The Stress Of City Life



The pull of the cities now has much of the world’s population living in close proximity to their neighbors. The exodus by the jaundiced few barely makes a dent in the drift. The advantages of urban life are many and obvious, but the planners and architects often overlook the disadvantages.

Schnell et al decided to take another look at the current “comfort level” in urban living (1). The attached micro-sensors and questionnaires to 36 young, healthy university students and set them loose in Tel Aviv for a year.

 Tel Aviv can be hot and humid, but cold in the winter. The students took this in their stride. The city noise level was a bigger stressor but not one that gave them a lot of trouble. The air pollution, carbon monoxide was measured  and was at a level that they didn’t notice, so for example when they went from a busy street into a building or into a park, they weren’t aware of a comfort level change.

The big stressor was “social load” which means crowding with people with loud voices. I can get behind that. If you’ve been stuck in close proximity with a several people using their cell phones you will certainly have felt the high social load as they all raise their voices to talk into the phones as the microphones are nowhere near their mouths and everyone else turns up their volume to make themselves heard.

At a party, after half an hour of drinking, it’s usual for the volume to have shifted up by 20 decibels or so, but in a pedestrian area it’s not good. Even the ubiquitous earbuds with the iPods don’t shut it out unless the volume is turned up to damaging levels. Quiet cities would be wonderful; electric cars and polite people is clearly the way forward.

This study is interesting, but didn’t have a big enough Awe-factor for some. The Guardian’s Improbable column (2) drew my attention to the News Alert quoting the research (3). The alert stresses that the carbon monoxide pollution was having a narcotic effect on the students and mitigating the affects of noise and social load, so was a good thing with no long term harmful effects.

I have read the original paper several times now and there is no mention of that. I wonder what sort of polluted air the News Alert author has been breathing? Too much CO, perhaps?

  1.  Schnell et al, J. Env. Monitoring & assessment, doi:10.1007/s10661-011-2286-1
  2. http://www.improbable.com/
  3. http://www.eurekalert.org/pub_releases/2011-11/afot-cm-110811.php


Shoal Sense

Eastern Mosquitofish           creative Commons Credit : Osado

Soon after I started out on my mile and a half trek to get coffee, a moderately sized dog fell into step alongside. He kept his station at two and a half feet away regardless of whether I slowed, accelerated, or weaved a little side to side. I stress it was only a little, and that it was due to a shortage of caffeine and not a surplus of ethanol. His owner was at the end of a long lead some way behind and he too kept station, so we were like a mini-shoal of queer fish, albeit 2-dimensional, progressing smartly along the sidewalk.

Animal synchronized motion as we see with flocks of starlings or shoals of mackerel are compelling to watch as suddenly the group seems to fold and move in a different direction. The reaction speed is amazing. The whole thing seems to be democratic with no evidence of an alpha-mackerel leading the pack. As mackerel are rumored to have a very short attention span, (rather like most politicians, if Republican Party debates are any indication,) it would have to be democratic as no one would be able to remember where they were going in the first place.

However, science is rather more interesting than politicsand Herbert-Read et al have been studying the shoaling behavior of a mini-shoal in a tank (1). The chosen fish were Eastern mosquito fish which move about in small shoals eating algae and plankton with a taste for mosquito larvae should the opportunity arise.

After a lot of photography, plotting trajectories and speeds, the results were that the shoaling had only three simple rules.

Firstly, the fish liked to be close to their neighbors, so that they liked other fish to be within their social space. 6 cm is a good social distance. Secondly, they didn’t want their personal space invaded so they accelerated away if a neighbor was tailgating. Thirdly, they seemed to be only able to think about one neighbor at a time and so were actually responding to their nearest neighbor interaction, so trusting that everything else would take care of itself.

Whenever I drive on a busy freeway, I see a lot of drivers who appear to be obeying the same three rules as they accelerate up close and then brake and dodge to one side or another if there is a space. It seems to be only the verges which prevent the traffic all changing direction like a shoal of mackerel, so that if that predatory semi came rushing in from a rest stop, the whole column would take a sharp left to avoid the large teeth on the front of the Mack truck.

  1. www.pnas.org/cgi/doi/10.1073/pnas.1109355108

Robot Spiders To The Rescue


3–D printing has the ability to build up complex units with the moving parts built-in. In other words, a machine can be printed without subsequent assembly. Alternatively, working components can be printed and then assembled into a final unit, thus providing more flexibility in the final device. The latest fun thing to be produced this way is a spider robot that can scuttle into places where sensible people would avoid (1). So hazardous toxic areas, or small spaces in collapsed buildings can be explored. Soon we’ll hear the call “send in the spiders” when the disaster response team arrives.

