Category Archives: health

Most traffic deaths are from driving too slow

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About 40,100 Americans lose their lives to traffic accidents every year. About 10,000 of these losses involve alcohol, and about the same number involve pedestrians, but far more people have their lives sucked away by waiting in traffic, IMHO. Hours are spent staring at a light, hoping it will change, or slowly plodding between destinations with their minds near blank. This slow loss of life is as real as the accidental type, but less dramatic.

Consider that Americans drive about 3.2 trillion miles each year. I’ll assume an average speed of 30 mph (the average speed registered on my car is 29 mph). Considering only the drivers of these vehicles, I calculate 133 billion man-hours of driving per year; that’s 15.2 million man-years or 217,000 man-lifetimes. If people were to drive a little faster, perhaps 10% faster, some 22,000 man lifetimes would be saved per year in time wasted. The simple change of raising the maximum highway speed to 80 mph from 70, I’d expect, would save half this, maybe 10,000 lifetimes. There would likely be some more accidental deaths, but not more accidents. Tiredness is a big part of highway accidents, as is highway congestion. Faster speeds decreases both, decreasing the number of accidents, but one expects there will be an increase in the deadliness of the accidents.

Highway deaths for the years before and after Nov. 1995. Most states raised speeds, but some left them unchanged.

Highway deaths for the years before and after speed limit were relaxed in Nov. 1995. At that time most states raised their speed limits, but some did not, leaving them at 65 rural, 55 urban; a few states were not included in this study because they made minor changes.

A counter to this expectation comes from the German Autobahn, the fastest highway in the world with sections that have no speed limit. German safety records show that there are far fewer accidents per km on the Autobahn, and that the fatality rate per km is about 1/3 that on other stretches of highway. This is about 1/2 the rate on US highways (see safety comparison). For a more conservative comparison, we could turn to the US experience of 1995. Before November 1995, the US federal government limited urban highway speeds to 55 mph, with 65 mph allowed only on rural stretches. When these limits were removed, several states left the speed limits in place, but many others raised their urban speed limits to 65 mph, and raised rural limits to 70 mph. Some western states went further and raised rural speed limits to 75 mph. The effect of these changes is seen on the graph above, copied from the Traffic Operations safety laboratory report. Depending on how you analyze the data, there was either a 2% jump (institute of highway safety) in highway deaths or perhaps a 5% jump. These numbers translate to a 3 or 6% jump because the states that did not raise speeds saw a 1% drop in death rates. Based on a 6% increase, I’d expect higher highway speed limits would cost some 2400 additional lives. To me, even this seems worthwhile when balanced against 10,000 lives lost to the life-sucking destruction of slow driving.

Texas has begun raising speed limits. Texans seem happy.

Texas has begun raising speed limits. So far, Texans seem happy.

There are several new technologies that could reduce automotive deaths at high speeds. One thought is to only allow high-speed driving for people who pass a high-speed test, or only for certified cars with passengers who are wearing a 5-point harness, or only on roads. More relevant to my opinion is only on roads with adequate walk-paths — many deaths involve pedestrians. Yet another thought; auto-driving cars (with hydrogen power?). Computer-aided drivers can have split second reaction times, and can be fitted with infra-red “eyes” that see through fog, or sense the motion of a warm object (pedestrian) behind an obstruction. The ability of computer systems to use this data is limited currently, but it is sure to improve.

I thought some math might be in order. The automotive current that is carried by a highway, cars/hour, can be shown to equal to the speed of the average vehicle multiplied by the number of lanes divided by the average distance between vehicles. C = v L/ d.

At low congestion, the average driving speed, v remains constant as cars enter and leave the highway. Adding cars only affects the average distance between cars, d. At some point, around rush hour, so many vehicles enter the highway that d shrinks to a distance where drivers become uncomfortable; that’s about d = 3 car lengths, I’d guess. People begin to slow down, and pretty soon you get a traffic jam — a slow-moving parking lot where you get less flow with more vehicles. This jam will last for the entirety of rush hour. One of the nice things about auto-drive cars is that they don’t get nervous, even at 2 car lengths or less at 70 mph. The computer is confident that it will brake as soon as the car in front of it brakes, maintaining a safe speed and distance where people will not. This is a big safety advantage for all vehicles on the road.

I should mention that automobile death rates vary widely between different states (see here), and even more widely between different countries. Here is some data. If you think some country’s drivers are crazy, you should know that many of the countries with bad reputations (Italy, Ireland… ) have highway death rates that are lower than ours. In other countries, in Africa and the mid-east death rates per car or mile driven are 10x, 100x, or 1000x higher than in the US. The countries have few cars and lots of people who walk down the road drunk or stoned. Related to this, I’ve noticed that old people are not bad drivers, but they drive on narrow country roads where people walk and accidents are common.

Robert Buxbaum, June 6, 2018.

Penicillin, cheese allergy, and stomach cancer

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penecillin molecule

The penicillin molecule is a product of the penicillin mold

Many people believe they are allergic to penicillin — it’s the most common perceived drug allergy — but several studies have shown that most folks who think they are allergic are not. Perhaps they once were, but when people who thought they were allergic were tested, virtually none showed allergic reaction. In a test of 146, presumably allergic patients at McMaster University, only two had their penicillin allergy confirmed; 98.6% of the patients tested negative. A similar study at the Mayo Clinic tested 384 pre-surgical patients with a history of penicillin allergy; 94% tested negative. They were given clearance to receive penicillin antibiotics before, during, and after surgery. Read a summary here.

