Tag Archives: health

Oxygenating blood directly

Engineering and biological constraints may make the following idea infeasible, but theoretically, one way to keep people with lung damage alive is to pump their blood through a machine that oxygenates it. Dialysis is an analogous treatment for kidney failure.

Blood would be taken out via a cannula, pumped through a system with a large surface area covered with an oxygen-permeable membrane. On the other side of the membrane is gaseous oxygen. After passing through, blood is pumped back into the body via another cannula.

The large surface area could be just two flat plates with a narrow gap between them. The oxygen-permeable plate probably needs to be thin, which makes it weak. Positioning the plates horizontally allows the pressure of the blood between the plates to support the top plate. The pressure of the oxygen above it could be regulated so the plate does not bulge outward. With careful pressure management, the plate does not have to be rigid, could be just a thin film.

The potential complications are in the details: ideally the blood would be taken from the arteries leading from the heart to the lungs and inserted into the veins going from the lungs to the heart, but puncturing these vessels is dangerous. Taking the blood from an arm or leg vein is straightforward, but there may be biological problems if oxygenated blood is pumped back into a vein instead of an artery.

Sudden lung failure does not leave enough time for such a system to be set up, because death occurs quickly without oxygen. However, if the lung failure is predicted with high probability in advance (such as when a disease is disabling the lungs), then the person can be connected to the oxygenation system and kept alive. This buys time for either the disease to be cured, in which case the lungs may become functional again, or for lung transplantation if feasible.

On the optimality of self-quarantine

Is self-quarantine early in an epidemic optimal, either individually or for society?

Individual incentives are easier to analyse, so let’s start with these. Conditional on catching a disease, other things equal, later is better. The reasons are discounting and the advances in treatment. A delay of many years may increase the severity conditional on infection (old age weakens immunity), but such long time intervals are typically not relevant in an epidemic.

Conditional on falling ill within the next year (during which discounting and advances in treatment are negligible), it is better to catch the disease when few others are infected, so hospitals have spare capacity. This suggests either significantly before or long after the peak of the epidemic. Self-quarantine, if tight enough, may postpone one’s infection past the peak.

Another individually optimal choice is to get infected early (also called vaccination with live unattenuated virus), although not if immunity increases very little or even decreases. The latter means that one infection raises the probability of another with the same disease, like for malaria, HIV and herpes, which hide out in the organism and recur. Cancer displays similar comebacks. For viral respiratory diseases, as far as I know, immunity increases after infection, but not to 100%. The optimality of self-quarantine vs trying to be infected early then depends on the degree of immunity generated, the quality of the quarantine, whether the disease will be eradicated soon after the epidemic, and other details of the situation.

Individual optimality also depends on what the rest of the population is doing. If their self-quarantine is close to perfect, then an individual’s risk of catching the disease is very low, so no reason to suffer the disutility of isolation. If others quarantine themselves moderately, so the disease will be eradicated soon, but currently is quite infectious, then self-isolation is individually optimal. If others do almost nothing, and the disease spreads easily and does not generate much immunity, then an individual will either have to self-quarantine indefinitely or will catch it. Seasonal flu and the common cold (various rhinoviruses and adenoviruses) are reasonable examples. For these, self-quarantine is individually suboptimal.

Social welfare considerations seem to weigh in favour of self-quarantine, because a sick person infects others, which speeds up the epidemic. One exception to the optimality of self-quarantine comes from economies of scale in treatment when prevalence is not so high as to overwhelm the health system. If the epidemic is fading, but the disease increases immunity and is likely to become endemic, with low prevalence, then it may be better from a social standpoint to catch the disease when treatment is widely available, medical personnel have just had plenty of experience with this illness, and not many other people remain susceptible. This is rare.

Herd immunity is another reason why self-quarantine is socially suboptimal for some diseases. The logic is the same as for vaccination. If catching chickenpox as a child is a mild problem and prevents contracting and spreading it at an older age when it is more severe, then sending children to a school with a chickenpox epidemic is a smart idea.

Reducing the duration of quarantine for vulnerable populations is another reason why being infected sooner rather than later may be socially optimal. Suppose a disease is dangerous for some groups, but mild or even undetectable for most of the population, spreads widely and makes people resistant enough that herd immunity leads to eradication. During the epidemic, the vulnerable have to be isolated, which is unpleasant for them. The faster the non-vulnerable people get their herd immunity and eradicate the infection, the shorter the quarantine required for the vulnerable.

For most epidemics, but not all, self-quarantine is probably socially optimal.

