2019 Week 42: Hot, Loud, Crazy, and Numb.

Short version: Heating Engineering is effective but unintuitive. Tim Minchin’s Back tour, DNA and Microscopy, We loses billions, a dip in my Mental Health.

Long version:

Heating – Great Engineering Terrible Design

If you have radiators for heating the numbers on the valve are not arbitrary, but adjust flow to maintain temperature automatically. Therefore they can be set to a desired temperature and left in that position without need for adjustment based on weather.

Central heating was a novel experience for me when I moved to the UK. A common system (which is fitted in my home) is to have a single boiler that heats water (in my case by burning gas, the alternative being electric heating) that then flows into radiators throughout the house. Each radiator has a valve. Only recently I learned that the valves attached to each radiator are more complex than they appear; rather than simply controlling flow directly (like a tap at a sink), they contain a material that is sensitive to temperature (wax) and the flow is adjusted to keep the radiator at a fixed temperature. If the radiator is set at position 3, corresponding to 20°C, and the temperature in the room is 21°C, no water will flow as the expansion of wax closes the valve. If the room cools to 19°C then the wax contracts and opens the valve, allowing hot water to flow. This document from Honeywell provides some more explanation.

On the one hand, this is clever engineering that ultimately saves energy by preventing unnecessary heating. On the other, the arbitrary 0 to 5 scale, instead of marking the temperature that the valve maintains, makes this feature counter-intuitive. Without being told about this I doubt I would have ever noticed this self-regulation. The combined thermal mass of radiators and the rooms they heat is large, thus the changes from adjusting the valve occur too slowly to observe easily.

Even something ubiquitous and seemingly simple can be surprisingly complex.

Tim Minchin

I saw Tim Minchin play in Oxford this weekend. Songs included 15 Minutes and Woody Allen Jesus. The show was fun, loud, irreverent, self-indulgent, and self-aware. It was an immersive reminder to me that while technology gives us the incredible opportunity to experience almost the entire library of music almost anywhere, there is an intimacy and immediacy to seeing a live performance that makes the experience more powerful. In this comedic performance, the energy of the performers and their impromptu interactions with each other and the audience makes listening alone to recordings comparatively cold and dry.

At a few points while monologuing Minchin pointed out how his earlier songs which come from the perspective of a (relatively) impoverished artist now conflict with his huge (financial) successes. He also addressed the modern “tribes” of progressives and conservatives, and the contradiction of his (huge) personal carbon footprint and his concerns about the environment. It particularly hit home (given the last section of this blog post) to hear him describe his first experience with depression; being sad that his hundred-million-dollar cartoon was binned from a house looking over the ocean, which was paid for by his hugely successful musical. There is a sense that when one is so lucky, so privileged, that mental illness is unacceptable, and yet, it does affect us.

Two Interesting Things from Nature

A narrative regarding the discovery of the structure of DNA, and a comment about the need for easier access to microscopy.

Business in 2019

Is crazy. Consider this quote from this article:

If you wake up on a Casper mattress, work out with a Peloton before breakfast, Uber to your desk at a WeWork, order DoorDash for lunch, take a Lyft home, and get dinner through Postmates, you’ve interacted with seven companies that will collectively lose nearly $14 billion this year.

Derek Thompson
writes in The Atlantic

Venture capitalists have essentially subsidised tech-y westerners to the tune of $100 each (Assuming about 140 million people use these loss making services). Meanwhile WeWork seems to be imploding.

Mental Health

I’ve had a (hopefully brief) decline in mental health recently. It is tempting to look for causation. I could guess at less daylight, or colder temperatures, or working beyond a sustainable amount recently. Maybe it is my experimental work, which while intellectually stimulating, occasionally has patches of repeated failures. Each failed experiment whittles away at confidence and motivation, and creates a sense that the whole exercise is pointless. Importantly though, sometimes there is no cause, or the cause is not concurrent with the effect. All I really know is I woke up on Friday feeling numb, unmotivated, and wanting desperately to escape my own thoughts. I am very lucky to have colleagues and friends who are understanding and supportive. I have learnt that alcohol is a bad way to escape. I am trying to be patient with myself. If I get nothing useful done in a day that is frustrating, but a constant stream of self-berating doesn’t help. I know things will get better.

