Steven Eidman's Blog

The Official Blog of Steven Eidman

Archive for the ‘physics’ Category

Posted by steveneidman on March 3, 2010

Warning: Your Reality is Out of Date.

Introducing the Mesofact

By Samuel Arbesman  

When people think of knowledge, they generally think of two sorts of facts: facts that don’t change, like the height of Mount Everest or the capital of the United States, and facts that fluctuate constantly, like the temperature or the stock market close.

But in between there is a third kind: facts that change slowly. These are facts which we tend to view as fixed, but which shift over the course of a lifetime. For example: What is Earth’s population? I remember learning 6 billion, and some of you might even have learned 5 billion. Well, it turns out it’s about 6.8 billion.

Or, imagine you are considering relocating to another city. Not recognizing the slow change in the economic fortunes of various metropolitan areas, you immediately dismiss certain cities. For example, Pittsburgh, a city in the core of the historic Rust Belt of the United States, was for a long time considered to be something of a city to avoid. But recently, its economic fortunes have changed, swapping steel mills for technology, with its job growth ranked sixth in the entire United States.

These slow-changing facts are what I term “mesofacts.” Mesofacts are the facts that change neither too quickly nor too slowly, that lie in this difficult-to-comprehend middle, or meso-, scale. Often, we learn these in school when young and hold onto them, even after they change. For example, if, as a baby boomer, you learned high school chemistry in 1970, and then, as we all are apt to do, did not take care to brush up on your chemistry periodically, you would not realize that there are 12 new elements in the Periodic Table. Over a tenth of the elements have been discovered since you graduated high school! While this might not affect your daily life, it is astonishing and a bit humbling.

For these kinds of facts, the analogy of how to boil a frog is apt: Change the temperature quickly, and the frog jumps out of the pot. But slowly increase the temperature, and the frog doesn’t realize that things are getting warmer, until it’s been boiled. So, too, is it with humans and how we process information. We recognize rapid change, whether it’s as simple as a fast-moving object or living with the knowledge that humans have walked on the moon. But anything short of large-scale rapid change is often ignored. This is the reason we continue to write the wrong year during the first days of January.

Our schools are biased against mesofacts. The arc of our educational system is to be treated as little generalists when children, absorbing bits of knowledge about everything from biology to social studies to geology. But then, as we grow older, we are encouraged to specialize. This might have been useful in decades past, but in our increasingly fast-paced and interdisciplinary world, lacking an even approximate knowledge of our surroundings is unwise.

Updating your mesofacts can change how you think about the world. Do you know the percentage of people in the world who use mobile phones? In 1997, the answer was 4 percent. By 2007, it was nearly 50 percent. The fraction of people who are mobile phone users is the kind of fact you might read in a magazine and quote at a cocktail party. But years later the number you would be quoting would not just be inaccurate, it would be seriously wrong. The difference between a tiny fraction of the world and half the globe is startling, and completely changes our view on global interconnectivity.

Mesofacts can also be fun. Let’s focus for a moment on some mesofacts that can be of vital importance if you’re a child, or parent of a child: those about dinosaurs. Just a few decades ago, dinosaurs were thought to be cold-blooded, slow-witted lizards that walked with their legs splayed out beside them. Now, scientists think that many dinosaurs were warm-blooded and fast-moving creatures. And they even had feathers! Just a few weeks ago we learned about the color patterns of dinosaurs (stripes! with orange tufts!). These facts might not affect how you live your life, but then again, you’re probably not 6 years old. There is another mesofact that is unlikely to affect your daily routine, but might win you a bar bet: the number of planets known outside the solar system. After the first extrasolar planet around an ordinary star made headlines back in 1995, most people stopped paying attention. Well, the number of extrasolar planets is currently over 400. Know this, and the next round won’t be on you.

The fact that the world changes rapidly is exciting, but everyone knows about that. There is much change that is neither fast nor momentous, but no less breathtaking.

 

Posted in Politics, culture, economics, economy, history, physics, psychology, tehcnology | Tagged: , | Leave a Comment »

Posted by steveneidman on February 4, 2010

It’s the Phenome and Not the Genome: Put Your Money on Mortal Flesh

by Abraham Verghese

doctor-David McNew-big.jpg

Strong is your hold O mortal flesh . . .

From The Last Invocation, Walt Whitman

Is it just me, or are you also getting a bit tired of all the hype about the genome? Don’t get me wrong– it’s pretty incredible that in my lifetime we have mapped out the 25,000 plus genes in our DNA. What’s even more amazing is that the price for that chart of the human genome has gone from millions to less than $50,000 and now it takes only a few weeks. I bet by next year it might be a few hundred dollars and take a day! Companies like 23andMe (an innovative venture with a great marketing plan) offer to check you for genetic markers that predict your risk for certain diseases for just a few hundred dollars.

