Word of the day: Hysteresis

Too long in a slump, and the slump starts to get permanent.

The Financial Times reports this morning that the Olympics don't seem to be leading to quite the tourist boom expected:

The games have attracted as many as 100,000 foreign visitors [per day] to London – more than in previous Olympics. But, on its own, that number significantly lags behind the estimated 300,000 foreign tourists [per day] who could be expected in a typical year.

As Richard Murphy points out, this means that one of the great hopes for bringing the country out of recession appears to be fading away. Which means the word of the day is hysteresis.

In general terms, hysteresis is similar to intertia; it is the concept that some things which are hard to get going may then require little input to maintain, and even more effort to reverse.

In specific economic terms, it is the theory that persistent levels of high unemployment raise the "natural" rate of unemployment, also known as NAIRU, the non-accelerating inflation rate of unemploymet. This is the level of unemployment at which, under neo-classical economics, inflation stays low and steady. (As a side-note, yes, neo-classical economics holds that a certain amount of unemployment is good. "Full employment" is thus a bad thing, because it leads to spiralling inflation)

Although it's not specifically related to GDP, it is always a fear when dealing with persistent unemployment and long periods of stagnation and recession. The cause of the phenomenon comes when layoffs in a particular sector increase the bargaining power of the remaining workers. as there are fewer of them left, they can demand higher wages, which become "sticky" in nominal terms, if the period of unemployment lasts long enough. If, at the end of the recession, the business then wants to hire new employees, they have to pay them the new, high wage. In practice, this means that either unemployment stays high permanently, or inflation goes up until the value of the high wage is back, in real tems, to where it was.

It doesn't look like we are seeing the "increased wages" part of the problem yet (since wages are very much stagnating), but that hasn't stopped Citigroup's Ajai Chopra warning everyone:

Our analysis of such hysteresis effects shows that the large and sustained output gap, the difference between what an economy could produce and what it is producing, raises the danger that a downturn reduces the economy’s productive capacity and permanently depresses potential GDP.

A street cleaner passes the Jobcentre Plus in Bath. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Getty
Show Hide image

A swimming pool and a bleeding toe put my medical competency in doubt

Doctors are used to contending with Google. Sometimes the search engine wins. 

The brutal heatwave affecting southern Europe this summer has become known among locals as “Lucifer”. Having just returned from Italy, I fully understand the nickname. An early excursion caused the beginnings of sunstroke, so we abandoned plans to explore the cultural heritage of the Amalfi region and strayed no further than five metres from the hotel pool for the rest of the week.

The children were delighted, particularly my 12-year-old stepdaughter, Gracie, who proceeded to spend hours at a time playing in the water. Towelling herself after one long session, she noticed something odd.

“What’s happened there?” she asked, holding her foot aloft in front of my face.

I inspected the proffered appendage: on the underside of her big toe was an oblong area of glistening red flesh that looked like a chunk of raw steak.

“Did you injure it?”

She shook her head. “It doesn’t hurt at all.”

I shrugged and said she must have grazed it. She wasn’t convinced, pointing out that she would remember if she had done that. She has great faith in plasters, though, and once it was dressed she forgot all about it. I dismissed it, too, assuming it was one of those things.

By the end of the next day, the pulp on the underside of all of her toes looked the same. As the doctor in the family, I felt under some pressure to come up with an explanation. I made up something about burns from the hot paving slabs around the pool. Gracie didn’t say as much, but her look suggested a dawning scepticism over my claims to hold a medical degree.

The next day, Gracie and her new-found holiday playmate, Eve, abruptly terminated a marathon piggy-in-the-middle session in the pool with Eve’s dad. “Our feet are bleeding,” they announced, somewhat incredulously. Sure enough, bright-red blood was flowing, apparently painlessly, from the bottoms of their big toes.

Doctors are used to contending with Google. Often, what patients discover on the internet causes them undue alarm, and our role is to provide context and reassurance. But not infrequently, people come across information that outstrips our knowledge. On my return from our room with fresh supplies of plasters, my wife looked up from her sun lounger with an air of quiet amusement.

“It’s called ‘pool toe’,” she said, handing me her iPhone. The page she had tracked down described the girls’ situation exactly: friction burns, most commonly seen in children, caused by repetitive hopping about on the abrasive floors of swimming pools. Doctors practising in hot countries must see it all the time. I doubt it presents often to British GPs.

I remained puzzled about the lack of pain. The injuries looked bad, but neither Gracie nor Eve was particularly bothered. Here the internet drew a blank, but I suspect it has to do with the “pruning” of our skin that we’re all familiar with after a soak in the bath. This only occurs over the pulps of our fingers and toes. It was once thought to be caused by water diffusing into skin cells, making them swell, but the truth is far more fascinating.

The wrinkling is an active process, triggered by immersion, in which the blood supply to the pulp regions is switched off, causing the skin there to shrink and pucker. This creates the biological equivalent of tyre treads on our fingers and toes and markedly improves our grip – of great evolutionary advantage when grasping slippery fish in a river, or if trying to maintain balance on slick wet rocks.

The flip side of this is much greater friction, leading to abrasion of the skin through repeated micro-trauma. And the lack of blood flow causes nerves to shut down, depriving us of the pain that would otherwise alert us to the ongoing tissue damage. An adaptation that helped our ancestors hunt in rivers proves considerably less use on a modern summer holiday.

I may not have seen much of the local heritage, but the trip to Italy taught me something new all the same. 

This article first appeared in the 17 August 2017 issue of the New Statesman, Trump goes nuclear