2019 Week 41: Changing your mind

Short version: An interesting question to reflect on, a mantra I find useful, another reason to avoid diabetes, the Nobel Prize rejection, and making my phone less distracting.

What would it take to change your mind?

I’ve been thinking about this question recently. In many ways our beliefs about the world, what we hold “in mind”, is intertwined with our identity. How those ideas form, and how they can be changed, informs who we are and how we act. I have not spent much time thinking about what specific influences would be required to change my beliefs. I would like to think that, as a scientist, I am willing to “turn on a dime” in response to strong evidence, but what specifically constitutes strong evidence?

On a population level changing minds is critical to governance. Journalist Carole Cadwalladr gave a TED talk with some fascinating images; advertisements run on Facebook that she suggests influenced Welsh citizens to vote against their own interests on the Brexit referendum. I wonder if those citizens would be able to identify what caused them to be so fearful of hypothetical Turkish migrants (specifically) or the EU (generally), and what evidence or experiences they would now require to lose those fears.

I would suggest you try the thought experiment (and would love to hear your thoughts!). Consider what might cause you to change your mind on beliefs that you hold at different strengths. What might make you change the political party you feel aligned with? Your religious views? Views on climate change? On who you are? At the moment my own thoughts are quite confused, but I find the exercise interesting.

A useful mantra

When trying to understand why someone has acted to cause you harm, I find it useful to remember the order of these three causes:
Apathy. Incompetence. Malevolence.

I realised that it is very rare that a negative occurrence is the result of malicious intent, but often we suspect that cause. I’ve explained my thoughts (and the three word reminder above) a couple times in person in recent weeks.

First for something malicious to occur someone needs to care enough to do consider a malicious act and then act on that thought. Most people just do not give significant thought to others, and generally people err on the side of inaction. Even when a relationship is positive and significant, the frequency of thinking of doing something good translating into actually doing it is relatively low, and most people only have a small number of such intense relationships. Consider how many such strong relationships you have, compared with how many people you cross paths with regularly, and this can likely be extrapolated to others. Just as apathy may cause you to thoughtlessly inconvenience one of these people, so too might their apathy inconvenience you. (There is a related punchline in a joke about gun ownership I rather enjoy: if you are buying a gun for personal defence you must (absurdly) have a high opinion of yourself that anyone cares enough about you to try and attack you).

Second, much of the time when we try to influence the world we make mistakes and influence it in an unintentional way. Just as a good intention can produce a bad outcome, so too does an attempt to manifest a bad intention have a chance of producing a good outcome, or no outcome at all. Since most people tend not to practice malicious acts regularly (I hope), then most people even if attempting to cause harm will do so poorly. More often people trying to be good may fail, and therefore accidentally cause harm. The harm is caused by incompetence rather than malice.

Finally, only if apathy and incompetence are considered and ruled out should we consider ill will. Our mind rushes to this conclusion first, stories we learn from an early age arrange themselves around characters acting in opposition, “good” vs “bad”. It is more comfortable to consider a simple and ordered narrative where people are competent and their actions match their intentions, rather than the complex disordered reality where the two are often not coupled. We are at the centre of our own misfortune, and so assume people can see what we do and must therefore notice and care about our strong emotion. Ultimately these are misguided assumptions.

Remember, when next bitterly considering why you were wronged, the likely reason is Apathy, then Incompetence, and only then, Malevolence.