In a blog by Molly Cotter posted Inhabitat there are some photographs of these little 8 legged monsters fresh off the printer (2). They are printed from polyamide and are very light. Perhaps the most notable thing about these robots is that they're very cheap to produce. Cheap means disposable, so if they do the job there is no need to recover them and try to clean them up from hazardous chemicals for example.

The spider body makes the platform on which various sensors may be mounted. Small microphones, sensors or cameras can be carried into inaccessible places by the spider bots. The Institute reports that some of them can jump around (1). Currently they are being produced at the Fraunhofer Institute. I expect that Halloween there can get pretty exciting with herds of these ghostly white spider bots scurrying around the corridors looking for trouble.

Some engineers have built small robots that can climb vertical surfaces like geckos. Perhaps that's the next step for the Fraunhofer guys with their spiders. So how do they scuttle and jump? By hydraulics. Fluid pumped into the legs extends them and when allowed to flow back the springy legs recoil.

  1. http://www.fraunhofer.de/en/press/research-news/2011/november/high-tech-spider.html
  2. http://inhabitat.com/3d-printed-robot-spider-can-save-lives-and-analyze-hazardous-surroundings/

Horsing Around


Prezwalski's Horse             Credit:   Joe Ravi CC-BY-SA.3.0


Horses, some of us keep them and ride them while the rest of us admire the animal and just imagine ourselves riding along with the hero in the cowboy movie that we’re watching. Like the dog, the horse has figured strongly in the development of our species since very early days. In the beginning, it was a good food supply. Of course, it still is in some countries, but horse is not a universal delicacy anymore.

In the latest issue of the Proceedings of the National Academy of Sciences, Pruvost et al suggest that archeologists “often argue whether Paleolithic works of art” are accurate images of the local livestock (1). The issue has come to a head with the cave drawings in France with pictures of spotted horses.

Today’s spotted horses carry an allele on their DNA, the Lp gene, which is unique to their color rendition and some samples of very old bones have indicated that in some cases, the same allele is present. (1,2). Thus the cave artists would have had spotted models to draw. After they’d dined well of course.

To me it seems strange that there would have been the suggestion that these were cartoon horses. The horses don’t look like modern horses, though. We have been tampering with their breeding for many, many centuries. That is, all except for one race of horses racing about on the Mongolian steppes – Prezwalski’s Horse, have escaped our interference and look very much more like the cave drawings than any of our modern breeds.

The assumption seems to have been that the cave drawings must have had religious significance and therefore wouldn’t be about real life. But perhaps they were drawn for practical purposes such as teaching the young what to hunt along with a Paleolithic lecture course on technique. Or maybe, people just enjoyed creating and looking at art, even then.

I wonder why we must always assume that everything left by the ancients was done for religious purposes. I would much rather think that it was the artists amongst us that played a big part in making us civilized.

  1. doi: 10.1073/pnas.1108982108
  2. http://www.newstrackindia.com/newsdetails/249343

Some Trash Cans Can Be Sociable Too.


“Tidy your room, now!” is a command that many of us have heard more than once in our youth. We probably found much more pressing things to do. But when we get older and walk around in a public place, some of us drop litter and the rest of us gnash our teeth and complain. Of course, if litterbins are full and overflowing, our ire might be directed at the local municipal bureaucrats, but when they aren’t full up we rant about the nature of the general population.

There may be a solution on the horizon, (not for the bureaucrats but for the general population,) in the form of sociable trash boxes or STBs. Yamaji et al have designed and built such devices and tried them out with children who are used as an unspoilt (that is naïve) model for behavior (1).

Robotic trash boxes were built and had different colors to indicate their favorite trash. They could rock and roll about and could see trash as well as kids. They were keenly aware of their spatial relations from proximity sensors. This defined three spaces – the large distance or public space, a social space (close enough to be aware that they were interacting) and an intimate or personal space.

The robot has a sensor that tells it that there is a human around that it can importune them for food. The 5 – 6-year olds didn’t take much notice of the STBs waggling and begging to be fed at long distance. However, if they came closer to the child and the trash can jiggled about with excitement, they were rather more successful. The kids didn’t care if they were up close and personal or just sociably close, they responded the same way about 30% of the time and picked up the trash and put it in the box.

That might sound like a reasonable success rate, but wait, the rate went up to a whopping 70% when the boxes swarmed together and made their approached . Even better as the boxes were in different colors, the kids sorted the trash into the right type of box for paper, plastic etc.

I’m sure that we’d all feel pressured to pick up our trash, or other peoples, and put it in the correct box when being approached by a swarm of hungry boxes, jiggling up and down begging to be fed. How could we just walk on by and leave them jumping up and down by a discarded soda can when all we would have to do is pick it up and pop it in the blue box?

  1. Y. Yamaji, T. Miyake, Y. Yoshiike, P. R. S. DeSilva & M. Okada, Int. J. Soc. Robotics, doi 10.1007/s 12369-011-01114-y