Do Elephants Jump? (8 page)
Read Do Elephants Jump? Online
Authors: David Feldman
Needles are used to poke patients. But are needles poked to create the holes through which the vaccine is pumped into our veins? The answer is a resounding no. As Jim Dickinson, president of K-Tube Corporation, wrote us:
I have been involved with making the stainless-steel tubing used for hypodermic needles for the past thirty-four years, and the question about how the hole is put in this tube has been asked many times. The secret about the hole is that we don’t put it in after, but before!
How? The answer comes from Michael A. DiBiasi, a senior mechanical engineer at medical supply giant Becton-Dickinson, who proudly asserts, “I am the guy who, among other things, puts the hole in the needle.”
The stainless steel “needle” part of the syringe is more commonly referred to as the “cannula,” and the “hole” that has aroused your curiosity is called the “lumen.” Cannulae are produced from large rolls of stainless steel strip stock. Depending upon the size requirements of the finished product, which is dictated by its intended use, the strip stock could be about as wide and as thick as a piece of Wrigley’s chewing gum, and may range down to about the width and thickness of one of the cutting blades in a disposable, twin-bladed razor.
The steel strip is drawn through a series of dies that gradually form the strip into a continuous tube. As the tube closes, the seam is welded shut and the finished tubing is rolled up onto a take-up reel. In this manner, the entire roll of flat steel is converted into a continuous roll of tubing. At this point, the tubing may be anywhere from about the diameter of a common wooden writing pencil, to about the diameter of an ink pen refill tube.
Next, the tubing is drawn through a series of tiny doughnut-shaped dies that further reduce its diameter while stretching the material, which thins the cross section of the tubing wall. Depending upon the desired target thinness of the cannula, and the physical properties required of the finished product, this process may or may not be accomplished using heat. In general, cannula tubing that is to be used for injecting liquids into the body may be produced with an outside diameter of about thirteen-thousandths of an inch, with a wall thickness of about three-thousandths or finer. Thus, the lumen may be as small as six- or seven-thousandths of an inch.
When all of the reduction processes are complete, the tubing is fed onto another take-up reel for transportation to one of several machines which cut the cannula stock into specific lengths for the next operation — point grinding [the point of the needle is chiseled or filed until the point is at its proper degree of sharpness].
As the stainless steel tube is pulled and lengthened by the dies, the dies create a bright, mirrorlike finish on the outside of the needle. The seam where the cylinder was welded together when the sheet metal was rolled into a tube all but disappears during this stretching and polishing process.
Even with changes in the production of needles, the holes prevail, as Jim Dickinson explains:
The most recent technology uses a laser to weld a very thin stainless steel jacket around the hole, where in older processes electric welding required a thicker jacket. Once the hole has been jacketed, we then make it smaller and smaller by squeezing the jacket down around it.
When we squeeze the hole it elongates, but try as we can, we have never been able to squeeze it completely out of the jacket. In other words, we have never been able to close the hole.
| Submitted by Matt Lawson of Tempe, Arizona. Thanks also to Ray Kelleher of Spokane, Washington; and Gregory Medley of Tacoma, Washington. |
All numbers are not created equal. Even numbers have cachet, while odd numbers are the black sheep of the integer family. And if there is a numerical caste system, fractions are at the lowest rung, always subject to being rounded off to the next whole number. Maybe this explains why more than ten Imponderables readers wrote to ask why U.S. FM frequencies end in odd fractions.
When the Federal Communications Commission moved FM radio to its current location in 1945, it placed the FM band between the television channel 6 (82 MHz through 88 MHz) and the Federal Aviation Administration frequencies (108 MHz through 136 MHz). Each station was allocated two-tenths of a megahertz (100 kHz on each side of its frequency) to avoid interference with adjoining station. The FM band was divided into 100 channels, starting at channel 200 (88.1) and ending at channel 300 (107.9).
Robert Greenberg, the late assistant chief of the FM branch, audio services division, of the Federal Communications Commission, wrote to
Imponderables
:
Since each channel is 200 kHz wide, the center frequency could not start right on 88 MHz, because it would overlap into television channel six’s spectrum and cause interference to channel six. Similarly, the same reason holds true at the high end of the FM band. To protect FAA frequencies starting above 108 MHz, the carrier frequency for the channel 300 would have to be below 108 MHz.
The irony is that the first channel below the FM band, channel 200, or 87.9, is rarely used because it is available only for use by low-power radio stations, and is assigned only if it doesn’t conflict with an existing television channel six.
So all the radio frequencies were bumped up one-tenth to odd numbers to accommodate a small number of tiny stations with few listeners.