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Orange showing three different strains of the penicillin mold; some of these are toxic.

This is very good news. Penicillin is a low-cost, low side-effect antibiotic, effective against many diseases including salmonella, botulism, gonorrhea, and scarlet fever. The penicillin molecule is a common product of nature, produced by a variety of molds, e.g. on the orange at right, and in cheese. It is thus something people have been exposed to, whether they realize it or not.

Penicillin allergy is a deadly danger for the few who really are allergic, and it’s worthwhile to find out if that means you. The good news: that penicillin is found in common cheeses suggests, to me, a simple test for penicillin allergy. Anyone who suspects penicillin allergy and does not have a general dairy allergy can try eating appropriate cheese: brie, blue, camembert, or Stilton. That is any of the cheeses made with penicillin molds. If you don’t break out in a rash or suffer stomach cramps, you’re very likely not allergic to penicillin.

There is some difference between cheeses, so if you have problems with Roquefort, but not brie or camembert, there’s still a good chance you’re not allergic to penicillin. Brie and camembert have a white fuzzy mold coat of Penicillium camemberti. This mold exudes penicillin — not in enough quantity to cure gonorrhea, but enough to give taste and avoid spoilage, and enough to test for allergy. Danish blue and Roquefort, shown below, have a different look and a sharper flavor . They’re made with blue-green, Penicillium roqueforti. This mold produces penicillin, but also a small amount of neurotoxin, roquefortine C. It’s not enough to harm most people, but it could cause an allergic reaction to folks who are not allergic to penicillin. Don’t eat a moldy orange, by the way; some forms of the mold produce a lot of neurotoxin.

For people who are not allergic, a thought I had is that one could, perhaps treat heartburn or ulcers with cheese; perhaps even cancer? H-Pylori, the bacteria associated with heartburn, is effectively treated by amoxicillin, a penicillin variant. If a penicillin variant kills the bacteria, it seems plausible that penicillin cheese might too. And since amoxicillin, is found to reduce the risk of gastric cancer, it’s reasonable to expect that penicillin or penicillin cheese might be cancer-protective. To my knowledge, this has never been studied, but it seems worth considering. The other, standard treatment for heartburn, pantoprazole / Protonix, is known to cause osteoporosis, and increase the risk of cancer, and it doesn’t taste as good as cheese.

A culture of Penicillium roqueforti. Most people are not allergic to it.

The blue in blue cheese is Penicillium roqueforti. Most people are not allergic.

Penicillin was discovered by Alexander Fleming, who noticed that a single spore of the mold killed the bacteria near it on a Petrie dish. He tried to produce significant quantities of the drug from the mold with limited success, but was able to halt disease in patients, and was able to interest others who had more skill in large-scale fungus growing. Kids looking for a good science fair project, might consider penicillin growing, penicillin allergy, treatment of stomach ailments using cheese, or anything else related to the drug. Three Swedish journals declared that penicillin was the most important discovery of the last 1000 years. It would be cool if the dilute form, the one available in your supermarket, could be shown to treat heartburn and/or cancer. Another drug you could study is Lysozyme, a chemical found in tears, in saliva, and in human milk (but not in cow milk). Alexander Fleming found that tears killed bacteria, as did penicillin. Lysozyme, the active ingredient, is currently used to treat animals, but not humans.

Robert Buxbaum, November 9, 2017. Since starting work on this essay I’ve been eating blue cheese. It tastes good and seems to cure heartburn. As a personal note: my first science fair project (4th grade) involved growing molds on moistened bread. For an incubator, I used the underside of our home radiator. The location kept my mom from finding the experiment and throwing it out.

Most flushable wipes aren’t flushable.

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I’m a chemical engineer running for Oakland county water resources commissioner, and as the main job of the office is sewage, and as I’ve already written on the chemistry, I thought I might write about an aspect of the engineering. Specifically about toilet paper. Toilet paper is a remarkable product: it’s paper, compact and low in cost; strong enough to clean you, smooth on your bum, and beyond that, it will disintegrate in turbulent water so it doesn’t clog pipes. The trick to TP’s dry strength and wet-weakness, is that the paper pulp, wood cellulose, is pounded very thin, yet cast fluffy. For extra softness, the paper is typically coated with aloe or similar. Sorry to say, the same recipe does not work for wet-wipes, paper towels or kleenex (facial tissues); all of these products must have wet-strength, and this can cause problems with sewer clogs.

Patent 117355 for perforated toilet paper claimed it as an improved wrapping paper.

Patent 117,355 for perforated toilet paper on a roll. It’s claimed as an improved wrapping paper.

Before there was toilet paper, the world was a much sadder, and smellier place. Much of the world used sticks, stones, leaves, or corn cobs, and none of these did a particularly thorough job. Besides, none of these is particularly smooth, or particularly disposable, nor did it fall apart — not that most folks had indoor plumbing. Some rich Romans had plumbing, and these cleaned themselves with a small sponge on the end of a stick. They dipped the sponge end in water for each use. It was disgusting, but didn’t clog the pipes. I’ve seen this in use on a trip to Turkey 25 years ago — not in actual use, but the stick and sponge was there in a smelly bucket next to the hole in the ground that served as the commode.