Diabetes and Alzheimer’s

Diabetes is a prevalent disease in the developed world, and can partially be addressed through lifestyle interventions, like maintaining a healthy diet (and hence weight) and exercising. If there weren’t already enough reasons to avoid diabetes, I’ve recently come across the term “type-3” diabetes, an alternate name for Alzheimer’s disease, due to similarities between the diseases and correlation between Alzheimer’s disease and type-2 diabetes.

Nobel Prize Winner’s Nature Rejection Letters

This week the Nobel Prizes were announced, including one for Peter J Ratcliffe, for his work on hypoxia. I’ve seen some tweets sharing a letter to Ratcliffe declining to publish a paper from him. The message is often one of encouragement to persevere in the face of criticism, or that Nature has made a serious blunder by not publishing the work.

The assumptions here are interesting. Ratcliffe’s Nobel Prize indicates a significant contribution, but it does not mean that every paper he wrote warranted publication at all, let alone publication in any specific journal. Perseverance is naturally a requirement for success in a field (trivially if you quit before you succeed you cannot succeed), but that perseverance needs to include a willingness to adapt to both criticism and praise from peers, not blindness to it (though that adaptation can also be bolstering evidence and pushing back against the criticism, rather than conceding to it). Finally the publisher here (Nature) is responding to the comments of the reviewers who would be other researchers in the field (peers), rather than merely dismissing the work, which I feel can be lost in the suggestion that Nature made a mistake not publishing the work: they were following the procedures which fundamentally led to their success and prestige as a journal.

As an aside: Ratcliffe ended up having 28 papers (to date) in Nature family journals, of which 3 are in nature itself, so I doubt anyone is holding a grudge.

Phone Distractions

I wrote about changing my search engine, and while some tasks now take longer I have adapted and think there is some improvement to the content I consume. This week, at a friend’s suggestion, I switched my phone to monochrome (greyscale), in an attempt to make it less visually alluring. I am surprised how effective such a small change is, the content is the same, but the stimulus is reduced, and it makes it easier to moderate my time mindlessly scrolling.

Oxford Half Marathon

This week I ran the Oxford half marathon, and while at the moment I am still overdue on the Blenheim Palace half race report, I’m hoping to write both and update the respective blog posts soon.

Photos from the week

2019 Week 40: Charts and Code

Short version: Intuitions about how we look at data. Taking small steps with code. Art at the Tate Modern.

Long version:

Sneaky Spreadsheets

This week I have been processing some experimental data and realised how the same data can be plotted in seemingly different ways. Often looking at the numbers themselves can be challenging, particularly if there are hundreds of points with multiple values at each point. For this example we take some simple data about income distribution in the UK. The numbers alone are accurate but making inferences takes consideration and a little mental arithmetic.

A linear column chart is the simplest and fastest way to visualise the data in a spreadsheet program (excel, google sheets, open office calc). It shows the 99th percentile as much larger than the other values, and the increases seem bigger between the higher percentiles.

Taking a logarithmic plot makes each step along the distribution seem more even, but the 99th percentile still seems noticeably larger.

But by changing the minimum axis value on a logarithmic plot the distribution seems much flatter overall.

And we can go to the opposite extreme, by plotting a pie chart the high income earners (top 1%) seem to take a massive share of the pie.


I am not proficient in code, and find that embarrassing. That is an odd statement, I’m not proficient at many things (skateboarding, Portuguese speaking, cello playing) but few of those things cause me to feel embarrassment. Technological proficiency, unlike skating or playing a string instrument, is a part of my identity, and I feel that being able to code (or at least write basic scripts) is a part of being good with tech. When I go to write code, I am confronted by the gap between what I feel my skill should be and where my skills actually are, which is uncomfortable. Moreover it causes me to hide, refraining from asking for help, and I end up doing things in a slow and repetitive way. To push back against that urge, here is an attempt to write a simple python script to extract folder information from a directory tree.

