Monday, June 27, 2011

Shakes on a Plane: Can Turbulence Kill You?

Image Credit: Jason Pratt

See that plane on the upper left?

Airplanes are scary. This indisputable fact originally came to my attention somewhere during college, when my relationship with flying matured from irritated ambivalence to full-blown phobic terror. There is something profoundly disturbing about being suspended thousands of feet in the air in a metal tube piloted by someone you’ve never even met. When I explain this to people who aren’t bothered by air travel, they foolishly try to persuade me with statistics about how flying is safer than driving blah, blah, blah…as though irrational fears could be soothed by something as banal as data.* Really, the only way to take my mind off my impending death is to pretend I’m not in an airplane at all. Distractions like food and music and in-flight magazine crossword puzzles go a long way toward accomplishing this, but all their hard work is undone the instant the plane encounters even a little turbulence. Turbulence has a way of snapping you back into the present moment, its every lurch and bump an unwelcome reminder that you’re hurtling through the stratosphere at over 500 miles per hour.

...this is what I think of every time I look at it.

My spring vacation† involved a total of 7 flights and amounted to something like 25 hours of time in the scary skies. Mercifully, every flight was smooth and trouble free, except for the very last one – a short jaunt from Dallas to Austin. I could tell the final phase of the trip was going to be less compliant than the previous portions. Thick clouds hung over the airport while we waited to board the plane. As soon as we were in the air, the pilots announced that there would be no beverage service due to some rough weather ahead. Throughout the next terrifying 40 minutes or so, we received various ominous announcements from the cockpit as the plane shuddered in increasingly malevolent winds, “We’re going to fly low today and try to stay below this storm,” and “Okay, so still pretty bumpy even at this altitude, but we should hopefully be there soon” etc. After we were safely back on the ground, I apologized to my boyfriend for all my in-flight whimpering, calling upon the mantra I’d heard dozens of times, “I know it’s just turbulence and it can’t hurt the plane, but it really feels like you’re about to crash.” But instead of laughing at me for being such a sissy, he launched into a lengthy discussion of how severe turbulence can cause plane crashes, and how the turbulence we’d just experienced had been pretty rough, and something about “wind shear” being capable of tearing planes in half.‡ I was really glad he didn’t share any of this with me during the flight.

Say It Isn’t So
Since anecdotal boyfriend babble is not always accepted as a reliable source, I’ve done some research on the question of whether turbulence can cause aviation disasters. The answer turns out to be a heavily-caveated yes. Turbulence can lead to plane crashes, but it is exceedingly rare. By some estimates, turbulence takes down about one plane per decade.§ This chaotic air movement - and its effects on the movement of the aircraft - is classified in degrees of light, moderate, severe and EXTREME (emphasis added by author). There’s also something called “chop” which is a more rhythmic bumpity-bumpity effect that comes in light and moderate flavors. Passenger perception of turbulence tends to be direr than that of experienced crew, so if you think you’ve been on the worst flight of your life, it’s likely you only witnessed moderate turbulence.

The good news is that airplanes are designed to withstand extreme turbulence (as well as lightning). The bad news is that, like all machines, airplanes age. Wear and tear that is no problem under normal circumstances can make aircraft less resilient to ridiculous levels of turbulence. Additionally, flying a plane that is being pummeled by rogue air masses isn’t the easiest thing in the world. Planes can be pretty much out of control during these episodes and, while temporary, the pressure is really on the pilot to react (but not overreact) in a way that keeps the aircraft from flying into the side of a mountain. If you think this all sounds melodramatic, consider a 1966 incident in which a BOAC (now British Airways) Boeing 707, flying near Mt Fuji, broke up in midair and crashed amidst harsh winds.

Your Wake, My Funeral
As frightening as that is, you should probably be more concerned about something called “wake turbulence”. Unlike turbulence created by naturally occurring differences in air flow (bad weather, pressure variations near mountains, jet streams, etc.), wake turbulence is caused by other airplanes, sort of like the wake created by a boat, except with air and much scarier. The worst part of wake turbulence is the creation of “wingtip vortices”, tornadoes of bumpy air generated by a plane’s wings that can take several minutes to dissipate.