The first reasonably modern toilet was invented in 1775 by Alexander Cummings, and by 1852 the first public flush toilets were available. The design looked pretty much like it looks today and the cost was 1¢. You got a towel and a shoe-shine too for that penny, but there was no toilet paper as such. Presumably one used a Roman sponge or some ordinary, standard paper. A popular wipe, back in the day was the Sears-Roebuck catalog. It came free to most homes and included a convenient hole in the corner allowing one to hang it in and outhouse or near the commode. It was rough on the bum, and didn’t fall apart. My guess is that it clogged the pipes too, for those who used it with flush toilets. The first toilet-specific paper wasn’t invented till 1859. Joseph Gayetty, an American, patented a product from pulverized hemp, a relatively soft fiber, softened further with aloe. This paper was softer than standard, and had less tendency to clog pipes.

Toilet paper has to be soft

Toilet paper is either touted to be soft or strong; Modern Charmin touts wet strength, while Cottonelle touts completeness of wipe: ‘go commando.”

The next great innovation was to make toilet paper as a perforated product on a roll. These novelties appear as US Patent #117,355 awarded to Seth Wheeler of Albany, NY 25 July 1871 (Wheeler also invented the classic roll toilet paper dispenser). Much of the sales pitch was that a cleaner bum would prevent the spread of cholera, typhoid, and other plagues and that is a legitimate claim. As the  market expanded, advertising followed. Some early brands touted their softness, others their strength. Facial tissues, e.g. Kleenex, were sold specifically as a soft TP-like product that does not fall apart when wet. Sorry to say, this tends to go along with clogged toilets; do not flush more than one kleenex down at a flush. Kleenex is made with the same short fibers and aloe as toilet paper, but it contains binders (glue) to give it wet-strength. My guess is that Charmin is made the same way and that it isn’t great on your plumbing.

Paper towels and most baby wipes are worse to flush than Kleenex. They are made with lots of binder and they really don’t fall apart in water. Paper towels should never be flushed, and neither should most baby wipes, even brands that claim to be ‘flushable.” When flushed, these items tend to soak up fat and become fat bergs – the bane of sewer workers everywhere. There is a class action law suit against flushable wipe companies, and New York City is pursuing legislation to prevent them from claiming to be flushable. Still, as with everything, there are better and worse moist-wipe options. “Cottonelle” brand by Kleenex, and Scott flushable wipes are the best currently. In a day or less they will dissolve in water. These products are made with binders like kleenex, but the binder glue is a type that dissolves in any significant amount of water. As a result, these brands fall apart eventually. For now, these are the only flushable brands I’d recommend flushing, and even then I suggest you only flush one at a time. In tests by Consumer Reports, other brands, e.g. Charmin and Equate flushable wipes do not dissolve. These manufacturers either have not quite figured out how to make dissolvable binders, or they can’t get around Kleenex’s patents.

Robert Buxbaum. October 10, 2016. If you live in Oakland County, MI, vote for me for water commissioner. Here’s my web-site with other useful essays. I should mention Thomas Crapper, too. He invented the push-button flush and made some innovations in the water cistern, and he manufactured high-end commodes for Parliament and the royal family, but he’s irrelevant to the story here.

How to help Flint and avoid lead here.

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As most folks know, Flint has a lead-poisoning problem that seems to have begun in April, 2014 when the city switched its water supply from Detroit-supplied, Lake Huron water to their own source, water from the Flint River. Here are some thoughts on how to help the affected population, and how to avoid a repeat in Oakland county, where I’m running for water commissioner. First observation, it is not enough to make sure that the source water does not contain lead. The people who decided on the switch had found that the Flint river water had no significant content of lead or other obvious toxins. A key problem, it seems: the river water did not contain anticorrosion phosphates, and none, it seems, were added by the Flint water folks. It also seems that insufficient levels of chlorine (hypochlorite) were added. After the switch, citizens started seeing disgusting, brown water come from their taps, and citizens with lead pipes or solder were poisoned with ppb-levels of lead. There was also an outbreak of legionaries disease that killed 12 people. It was the legionaries that alerted the CDC to the possibility of lead, since it seems the water folks were fudging the numbers there, and hiding that part of the problem.

Flint water, Sept 2015, before switching back to Lake Huron.

Flint water after 5 hours of flushing, Sept 2015, before switching back to Lake Huron.

The city began solving its problem by switching back to Detroit-supplied, Lake Huron water in October, 2015. Beginning in December, 2015, they started adding triple doses of phosphate to the wate. As a result, Flint tap-water is now back within EPA standards, but it’s still fairly unsafe, see here for more details.

There has been a fair amount of finger-pointing. At Detroit for raising the price of water so Flint had to switch, at water officials ignoring the early signs of lead and fudging their reports, at other employees for not adding phosphate or enough chlorine, and at “the system” for not providing Flint’s government with better oversight. My take is that a lot of the problem came from the ignorance of the water commission, and it’s commissioner. We elect our water commissioners to be competent overseers of complex infrastructure, but in may counties folks seem to pick them the same way they pick aldermen: for a nice smile, a great handshake, and an ability to remember names. That, anyway, seems to be the way that Oakland got its current water commissioner. When you pick your commissioner that way, it’s no surprise that he (or she) isn’t particularly up on corrosion chemistry, something that few people understand, and fewer care about until it bites them.

