Monthly Archives: July 2014

Click here for geometry problems

But this time, I decided to go with ‘bugs’ as well. This is the second worksheet I’ve given my son to kickstart his thinking about algebra for the coming school year.

Read each of the two problems carefully and follow the directions to convert the word problems into algebraic expressions.

Jill has locked more zombies in rooms. Every room has zombies with the same number of limbs.

1. In one room, she locked one zombie with ‘x’ number of limbs.
2. In a second room, she locked three more zombies with ‘x’ number of limbs.
3. In a third room she locked two zombies with ‘y’ number of limbs.

Write an equation to express the total number of zombies’ limbs ‘z’:

Simplify this equation by ‘combining terms’ – to do this, imagine that you combine the two rooms of zombies with ‘x’ limbs into one bigger room:

 

If x = 2 and y = 3, solve for z:

Bobby, in the second grade, doesn’t even know zombies are attacking. He’s doing a project with spiders and insects.

1. He put four grasshoppers in one box.
2. He put two big spiders in another box.
3. He put one small spider in the last box.

Write an equation to express the total number of legs ‘z’:

 

Simplify this equation by ‘combining terms’ – just like above, but combining the two boxes of spiders:

 

How many legs do grasshoppers have? X =

How many legs do big spiders have? Y =

How many legs do small spiders have? Y =

Given what you know about spiders and grasshoppers, solve for z:

 

It’s summer in Kansas, and although the weather has been mild and rainy all year, it has recently turned into the hot, humid days that I’ve come to expect since moving here five years ago.

As part of our effort to escape the sun, my son and I decided to do an experiment today on the the nervous system. It was a spontaneous idea based on something I recall Mr. Wizard doing years ago. In case you’re too young to be familiar with Mr. Wizard, he was something like a cross between Bill Nye and a crotchety old man chasing the neighborhood kids off his lawn.

In this experiment we wanted to ask whether all areas of the body were uniformly innervated. The way Mr. Wizard, and we, went about asking this was to make some assumptions and fashion a device to examine sensitivity based on those assumptions.

The reason I bring up the assumptions is that it is always important to recognize what you are taking for granted. This way, when you get your results, you can frame your conclusions within the scope of the assumptions you make (it will be obvious what I mean when we get to this point below).

Assumptions:

1. Sensory nerves are what allow us to feel touch (pain / pressure in this case) on our skin.

2. We receive input from our sensory nerves from different parts of our bodies and we can both feel the pain and distinguish where the pain is coming from (i.e. you can tell the difference between pain in your finger from pain in your foot).

3. We distinguish these pains due to signals coming from different nerves (or possibly clusters)

4. We can activate these pain sensing nerves with the prick of a needle.

Given all the above, we devised a gadget to provide the nerve stimulation and get a measure of how far apart two stimuli are from one another. This was done by fastening one needle to the end of a ruler and another to a paper sleeve that can move along the ruler, thereby adjusting the distance between the two needles.

This experiment reminds me of the time we made our own laser-assisted surveying tool to determine how tall a tree was and whether it might be in danger of crushing our house when I cut it down.

Then we gathered some experimental data by using this device to stab one another (not too hard) with the two needles at the same time and measure the distance (in mm) between the two needles. we recorded the minimum distances that we could feel two pin pricks. Closer than these distances, the pain felt like a single pin.

As a second variable in the experiment, my son and I are very different in height. Because of this, we chose not to average the data between us, but to just have two measures (one for him and one for me) coming from each test point.

Here is a graphic representation of our data:

Minimum distance (in mm) that each subject could feel two pin pricks rather than one.

Conclusion:

We propose that different areas of the body are differently sensitive. This followed a fairly predictable pattern with the fingers and tongue being the most sensitive and the arm and back being the least sensitive. Although we don’t have sufficient data to be certain, it appears that Harry (a smaller child) was more sensitive throughout his body that Jack (an adult). Further, as distances got smaller, error in our apparatus made it impossible to get accurate results for the finger and tongue. Assuming that differences in sensitivity are determined by the degree of innervation and accurately provide a measure of innervation, then the arm and back are populated by many fewer nerves than the fingers and tongue.

Exploring the universe with lego

Some good news from The New Yorker this week…

First, the (nearly) nonagenarian magazine is opening up a large part of its archives to non-subscribers. A look into this library can be found here.

Second, Andy Borowitz reports that once, this nation actually believed in science. That’s right, these United States supported and the advancement of science as a public good. We have to wind back the clock to a time not so long ago, when science had a convergence of basic and applied goals. The public was rallying behind a space race to the moon (we chose the moon as the finish line because it was the only time we were ahead), while the politicos rallied behind the rockets that propelled them. After all, if we can put something on the moon with such precision that people could survive the journey, we can certainly put a rocket (and whatever payload we wanted) into any backyard in the world (even the Kremlin). 