Visually distinct social classes in agrarian societies

One argument advanced for why slavery in the US was special among the world’s slaveholding societies is that one race enslaved another. However, before the age of genetic testing, the races could only have been distinguished visually. Similarly obvious differences in the looks of slaves and masters, or serfs and nobility occurred in all agrarian societies. The obviousness of distinct looks is meant in the statistical sense: with what accuracy could people classify others into slaves and masters, or peasants and lords, averaged both across the population judging and the population judged? I believe the accuracy was close to perfect – comparable to the classification accuracy of US slaves and slaveholders – for the following reasons.

Serfs were malnourished in childhood, thus short. They did hard physical labour without stretching much, thus were bent over, with back and leg muscles better developed than the rest. They spent the day outdoors without sunscreen, wearing limited clothing, thus were tanned. The lack of sunglasses caused them to squint, creating characteristic wrinkles on the face. They seldom had opportunity to wash, thus had ingrained dirt in their skin that would not have come out with a single hard scrubbing. Both corporal punishment and intrafamily violence caused many of them to have visible scars, missing teeth, crooked noses. By contrast, the well-fed nobility were tall and practised proper erect posture in childhood for table manners and dance lessons. Their physical exercise was mostly cardiovascular, without heavy lifting, thus they were either slim or fat, but not muscular. Fencing may have developed noblemen’s quadriceps, biceps and wrist muscles, not so much the trunk. The nobility’s fashionable paleness was further ensured by wearing gloves and hats and carrying parasols during the short time spent outdoors.

All these physical contrasts ensured that even in the same clothes and surroundings, without talking or moving, a peasant and a noble could be distinguished at a glance. In this sense there was nothing special about US slavery.

The belief that US slaves were more distinguishable from their owners than those of other slaveholding societies is based on modern experience – nowadays, people of the same race but different social class are difficult to distinguish based on their physical appearance. Similar nutrition, sports opportunities and outdoor exposure lead to similar stature, musculature and tan.

Free food for health and the environment

To motivate choosing vegan or environmentally friendly or healthy food, one option is to provide it for free. If people have eaten their fill, they are less likely to buy extra, whether meat or unhealthy. There are tradeoffs of course – any free resource tends to be overused.

For free food to be environmentally friendly, it should not be wasted and disposable utensils should be avoided. Food waste can be reduced by providing small portions to be eaten on the spot, with unlimited free refills of these small portions. All-you-can-eat restaurants already use this strategy by providing only small plates and bowls. The oversight of the food servers and other eaters and their disapproval of wasting food is a social deterrent.

The use of disposable dishes may be reduced by not providing any, requiring people to bring their own utensils, but some will then bring disposable and some will substitute away from the free food toward buying (unhealthy, delivered) meals in disposable containers. It is an empirical question whether the potential use of disposables outweighs the benefit of switching people to healthy and environmentally friendly eating. A dishwasher next to the food station eases the use of reusable kitchenware. Handheld foods (buns, sandwiches, wraps, whole fruit) do not require dishes.

Free food may lead to overeating and increase obesity. Any free resource tends to be over-used, especially if in limited quantity or available for a limited time. The latter overuse motives are eliminated by making the free food continuously available, but this exacerbates potential overeating. The obesity effect can be reduced by offering only healthy food without the somewhat addictive additives sugar, salt and monosodium glutamate. Foods like celery, iceberg lettuce, whole linseeds that provide fewer calories than it takes to chew and digest them (given inefficient human digestion, as opposed to the calories measured by the burn method) may actually reduce obesity when distributed for free. Again, it is an empirical question whether the potential costs of overeating and obesity neutralise the benefit of substituting towards healthier and environmentally friendlier foods.

Given how cheap basic healthy foods are (rice and other dry grains under a dollar per kilo, cabbage, bananas, lemons, dry peas and lentils two dollars per kilo), the social benefit of providing these for free may outweigh the deadweight loss of taxation to finance their purchase. In this case, the government would actually save money in the long run (over the average life expectancy) by offering free food. Cooking the foods would increase the costs slightly, but not much if it is done continuously in bulk by machines (rice cookers, bread machines). No need to wash the cookers if a new batch goes in within hours and the heat sterilises the machine. Or the machine can wash itself if it is connected to a water supply, a drain and a soap dispenser and either has a mixing blade in it like a blender or the water supply has sufficient pressure to flush out the soap residue.

„People should have a choice” works both ways

Initiatives to counter unhealthy and destructive habits (smoking, gambling, junk food consumption) by taxing or restricting the addictive goods and services are often opposed with the argument that people should have a choice. One counterargument is that removing temptations from one’s future self is also a choice that people should have. For example, banning oneself from casinos. Similar registries could be instituted to ban oneself from buying alcohol or tobacco – the sales already require checking ID, so all that is needed is to compare the person’s identity against a database. For example, using a machine-readable ID which causes the machine to display “Do not sell” for people who have put themselves on the relevant list. Countries with universal machine-readable identification documents can use their existing systems for this. Examples are the European Union national identity cards.