Flint river water contains corrosive chloride that probably helped dissolve the lead from pipes and solder. Contributing to the corrosion problem, I’m going to guess that Flint River water also contains, relatively little carbonate, but significant amounts of chelating chemicals, like EDTA, in 10s of ppb concentration. EDTA isn’t poisonous at these concentrations, but it’s common in industry and is the most commonly used antidote for lead poisoning. EDTA extracts lead and other metals from people and would tend to contribute to the process of extracting lead and iron oxide from the pipes surface into the drinking water. With EDTA in the water, a lot of phosphate or hypochlorite would be needed to avoid the lead poisoning problem and the deadly multiplication of disease.

Detroit ex-mayor Kwame Kilpatrick has claimed that both Flint water and Detroit water were known to be poisoned even a decade before the switch. I find these claims believable given the high levels of lead in kids blood even before the switch. Also, I note that there are areas of Detroit where the blood-lead levels are higher than Flint. Flint tested at the taps in a way that fudged the data during the first days of the poisoning, and I suspect many of our MI cities do this today — just to make the numbers look better. My first suggestion therefore is to test correctly, both at the pipes and at the taps; lead pipes are most-often found in the last few feet before the tap. In particular, we should test at all schools and other places where the state has direct authorization to fix the problem. A MI senate bill has been proposed to this effect, but I’m not sure where it stands in the MI house. It seems there are movements to add lots of ‘riders’ and that’s usually a bad sign.

Another thought is that citizens should be encouraged to test their private taps and helped to fix them. The state can’t come in and test or rip out your private pipes, even if they suspect lead, but the private owner has that authorization. The state could condemn a private property where they believe the water is bad, but I doubt they could evict the residents. It’s a democratic republic, as I understand; you have the right to be deadly stupid. But I’ll take my own suggestion to encourage you: If you think your water has lead, take a sample and call (517) 335-8184. Do it.

Another suggestion, perhaps the easiest and most important, is drink bottled water for now, and if you feel you’ve been poisoned, take an antidote.  As I understand things, the state is already providing bottles of imported water. The most common antidote is, as I’d mentioned, EDTA. Assuming that Flint River water had enough EDTA to significantly worsen the problem, the cheapest antidote might be Flint River water, assuming you drew it in lead-free pipes and chlorinated sufficiently to rid it of bugs. If there is EDTA it will help the poisoned. Another antidote is Succinic acid, something sold by REB Research, my company. As with EDTA it is non-toxic, even in fairly large doses, but its use would have to be doctor- approved.

Robert E. Buxbaum, January 19-31, 2016. I hope this helps. We’d have to check Flint River water for levels of EDTA, but I suspect we’d find biologically significant concentrations. If you think Oakland should have an engineer in charge of the water, elect Buxbaum for water commissioner.

Zombie invasion model for surviving plagues

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Imagine a highly infectious, people-borne plague for which there is no immunization or ready cure, e.g. leprosy or small pox in the 1800s, or bubonic plague in the 1500s assuming that the carrier was fleas on people (there is a good argument that people-fleas were the carrier, not rat-fleas). We’ll call these plagues zombie invasions to highlight understanding that there is no way to cure these diseases or protect from them aside from quarantining the infected or killing them. Classical leprosy was treated by quarantine.

I propose to model the progress of these plagues to know how to survive one, if it should arise. I will follow a recent paper out of Cornell that highlighted a fact, perhaps forgotten in the 21 century, that population density makes a tremendous difference in the rate of plague-spread. In medieval Europe plagues spread fastest in the cities because a city dweller interacted with far more people per day. I’ll attempt to simplify the mathematics of that paper without losing any of the key insights. As often happens when I try this, I’ve found a new insight.

Assume that the density of zombies per square mile is Z, and the density of susceptible people is S in the same units, susceptible population per square mile. We define a bite transmission likelihood, ß so that dS/dt = -ßSZ. The total rate of susceptibles becoming zombies is proportional to the product of the density of zombies and of susceptibles. Assume, for now, that the plague moves fast enough that we can ignore natural death, immunity, or the birth rate of new susceptibles. I’ll relax this assumption at the end of the essay.

The rate of zombie increase will be less than the rate of susceptible population decrease because some zombies will be killed or rounded up. Classically, zombies are killed by shot-gun fire to the head, by flame-throwers, or removed to leper colonies. However zombies are removed, the process requires people. We can say that, dR/dt = kSZ where R is the density per square mile of removed zombies, and k is the rate factor for killing or quarantining them. From the above, dZ/dt = (ß-k) SZ.

We now have three, non-linear, indefinite differential equations. As a first step to solving them, we set the derivates to zero and calculate the end result of the plague: what happens at t –> ∞. Using just equation 1 and setting dS/dt= 0 we see that, since ß≠0, the end result is SZ =0. Thus, there are only two possible end-outcomes: either S=0 and we’ve all become zombies or Z=0, and all the zombies are all dead or rounded up. Zombie plagues can never end in mixed live-and-let-live situations. Worse yet, rounded up zombies are dangerous.