import os
import re
print "This removes files from saved directory trees"
path = "./"
print "I will run in the local folder"
linecount = 0
for filename in os.listdir(path):
        if filename[len(filename)-4:]==".txt":
            with open(os.path.join(path, filename), "r") as file:
                output= open(filename[0:len(filename)-4]+"_folders.txt","w+")
                for line in  file:
                    if len(line) > 6:
                        if line[len(line)-6]!=".":
                            if line[len(line)-5]!=".":
                                if line[len(line)-6:]!="Cloud\n":
                                    linecount = linecount +1
            print("I found "+str(linecount)+" lines and put them into "+filename[0:len(filename)-4]+"_folders.txt")
            linecount = 0
            print("I did not process "+filename)
            linecount = 0

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Photos from the week

From the Tate Modern exhibition by Olafur Eliasson

2019 Week 39: Microwaves, Search, and Running.

Short version: I try and explain how microwaves work, I changed my search engine, and ran the Blenheim Palace half marathon.

Long version:

Microwave (ovens)

This week over a (reheated) dinner I tried to explain how microwave ovens work. It was a good reminder of the difficulties of discussing science; first in actually knowing the underlying science, then in communicating it to different people with different (unknown) levels of prior understanding. It was humbling to stumble between gaps in my understanding of a common household appliance and a failure to find the language to explain what I did understand. After refreshing myself on the physics, I try to explain again.

To start:
Microwave ovens convert electrical energy to heat, and are used for warming and cooking food. Other electrical cooking appliances (e.g. stoves, ovens, grills, toasters, and kettles) use the property that a flow of electricity heats the wire (conductor) it flows through. Microwaves make electromagnetic waves (like visible light or radio waves) in the microwave region of the spectrum (hence the name), which heat food (particularly water) as they pass through it. Conventional methods of heating food heat from the surface which gradually warms inwards, where as microwaves can heat food from the inside directly.

Assumed knowledge:
It is easy (and fun!) to get into a spiral of questions about what “heat”, “food”, “electricity” and “electromagnetic waves” are. More information about the parts of a system help build a foundation form where the combined system can be understood; it is hard to understand the science of cooking without understanding a little of the chemistry of what food is, or the physics of what heat is. Also seemingly unrelated knowledge can be useful; if how a musical instrument generates certain sounds is known, then the similar principles of resonant frequencies helps to explain how the microwaves are generated by the magnetron, another type of resonant cavity.

The best I can do:
Food goes in a metal box (a cavity) that stops microwaves escaping. Electricity (240 V AC mains) goes to a transformer that changes the voltage into two windings, a high voltage (approx 2000V) and a low voltage (approx 5 V). The lower voltage powers the user interface (e.g. the clock) and the higher voltage powers the microwave generator, called a magnetron. The magentron is a cylindrical vacuum cavity (closed metal tube with no air) where electrons are thrown off a central filament and travel to the outer walls. Strong magnets cause the electrons to travel along curved paths, and the cavity has spokes that extend from the outer walls most of the way towards the central filament. The spacing of these spokes and the strength of the magnets is tuned so that a specific frequency of electromagnetic radiation (microwaves) are generated by moving charger in the magentron, and these microwaves are guided by a metal tube (wave guide) into the larger cavity containing the food. The generated microwaves bounce around the cavity until they interact with water molecules (and sugars and some fats) in food to vibrate them. This is observed microscopically as heating.

A comprehensive explanation:
Can be found in this paper by Michael Vollmer. Also this video is a good guide.

Microwaves and super-res:
At the moment I work with super-resolution microscopes, which connects with microwave ovens in an interesting way: The grill that lets the user see their food being heated has holes (approx 1 mm across) that are much larger than the wavelength of visible light (approx 0.001 mm) but much smaller than the wavelength of the microwaves (approx 122 mm). Waves cannot “see” and object much smaller than the wavelength of the wave, called the “diffraction limit”. Thus the grill on the door of a microwave oven is “diffraction limited” from the perspective of the microwaves, in the same way that cellular structures can be “diffraction limited” from visible light. I am not sure if the equivalent optics exist for microwaves as in visible light, but it could be possible (though not particularly useful) to super-resolve structures using microwaves. Given microwaves are used in radar, perhaps such techniques are already used for detection of rain, birds, or aircraft.

