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.

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
Total93.7141.8

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.

Apologies

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:

Flow

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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