How odd.
Submitted by: Rick Deutsch of San Jose, California. Thanks also to Steve Thompson of La Crescenta, California; Josh Gibson of Silver Spring, Maryland; Susan Irias of parts unknown; Nadine Sheppard of Fairfield, California; Fred White of Mission Viejo, California; Anthony Bialy of Kenmore, New York; Gilles Dionne of Mechanic Falls, Maine; Robert Baumann of Secaucus, New Jersey; Doris Melnick of Rancho Palos Verdes, California; and many others.
All that glitters can’t be hocked at the local pawnshop. The shiny stuff we sometimes see on roadways and sidewalks isn’t valuable, but it is variable — many components of concrete may glitter.
The most common ingredient among the glitterati is probably the minerals, such as quartz, that are found naturally in stones. The stones are crushed into a sandlike consistency and mixed with cement to form concrete or as part of the aggregate mixture in asphalt. Sometimes crushed glass is used as well and glass glitters mightily when exposed to light.
Because of the constant wear on road and sidewalk surfaces, the glitter effect tends to increase with time. As Thomas B. Dean, former executive director of the Transportation Research Board, wrote
Imponderables
:
The fine aggregate/sand used in portland cement concrete is like a natural mirror; that is, it reflects light. In theory, all aggregate in concrete is completely coated with cement. However, the aggregate on the very top surface of the street or sidewalk will lose part of that coating due to weathering and vehicular or pedestrian traffic. Once exposed, the light from the sun, headlights, streetlights, or other sources bounce off the tiny surfaces of the aggregate, causing the streets and sidewalks to glitter.
Sometimes transportation engineers might actively seek out reflective surfaces on the roads they are designing. If so, they may add glass as a reliable and inexpensive solution to this need, says Jim Wright, of the New York State Department of Transportation. For aesthetic reasons, designers might want sidewalks to have a shiny surface, and may smooth down concrete with a rotary or blade to let the minerals in the sand strut their stuff on the surface.
More often, glass is included as a recycling measure. In fact, according to Billy Higgins of the American Association of State Highway and Transportation Officials, sometimes extremely non-glittery used tires are thrown into the aggregate mix as well, to put them to better use than as permanent residents at the local landfill.
| Submitted by Sherry Steinfeld of East Rockaway, New York. |
No, we’re not referring to the big hole that sewers place their fingers into, but the little dimply indentations that digitabulists (thimble collectors) call “knurling.” Were the little holes for ventilation (who wants a sweaty middle finger?), for decoration (we note that not all thimbles feature knurling), or to provide traction for the needle?
We spoke to a representative of thimble maker A. Meyers and Sons, who at first advanced still another theory that the holes were there to provide traction so that the stitcher could hold the fabric more securely. She checked with the sages at her venerable company and quickly changed her explanation: The holes were there to grip errant needles — they were a safety feature.
Other sewing experts we consulted agreed. As we heard from a representative from Silent Stitches Needlework:
Those innocent little indentations on the top and sides of a thimble prevent the needle from slipping as you push the needle through the cloth being sewed.
Just as we were smiling complacently, Terry Collingham, of Colonial Needle Company, wanted us to know that there were more holes in thimbles than we could have imagined:
Just to confuse the issue even further, we also carry open-top thimbles where the top is completely open. The purpose of the hole on top is to accommodate long fingernails. Tailors and seamstresses also use this type because people in this line of work wear a thimble all day and don’t want their fingers covered. In using this type of thimble, the stitcher must push from the side and never from the top — these also have dimples to prevent slippage.
| Submitted by Jenny Dennis of Hollywood, California. Thanks also to Bob Nissen of Syosset, New York. |
When the red, red robin comes bob-bob-bobbin’ along, it’s not bobbing out of
joie de vivre
. The robin probably has one thing on its mind: food.
Different birds use different techniques to locate food. For example, sandpipers have long bills with sensitive tips — they might be able to feel worms that they can’t even see. Kiwis’ nostrils are located at the tip of their bills, so they can often smell their future prey in a way that other birds cannot.
But chances are that most of us are observing robins when we think about this Imponderable. Common garden birds in North America, robins exhibit striking routines when hunting worms in our backyards. Characteristically, a robin will cock its head at a funny angle just before pecking, elongating its body with its head as far off the ground as possible, and then violently plunging the bill into the soil. Earthworms are thought to comprise about 20 percent of an adult robin’s diet, but virtually all of young nestling robins’ nutrition, and parents must hunt and deliver their nestling’s worms, too. Robins sometimes come up dry when pecking, but their “batting average” is remarkably high, and ornithologists have logged success rates as high as twenty earthworms captured per hour.