Small Nudge to Search:

This week I changed my default search engine from google to google scholar.

This has had frustrating consequences; where as typically to find out where a place is, what tomorrow’s weather would be, or to play a song, I simply press the hot-key for a new browser tab and type what I want, that now gives me search results from the academic literature. There are no papers telling me if it will rain in Oxford tomorrow.

I do think this is a useful step. I’ve been reading a little about nudges, a concept linked to Richard Thaler. Changing the default search makes it slightly easier to do literature searches, and slightly harder to do general web searches, which I hope (and expect) will nudge me towards consuming better quality content.

Value-Action Gap

I came across the term “Value-action Gap“, which adds a technical but intuitive term where I would otherwise use the more judgemental “hypocrisy” or the more debater-jargon “principle consistency”. I like hearing opinions on why it is that people often act out of alignment with their beliefs, and am often surprised at my own capacity for cognitive dissonance.

Blenheim Palace Half Marathon

Slightly disappointed with my time, but it was a fun race. I will be adding a race report soon. Edit; I have now added the race report here.

Photo from the Week:

2019 Week 38: Food Miles and Mental Health

Short version: I ate an apple, which got me thinking about climate change. I’ve also been talking about mental health. Purdue went bust. Not every article with 300 citations is novel.

Long version:

Climate Economics: Food Miles

I was eating an apple, here in Oxford, and discovered from the oft mocked apple sticker that it had been grown in an orchard in New Zealand (on the other side of the planet). This struck me as a problem; surely the fuel in transporting food around the world is an externality contributing to climate change. I wanted to know the specific quantity of fuel burned to make this possible, and found this study from New Zealand university Lincoln that claims there is a smaller climate impact from consuming New Zealand apples in the UK compared with local ones. I am sceptical, and will hope to follow up on this in a later post, but the data is summarised in table 7.3 on page 72. Summarising and converting the units to equivalent millilitres of Diesel burned we get:

Equivalent Fuel Burned
(diesel in mL) per apple (assume 100 g) for
NZ ApplesUK Apples
Direct energy consumption at orchard15.679.4
“Chemicals” e.g. fertiliser pesticides12.917.6
Shipping (NZ) and “Cold storage” (UK)65.244.8

So New Zealand is much more efficient at producing apples (about 5x less energy per apple is needed at the orchard), which largely corresponds to better yield per area of land (at 50 tonnes vs 14 tonnes of produce per hectare in New Zealand and the UK respectively), but also is due to better use of renewable electricity generation in NZ (particularly hydroelectric, wiki links to UK and NZ). This energy difference is almost entirely closed by the fuel used in shipping, but the use of “cold storage” of apples in the UK emits a further 44.8 mL equivalent diesel burned.

In short, the study suggests that fresh apples in the UK cause the same emissions per apple as New Zealand apples shipped to the UK, but if the apples are kept in refrigerated storage then the UK apples have a worse impact on the climate.

One notable thing from this exercise is that when you buy a 20p apple at Tesco, you are also paying for about 15p of diesel that was burned to get it from the tree to you.

Climate Change

This week’s Economist cover is a graphic that describes the warming climate. Meanwhile this photo article from the Guardian (also this week) hit me emotionally. The climate is changing, and the effects are disturbing. Currently my approach is very ivory tower: observing and considering, but not actively campaigning. I have friends who are much more active in Green Political Parties and movements like Extinction Rebellion. I think it may be time to explore similar options. I could blog each week about climate change in an attempt to raise awareness, but I would be very surprised if any of my readers were unaware of the issues?