If you start with a small fraction of infected people Z0/S0 <<1, the equations above suggest that the outcome depends entirely on k/ß. If zombies are killed/ rounded up faster than they infect/bite, all is well. Otherwise, all is zombies. A situation like this is shown in the diagram below for a population of 200 and k/ß = .6

FIG. 1. Example dynamics for progress of a normal disease and a zombie apocalypse for an initial population of 199 unin- fected and 1 infected. The S, Z, and R populations are shown in (blue, red, black respectively, with solid lines for the zombie apocalypse, and lighter lines for the normal plague. t= t Nß where N is the total popula- tion. For both models the k/ß = 0.6 to show similar evolutions. In the SZR case, the S population disap- pears, while the SIR is self limiting, and only a fraction of the population becomes infected.

Fig. 1, Dynamics of a normal plague (light lines) and a zombie apocalypse (dark) for 199 uninfected and 1 infected. The S and R populations are shown in blue and black respectively. Zombie and infected populations, Z and I , are shown in red; k/ß = 0.6 and τ = tNß. With zombies, the S population disappears. With normal infection, the infected die and some S survive.

Sorry to say, things get worse for higher initial ratios,  Z0/S0 >> 0. For these cases, you can kill zombies faster than they infect you, and the last susceptible person will still be infected before the last zombie is killed. To analyze this, we create a new parameter P = Z + (1 – k/ß)S and note that dP/dt = 0 for all S and Z; the path of possible outcomes will always be along a path of constant P. We already know that, for any zombies to survive, S∞ = 0. We now use algebra to show that the final concentration of zombies will be Z∞ = Z0 + (1-k/ß)S0. Free zombies survive so long as the following ratio is non zero: Z0/S0 + 1- k/ß. If Z0/S0 = 1, a situation that could arise if a small army of zombies breaks out of quarantine, you’ll need a high kill ratio, k/ß > 2 or the zombies take over. It’s seen to be harder to stop a zombie outbreak than to stop the original plague. This is a strong motivation to kill any infected people you’ve rounded up, a moral dilemma that appears some plague literature.

Figure 1, from the Cornell paper, gives a sense of the time necessary to reach the final state of S=0 or Z=0. For k/ß of .6, we see that it takes is a dimensionless time τ of 25 or to reach this final, steady state of all zombies. Here, τ= t Nß and N is the total population; it takes more real time to reach τ= 25 if N is high than if N is low. We find that the best course in a zombie invasion is to head for the country hoping to find a place where N is vanishingly low, or (better yet) where Z0 is zero. This was the main conclusion of the Cornell paper.

Figure 1 also shows the progress of a more normal disease, one where a significant fraction of the infected die on their own or develop a natural immunity and recover. As before, S is the density of the susceptible, R is the density of the removed + recovered, but here I is the density of those Infected by non-zombie disease. The time-scales are the same, but the outcome is different. As before, τ = 25 but now the infected are entirely killed off or isolated, I =0 though ß > k. Some non-infected, susceptible individuals survive as well.

From this observation, I now add a new conclusion, not from the Cornell paper. It seems clear that more immune people will be in the cities. I’ve also noted that τ = 25 will be reached faster in the cities, where N is large, than in the country where N is small. I conclude that, while you will be worse off in the city at the beginning of a plague, you’re likely better off there at the end. You may need to get through an intermediate zombie zone, and you will want to get the infected to bury their own, but my new insight is that you’ll want to return to the city at the end of the plague and look for the immune remnant. This is a typical zombie story-line; it should be the winning strategy if a plague strikes too. Good luck.

Robert Buxbaum, April 21, 2015. While everything I presented above was done with differential calculus, the original paper showed a more-complete, stochastic solution. I’ve noted before that difference calculus is better. Stochastic calculus shows that, if you start with only one or two zombies, there is still a chance to survive even if ß/k is high and there is no immunity. You’ve just got to kill all the zombies early on (gun ownership can help). Here’s my statistical way to look at this. James Sethna, lead author of the Cornell paper, was one of the brightest of my Princeton PhD chums.

Is college worth no cost?

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While a college degree gives most graduates a salary benefit over high school graduates, a study by the Bureau of Labor statistics indicates that the benefits disappear if you graduate in the bottom 25% of your class. Worse yet, if you don’t graduate at all you can end up losing salary money, especially if you go into low-paying fields like child development or physical sciences.

Salary benefits of a college degree are largely absent if you graduate in the bottom 25% of your class.

The average college graduate earns significantly more than a high school grad, but not if you attend a pricy school, or graduate in the bottom 1/4 of your class, or have the wrong major.

Most people realize there is a great earnings difference depending on your field of study with graduates in engineering and medicine doing fairly well financially and even top graduates in child development or athletic sciences barely able to justify the college and opportunity costs (worse if they go to an expensive college), but what isn’t always realized is that not all those who enter these fields graduate. For them there is a steep loss when the four (or more) years of lost income are considered.

risk premium in wages

If you don’t graduate or get only an AA or 2 year degree the increase in wages is minimal, and you lose time working and whatever your costs of education. The loss is particularly high if you study social science fields at an expensive college, and don’t graduate, or if you graduate in the bottom of your class.