Image Credit: NASA Langley Research Center
As with boat wake, this form of turbulence is not a problem for the planes creating it, but rather for the planes near it. Airports enforce strict limits regarding how much time must pass in between take-offs and landings to prevent one plane from getting caught in another’s wake. However, airports are increasingly crowded places with limited runway resources. Since they are travelling at slower speeds and pitched at awkward angles, planes that are taking off or landing are more vulnerable to turbulence. And, unfortunately, take off and landing are exactly the times when planes fly closest to one another.

As with other forms of turbulence, wake turbulence is more of a threat to small planes (especially when caused by the significant wakes of large commercial jets). Probably the largest aircraft to crash as a result of the phenomenon was a McDonnell Douglas DC-9 that got caught in the wake of a Lockheed L-1011 in 1972, prior to the implementation of the above-mentioned spacing regulations.** Wake turbulence allegedly also contributed to the 2001 demise of American Airlines Flight 587, though this crash is officially attributed to pilot error in response to the wake.

Reality Check
And now let me stress how very, very rare these occurrences are. Finding examples with which to freak you out was no easy task. Really, the biggest of your worries in the realm of bumpy air is encountering clear air turbulence (CAT) when you don’t have your seatbelt fastened. This is the surprise turbulence that occurs on a sunny day in seemingly smooth skies. The major impact of turbulence is not the causing of plane crashes, but rather bodily injury from all that jerking around. Every year, dozens of un-seatbelted passengers are seriously injured (and occasionally even killed) from being thrown around the cabins of twitchy planes. Your pilot isn’t just being an overbearing nag when he (or she) asks you to keep your seatbelt fastened when you aren’t walking around the cabin. CAT can come out of nowhere and knock the #%$ out of a plane. So buckle up, people.

* By the way, I’m afraid of cars too, making such logic even more useless to me.

† I went to Spain. It was lovely, thanks for asking.

‡ Wind shear turns out to be variations in speed and direction of air movement, which often leads to turbulence. Possibly he was talking about wake turbulence rather than wind shear. Maybe he even said wake turbulence. I don’t know, I was still a bit rattled (pun not intended, but permitted) at the time.

§ This was reported in the Guardian (via the aviation consultant Ascend) and they didn’t elaborate on what types of planes – or types of turbulence for that matter –were involved in these disasters.

** The DC-9 is still relatively small compared to a wide-body behemoth like the Lockheed L-1011.

Friday, June 10, 2011

Scientists make shocking discovery: dogs cannot read our minds

It's like The Village of the Damned. Image Credit: Tanakawho

“Canine telepathy?” asked one press release, referring to the similarly provocatively titled “Can your dog read your mind? Understanding the causes of canine perspective taking”, published online this week in the journal Learning and Behavior. The answer, of course, was no, although that was hardly the question being posed. The paper was not a cross-species ESP study, with dogs sitting in one room and being asked to guess what geometric shapes humans sitting in the adjacent room were being shown, but something a bit more practical. The authors examined how well different types of canids*(domestic dogs as well as wolves) were able to spot which of two humans was the attentive one – the one that would be more likely to reward them with treats.

While many animal lovers claim that dogs can tell when their owners are angry or sad – or merely plotting to take them to the vet – there is little more than anecdote to back this up. Yet it does often seem like dogs know what we’re up to. The dogs in my father’s household, who wouldn't exactly be described as well behaved, transform into circus-level performers when “chew-chews” (dog treat jargon) are about to be doled out. Treats are distributed after the correct execution of a command. Having spent far more time on “sit” than alternatives such as “roll over” or “play dead”, the dogs immediately place their butts on the ground as soon as a human picks up the biscuit jar. But do they believe that sitting somehow pleases us (not entirely false, though technically the desired behavior was obeying of commands) or have they just learned through trial and error that sitting = chew-chew? Forget whether dogs can read our thoughts, can they even comprehend that we have thoughts, that we pay attention (or don’t pay attention) and, if not, how do they manage to adjust their behavior to suit our wishes?

To answer some of these questions, scientist tested four types of canids – pet dogs (tested indoors), pet dogs (tested outdoors), animal shelter dogs, and tame wolves.† After preliminary “pre-training”, dogs were given the choice of begging for treats from either an attentive human – one that could see the dog – or a human whose attention was somehow diminished. The obscuring of attention was achieved by one of four means – the human 1) having their back turned to the dog, 2) reading a book, 3) holding a camera over their eyes or 4) wearing a bucket over their head. If that last one sounds a bit ridiculous, that was sort of the idea – to create a situation the animals were unlikely to have encountered previously.

