It’s Not Easy Being Green – The Electric Car

When Kermit the Frog first sang the line “it’s not easy being green,” I don’t think he was talking about the environment. We live in the “green” age in which there is an overwhelming drive to reduce our impact on the environment.

 

 

Recycling is a way for everyone to do his or her part for the “green” movement. California has been “green” for a long time. I remember separating paper, plastic, aluminum and glass from garbage for recycling at least 15 years ago, if not more.

 

Al Gore is doing his part by talking about the relationship of greenhouse gases to climate change. Some people doubt the connection, and I can respect that; everyone is entitled to his or her opinion. However, I am certain that everyone agrees that the weather is not what it used to be. That’s climate change in my book.

 

What about fuel efficiency?

 

With gas prices well over $4 at every pump I visit, I have been thinking about hybrid cars. I know many people who own a Toyota Prius, which can get about 45 miles per gallon. While this gas mileage sounds terrific, I was thinking about alternatives to gas powered engines.

 

The federal government is making a big fuss over hydrogen fuel cells and throwing a lot of money into developing this technology for widespread use. I’m not familiar with the details of this technology, but I know that the byproduct is water. I’m more concerned about how to store the hydrogen and oxygen that is required to make the car go. I need to read more about this technology, and I’m sure there are some very smart people working on this problem.

 

What about an electric car?

 

Believe it or not, this has already been done.

 

When I was in college, I was introduced us to a car called the EV-1, which was made by General Motors. An electric car? Surely it would be wimpy!

 

I was wrong. The EV-1 was fast, it could go from 0 to 60 mph in 4 seconds, and its surprisingly quiet. The EV-1 had a range of 120 miles on a single charge. I figured this car would be all the rage in California, since the state was into being “green” before it became popular.

 

Interestingly enough, 1997 was the last I heard of the EV-1, and then I saw a documentary called “Who Killed the Electric Car?” in June 2008.

 

This documentary discussed the EV-1 and points out what an amazing machine it was; the car was way ahead of its time. Eventually the program ended. Why? Was it corporate greed? Was it there not enough demand? Watch the documentary and come to your own conclusion.

 

With $4 per gallon gas, it seems that there would be significant demand for an electric car. I hope General Motors and other car makers follow up on it. Technology has improved over the past 10 years, so I imagine the next electric car will be even better. My fingers are crossed!

 

Dr. Dave

Wild Summer Weather!

The weather in the Midwest has been wild this summer. There have been many reports of tornado damage and severe flooding across several states in the region. Why does wild weather happen during this time of year?

 

It’s all about Heat

It is common knowledge that temperatures rise as winter changes into spring and summer. Higher temperatures means more heat, and heat is the driving force behind wild weather. This is why you don’t see thunderstorms in the winter.

 

Wild weather occurs when the air is warm, full of moisture, and unstable. It is easy to figure out when the air is warm and full of moisture, just think of a hot and humid day. How can you tell if the air is unstable?

 

Use your eyes

The air above us can either be stable or unstable. The easiest way to tell if the air is unstable is to look at the clouds in the sky. Tall and puffy clouds are a sure sign of unstable air. If the air is stable, the clouds will form a flat layer.

 

Here is a picture I took of a tall and puffy Thunderstorm cloud (called a Cumulonimbus) while flying over Florida. This cloud was able to get very tall and puffy because the air is very unstable.

 

Meteorologist (weather scientists) know when wild weather is coming by study charts and data from satellites in space. 

Take a look at this weather map from the National Oceanic and Atomspheric Adminstration (NOAA). What do you notice?

 

The “H” and “L” you see on the map refers to areas of High pressure and Low pressure. The weather person on TV will refer to this as “barometric pressure” and will say if it is rising or falling.

 

In general:

– If the barometric pressure is rising or is High, expect good weather.

– If the barometric pressure is falling or is Low, expect bad weather.

 

Notice that the areas of low pressure have a lot of rain and thunderstorm warnings.

 

Another thing to notice are the lines of blue flags and red half circles. These lines indicate a weather front. What is a weather front? 

 

A weather front is the boundary between two different air masses. Cold fronts are the line of blue flags and warm fronts are the line of red half circles. The direction that the flags and circles are pointing show the way the weather fronts are moving.