A report from the New York Federal Reserve finds that the highest pay major is petroleum engineering, mid-career salary $176,300/yr, and the bottom is child development, mid-career salary $36,400/yr (click to check on your major). I’m not sure most students or advisors are aware of the steep salary difference, or that college can have a salary down-side if one picks the wrong major, or does not complete the degree. In terms of earnings, you might be better off avoiding even a free college degree in these areas unless you’re fairly sure you’ll complete the degree, or you really want to work in these fields.

Top earning majors Fed Reserve and Majors that pay you back.

Top earning majors: Majors that pay.

Of course college can provide more than money: knowledge, for instance, and learning: the ability to reason better. But these benefits are likely lost if you don’t work at it, or don’t go in a field you love. They can also come to those who study hard in self-taught reading. In either case, it is the work habits that will make you grow as a person, and leave you more employable. Tough colleges add a lot by exposure to new people and new ways of thinking about great books, and by forced experience in writing essays — but these benefits too are work-dependent and college dependent. If you work hard understanding a great book it will show. If you didn’t work at it, or only exposed yourself to easier fare, that too will show.

As students don’t like criticism, and as good criticism is hard to give — and harder to give well, many less-demanding colleges ,give little or no critical feedback, especially for disadvantaged students. This disadvantages them even more as criticism is an important part of learning. If all you get is a positive experience, a nice campus, and a dramatic graduation, this is not learning. Nor is it necessarily worth 4-5 years of your life.

As a comic take on the high time-cost of a liberal arts education, “Father” Guido Sarduchi, of Saturday Night LIve, describes his “5 minute college experience.” To a surprising extent, it provides everything you’ll remember of 4 year college experience in 5 minutes, including math, history, political science, and language (Spanish).For those who are not sure they will complete a liberal arts education, Father Sarduchi’s 5 minutes may be a better investment than a free 4 years in community college.

Robert. E. Buxbaum. January 21-22, 2015. My sense is that the better part of education is what you get when you don’t get what you want.

Statistics of death and taxes — death on tax day

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Strange as it seems, Americans tend to die in road accidents on tax-day. This deadly day is April 15 most years, but on some years April 15th falls out on a weekend and the fatal tax day shifts to April 16 or 17. Whatever weekday it is, about 8% more people die on the road on tax day than on the same weekday a week earlier or a week later; data courtesy of the US highway safety bureau and two statisticians, Redelmeier and Yarnell, 2014.

Forest plot of individuals in fatal road crashes over 30 years. X-axis shows relative increase in risk on tax days compared to control days expressed as odds ratio. Y-axis denotes subgroup (results for full cohort in final row). Column data are counts of individuals in crashes. Analytic results expressed with 95% confidence intervals setting control days as referent. Results show increased risk on tax day for full cohort, similar increase for 25 of 27 subgroups, and all confidence intervals overlapping main analysis. Recall that odds ratios are reliable estimates of relative risk when event rates are low from an individual driver’s perspective.

Forest plot of individuals in fatal road crashes for the 30 years to 2008  on US highways (Redelmeier and Yarnell, 2014). X-axis shows relative increase in risk on tax days compared to control days expressed as odds ratio. Y-axis denotes subgroup (results for full cohort in final row). Column data are counts of individuals in crashes (there are twice as many control days as tax days). Analytic results are 95% confidence intervals based on control days as referent. Dividing the experimental subjects into groups is a key trick of experimental design.

To confirm that the relation isn’t a fluke, the result of well-timed ice storms or football games, the traffic death data was down into subgroups by time, age, region etc– see figure. Each groups showed more deaths than on the average of the day a week before and after.

The cause appears unrelated to paying the tax bill, as such. The increase is near equal for men and women; with alcohol and without, and for those over 18 and under (presumably those under 18 don’t pay taxes). The death increase isn’t concentrated at midnight either, as might be expected if the cause were people rushing to the post office. The consistency through all groups suggests this is not a quirk of non-normal data, nor a fluke but a direct result of  tax-day itself.Redelmeier and Yarnell suggest that stress — the stress of thinking of taxes — is the cause.

Though stress seems a plausible explanation, I’d like to see if other stress-related deaths are more common on tax day — heart attack or stroke. I have not done this, I’m sorry to say, and neither have they. General US death data is not tabulated day by day. I’ve done a quick study of Canadian tax-day deaths though (unpublished) and I’ve found that, for Canadians, Canadian tax day is even more deadly than US tax day is for Americans. Perhaps heart attack and stroke data is available day by day in Canada (?).

Robert Buxbaum, December 12, 2014. I write about all sorts of stuff. Here’s my suggested, low stress income tax structure, and a way to reduce/ eliminate income taxes: tariffs– they worked till the Civil war. Here’s my thought on why old people have more fatal car accidents per mile driven.

Seniors are not bad drivers.

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Seniors cause accidents, but need to get places too

Seniors are often made fun of for confusion and speeding, but it’s not clear they speed, and it is clear they need to get places. Would reduced speed limits help them arrive alive?