Other ways to remove temptations from one’s way are restrictions on advertising, eliminating vending machines from a building, liquor stores near schools, alcohol and tobacco from the more visible areas of grocery shops. Just like people should have a choice to block spam emails, calls, web browser ads, they should have a choice to ban street advertising (of addictive goods or anything else) in their residential or work areas. Removing a public ad restricts some people’s right to see it, but empirically most people do not want to see more marketing in public spaces or elsewhere. Symmetrically, displaying a public ad restricts people’s right to avoid seeing it, so the question is how many people’s rights are restricted by banning vs allowing advertising.

The problem of annoying public advertisements may be resolved by smart glasses like Google Glass if these can detect advertisements appearing in the field of view and block these or replace with other images before the user sees these, similarly to how adblock software in browsers works.

Dark-coloured buildings and cars are silly

Many buildings in Australia, especially new developments, are black, dark grey or brown, or at least the roof is. Many cars are black (other dark colours are less prevalent). The dark colouring increases both cooling and heating costs, because it absorbs and emits solar and infrared radiation faster. In addition, the dark buildings are depressing and ugly. Dark-coloured cars are more difficult to notice, especially in low-visibility conditions, thus have more accidents. White or yellow vehicles are the safest (Lardelli-Claret et al. 2002, Solomon and King 1995).

For cars, the choice of black colour is probably caused by the owner’s desire to seem wealthy by making the car look expensive – limousines in films and popular culture are often black. For buildings, the association in people’s minds between colour and price is weak. If anything, light-coloured houses, reminiscent of Mediterranean villas and the White House, may slightly raise the owner’s status. The reason for dark-coloured roofs may be the cost – tar paper is a cheap material, easy to install. Windows may appear dark due to the one-way glass used. However, for walls, the cheapest material is usually bare concrete, as shown by its choice for purely functional structures (warehouses, barriers, piers, military buildings). For private dwellings, wood or brick may be the cheapest. Neither concrete, wood nor brick is particularly dark in colour, so the choice to build black or brown houses is puzzling. Maybe it is an architectural fad – fashions often trump practicality.

Blind testing of bicycle fitting

Claims that getting a professional bike fit significantly improves riding comfort and speed and reduces overuse injuries seem suspicious – how can a centimetre here or there make such a large difference? A very wrong fit (e.g. an adult using a children’s bike) of course creates big problems, but most people can adjust their bike to a reasonable fit based on a few online suggestions.

To determine the actual benefit of a bike fit requires a randomised trial: have professionals determine the bike fit for a large enough sample of riders, measure and record the objective parameters of the fit (centimetres of seatpost out of the seat tube, handlebar height from the ground, pedal crank length, etc). Then randomly change the fit by a few centimetres or leave it unchanged, without the cyclist knowing, and let the rider test the bike. Record the speed, ask the rider to rate the comfort, fatigue, etc. Repeat for several random changes in fit. Statistically test whether the average speed, comfort rating and other outcome variables across the sample of riders are better with the actual fit or with small random changes. To eliminate the placebo effect, blind testing is important – the cyclists should not know whether and how the fit has been changed.

Another approach is to have each rider test a large sample of different bike fits, find the best one empirically, record its objective parameters and then have a sample of professional fitters (who should not know what empirical fit was found) choose the best fit. Test statistically whether the professionals choose the same fit as the cyclist.

A simpler trial that does not quite answer the question of interest checks the consistency of different bike fitters. The same person with the same bike in the same initial configuration goes to various fitters and asks them to choose a fit. After each fitting, the objective sizing of the bike is recorded and then the bike is returned to the initial configuration before the next fit. The test is whether all fitters choose approximately the same parameters. Inconsistency implies that most fitters cannot figure out the objectively best fit, but consistency does not imply that the consensus of the fitters is the optimal sizing. They could all be wrong the same way – consistency is insufficient to answer the question of interest.

Asking questions of yourself

To make better decisions, ask about all your activities “Am I doing this right? Is there a better way?” I would have benefited from considering such questions about many everyday tasks. For example, I brushed my teeth wrong (sawing at the roots) until late teens, brushed my teeth at the wrong time (right after a meal when the enamel is soft) until my 30s. I only learned to cut my own hair in my mid-20s, and this was the highest-return investment I ever made, because a hair clipper costs as much as a haircut, so pays for itself with the first use.

Peeling a kiwi with a spoon is far easier than slicing with a knife. All it took to learn this was one web search, but it required asking myself the question of whether I was peeling fruit optimally. Same for extracting the seed from an avocado.