But the fact remains that for most of us, the genotype is much less relevant than the phenotype. What is phenotype? It is the things we can see, the outward or observable physical or biochemical characteristics and they are determined by both your genetic makeup and environmental influences. Your blond hair, your weight, your strange nose, green eyes and that funky shaped little toe of yours –all examples of phenotype.

So what do I mean when I say phenotype is more relevant than genotype? Well, let’s say a new patient, a male, walks into my office and he is in his fifties. Let’s say he happens to have the outline of a pack of cigarettes showing in his front pocket. As a male he already has one risk factor for coronary artery disease–just being male, alas. The cigarettes tell me that he is four times more likely to have a heart attack than his peers who don’t smoke. His risk of sudden death is at least doubled. Let’s say I notice he happens to be carrying more than 30 pounds of extra poundage above the belt line: that allows me to predict he has a higher chance of being at risk for diabetes, if he is not already frankly diabetic. Let’s say that I notice too the pale outline of a recently-removed wedding ring (I can’t help it, my eyes are always looking at the body as text–even when I am out of the hospital), then I know that his risk of death as a  recently divorced man can be double that of his married peers.

At this point, before he has even said a word or before I have examined him, I already know so much about his risk of death and disease. Once we talk and I learn more about his job, his stress, his heredity, his habits, his past illnesses, then my predictions get more accurate. Once he disrobes and I examine him, I might find other phenotypic markers that predict risk (such as yellow plaques related to high cholesterol on his eyelids or elbows; high blood pressure; skin tags and velvety darkened areas of skin that predict diabetes; narrowed blood vessels when I look into the back of his eye . . . the list could go on for pages). In short, I’ll have an excellent sense of my patient’s risk for death or disease. At that point, mapping his whole genome, sexy as it might seem, won’t tell me much more than I know and will probably matter much less than getting him to quit smoking, exercise and lose weight.

The famous Whitehall Study of British Civil Servants ranging in ages from 20 to 64 found that the lower grades of civil service had higher mortality rates from heart disease and from all causes than did people in higher grades, even after accounting for risk factors like obesity and smoking. (Yes, it was counterintuitive and that is why we do studies).  Stress was thought to be the factor responsible for this disparity.

The Whitehall studies are ongoing and one of the latest reports from that study made me think of Walt Whitman and reminded me that the phenotype is so relevant. In their report (titled, “Utility of genetic and non-genetic risk factors in prediction of type 2 diabetes: Whitehall II prospective cohort study” and appearing in the British Medical Journal, 2010 Jan 14;340:b4838), the scientists compared a panel of genetic tests for diabetes (common single nucleotide polymorphisms) with non-genetic or phenotypic findings like age, sex, drug treatment, family history of type 2 diabetes, body mass index, smoking status, HDL, triglycerides, fasting glucose.

What they found was that the phenotypic tests did better. Indeed the gene tests added little to the risk already determined by phenotypes. In their own words, “the addition of genotypes to phenotype based risk models produced only minimal improvement in accuracy of risk estimation  . . .”  Translation: use your eyes, take a good history, weight the patient and get a few simple blood tests, and you can predict risk far better than a panel of genetic tests. 

I am not a Luddite (I find I say that a lot) and indeed, I do think the genome studies will help us eventually understand more about causes of disease, and perhaps even point to particular treatments. But utill then the message for us in the trenches is: Strong is your hold O mortal flesh and that’s where the money (speaking diagnostically) is.

Posted in Healthcare, Law, Medicaid, Politics, Steven Eidman, abortion, business, culture, economics, economy, gender, physics, psychology, tehcnology | Tagged: , , , , , , | Leave a Comment »

Your Plane is Going Down. Now What?

Posted by steveneidman on February 1, 2010

How to Fall 35,000 Feet—And Survive

By Dan Koeppel

6:59:00 AM

35,000 Feet

You have a late night and an early flight. Not long after takeoff, you drift to sleep. Suddenly, you’re wide awake. There’s cold air rushing everywhere, and sound. Intense, horrible sound. Where am I?, you think. Where’s the plane?

You’re 6 miles up. You’re alone. You’re falling.

Things are bad. But now’s the time to focus on the good news. (Yes, it goes beyond surviving the destruction of your aircraft.) Although gravity is against you, another force is working in your favor: time. Believe it or not, you’re better off up here than if you’d slipped from the balcony of your high-rise hotel room after one too many drinks last night.

Or at least you will be. Oxygen is scarce at these heights. By now, hypoxia is starting to set in. You’ll be unconscious soon, and you’ll cannonball at least a mile before waking up again. When that happens, remember what you are about to read. The ground, after all, is your next destination.

