour at Apple stores on Black Friday.

And it's not just Apple-mania we're talking about here, with Samsung said to have moved an impressive 600,000 of its Android-powered Galaxy Tabs in just a few weeks.

Personally, I'm not ready to call my iPad my "primary" computer just yet. Sure, I use it all the time when I'm Web browsing in my living room, but when it's time to go to work, I fire up my desktop or laptop. Then again, I'll probably be keeping my current desktop iMac for a good three or four years, at least, while I'm sure I'll pony up for a new iPad the moment it comes out.

What about you: Can you envision the day when a tablet might be your computing platform of choice? Has that day already come? Or will you always turn to a PC first?

Europe debt fears pile pressure on Spain, others

 Investors sold off government bonds from Spain, Portugal and Italy on Tuesday amid worries that Europe's debt crisis has not been contained by Ireland's bailout but is putting pressure on other fiscally weak countries.

The yields on Spain's 10-year bonds jumped as high as 5.7 percent by midmorning, making for a euro-era record difference of 305 basis points against the benchmark Germany 10-year bond, which had a yield of 2.7 percent.

The spread on Italy's 10-year bond reached 210 points, also the highest since the launch of the euro, before easing back somewhat. Portugal, whose yields soared last week, saw its spread edge higher as well.

Spain and Portugal have continually denied they will need a bailout like Ireland and Greece but investors have become increasingly skeptical that the series of bailouts will stop with Ireland.

While rescuing Portugal would be about as costly as Greece or Ireland, who each represent less than 2 percent of the eurozone economy, a Spanish bailout would test the limits of Europe's finances. It accounts for over a tenth of the eurozone economy, and Italy is even larger.

"It is clear that the market is aware of the tight-rope that 'peripheral' governments are walking," said Neil Mellor, currency strategist at Bank of New York Mellon.

Portugal's central bank warned in a report Tuesday that the financial system is facing "serious challenges," as foreign concerns about public, private and corporate debt have made it harder for Portuguese banks to raise money on international markets.

Continuing to request financing from the European Central Bank is "unsustainable," the report warned, saying banks should adopt a commercial policy of encouraging saving to ensure their liquidity.

Traders worry that instability in Portugal could easily cross the border into Spain.

Spanish Prime Minister Jose Luis Rodriguez Zapatero has vigorously defended the nation's economy and finances. He insisted over the weekend that his administration will forge ahead with austerity measures and force troubled banks and regional governments to reveal information about savings and restructuring efforts so as to restore confidence.

Zapatero claims the structural reforms under way, which include loosening hiring and firing restrictions in the job market, freezing pensions and liberalizing the energy sector, will eventually boost the country's competitiveness, among the worst in the eurozone.

He maintains Spain's plans to reduce its deficit are being fulfilled scrupulously and added that the country's total debt was still 20 percentage points below the European average despite the crisis. Spain's debt at the end of 2009 was euro560 billion ($740 billion), roughly 60 percent of its GDP.

Still, the country is struggling to emerge from a near two-year recession and has a eurozone high unemployment rate of near 20 percent.

Portugal's government has also repeatedly insisted that its austerity program of tax hikes and pay and welfare cuts next year will be enough to restore its fiscal health. However, investors fear a likely economic downturn because of the belt-tightening will make it harder for the Portuguese to meet their debt obligations.

Jean-Claude Juncker, the head of the Eurogroup, which represents the 16 euro nations, was quoted as saying Tuesday that other countries in the bloc were not leaning on Portugal to accept a rescue.

"There is no pressure. It's up to the Portuguese government to decide whether it wants help," Juncker told Portuguese reporters during a visit to Tripoli, Libya, according to the national news agency Lusa.

Madrid's main stock index, which has had more than a week of negative trading and saw a sharp drop on Monday, was down another 0.8 percent on Tuesday, while Portugal's main index was 0.5 percent lower.

Google Launches Interactive Book to Teach Everyone About the Web

In an attempt to teach the average person about the fundamentals of browsers and the web, Google has released an interactive online book that explains concepts like, TCP/IP, HTML, browser extensions and malware.

The short book, 20 Things I Learned About Browsers and the Web, is a step-by-step explanation of the web and how it works. It was created by the Google Chrome team using HTML5, but it also features a lot of clever illustrations by award-winning German illustrator and children's author Christoph Niemann.

The focus of the book is on 19 different topics (plus a recap, making for 20 things). It starts with "What Is the Internet?" and then dives into cloud computing, web apps, web programming languages, browsers, privacy, security and open source.

While regular readers of Mashable may be very familiar with these web concepts (and much more), Google realizes that most people have no clue about the function of a browser or what HTML5 actually is. This was exemplified last year when Google took to the streets and asked people, "What is a browser?" Less than 8% of the people it polled gave a correct answer.

With 20 Things I Learned About Browsers and the Web (available at 20thingsIlearned.com), Google can point these users to a website that will fill them in on the basics. While it's not a perfect solution (we suspect the book's too long for many in our attention-deficient society), it's definitely something I'd show to my mom or my technologically challenged friends.