As a general rule, when opposite weather fronts (warm and cold) collide, wild weather will happen. Notice that there is an area shaded in yellow that warns “Severe Thunderstorms Possible” near where a warm front is cutting a cold front in half.

 

The Big Picture

The weather map shown above is a typical example of what happens during the summer over the middle of America. Cold dry air from the Artic moves south over Canada, while warm moist air from the Gulf of Mexico moves north. These air masses collide and cause wild summer weather. Sometimes the storms can be so big that is stretches across the U.S. from north to south.

 

These storms can pack a punch, which means it has energy in the form of heat and wind. I wonder if scientists can create a technology that drains a storm of this energy and transform it into electricity. This way, the storm won’t cause damage and people will have a natural source of power. What do you think?

 

Dr. Dave

The Physics of Free Running

Good news everyone, I am officially Dr. Dave! I spent the past few months writing my Ph.D. thesis, and I successfully defended my dissertation. I apologize for not posting regularly, but I am sure you understand. 

 

Thesis Break, Bond Style! 

While I was writing my thesis, I would occasionally take a break and watch a movie. One of the movies I watched was Casino Royale, the most recent entry in the Bond franchise.

 

 

Chase scenes are standard in Bond movies and Casino Royale had its fair share. My favorite is when Bond pursues a bomb maker, Mollaka, on foot through a construction site in Madagascar.

 

Below is a link to the scene posted on YouTube. The clip is about 9 minutes long.

 

In this foot chase, Bond and Mollaka have two different styles. Mollaka is graceful and efficient; Bond is aggressive and haphazard. It is clear that Mollaka has an advantage over Mr. Bond.

 

Free Running

Sébastien Foucan, the founder of a sport called free running, played Mollaka. Free running is a sport that is dedicated to efficient motion between two points.

 

During the foot chase, Mollaka knew how to use his environment to keep him moving forward. While his jumps were very fancy to watch, he was clearly using the laws of physics to his advantage.

 

Rolling, Rolling, Rolling

Free running reminds me of martial arts. I have several friends who perform similar acrobatic feats during martial arts demonstrations. The core philosophy of many martial arts is to redirect energy, and I imagine the same holds true for free running.

 

A basic move taught in many martial arts is rolling. A proper roll is a useful move that is designed to dissipate energy in a fall or jump.

 

Look at this YouTube video showing how rolls are done. The people in this video clearly know what they are doing. Please don’t try this at home without the proper equipment. You can easily injure yourself.

 

The examples toward the end of the video show why the roll is a great move–it helps the free runner maintain his forward momentum after a jump and places him on his feet.

 

The Physics of Going Splat 

In the YouTube examples above, we can see how rolling is very useful to free runners. Let’s learn about the physics of this motion.

 

Let’s imagine we have a ball of pizza dough. What happens if you throw it against the wall? I would predict that it would go splat and flatten. Why?

 

When the dough collides with the wall all the energy of motion–called kinetic energy– is instantly absorbed by the pizza dough. Let’s think about what happen in another example.

 

Now imagine that we roll the ball of dough on the ground towards a wall. What happens in this case? The ball of dough will gradually lose speed before hitting the wall. In this example, the dough is more likely to maintain its shape because the energy is lost gradually as it rolls rather than suddenly at impact.

 

In both cases, a similar amount of energy is lost. What matters most is the amount of time required for the dough to slow down. If it the dough stops suddenly, then it will flatten. If the dough slows gradually, it will retain its original shape.

 

Over the Handlebars 

While pizza dough is a good example, let’s think about how this works on a human body. The following is a true story.

 

A friend of mine was riding his bike in the park. Suddenly, a child jumped in front of him, causing my friend to swerve and avoid the child. Unfortunately my friend hit a bench and went flying over the handlebars.

 

 

Being a black belt martial artist, he instinctively curled up into a ball and rolled on the pavement; he rolled a few times before coming to a complete stop.

 

The Physics of Not Going Splat 

My friend was able to avoid significant injury because was able to roll and gradually dissipate his kinetic energy. Imagine what would have happened if he landed hard onto the pavement. His body would have suddenly impacted the ground and instantly absorbed all kinetic energy. If you have ever experienced a crash, then you know this is a painful experience.

 

In the example of pizza dough mentioned above, a direct impact caused the dough to lose its shape. On the human body, a sudden impact would cause significant injury, like cuts and bruises, even broken bones. Ouch!