Cracking the shell of a hard-boiled egg, making two holes at the ends and blowing air under the membrane before peeling is another trick I wish I had known earlier.

Microwaved food is cooler in the centre, so to avoid scalding one’s mouth, it is helpful to start eating it from the middle. Cooked food left in a covered cooking pot or transferred to a storage container while still mildly hot does not go bad at room temperature for several days – doing this experiment required posing this hypothesis. Drinking without touching the bottle with one’s mouth turns out to be quite easy and is widespread in India.

Only after learning to drive did I start meaningfully using gears on a bicycle, and it took about 15 years more to start shifting approximately correctly (pedalling cadence 60-100 rotations per minute, downshifting before stopping, avoiding cross-geared riding). Similarly for basic bike maintenance like cleaning and oiling the chain, selecting the appropriate front and rear tire pressure given one’s weight and tire widths. Seat height is one thing I figured out early, but not handlebar height.

As a teenager, I would have benefited from asking myself whether I was overtraining, whether my nutrition was reasonable, how soon to return to training after various injuries and whether to seek medical assistance with these. Questioning the competence of coaches and doing a simple web search for sports medicine resources would have prevented following some of their mistaken advice.

Sometimes asking yourself the question reveals that you are already doing the task correctly. On the internet, people claim that they do not use shampoo, just water, and their hair stays clean-smelling and more lush than using detergent. An experiment not to use shampoo was a failure for me, causing greasy hair and lots of dandruff after a few days. The optimality of shampoo may depend on individual scalp and hair characteristics. On the other hand, a single-blade disposable razor and cold water give me a better shave than multi-bladed fancy brands with foam (that get clogged), and the disposable razor stays sharp enough for a month or two of everyday shaving.

When going to teach, it may be worth asking whether the room is the correct one, even if some students show up and the room is free, because once in this situation I was in a room with the right label, but in the wrong building.

On the other hand, constantly doubting oneself is unhealthy and unhelpful. If enough evidence points one way, then it is time to make up one’s mind.

Why princesses and princes are described as attractive

The bards and scribes who recorded events for posterity received their income essentially in the form of tips from the rulers and the rich, so had an incentive to flatter, describing their patrons as more attractive, virtuous, brave, etc than they really were.

In addition to the exaggeration of their actual attractiveness in reports that have reached us, the children of the wealthy probably really were more beautiful than the poor. Richer youth were better fed and cared for, thus had fewer developmental abnormalities (e.g. bent legs from calcium deficiency) and diseases. The poor were malnourished, lived in dirty conditions and were subject to violence, therefore were more likely stunted, stank and had skin diseases, missing teeth and scars. The latter two distinctions in looks have to a lesser extent lasted to the present day, for the same reason.

Attractiveness consists of the visual, audible and olfactory signals of a fit mate (healthy, fertile conspecific), because organisms evolved to consider fit mates attractive. In times when most people were malnourished and diseased, a well fed and healthy rich person would have been much fitter than most, thus a preferred sexual partner for others.

On the other hand, conditional on surviving to adulthood, the poor likely had better immune-related genes, because they were under stronger selection pressure. Poorer people also experienced more infections, thus acquired stronger immunity to more diseases if they survived. Then conditional on equal looks, a person from a poorer background would have been a fitter mate. Also, the ruling class intermarried to keep wealth in the family, so were inbred (hereditary diseases among European royalty are an example consequence). For these two reasons, it is not surprising that the rulers and the rich found some poor people sexually attractive, specifically the outwardly healthiest-appearing among those who reached maturity.

Multifunctional layered clothing

Hiking websites recommend wearing layers, because these make adjusting between warm and cold weather or uphill and downhill walking simple. One thick garment would only work for cold, but taking it off when it gets too hot may leave only too thin clothing.

The same principle of layers applies for everyday clothes. My office is 12 degrees in winter mornings, so I wear two pairs of pants, sometimes two vests and a fleece. Instead of one thick pair of pants that would only suit cold temperatures, thin pants can be worn singly in warm weather and doubled up in cold.

For cycling in the cold, shorts can be worn under long athletic slacks. This principle should also work for hats – two thin fleece ski caps instead of one thick, but I have not tested it. Similarly, two pairs of socks. Although, just like with thick socks, if doubled socks make the shoes fit too tightly, then the reduced circulation increases the cold feeling.

Toe warmer making instructions on the internet suggest using the cut-off front parts of old socks. A more multifunctional option is to roll back existing socks halfway, so both the toe and the ankle part of the sock cover the toes, as in the following image.

Cut socks only work as toe warmers, but rolled-back socks can be used year round.