Results showed that not only could domestic dogs read some signs of inattentiveness, so could wolves. All animals fared well in the task that involved choosing the attentive human over the one with their back turned. This provides possible evidence against the argument that dogs’ ability to read human mannerisms is a product of their domestication. In fact, in general, animal shelter dogs (whose home environments lacked the enrichments afforded to pet dogs) performed closer to wolves than to pet dogs. Response to the obstacles of camera and bucket were not extraordinary in most subjects, but in tasks where the inattentive human held a book, pet dogs (in both indoor and outdoor settings) did notably better at begging from the attentive human rather than the distracted reader. The book scenario was chosen specifically to simulate the kind of hurdle to getting attention that the average pet dog experiences in their daily routine. As expected, wolves and shelter dogs largely missed this subtle cue.

Additionally, when the challenging bucket task was repeated for long enough that animals might have a chance to learn from reinforcement (20 trials each), both dogs’ and wolves’ performance improved in tasks where they were rewarded for begging food from the attentive human. However, most failed to get the hint when treats were given out by the inattentive bucket-headed human.

Overall the researchers concluded that conditioning is important for canids to learn which human behaviors and mannerism will improve their chances of getting rewards, but that “a willingness to accept humans as social companions” was also key. Domestication, it seems, was not a requirement. What does all this say about whether dogs can conceive of thoughts in humans? Nothing. The authors readily admit that their tests were not designed to determine the mental process behind the animals’ decisions. That’s probably a wise move given that it’s pretty challenging (impossible?) to study cognition in non-verbal animals. Nevertheless they’ve managed to provide some insight as to how dogs “know” when we’re more likely to be receptive to their needs. Meanwhile, domesticated cats have long known that they can turn an inattentive reader into a receptive provider of affection and dinner simply by sitting on the distracting book. I draw no conclusions from that last (non-experimentally obtained) observation. Any inferences about the relative intelligence of cats and dogs are entirely of your own making.

* Canidae is a family of mammals that includes domestic dogs (Canis lupus familiaris) and wolves (various subspecies of Canis lupus) and well as foxes, coyotes and jackals.

† The whole indoor/outdoor business with the pet dogs was done to match the necessary testing conditions for the other animals. Wolves were tested outside, whereas shelter dogs were tested inside.

Wednesday, June 1, 2011

Indifferential Diagnosis #2: Hair Loss

Welcome to the long-overdue 2nd installment of Indifferential Diagnosis, the feature that poses – and even suggests possible answers for – the age-old question, “What’s wrong with you?” Last time we learned about visual hallucinations; today we delve into the equally disorienting world of hair loss. But before we begin, I would like to again draw your attention to the important disclaimer that I am not a doctor and indifferential is not a word.

As anyone who has ever swept the floors of an apartment inhabited by several females (or long-haired males) can tell you, human hair falls out all the time. The average adult head houses over 100,000 hairs and sheds between 50 and 100 of them each day. Hair loss – or alopecia, to use the clinical term – becomes noteworthy if it exceeds these parameters long enough to leave bald patches and/or completely eliminate hair. Hair can be lost from just the head or from the whole body. And, while it is typically associated with males of a certain age, the problem can occur at any age and in both genders.

Androgenetic and Involutional Alopecia
These are the staples of human balding and both increase with age. Prior to its ousting from the scalp, any given strand of hair has gone through a growth phase (2 to 3 years) and a rest phase (3 to 4 months). After a hair falls out, a new one takes its place and the cycle starts over – growth, rest, shedding of hair. Involutional alopecia is a gradual thinning of the hair caused by a shortened growth phase. Less growth means more hairs in rest phase, a higher rate of shedding and shorter hairs overall.

While living long enough almost guarantees some age-related thinning of hair, androgenetic alopecia – which you may know as “male pattern baldness” – only affects part of the population and is believed to be governed by hereditary factors. The “pattern” starts with a receding of the hairline at the temples, accompanied by the classic bald patch at the crown of the head (the spot where you would wear your yarmulke, if you’re into that sort of thing). Gradually these hairless patches may bleed into each other, resulting in the full Patrick Stewart effect.

Women too can be afflicted with androgenetic alopecia, but it tends to be less severe and starts later in life. Men with the genetic predisposition can experience noticeable hair loss as early as their teens. Hair loss from either androgenetic and involutional alopecia is largely permanent. As with aging overall, society has yet to produce a solid cure for this kind of gradual balding.