Mental Health

Last week my friend Jessy shared some insight from her time answering a crisis hotline (read on facebook or linkedin). At work we now have staff trained in mental health first aid. It is good to see mental health issues lose their stigma, even if it is a gradual process. I thought someone might find things I do to maintain good mental health useful.

Mental Health Tool kit
(or “Things I do that I think help me mentally”)
Have a plan: Be enrolled in a health care program, have a GP, speak to them about mental health. Know services in your area. Have hotlines in your contact list. (If you broke your leg or developed an odd growth you would know what to do, what if you broke your mind or developed an odd pattern of thoughts?)
Reflect: Write things down to get them out of your head. Write a couple words about how you feel each day somewhere. Notice if something keeps coming back. Even just putting information somewhere else helps me relax that I won’t forget it, so I can let it go even briefly.
Exercise: Match the mental stress with physical stress, release endorphins. “Get out of your mind by getting into your body”. Do something that makes you sweat for 10 minutes. Endorphins make you feel better. Matching the physical stress to your mental stress helps align how you feel. If you are physically worn out, you will sleep.
Sleep: Get good sleep. Put distractions far away. Passing out from alcohol is not sleep.
Eat Clean: Sugary oily foods (fast foods) taste great but make you feel terrible. You also know that they are bad for you so you feel guilty. Eating well makes you feel better.
Control: Organise your room. Go somewhere you want to (ideally under your own power like walking or cycling). You have so much freedom and power. Remind yourself of this by using it.
Breathe: Slow your breathing. Count four on the way in, hold for four, count four on the way out, hold for four, repeat until you don’t remember how long you’ve been trying this.
Mindfulness: Take some time to practice mindfulness (this is a skill that I can’t explain in a couple sentences, but I’d recommend trying the free sessions on Headspace).
Unplug: Go offline. You don’t need technology to survive. Switch off. Leave smart devices behind. Even leave your watch behind to lose track of time. Just be.

Purdue Pharma

On Monday Purdue Pharma filed for bankruptcy. Opiates are incredibly useful and powerful drugs, but are also addictive. The US over prescribed them, peaking at 81.2 prescriptions per 100 persons in 2010-2012. Those prescriptions and subsequent addictions and addiction related deaths are linked to the marketing of OxyContin in many lawsuits against Purdue Pharma. For a humorous take on a dire situation, see John Oliver (April 2019).

Quirks of Academia

A high school student in Australia recently published in a mathematics journal, and it made the news. I have read some slightly bitter comments along the lines of “so what”. There is a lot of pressure inside academia to publish papers (a metric of performance) and seeing a relatively simple result gain media coverage can inspire envy.

Tumbling down the rabbit hole led me to this (now defunct) blog, poking fun at Mary M Tai’s paper and claim to have developed a new method for finding the area under curves. That method may actually be over 2000 years old. That paper has 363 citations today (another metric of academic performance). I found this funny.

Photo from the Week

Some late nights in the lab have let me share runs with the wildlife of Oxford.

2019 Week 37: Bottles, Birds, Blunders, and Bumper Cars.

Short version: Plastic is everywhere, but it doesn’t make you sick. There are some familiar bird sounds at the new physics building. An honest apology keeps me involved. Oxford’s St Giles Fair returns.

Long version:

Plastic in Water

I woke up from a dream this week thinking about the amount of plastic particles humanity has introduced into the environment. The disturbing reality is that just as we have added enormous amounts of plastic to the ocean so too have we added plastic to the water we drink and the food we eat, and hence to ourselves. Plastic has been falling out of popularity, with campaigns to reduce the use of plastic in supermarkets, and bans of plastic drinking straws in the US. It is relatively rare that organic molecules become well known, but BPA (a monomer for poly-carbonate) has attracted sufficient controversy to become a household acronym (particularly when followed by the word “free”).