I’m balking at bringing up this recent political hot potato, but because it is specifically referencing science and infectious disease, I feel like I ought to throw in my two bits. 

Rep. Phil Gingrey of Georgia recently voiced his concern that the children sent into this country illegally following political unrest in their home countries are likely to be brining many diseases across the border with them. What I take issue with are the diseases he is suggesting that these children might carry. 

From a M. Richinick article posted on msNBC:

“Reports of illegal migrants carrying deadly diseases such as swine flu, dengue fever, Ebola virus and tuberculosis are particularly concerning. Many of the children who are coming across the border also lack basic vaccinations such as those to prevent chicken pox or measles. This makes those Americans that are not vaccinated – and especially young children and the elderly – particularly susceptible,” Gingrey, a longtime physician, wrote in the letter.

Gingrey defended his letter Tuesday.

“The border patrol gave us a list of the diseases that they’re concerned about, and Ebola was one of those,” he told NBC News’ Luke Russert. ”I can’t tell you specifically that there were any cases of Ebola, I don’t think there were, but of course Tuberculosis, Chagas disease, many – small pox, some of the infectious diseases of children, all of these are concerns.”

 

The disease that has caught the most attention is Ebola. And given the recent outbreaks of Ebola in West Africa, it would be a major concern if it were to be brought into the States. Fortunately, the only cases of Ebola ever reported are in West Africa (For the geographically impaired, Africa hasn’t been close to Central America since about 100 million years ago). 

Another disease I would really, really worry about is Smallpox. Because there hasn’t been a recorded case anywhere in the world since 1978, it would be very bad if these kids had it.

We have related insects here in the US, but not the same Kissing Bugs.

Lastly, Chagas Disease. This one is at least possible. Lots of people do get Chagas Disease, and it is prevalent in Central and South America, where it is transmitted by its host, the Kissing Bug, which lives in thatch roofs and infects people sleeping in these homes by biting them and defecating on their faces. The infectious organism, T. cruzi, gets transmitted when these bite victims scratch at the bite and get the contaminated feces in the bite wound. Blood-to-blood contact can also spread this disease, but that is quite uncommon. So, again, I have to say I’m not too worried about Chagas Disease either.

Sorry for not putting more references in this post – perhaps I’ll edit it later. Right now I’d call it a rant. And… one last thing to add before I sign off: Gingrey is an OB/Gyn

While I was in the garden today I was listening to This American Life episode: 293. The gist of the episode was to uncover the occasions where having just a bit of knowledge was enough to get people in trouble. The first act consisted of Nancy Updike reflecting on things that she and others grew up ‘knowing.’ Things that parents or other figures of authority told them when they were small. Things that were just plain wrong. Yet, these ideas crystalized and remained somehow fixed in their minds even as they grew up to be old enough to know better.

One example was believing that unicorns were real. “Are they endangered or already extinct?” Like many of the anecdotes in this segment, the question was followed by stunned silence by all listeners.

Another take on the pitfalls of having just enough rope to hang yourself came from a story about an electrician, Bob Berenz. During the course of doing some background study in physics to help in realizing a dream of building a superconductor,” he happened upon the biggest idea of his life: A revelation about physics that would disprove Einstein, and Newton.”

Pursuing his new idea that all of modern physics was wrong, Bob has hit roadblock after roadblock, leaving him to with the conclusion that physics in such a closed community that no one else’s ideas are ever given a chance. To help resolve this, the producer of this story, Robert Powell, takes Bob to meet a physics professor and hash out his ideas. 

At this point, something happened that made me sad. This was a perfect moment for the professor, Dr. Brandt Watson, to embrace the teachable moment with Bob, but either he did not – or this was edited out of the story as I heard it. What I wanted to hear was not an argument about the math or confusion of terms (although these are obviously very important), but that the only way we know something (as well as we ever can) is to do experiments designed to falsify our thesis.

From the 1925 Boy Scientist, an illustration of how gravity bends light, in accordance with Einstein’s theory

I can only assume that Bob’s hypothesis made some sort of testable claim. Einstein, himself, struggled with this for many years before his ideas were put to a test to determine whether massive objects could bend light. The best way to test something – even a poor hypothesis – is to determine what it predicts in key situations and then see if the predictions are accurate.

Alas, poor Bob left Dr. Watson’s office unmoved by Watson’s criticisms.