 

Whether you are a martial artist or a free runner, the ability to move with proper technique helps to prevent injury. By understanding physics we now know why. Remember, it all boils down to how fast or slow kinetic energy is dissipated.

 

–Dr. Dave

Science Is History

History classes have been a source of great life lessons for me. Apparently, ancient civilizations hold the key for understanding our modern society and the future.

“Ancient civilizations hold the key for understanding our modern society and the future?” – at least that’s what my teachers told me.

My problem with History classes is that I dislike memorizing details. Do you know the exact dates for the rise and fall of the Roman Empire? These were the types of details I had to memorize just so I could answer one or two questions on a test. I have a general idea when important historical events occur, and who was involved, but I never understood how memorizing an exact date or year could help me. Why wouldn’t I just look up that kind of stuff on Google or in a book? 

I preferred to learn history in terms of how its ancient ideas impact our everyday lives. Did you know that a 2000 years old civilization formed the foundation of the U.S. government? Now that is pretty cool.

The ancient Romans developed a unique system for laws and government.  Although it was not perfect, most nations of the world have based their government on an upgraded version of the ancient Roman system.

Below is a map of the Roman Empire:

They covered a lot of territory, didn’t they? That’s some empire.

Science – A Window into the Past

Believe it or not, science is also a lesson in history. Everything you learn is about stuff that someone figured out in the past.

Scientists don’t concern their work on rules that govern civilizations, but they do want to know about the rules that govern nature. Does this sound familiar? In the past, as scientists gained knowledge, it improved our technology and the conditions of life. One year, a person was doing manual labor, and the next year, they were able to buy a machine to do it.

We live in the world of the Internet, iPods, LCD TVs and hybrid cars. It is easy to lose sight of the impact of science, because we are immersed in it. Can you imagine a world where none of these things existed?

Early civilizations that had no knowledge of science regarded the Moon as a god. In 3000 years, scientists gained enough knowledge to send a man named Neil Armstrong to walk on its surface.

In the 1950s, sailors who crossed the oceans used the stars and math to navigate their ship to their destination in an accurate way, just like their seafaring ancestors did 500 years ago. We have GPS today, which makes finding your way on land, sea and air to be a no-brainer.

Can you imagine what it would have been like without it?

Does anyone know what the picture below is? You may have seen one before with sailors or travelers in a history book.  It is called a “sextant.”  Navigators used this tool to take measurements of the stars. Think of it as an ancient GPS!

It took awhile to use a sextant to figure out where you are, but it worked. Imagine having one of these on the dashboard in your car. 

Why Science?

We learn science to understand the natural world and rules that govern it. Through science we learn the process of problem solving – a logical method of trial and error. We also learn lessons from the past that have already been solved.

Don’t Give Up

I enjoy history, literature, music and sport, but I do not give them up just because I am not devoting my life to it. I learn to appreciate all these things. All I ask that science be given a fair chance like Shakespeare, Football, and Napoleon.

As the Spanish philosopher George Santayana once said, “Those who cannot learn from history are doomed to repeat it.”

The same applies to science.

Humans have accumulated a tremendous amount of knowledge and it is up to future generations to add to it.

By the way, my teachers were right; art, history, literature, science and sport teach valuable lessons that makes life interesting.

It is never to late to show your appreciation through learning.

-Dr. Dave

Mutant Bacteria!

There has been a lot talk in the news about MRSA, which stands for Methicillin-Resistant Staphylococcus Aureus.

Scientists often call MRSA a “superbug” because it no longer can be killed by a certain kinds of antibiotics related to penicillin.

How is it that bacteria become “superbugs?”

Bacteria are tiny, one-celled organisms that come in many shapes and sizes. All bacteria use DNA as the blueprint of life and have tools (called enzymes) to copy itself when ample nutrients are present.

Before copies can be made, a bacterium has to duplicate its DNA. An enzyme called DNA Polymerase (the horseshoe shaped object shown in green in the picture above) accomplishes this task. This enzyme is found in bacteria, insects, plants, animals, and even humans!

When making copies of DNA, most DNA Polymerases can proofread the blueprint to check for errors. Human and plant Polymerases are very good at finding errors, but some bacterial Polymerases are not. If an error does occur in the blueprint, scientists call this a mutation.

Mutants!