Tell-tale signs: The pattern of androgenetic alopecia is pretty easy to spot. Having relatives with similar hair loss histories is also a good indicator that you’re suffering from male pattern baldness.

Amidst all the other risks associated with childbirth, hair loss gets little press. But major hormonal changes that occur during/after pregnancy can make your hair fall out. Menopause is another likely source for this. In both cases what happens is that a large number of hairs opt to exit the growth stage and make a beeline for the rest stage, yielding a bunch of shedding.* The good news is that such hair loss is only temporary. Once things calm down with the endocrine system, the normal growth cycle resumes, allowing hair to return at its previous rate.

Tell-tale signs: This condition has a more sudden onset than that of age-related thinning. The volume of extra hairs in your brush will inspire mild panic rather than just nagging doubt. There’s no reason to panic though. Don’t panic. Panicking never helped anyone grow hair.

Hair loss can be caused by exposure to an array of chemicals. These range from overdoses of medications – examples: Warfarin, a blood-thinner (though in higher doses it also functions as rat poison); Lithium, a mood-stabilizer (it’s not great for your kidneys either, FYI) – to work-related hazards (metals like mercury and arsenic have been causing problems for ages) to cold-blooded, premeditated attempts on your life made by your enemies. If you don’t take medications and your job exposes you to nothing stronger than white out and ball-point pens, you may want to ask yourself, “Who would benefit from my death and how much access do they have to my morning coffee?” Depending on what toxin is entering your system, the effects can be immediate (Warfarin) or build up slowly over time (arsenic), important factors to consider in deducing your would-be murderer.

Tell-tale signs: Poisons don’t just cause hair loss, they make people sick all around. Look for accompanying symptoms like nausea, weakness, dizziness, headaches, etc. Being poisoned will make you feel thoroughly awful.

Here’s an interesting source of bald patches – pulling out your own hair one strand at a time. Strange though it may sound, up to 4% of people are afflicted with an uncontrollable compulsion to pluck hairs from their head, eyebrows, etc. Think of it as an extreme form of hair twirling. The problem usually starts in adolescence or childhood, and many people outgrow it somewhere during adulthood.

Tell-tale signs: Hopefully you will realize if you’ve been doing this yourself, so this is more for spotting the condition in others (namely, your offspring). Watch out for bald-patches and vigorous denial of these being self-inflicted. Other anxiety-soothing fidgets (like nail biting) may also be an indicator. Trichotillomania isn’t especially common in calm and well-adjusted types.

Alopecia Areta
If you haven’t heard that term before, brace yourself for some disheartening news; there is a malady out there that can cause sudden and sometimes profound hair loss in perfectly healthy individuals and for no apparent reason. Alopecia areta (AA) is thought to be an autoimmune disease in which the body’s immune system targets its own hair follicles as perceived pathogens. Often the hair grows back, but it can fall out again and there is no way to predict when and if these recurrences will happen. At its most severe, the disease causes the loss of all hair from all parts of the body – a conditional called Alopecia universalis.

Tell-tale signs: The fun generally begins with a small bald patch somewhere on the scalp, unaccompanied by skin abnormality or discoloration. The complete absence of any likely cause is also a good indicator that AA may be to blame. Other than being freaked out by losing their hair, patients feel perfectly fine. The condition isn’t especially common though (less than 2% of the population suffers from it), so before you race to the doctor, you may want to review that paragraph on male pattern baldness (pretty ubiquitous once you get past your 20s). 

I used to think that ringworm was an actual parasite, but it’s just a fungal infection. Less gross, but still no fun. If it occurs on your scalp it will cause the hair in the infected area to fall out. The problem is easily treatable with antifungal creams, and your hair will grow back after the skin heals. Oh, and don’t forget that this is contagious. Housemates and pets (cats are notorious for spreading this stuff around) may also benefit from medication.

Tell-tale signs: The skin exposed by the lost hair will look infected (since it is). Unhappy words like “itchy”, “scaly” and “oozing” often crop up in descriptions of ringworm.

Diabetes, Thyroid disorders, Lupus
Hair loss can be a symptom of an underlying disease. These are serious conditions that I can't help you with. Go see a doctor already.

* This change in the growth cycle is known as telogen effluvium (telogen is the rest phase) and can also be brought on by disruptions like stress, malnutrition or a high fever.

The fungus that causes ringworm – Microsporum gypseum – also causes athlete’s foot. It’s an icky world we live in.