Seniors have more accidents per-mile traveled than middle age drivers. As shown on the chart below, older Canadians, 75+, get into seven times more fatal accidents per mile than 35 to 55 year olds. At first glance, this would suggest they are bad drivers who should be kept from the road, or at least made to drive slower. But I’m not so sure they are bad drivers, and am pretty certain that lower speed limits should not be generally imposed. I suspect that a lot of the problem comes from the a per-mile basis comparison with folks who drive long distances on the same superhighways instead of longer, leisurely drives on country roads. I suspect that, on a per-hour basis, the seniors would look a lot safer, and on a per highway-mile basis they might look identical to younger drivers.

Canadian Vehicle Survey, 2001, Statistics Canada, includes drivers of light duty vehicles.

Deaths per billion km. Canadian Vehicle Survey, 2001, Statistics Canada, includes light duty vehicles.

Another source of misunderstanding, I find, is that comparisons tend to overlook how very low the accident rates are. The fatal accent rate for 75+ year old drivers sounds high when you report it as 20 deaths per billion km. But that’s 50,000,000 km between fatalities, or roughly one fatality for each 1300 drives around the earth. In absolute terms it’s nothing to worry about. Old folks driving provides far fewer deaths per km than 12-29 year olds walking, and fewer deaths per km than for 16-19 year olds driving.

When starting to research this essay, I thought I’d find that the high death rates were the result of bad reaction times for the elderly. I half expected to find that reduced speed limits for them helped. I’ve not found any data directly related to reduced speeds, but now think that lowered speed limits would not help them any more than anyone else. I note that seniors drive for pleasure more than younger folks and do a lot more short errand drives too — to the stores, for example. These are places where accidents are more common. By contrast, 40 to 70 year olds drive more miles on roads that are relatively safe.

Don't walk, especially if you're old.

Don’t walk, especially if you’re old. Netherlands data, 2001-2005 fatalities per billion km.

The Netherlands data above suggest that any proposed solution should not involve getting seniors out of their cars. Not only do seniors find walking difficult, statistics suggest walking is 8 to 10 times more dangerous than driving, and bicycling is little better. A far better solution, I suspect, is reduced speeds for everyone on rural roads. If you’re zipping along a one-lane road at the posted 40, 55, or 60 mph and someone backs out of a driveway, you’re toast. The high posted speeds on these roads pose a particular danger to bicyclists and motorcyclists of all ages – and these are folks who I suspect drive a lot on the rural roads. I suspect that a 5 mph reduction would do quite a lot.

For automobiles on super-highways, it may be worthwhile to increase the speed limits. As things are now, the accident fatality rates are near zero, and the main problem may be the time wasted behind the wheel – driving from place to place. I suspect that an automobile speed limit raise to 80 mph would make sense on most US and Canadian superhighways; it’s already higher on the Autobahn in Germany.

Robert Buxbaum, November 24, 2014. Expect an essay about death on tax-day, coming soon. I’ve also written about marijuana, and about ADHD.

Change your underwear; of mites and men

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The underware bomber mites make it right.

Umar, the underwear bomber.

For those who don’t know it, the underwear bomber, Umar Farook Abdulmutallab, wore his pair of explosive underwear for 3 weeks straight before trying to detonate them while flying over Detroit in 2009. They didn’t go off, leaving him scarred for life. It’s quite possible that the nasty little mites that live in underwear stopped the underwear bomber. They are a main source of US allergens too.

Dust mite, skin, and pollen seen with a light microscope. Gimmie some skin.

Dust mite, skin, and pollen seen with a light microscope. Gimmie some skin.

If you’ve ever used an electron microscope to look at household objects, you’ll find them covered with brick-like flakes of dried out skin-cells: yours and your friends’. Each person sheds his or her skin every month, on average. The outer layer dries out and flakes off as new skin grows in behind it. Skin flakes are the single largest source of household dust, and if not for the fact that these flakes are the main food for mites, your house would be chock full of your left over skin. When sunlight shines in your window, you see the shimmer of skin-flakes hanging in the air. Under the electron microscope, the fresh skin flakes look like bricks, but mite-eaten skin flakes look irregular. Less common, but more busy are the mites.

The facial mite movie. They live on in us, about 1 per hair follicle, particularly favoring eyelashes. Whenever you shower, your shower with a friend.

The facial mite movie. They live on in us, about 1 per hair follicle, particularly favoring eyelashes. Whenever you shower, you shower with a friend.

Dry skin is mostly protein (keratin), plus cholesterol and squalene. This provides great nutrition for dust mites and their associated bacteria. In warm, damp environments, as in your underwear or mattress, these beasties multiply and eat the old skin. The average density of dust mites on a mattress is greater than 2500/gram of dust.[1]  The mites leave behind excrement and broken off mite-limbs: nasty bits that are the most common allergens in the US today.

An allergy to dust shows up as sneezing, coughing, clogged lungs, and eczema. The most effective cure is a high level of in-home hygiene; mites don’t like soap or dry air. You’ve go to mop and vacuum regularly. Clean and change your clothing, particularly your undergarments; rotate your mattresses, and shake the dust out of your bedding. Vacuuming is less-effective as a significant fraction of the nasties go through the filter and get spread around by the vacuum blower.

As it turns out, dust mites and their bacteria eat more than skin. They also eat dried body fluids, poop residue, and the particular explosive used by Umar Farook, pentaerythritol tetra nitrate, PETN (humans can eat and metabolize this stuff too — it’s an angina treatment). The mites turn PETN into less-explosive versions, plus more mites.