Granted, the odds of surviving a 6-mile plummet are extra­ordinarily slim, but at this point you’ve got nothing to lose by understanding your situation. There are two ways to fall out of a plane. The first is to free-fall, or drop from the sky with absolutely no protection or means of slowing your descent. The second is to become a wreckage rider, a term coined by Massachusetts-based amateur historian Jim Hamilton, who developed the Free Fall Research Page—an online database of nearly every imaginable human plummet. That classification means you have the advantage of being attached to a chunk of the plane. In 1972, Serbian flight attendant Vesna Vulovic was traveling in a DC-9 over Czechoslovakia when it blew up. She fell 33,000 feet, wedged between her seat, a catering trolley, a section of aircraft and the body of another crew member, landing on—then sliding down—a snowy incline before coming to a stop, severely injured but alive.

Surviving a plunge surrounded by a semiprotective cocoon of debris is more common than surviving a pure free-fall, according to Hamilton’s statistics; 31 such confirmed or “plausible” incidents have occurred since the 1940s. Free-fallers constitute a much more exclusive club, with just 13 confirmed or plausible incidents, including perennial Ripley’s Believe It or Not superstar Alan Magee—blown from his B-17 on a 1943 mission over France. The New Jersey airman, more recently the subject of a MythBusters episode, fell 20,000 feet and crashed into a train station; he was subsequently captured by German troops, who were astonished at his survival.

Whether you’re attached to crumpled fuselage or just plain falling, the concept you’ll be most interested in is terminal velocity. As gravity pulls you toward earth, you go faster. But like any moving object, you create drag—more as your speed increases. When downward force equals upward resistance, acceleration stops. You max out.

Depending on your size and weight, and factors such as air density, your speed at that moment will be about 120 mph—and you’ll get there after a surprisingly brief bit of falling: just 1500 feet, about the same height as Chicago’s Sears (now Willis) Tower. Equal speed means you hit the ground with equal force. The difference is the clock. Body meets Windy City sidewalk in 12 seconds. From an airplane’s cruising altitude, you’ll have almost enough time to read this entire article.

7:00:20 AM

22,000 Feet

By now, you’ve descended into breathable air. You sputter into consciousness. At this altitude, you’ve got roughly 2 minutes until impact. Your plan is simple. You will enter a Zen state and decide to live. You will understand, as Hamilton notes, “that it isn’t the fall that kills you—it’s the landing.”

Keeping your wits about you, you take aim.

But at what? Magee’s landing on the stone floor of that French train station was softened by the skylight he crashed through a moment earlier. Glass hurts, but it gives. So does grass. Haystacks and bushes have cushioned surprised-to-be-alive free-fallers. Trees aren’t bad, though they tend to skewer. Snow? Absolutely. Swamps? With their mucky, plant-covered surface, even more awesome. Hamilton documents one case of a sky diver who, upon total parachute failure, was saved by bouncing off high-tension wires. Contrary to popular belief, water is an awful choice. Like concrete, liquid doesn’t compress. Hitting the ocean is essentially the same as colliding with a sidewalk, Hamilton explains, except that pavement (perhaps unfortunately) won’t “open up and swallow your shattered body.”

With a target in mind, the next consideration is body position. To slow your descent, emulate a sky diver. Spread your arms and legs, present your chest to the ground, and arch your back and head upward. This adds friction and helps you maneuver. But don’t relax. This is not your landing pose.

The question of how to achieve ground contact remains, regrettably, given your predicament, a subject of debate. A 1942 study in the journal War Medicine noted “distribution and compensation of pressure play large parts in the defeat of injury.” Recommendation: wide-body impact. But a 1963 report by the Federal Aviation Agency argued that shifting into the classic sky diver’s landing stance—feet together, heels up, flexed knees and hips—best increases survivability. The same study noted that training in wrestling and acrobatics would help people survive falls. Martial arts were deemed especially useful for hard-surface impacts: “A ‘black belt’ expert can reportedly crack solid wood with a single blow,” the authors wrote, speculating that such skills might be transferable.

The ultimate learn-by-doing experience might be a lesson from Japanese parachutist Yasuhiro Kubo, who holds the world record in the activity’s banzai category. The sky diver tosses his chute from the plane and then jumps out after it, waiting as long as possible to retrieve it, put it on and pull the ripcord. In 2000, Kubo—starting from 9842 feet—fell for 50 seconds before recovering his gear. A safer way to practice your technique would be at one of the wind-tunnel simulators found at about a dozen U.S. theme parks and malls. But neither will help with the toughest part: sticking the landing. For that you might consider—though it’s not exactly advisable—a leap off the world’s highest bridge, France’s Millau Viaduct; its platform towers 891 feet over mostly spongy farmland.

Water landings—if you must—require quick decision-making. Studies of bridge-jump survivors indicate that a feet-first, knife-like entry (aka “the pencil”) best optimizes your odds of resurfacing. The famed cliff divers of Acapulco, however, tend to assume a head-down position, with the fingers of each hand locked together, arms outstretched, protecting the head. Whichever you choose, first assume the free-fall position for as long as you can. Then, if a feet-first entry is inevitable, the most important piece of advice, for reasons both unmentionable and easily understood, is to clench your butt.