When people hear the word “mutant” they think of X-men or the Teenage Mutant Ninja Turtles. Although this is science fiction, Hollywood has shown that there are good mutants and bad mutants. The same applies to bacteria.

For example, scientists have engineered good mutant bacteria that can make insulin, a hormone used by diabetics to control blood sugar levels.

An example of a bad mutant bacterium is MRSA, which we talked about above.

More About Mutations

The DNA blueprint holds the master plans for all the machinery required for a cell to function properly. If there is a mutation in the blueprint, there is a chance that a cell’s machinery of life will be altered, and it can result in one of three possible outcomes:

1. The altered machinery continues to function normally.

2. The altered machinery is faulty and can cause bacterial death.

3. The altered machinery is enhanced and it helps the bacteria survive harsh conditions.

Survival of the Fittest!

Harsh conditions could mean a variety of things to bacteria, from low nutrient levels to the presence of antibiotics.

We already know that antibiotics can kill bacteria, but what happens if a mutation helps the bacteria survive? Scientists call this resistance.

Bacterial resistance to antibiotics is a very scary thing. Diseases that were once curable are now becoming a challenge to control.

The world’s best scientists are working hard to discover new kinds of antibiotics. Hopefully there will be breakthroughs that will lead to new medicines that will control the spread of these lethal bacteria.

-Dr. Dave

Use Your Head…for Math! Part 2

In my last post I talked about the importance of doing math in your head and using estimates to make it easier. My example focused on flying because it is something that I enjoy doing and math plays a key role in it.

I was thinking that I needed a better example, an everyday example. I found it when I went shopping for shoes last week.

With winter on its way out, several stores are having their annual “end of winter sale.” I live in Chicago and I like to be outdoors. This means that I need a good pair of boots that can withstand the cold, keep the slush out, and be comfortable to walk in.

In one shoe store, I found a pair of high quality boots that originally cost $84.99, and were on sale for 35% off. Using a few simple math tricks, I was able to calculate how much the shoes would cost in my head.

Why bother doing the math? You will find that out in the end.

How did I do the math? Let me share this with you now.

Simplify the problem!

$84.99, is a hard number to use. When I was younger, I thought that the $0.99 at the end of every price was put there to scare me away from doing math in my head. This is a lame excuse. I quickly learned to round the prices up to make the number easier to handle. In this case we will use $85.

Percentages are also a intimidating, especially for a number like 35%. The key to figuring out percentages is to break it down into simpler numbers. When calculating a sale price I find that the easiest percentages to calculate are 50%, 10%, and 5%.

I selected these numbers because…

50% is half, so divide the price by two.

10% is 1/10, so divide the price by 10.

5% is half of 10%, so determine the 10% price and then divide it in half.

For numbers like 35%, use a combination of the numbers above. For example, the number 35 breaks down into 10 + 10 + 10 + 5, or (3 x 10) + 5.

Since the boots cost $85, 10% is $8.50 and 5% is half of the 10% price, or $4.25. To figure out what 35% is, multiply (3 x $8.50) and then add $4.25.

Ok, I know you are thinking that 3 x $8.50 is not simple math.

Here’s how I see it. I know that 3 x $8 is $24 and 3 x $0.50 is $1.50. Add them together to get $25.50. Doing math this way makes the problem easier to solve.

To figure out the final discount, add $4.25 and $25.50. This gives $29.75 for the 35% price. That’s nearly $30 off!

This means I should pay about $55 before taxes. The actual price is $55.24, so our estimate is very good.

So why bother doing the math?

When I asked people about how they solve this kind of math problem, most said that they trust the register so they do not worry about doing math in their head.

I disagree with them because I have had many experiences like the one below.

When I took the boots to the register, I was expecting the price to be around $55. The clerk scanned the shoes and the computer said the shoes cost $63.74.

There had to be a mistake somewhere.

I quickly estimated that $63.74 reflected 25% off, not the 35% that was advertised. How did I do this?

I figured this out by first rounding $63.74 up to $64 because it is easier to deal with.

The difference between $64 and $55 is $9. This is close to $8.50, or about 10% (we figured this out earlier). Since the price rang up higher, that means the discount was 10% less than 35%, giving 25%.

I told the sales clerk that that the shoes were on sale for 35%, not 25%. As it turns out, the same pair of shoes were on sale last week for 25%, and this week they were on sale for 35%.