When you ponder the possibilities, it’s conceivable that a bird could use any of the five senses to figure out where to peck:
1. Visual — maybe they can see the worm, or see movement on the ground that tips off the presence of worms.
2. Auditory — robins might be able to hear worms moving below.
3. Taste — a soil hors d’oeuvre might provide clues to the location of the worm.
4. Olfactory — the robin might be able to smell worms.
5. Vibrotactile — perhaps the robins’ feet can pick up vibrations created by worms under the ground.
Much to our surprise and pleasure, biologists haven’t ignored this Imponderable. Scientific foundations might not provide multimillion-dollar grants to study worm seeking, but nevertheless some scholars have conducted hard research into the feeding tactics of
Turdus migratorius
(robins don’t have the most fortunate scientific name). Our first hero is Frank Heppner, Ph.D., who performed the earliest controlled experiments on this Imponderable in the mid-1960s. His biggest challenge in designing the study was trying to figure out how to isolate the different senses of his captured robins. Heppner made no assumptions about which of the five senses robins used to snare worms. Here’s how he approached all five of the possibilities.
Smell — Heppner coated worms with rotten eggs, decaying meats, rancid butter, foul-smelling acids, and other putrid-smelling substances. This turned off the robins about as much as spraying perfume on a beautiful woman would turn off Don Juan. The robins ate the worms eagerly, not indicating any reaction to the foul smells. If the worms emit smells that provided olfactory clues to the robins, the birds still found and ate the prey even without the “good worm smell.” (Robins, like most birds, have a poor sense of smell, so this sense was always suspect as the key factor in finding worms).
Touch — Heppner drilled wormholes in the ground and placed dead worms in the holes. The robins snapped up these worms, too. So if robins feel worm movement through their feet, they obviously wouldn’t obtain any such advantage from dead worms.
Taste — Heppner found no indication that birds were picking up samples of dirt “on speculation” to find worms. Robins were too successful in finding worms on their first peck to consider taste as a major factor.
Hearing — Heppner tape-recorded the low-frequency sounds that burrowing earthworms make and then played the recordings back to the robins when actual worms were not present. The worms completely ignored the
Earthworms’ Greatest Hits.
Visual — Heppner drilled holes that looked exactly like wormholes, but did not place any worms, dead or alive, in the holes. Robins were uninterested in what was inside these holes.
Heppner concluded in his 1965 report that robins see their worm prey before pecking. In the experiments he conducted, robins found and ate worms whether or not the worms were dead or alive, and regardless of what the worms smelled like. Heppner’s research stood as the definitive experiment on robins’ worm feeding, and if you look at the popular literature on robins, you’ll find that most of the literature assumes the validity of Heppner’s conclusions.
But if Heppner was the early bird on this research, a pair of young biologists, Dr. Robert Montgomerie from Queen’s University in Ontario, Canada, and Dr. Patrick Weatherhead from Carleton University in Minnesota, still thought they could capture the worm. They weren’t convinced that robins found worms only through visual means, and in the mid-1990s, they decided to test the thesis. In their article, “How Robins Find Worms,” published in the British scientific journal
Animal Behavior,
the biologists revealed their doubts about Heppner’s conclusions:
In an experimental study of robin foraging behaviour, Heppner (1965) concluded that American robins locate earthworms exclusively by visual clues. He based this conclusion on a series of experiments in which robins were able to find earthworms placed in holes in a lawn (but still visible) even in the presence of loud white noise (which would have obscured any auditory clues).
Our own field observations of robins suggested to us that they might also use other sensory modes while searching for earthworms. When they cock their head, they appear to be listening, and we have watched robins successfully foraging on lawns where the grass was long enough to make earthworms difficult to see. We also watched a captive robin catch earthworms buried in soil where we could detect no visual clues that would reveal an earthworm’s location. Thus it seemed to us that auditory, olfactory, or vibrotactile cues might be used in addition to visual cues when locating prey.
Unlike Heppner, Montgomerie and Weatherhead didn’t bother to test taste as a major cue for robins, presumably because they discounted any chance of its importance. The duo captured some robins and placed them in an outdoor aviary in Ontario. They used “feeding trays” filled with soil, into which worms were placed in random but known locations. Usually, the trays were set on the ground so that the robins could “jump” on to the soil of the tray and hunt for worms. At other times, usually to test the robins’ vibrotactile abilities, the trays were placed at a slight angle above the ground, so that the robins could peck into the soil without standing on the dirt.