No matter the surface, definitely don’t land on your head. In a 1977 “Study of Impact Tolerance Through Free-Fall Investigations,” researchers at the Highway Safety Research Institute found that the major cause of death in falls—they examined drops from buildings, bridges and the occasional elevator shaft (oops!)—was cranial contact. If you have to arrive top-down, sacrifice your good looks and land on your face, rather than the back or top of your head. You might also consider flying with a pair of goggles in your pocket, Hamilton says, since you’re likely to get watery eyes—impairing accuracy—on the way down.

7:02:19 AM

1000 Feet

Given your starting altitude, you’ll be just about ready to hit the ground as you reach this section of instruction (based on the average adult reading speed of 250 words per minute). The basics have been covered, so feel free to concentrate on the task at hand. But if you’re so inclined, here’s some supplemental information—though be warned that none of it will help you much at this point.

Statistically speaking, it’s best to be a flight crew member, a child, or traveling in a military aircraft. Over the past four decades, there have been at least a dozen commercial airline crashes with just one survivor. Of those documented, four of the survivors were crew, like the flight attendant Vulovic, and seven were passengers under the age of 18. That includes Mohammed el-Fateh Osman, a 2-year-old wreckage rider who lived through the crash of a Boeing jet in Sudan in 2003, and, more recently, 14-year-old Bahia Bakari, the sole survivor of last June’s Yemenia Airways plunge off the Comoros Islands.

Crew survival may be related to better restraint systems, but there’s no consensus on why children seem to pull through falls more often. The Federal Aviation Agency study notes that kids, especially those under the age of 4, have more flexible skeletons, more relaxed muscle tonus, and a higher proportion of subcutaneous fat, which helps protect internal organs. Smaller people—whose heads are lower than the seat backs in front of them—are better shielded from debris in a plane that’s coming apart. Lower body weight reduces terminal velocity, plus reduced surface area decreases the chance of impalement upon landing.

7:02:25 am

0 Feet

The ground. Like a Shaolin master, you are at peace and prepared. Impact. You’re alive. What next? If you’re lucky, you might find that your injuries are minor, stand up and smoke a celebratory cigarette, as British tail gunner Nicholas Alkemade did in 1944 after landing in snowy bushes following an 18,000-foot plummet. (If you’re a smoker, you’re super extra lucky, since you’ve technically gotten to indulge during the course of an airliner trip.) More likely, you’ll have tough work ahead.

Follow the example of Juliane Koepcke. On Christmas Eve 1971, the Lockheed Electra she was traveling in exploded over the Amazon. The next morning, the 17-year-old German awoke on the jungle floor, strapped into her seat, surrounded by fallen holiday gifts. Injured and alone, she pushed the death of her mother, who’d been seated next to her on the plane, out of her mind. Instead, she remembered advice from her father, a biologist: To find civilization when lost in the jungle, follow water. Koepcke waded from tiny streams to larger ones. She passed crocodiles and poked the mud in front of her with a stick to scare away stingrays. She had lost one shoe in the fall and was wearing a ripped miniskirt. Her only food was a bag of candy, and she had nothing but dark, dirty water to drink. She ignored her broken collarbone and her wounds, infested with maggots.

On the tenth day, she rested on the bank of the Shebonya River. When she stood up again, she saw a canoe tethered to the shoreline. It took her hours to climb the embankment to a hut, where, the next day, a group of lumberjacks found her. The incident was seen as a miracle in Peru, and free-fall statistics seem to support those arguing for divine intervention: According to the Geneva-based Aircraft Crashes Record Office, 118,934 people have died in 15,463 plane crashes between 1940 and 2008. Even when you add failed-chute sky divers, Hamilton’s tally of confirmed or plausible lived-to-tell-about-it incidents is only 157, with 42 occurring at heights over 10,000 feet.

But Koepcke never saw survival as a matter of fate. She can still recall the first moments of her fall from the plane, as she spun through the air in her seat. That wasn’t under her control, but what happened when she regained consciousness was. “I had been able to make the correct decision—to leave the scene of the crash,” she says now. And because of experience at her parents’ biological research station, she says, “I did not feel fear. I knew how to move in the forest and the river, in which I had to swim with dangerous animals like caimans and piranhas.”

Or, by now, you’re wide awake, and the aircraft’s wheels have touched safely down on the tarmac. You understand the odds of any kind of accident on a commercial flight are slimmer than slim and that you will likely never have to use this information. But as a courtesy to the next passenger, consider leaving your copy of this guide in the seat-back pocket.

Posted in aviation, physics, tehcnology | Tagged: , , | Leave a Comment »