Ultimately, however, a reason plastic is so ubiquitous is probably also a reason it is relatively harmless: plastics are fairly inert. They don’t break down easily, and so similarly don’t get broken down or absorbed by the body easily. This study found worryingly that Chinese infants’ exposure to BPA is 10x higher than that of adults, but also found that these levels of exposure pose little risk to health.

There is a fairly comprehensive and recent report from the World Health Organisation, which similarly concludes that plastic is everywhere, but there is not evidence that it is causing harms to health. It does suggest the need for further investigation into possible health effects, and that plastic waste management needs to be improved.

Interesting to me was that while browsing this topic, I came across the website “plasticsmakeitpossible“, produced by the American Chemical Council, which in turn is made up of some pretty large companies. I’ve not delved much into how established corporations sway public opinion at arms length, and I think it would be interesting to discuss websites like “plasticsmakeitpossible” in a future blog post.

Bird Calls

This week while waiting outside the Clarendon Laboratory, I heard the strangely familiar sound of Kookaburras coming from the new physics building (the Beecroft Building). My first thought is that the birds were being kept nearby for study, but after hearing the exact same pattern of calls (recording below) I realised it was being played on a loud speaker. My guess is that it is to deter real birds from nesting/resting on the new building, but I could not find any details of this system from the architects website. The sounds do not play at regular intervals so I suspect some sort of motion sensors are involved.


I recently received an email from a study explaining that a large amount of valuable data had been deleted. It must have been tempting to try to blame the system or a fault in the technology, but this individual took ownership of their mistake (essentially having pressed the wrong buttons), and I found myself with more trust in them as a result.

This event is also a useful reminder to implement good data management processes, including backups of irreplaceable data and some sort of delay mechanism for the permanent deletion of data.

St Giles Fair

Oxford hosts the St Giles Fair on the Monday and Tuesday following the first Sunday in September. For at least 200 years the central streets of Oxford have been closed to make way for stalls and rides, and strolling through the rides, games, and food stalls is becoming a tradition for me as well.

Photos from the Week

2019 Week 36: Flow and Food

Short version: I was thinking about how long things last. I’m looking for a good methodology for self-experimentation.

Long version:


This week I was thinking about flow, particularly through a reservoir or storage vessel, as a model for people and cities. The intuition starts with a bucket, being filled by a dripping tap and emptying from a small hole in a bottom, such that the amount of water in the bucket is fixed. Over some amount of time, all the water that was in the bucket will be replaced. If the flow in and out is very small relative to the size of the bucket, the time to replace every molecule of water in the bucket is very large (as the molecules become less concentrated, more new molecules are lost in each drop out), where the extreme case has the no flow and the original water stays in the bucket forever. In other extreme, where the hole and tap are the so large that the entire volume of the bucket is replaced with each drop, it is essentially a pipe and so the replacement rate is essentially infinite (though there is a speed with which molecules diffuse against the direction of flow in a pipe, perhaps something to look into later).

I will update this post shortly with some more thoughts, but taking as an example the question “how much of the bone in your body is made up of calcium consumed by your mother”:

1000-1300 mg/day (calcium intake) = 32.5 mmoL per day in/out. We assume some constant calcium mass in the human body e.g. 1.5% by mass calcium so for 75 kg= 975 g calcium. Probabilities give p(excretion in a day) = 1.3/975 so p(remain) = 1-(1.3/975) = 0.9986 per day = 61% remains per year = 0.61^(age in years) = amount remaining, so after 100 years 7.08e-22% remains or 10 molecules from birth. This of course is very crude. People are not born with the same weight of bone as an adult, which would make this an overestimate of calcium remaining. However not all the body’s calcium is replaced equally frequently, some may be trapped much longer deep in thick pieces of bone, meaning the flow estimate would underestimate. Suffice to say, I confidently predict we all have some calcium in our bodies originally consumed by our mothers.