Mighty mites as seen with electron microscopy. They eat more than skin.

Mighty mites as seen with electron microscopy. They eat more than skin.

There are many varieties of mite living on and among us. Belly button mites, for example, and face mites as shown above (click on the image to see it move). On average, people have one facial mite per hair follicle. It’s also possible that the bomber was stopped by poor quality control engineering and not mites at all. Religion tends to be at odds with a science like quality control, and followers tend to put their faith in miracles.

Chigger turning on a dime

Chigger turning on a dime

larger than the dust mite is the chigger, shown at left. Chiggers leave visible bites, particularly along the underwear waste-band. There are larger-yet critters in the family: lice, bed bugs, crabs. Bathing regularly, and cleaning your stuff will rid yourself of all these beasties, at least temporarily. Keeping your hair short and your windows open helps too. Mites multiply in humid, warm environments. Opening the windows dries and cools the air, and blows out mite-bits that could cause wheezing. Benjamin Franklin and took air-baths too: walking around naked with the windows open, even in winter. It helped that he lived on the second floor. Other ways to minimize mite growth include sunlight, DOT (a modern version of DDT), and eucalyptus oil. At the very minimum, change your underwear regularly. It goes a long way to reduce dust embarrassing moments at the jihadist convention.

Dr. Robert E. Buxbaum, Sept 21, 2014. Not all science or life is this weird and wonderful, but a lot is, and I prefer to write about the weird and wonderful bits. See e.g. the hazards of health food, the value of sunshine, or the cancer hazard of living near a river. Or the grammar of pirates.

In praise of openable windows and leaky construction

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It’s summer in Detroit, and in all the tall buildings the air conditioners are humming. They have to run at near-full power even on evenings and weekends when the buildings are near empty, and on cool days. This would seem to waste a lot of power and it does, but it’s needed for ventilation. Tall buildings are made air-tight with windows that don’t open — without the AC, there’s be no heat leaving at all, no way for air to get in, and no way for smells to get out.

The windows don’t open because of the conceit of modern architecture; air tight building are believed to be good design because they have improved air-conditioner efficiency when the buildings are full, and use less heat when the outside world is very cold. That’s, perhaps 10% of the year. 

No openable windows, but someone figured you should suffer for art

Modern architecture with no openable windows. Someone wants you to suffer for his/her art.

Another reason closed buildings are popular is that they reduce the owners’ liability in terms of things flying in or falling out. Owners don’t rain coming in, or rocks (or people) falling out. Not that windows can’t be made with small openings that angle to avoid these problems, but that’s work and money and architects like to spend time and money only on fancy facades that look nice (and are often impractical). Besides, open windows can ruin the cool lines of their modern designs, and there’s nothing worse, to them, than a building that looks uncool despite the energy cost or the suffering of the inmates of their art.

Most workers find sealed buildings claustrophobic, musty, and isolating. That pain leads to lost productivity: Fast Company reported that natural ventilation can increase productivity by up to 11 percent. But, as with leading clothes stylists, leading building designers prefer uncomfortable and uneconomic to uncool. If people in the building can’t smell an ocean breeze, or can’t vent their area in a fire (or following a burnt burrito), that’s a small price to pay for art. Art is absurd, and it’s OK with the architect if fire fumes have to circulate through the entire building before they’re slowly vented. Smells add character, and the architect is gone before the stench gets really bad. 

No one dreams of working in an unventilated glass box.

No one dreams of working in a glass box. If it’s got to be an office, give some ventilation.

So what’s to be done? One can demand openable windows and hope the architect begrudgingly obliges. Some of the newest buildings have gone this route. A simpler, engineering option is to go for leaky construction — cracks in the masonry, windows that don’t quite seal. I’ve maintained and enlarged the gap under the doors of my laboratory buildings to increase air leakage; I like to have passive venting for toxic or flammable vapors. I’m happy to not worry about air circulation failing at the worst moment, and I’m happy to not have to ventilate at night when few people are here. To save some money, I increase the temperature range at night and weekends so that the buildings is allowed to get as hot as 82°F before the AC goes on, or as cold as 55°F without the heat. Folks who show up on weekends may need a sweater, but normally no one is here. 

A bit of air leakage and a few openable windows won’t mess up the air-conditioning control because most heat loss is through the walls and black body radiation. And what you lose in heat infiltration you gain by being able to turn off the AC circulation system when you know there are few people in the building (It helps to have a key-entry system to tell you how many people are there) and the productivity advantage of occasional outdoor smells coming in, or nasty indoor smells going out.

One irrational fear of openable windows is that some people will not close the windows in the summer or in the dead of winter. But people are quite happy in the older skyscrapers (like the empire state building) built before universal AC. Most people are nice — or most people you’d want to employ are. They will respond to others feelings to keep everyone comfortable. If necessary a boss or building manager may enforce this, or may have to move a particularly crusty miscreant from the window. But most people are nice, and even a degree of discomfort is worth the boost to your psyche when someone in management trusts you to control something of the building environment.

Robert E. Buxbaum, July 18, 2014. Curtains are a plus too — far better than self-darkening glass. They save energy, and let you think that management trusts you to have power over your environment. And that’s nice.