The register was not updated with the new price.

By doing math in my head I was able to catch the mistake. If I had trusted the register, I would have paid $9 more than I should have.

With $9 I could buy lunch or about 3 gallons of gas.

What could you do with $9?

-Dr. Dave

Use Your Head…for Math!

When I was young, I wanted to earn my pilot’s license. All my teachers knew this, and they always told me that pilots were good at doing math without calculators.

During my flight training, I encountered all sorts of math problems in the form of how to properly loading the plane with people and fuel (weight & balance) and navigation. I am very glad I followed my teachers’ advice.

Let’s take a closer look at the issues pilots have to face and examples of the problems they have to solve. Towards the end, I will share how I do math in my head.

Weight and Balance

Flying an airplane is a balancing act. Think of an airplane as a seesaw.

Pilots try to achieve the a condition similar to when a seesaw is in balance. This is possible by distributing the weight evenly. If an airplane is out of balance, it will fly poorly or not at all. Gasp!

Navigation

Pilots have to know how to get to their destination using tools like radios and GPS. Modern airplanes have a lot of fancy computers onboard that make navigation easier, but mistakes can occur. I was trained to always double check the computer because the best onboard computer is the pilot’s brain.

Always Ask, “Does the Answer Make Sense?”

When I was in elementary school, I had a friend who used calculators a lot. On the day of a big test, his calculator broke and so he borrowed a calculator that was different from the one he was used to; it had twice as many buttons. He did very poorly on this test, and he blamed the calculator for giving him the wrong answers. It turns out he was at fault. Why?

Calculators and computers are just machines that do exactly what you tell it to do. For example, if your problem is 44 x 5, but you accidentally type 44 + 5, the math will be correct, but the answer will be wrong.

Similarly, onboard flight computers are very useful tools for flying, but it is up to the pilot to make sure the computer is correct. How do we do it?

The Power of Estimation

When flying an airplane, I have to deal with numbers that are not as easy to use. Let’s say that my cruising speed is 167 miles-per-hour (mph), and my destination is 302 miles away.

The onboard flight computer says it will take 1 hour 49 minutes.

Is the flight computer right? Does this flight time make sense?

If I used the exact numbers in my head, I would probably be more focused on doing math than flying the plane. This is dangerous. Instead, I will round numbers up or down to make the math easier.

The Easy Way

In this example I would round the distance down to 300 miles (from 302 miles) and use 150 mph (instead of 167 mph).

300 miles divided by 150 mph is easy to solve.

The answer is 2 hours, which is close to what the onboard computer is saying.

Also, since I know I am going faster than 150 mph, I know I will reach my destination sooner than 2 hours. My logic agrees with the onboard computer and so the flight time “makes sense.”

It Works!

I have been in a situation where my flight examiner intentionally programmed an error into the onboard flight computer. I noticed that the error early on because I always asked myself “does the flight computer make sense?” I was able to catch the error before it became a problem later in the flight. The examiner was impressed.

Asking, “does the answer make sense” when solving any sort of problem helps to check your work. I can remember many times where I checked my work without a calculator, using estimation and simple math, and I uncovered a calculation error.

My teachers were right; doing math in your head is an important skill. Thanks to their advice, my dream came true and I earned my pilot’s license.

-Dr. Dave

P.S. There is another way that I use to solve the flight time problem shown above. It is more advanced so I saved it at the end for those who are interested.

A Little More Advanced

I know that 10% of 150 mph is 15 mph. If I add 150 mph with 15 mph, I get 165 mph, which is very close to 167 mph.

If I am going 10% faster than 150 mph, I know I will arrive 10% sooner than 2 hours (120 minutes). 10% of 120 minutes is 12 minutes.

Arriving 10% sooner means I will arrive in 2 hours – 12 minutes, or 1 hour and 48 minutes.

This agrees with the flight computer!

Pitching Ace and Physics Master

Physics is concerned with how things move, energy, space, and time. In an everyday sense physics explains how planes fly, how electricity flows from an electrical outlet to a light bulb, and even how glasses help people to see better.

 

Perhaps one of the coolest everyday example of physics is in sports. Since spring is around the corner, I will focus on baseball.

I think pitchers are masters of physics. They know how to throw a ball with great speed and precision so that it will land in the strike zone.