Supplements and Superfoods

I’ve been hearing bits and pieces about “superfoods”, dietary supplements, and generally nutrition comes up when eating with others. There’s a lot to be skeptical about when it comes to alleged benefits of oils, powders, and pills, as the authors of Reality check: no such thing as a miracle food discuss. I’d be interested in testing the effects of some of these, being inspired by the likes of Tim Ferriss or Peter Attia, but I don’t have an obvious experiment in my head. If you have suggestions I’d love to hear from you, and will try and look more into the literature around nutrition. A good starting point on supplements is this NHS report.

Photos from the week

2019 Week 35: Tears, Triathlons

Short version: Back to work. Jocko’s letter made me cry and that’s OK. First triathlon, went fine. Sriracha sauce as a spaceship.

Long version:

Back to work

I returned to work this week after taking nearly two weeks of holiday. I continue to find it odd that when I am busier I also get more done, but I also suspect that is the combination of routines and inspiring colleagues. The ONI band is practicing more often, and live music provides a wonderful reminder of my family home. Hearing from others about their successes both in work and outside it creates some envy, but also motivates me to strive to make more out of my time.

Something that made me cry

At the end of my holiday I took some time to reflect on the past year, including when I experienced particularly strong emotions. Often in a professional context it is appropriate to suppress emotions, and it is also common that men feel the need to project a stoic facade at the world. In the past I have taken this too far and lost awareness of my emotions, which is detrimental. I still feel generally we should act out of reason rather than emotion, but we should also be aware of our emotions and use their patterns to guide our understanding of ourselves. To this end, I wanted to share this letter written by a Navy Seal to his daughter. It left me feeling a powerful mix emotions, seeing aspects of myself in both the father and the daughter. It left me in tears.

First Triathlon

I took part in my first triathlon on Monday. It was fun. I’ve written a race report you can read here.

Instagram Art

Social media is often an echochamber, but there are opportunities to find new ideas. This week I came across spacegooose who imagines everyday items as spaceships, e.g. Sriracha sauce.

Photos from the Week

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2019 Week 34: Paris

Short version: Here are some observations about Paris.

Long Version:

Milk and Water

Growing up in Australia and now living in the United Kingdom, when I buy milk I usually look for refrigerated shelving. As it turns out, this is not where you find milk in French supermarkets, as Ultra-high Temperature (UHT) processing removes the need for refrigeration before opening. Table of UHT milk consumption by country here.

Paris is the first city in the world I’ve found sparkling water available on tap in an outdoor public space.

Queues at the Louvre

At the Louvre tourists queue for hours to see the Mona Lisa and take a photo of it. I’ve been thinking about this behaviour. The painting is aesthetically pleasing, historically significant, and widely discussed, but so are many paintings on display in galleries around the world. Particularly odd is that most people who get to it are unable to get particularly close to it, and use that brief encounter to look at it through their phone or camera. Given high resolution images of the Mona Lisa are easily available, I would almost go so far as to call this behaviour the “wrong” way to consume art, but on reflection I can’t justify why this is so. I would suggest that the experience of the scale of enormous historic paintings such as Oath of the Horatii or The Raft of the Medusa in person provides something difficult to gain from digital copies.


Wandering the streets of Paris it is clearly a multicultural, multiethnic city. It was notable that those different groups tended to clump, both on the larger scale of multiple city blocks, but also on public transport. Race is a sensitive issue though, and as I lack experience writing about it I’m hesitant to address it hurriedly.

Photos from the Week

2019 Week 33: Holidays

Short version: I’m on holiday.

Long version:


Amusingly while departing Oxford I came across this piece about vacations. It is noticeable here in Paris that the city has emptied out; plenty of stores and cafes have a note in the window mentioning a reopening later in the month.

I’ve enjoyed taking the time to read, think, and jot down some of these thoughts. Alas at the moment most of these thoughts are barely comprehensible to me on rereading, and will require a little more work before sharing.

Photos from the week come from some lovely runs around Oxford and Paris.

Photos from the Week