The only other big change from Heppner’s methodology is that for most of the experiments, Montgomerie and Weatherhead used mealworms (which are smaller than the earthworms that robins usually eat in “real life”) as the bait. Needless to say, robins ate mealworms with gusto, too, and when offered earthworms instead by the biologists, robins didn’t act differently from the way they did when pecking at mealworms.
Just as Heppner did thirty years before, Montgomerie and Weatherhead devised ingenious experiments to isolate particular senses:
Olfactory — The scientists placed two live mealworms and two freshly killed mealworms in the feeding trays. The odor from the live and dead worms were deemed to be very similar, yet the robins were much more successful at finding the live worms. The conclusion: smell was unlikely to be a significant factor in robins finding the worms.
Vibrotactile — The feeding trays were suspended and angled so that the birds didn’t stand upon the soil, yet the birds were successful at finding their beloved worms. Vibrotactile cues didn’t seem necessary for the robins.
Visual — A few live mealworms were buried in random locations on the feeding tray. The entire surface of the tray was then covered with a thin, but opaque piece of cardboard. Then more soil was piled on top of the cardboard. The robins were deprived of any visual cues, and the cardboard probably eliminated or at least drastically reduced any remaining vibrotactile or olfactory cues. The results: Although blocking visual access to the worms reduced their success rates, robins were still rather proficient at capturing their food, much more often than would be expected by chance — robins seemed to be capable of finding buried worms without any visual cues.
Auditory — The first three experiments led the experimenters to the belief that hearing might play an important if not dominant role in robins’ finding worms, so the biologists designed a test to stifle auditory input while still allowing cues for all the other senses. They buried live worms randomly and then rigged a device to emit white noise (from the middle of the soil tray) that was sufficiently loud to mask out any sounds emanating from the movement of worms. The experimenters acknowledge in their report that the white noise might have affected some possible vibrotactile cues.
Still, the results were striking. When faced with the auditory distraction, the robins didn’t strike as often, and when they did plunge into the soil, their success rate was higher than a random strike, but not as high as when the noise was absent. Montgomerie and Weatherhead concluded that the birds were having trouble locating the worms. They presumed that the robins’ decent success rate probably meant that the white noise was not completely masking the sounds made by worms.
The biologists tried to entice the robins to strike by playing recordings of the sound of moving mealworms and piping the sound through the soil when no worms were actually present in the soil. But the robins didn’t fall for the “worm and switch.” Perhaps the sound quality wasn’t an exact match; perhaps robins require more than one sensory cue to “go for it.”
Montgomerie and Weatherhead concluded that all of the experiments indicated that robins could find worms when auditory cues are available and some or all of the other cues are removed. But by no means did they prove that hearing is the only sense that robins rely upon to catch worms.
At the end of their report, Montgomerie and Weatherhead attempt to reconcile their conclusions with Heppner’s. They believed that Heppner demonstrated that robins could capture worms when they could see them, even when auditory and olfactory cues were missing, but “he didn’t test whether the robins could use other senses in the absence of visual cues.” They theorize that robins probably use a combination of cues, with visual and auditory cues probably playing the prominent role. Even if hearing is ultimately more important, they believe, robins will use all the visual cues they can amass. As Montgomerie wrote in a note to
Imponderables
: “Heppner showed that robins
could
use vision but not that they
couldn’t
use hearing.”
Of course, we offered Professor Heppner rebuttal space, and he graciously responded, despite it “being almost forty years since I worked on the robin business.” In this e-mail, Heppner revealed that he blindfolded robins in his study, and
Blindfolded birds just sat on the ground — they didn’t hunt at all. Robins are perhaps not God’s most intelligent creatures — perhaps they thought it was night.
Heppner was receptive to other theories, but didn’t sound completely convinced that he was wrong, although he opens the door a crack:
I am sticking to my original conclusion — based on the available evidence, robins
can
find worms by sight (and perhaps under certain circumstances, they can do it by sound).
Heppner concluded his note with a charming aside. After devising ingenious methods to test various hypotheses, and being challenged thirty years after the fact by other creative researchers, he concedes that science, and Imponderability, must yield to moral concerns:
The problem with this question is that you can’t really do the crucial experiment. If you surgically deafened robins, and they still found the worm, there’s your answer (earplugs wouldn’t do it, because there could still be bone transmission of sound). But even though robins aren’t particularly lovable birds, I don’t want to irreversibly deafen a bunch of robins just to satisfy my curiosity — this is not finding the cure for cancer, after all — and evidently, neither does anyone else.
| Submitted by Roy Dunten of Hermistown, Oregon. |