Let’s take a closer look at the pitching process.

During the wind-up, a pitcher uses his body to transfer energy to the ball. This energy is called kinetic energy, the energy of motion.

As the baseball is being released, pitchers sometimes add some spin. This can cause the ball to take a curving path, rather than straight path, which can confuse the batter.

Breaking it Down

We know from experience that if we hold a ball and simply let it go, gravity will pull it down.

We also know that when we throw the ball straight ahead, the ball will fly forward while arcing downwards. If you think about it, there are two things the affect how the ball flies, the throw and gravity.

Now, if you throw the ball, but this time you release it with a spin, the ball will fly forward, arc downwards, and curve in the direction of the spin. In this case the throw, gravity, and the spin affects how the ball flies.

The best way to understand this concept is with a few good examples. A friend suggested this impressive wiffleball pitching video because it clearly illustrates the effect of spin on pitching. Keep your eyes on the ball!

The pitchers in this video are able to get such amazing curveballs because the plastic wiffleball is very light and more easily affected by spin than a heavier baseball.

 

When baseball season starts-up, do not forget to root for your favorite physics master, I mean pitcher!

-Dr. Dave

Indiana Jones and the Mystery of the Cracking Whip

Indiana Jones and the Raiders of the Lost Ark is my favorite movie. I was watching it (again), and a friend asked me why a whip makes that characteristic “crack” sound. As a reminder, below is a YouTube video montage of Indiana Jones’ favorite weapon.

Where does the sound come from?

When you move something through the air really fast, it typically makes a “whoosh” kind of sound. If you swing a bat very fast, you can hear this sound. This is just the air moving around the bat. Cars and planes also make their own “whoosh” kind of sound, but no “crack” sound.

The distinctive whip “crack” sound occurs when the tip of the whip is moving at supersonic speeds.

This means that the tip of the whip is breaking the sound barrier! Isn’t that cool!

A similar sound is made when a fighter jet breaks the sound barrier. Check out this You Tube video of a fighter jet breaking the sound barrier.

I mentioned that only the tip of the whip moves at supersonic speed. As Indiana swings and snaps the whip, all of the energy of motion moves down to the tip and causes it to changes directions rapidly. When done properly, it cracks.

-Dr. Dave

What is Fog?

Fog can be thought of as a cloud that is on the ground.  Clouds are usually very thick and almost impossible to see through, while fog can vary in thickness.

Did you know that Meteorologists (scientists that study the weather) officially define a day as foggy if the visibility is about 6/10 mile or less?  If the visibility is greater than 6/10 mile but less than 1 1/4 miles, it is officially call mist.  I don’t know who came up with those numbers but I know that fog poses a challenge to safe driving or flying.

 

Here is a really cool picture of a plane landing through the fog from www.airliners.net.

 

 

Recipe for fog

Fog typically occurs when the air is calm, cool, and full of water vapor.

 

Depending on where you live, and what season it is, your local TV weather person will give the temperature, dew point, and humidity.  The temperature tells us how hot or cold the day will be.  The dew point is the temperature the air needs to be cooled to form dew, fog, or clouds.

Both the dew point and humidity both tell us how much water vapor is in the air. 

Key points

• If the temperature and dew point are within a few degrees of each other, then it means that the humidity is high and it is probably raining, snowing, or foggy.
• If the temperature and dew point are far apart, it means the humidity is low.
• Humidity is relative to the temperature.  Cool air holds less water than warm air.  This means that a hot, humid summer’s day holds more water vapor than a cold, humid winter’s day. 

Putting it all together

Chicago recently experienced fog so thick that hundreds of flights were canceled into the area airports and there were many car accidents.  The fog came on the heels of serious snowfall resulting in 10 inches of snow on the ground.  A few days later the air began to warm slight above freezing and the snow to melt and evaporate.  This filled the air with water vapor and, because it was not windy, the air was clam enough for fog to form.

In an earlier post on Hurricanes and Latent Heat, I discussed condensation, the process that causes water to form on the outside of a cold glass of soda on a hot and humid day.  Did you know that fog and clouds form in a similar fashion?  It’s true!  Tiny particles of dust and pollution give water a surface to condense on to form visible moisture.

If you would like to read more about fog, this link to Wikipedia has a section that discusses it in greater detail.

-Dr. Dave