A torus knot is a special type of knot that is tied on the surface of a torus (a doughnut-shaped surface). More formally, a torus knot is defined by two integers \( p \) and \( q \), where \( p \) represents the number of times the knot winds around the torus's central axis (the "hole" of the doughnut) and \( q \) represents the number of times it wraps around the torus itself.

A Universal Linear Accelerator (ULA) is a type of particle accelerator that uses electromagnetic fields to accelerate charged particles, such as electrons, protons, or ions, in a straight line. The term "universal" suggests that this type of accelerator can be adapted for various applications and can accelerate different kinds of particles.

As of my last knowledge update in October 2021, "Georgia Rodgers" does not refer to a widely recognized public figure, event, or concept. It's possible that the name could refer to a private individual or perhaps has gained prominence after my last update.

Acoustic measurement refers to the process of quantifying various sound-related parameters in a given environment. These measurements are critical in various fields, including engineering, environmental science, music, architecture, and health. The following are common aspects of acoustic measurement: 1. **Sound Pressure Level (SPL)**: Measured in decibels (dB), this quantifies the pressure of sound waves in the air relative to a reference level.

A-weighting is a frequency weighting used in sound measurements to reflect the relative loudness perceived by the human ear. The human auditory system does not respond equally across all frequencies; it is more sensitive to mid-frequency sounds (typically around 1 kHz to 4 kHz) and less sensitive to very low and very high frequencies.

The absolute threshold of hearing refers to the minimum sound level that an average human ear can detect. It is the point at which a sound becomes audible and is typically measured in decibels (dB) relative to a standard reference level. The absolute threshold can vary based on several factors, including frequency and individual differences in hearing acuity.

Acoustic communication refers to the use of sound waves to convey information between individuals or systems. This form of communication can be observed in various contexts and across many species, including humans, animals, and artificial systems. Here are some key aspects of acoustic communication: 1. **Biological Communication**: In the animal kingdom, many species utilize acoustic signals for communication. For example, birds sing to attract mates, warn of predators, or establish territory.

Auralization is the process of creating sound simulations or reproducing audio environments in a way that allows listeners to perceive and experience an auditory scene as if they were present in that environment. It is often used in the fields of architecture, acoustics, and virtual reality, helping to visualize how sound will behave in a specific space before it is built or modified. The process typically involves the use of computer modeling and simulation tools that analyze how sound waves interact with various surfaces and objects within a given environment.

Induced characters refer to representations of a group that arise from the representation of a subgroup. In the context of representation theory—an area of mathematics that studies abstract algebraic structures through linear transformations—induced characters are a way to construct new representations of a group via a subgroup.

Acoustic radiation force is a phenomenon that occurs when an acoustic wave, such as ultrasound, interacts with an object or a medium. It results from the pressure variations produced by the sound waves as they propagate and can lead to a net force acting on small particles, bubbles, or biological tissues within the medium. ### Key Aspects of Acoustic Radiation Force: 1. **Mechanism**: When an ultrasound wave passes through a medium, it generates regions of high and low pressure.

Attenuation refers to the reduction in the strength or intensity of a signal as it travels through a medium. This concept is applicable in various fields, including telecommunications, acoustics, and optics. In general terms, attenuation can be described as the loss of energy or the decrease in amplitude of a signal due to factors such as: 1. **Distance**: As a signal travels further from its source, it typically loses strength.

Aeroacoustics is a branch of engineering and applied physics that studies the generation, propagation, and interaction of sound (acoustic phenomena) in fluid flows, particularly in air. It combines elements of fluid dynamics and acoustics to understand how aerodynamic forces and structures produce sound. Key areas of interest in aeroacoustics include: 1. **Sound Generation**: Investigating how different flow phenomena, such as turbulence, boundary layer interactions, and shock waves, create sound.

The projects you do must always aim to achieving some novel result.

You don't have to necessarily reach it. But you must aim for it.

Novel result can be taken broadly.

E.g., a new tutorial that explains something in a way never done before is novel.

But there must be something to your project that has never been done before.

You can start by reproducing other's work.

Poor countries don't have a lot of money.

Therefore, you have to pick a few key the next big thing deep tech bets, and invest on those enough.

These have to be few, because your country is poor, and so you can't invest on everything.

Therefore, the bets have to be well selected, because it is useless to make several insufficient investments: you have to pick a few ones, and put enough time and money into each one of them for them to stand any chance. These bets should be made and reevaluated on 5/10 year horizons.

The key things that you have to select are:

And then you only tax those companies heavily when the start to bring in real money. These are startups remember! You only need 5 unicorns a year to call it a success. And countries should not be greedy and invest through equity, but rather recoup their investment through taxation alone.

Ciro's second removed uncle, who was a physicist at the University of Campinas, one of the best universities in the country, told him an anecdote. He had moved from fusion energy research to solar cell research. At some point, there was a research lab that needed 10 million to buy a machinery critical for their experiment. They asked and asked, and finally the government gave them only 2 million. So in the end they spent those 2 million in random ways, but of course did not achieve their research goal and no money came out of it.

He also explained how as a result of the insufficient investments, he felt clearly that some of the semiconductor production facilities related to solar power he saw simply were not able to control the production process adequately to produce consistent silicon. As a result, everything failed sooner or later as people found more and more bugs that they did not have the time to solve.

Another key investment is enticing back experienced exchange-students who have learnt new techniques to be heads of laboratory/founders to back in your country.

A fantastic initiative from Brazil for example is BRASA, which aims to put together Brazilian exchange students to make a difference back in Brazil.

Do not try to forbid external companies from selling in your country. Instead, fund your own companies to be able to fight the external market off. And if they can't, let them die and pick a different bet. Video "How Taiwan Created TSMC by Asianometry (2020)" has a good mention. Protectionism is something that Brazil notably tried to do, and look at what it led, not a single international success.

Future self, answer these.

10 years:

20 years

40 years:

www.tritoncycles.co.uk/urban-bikes-c4/hybrid-c30/trek-fx-3-equipped-urban-bike-2021-p39860/s102315 XL color Dnister Black. £675.00 plus £35.00 delivery. Disc breaks, 2x9 gears. Bought 2023 on a bit of a sale.

The 2020 one on official website: www.trekbikes.com/gb/en_GB/bikes/hybrid-bikes/fitness-bikes/fx/fx-3-disc/p/28474/ archive.ph/wip/jMDdw TODO find 2021.

Specs upon buying:

Weight after bought measured differentially on bathroom scale: 13.5 kg

Gears: 11-36T on back, 46-30T on front. So min speed is 30/36 = 0.83 and max is 46/11 = 4.18, so range is 4.18 / 0.83 ~= 5. Compared to Kross which was 11-32 on back vs 48-28 on front, so min 28/32 = 0.875 and max 48/11 = 4.36. So the ranges are very comparable! This confirms Ciro's suspicion that 3 speeds on cranckset is just useless.

I was sized just at the lower limit of XL, but decided to go for it. The seatpost goes all the way into the tube, which is a good thing, might help with noises?

Frame serial under bottom bracket: WTU173C0374S. Registered at: www.bikeregister.com/

Initial impressions:

I'm unable to place a U-lock carrier on this bike in a way that doesn't block one of the two bottles inside frame, or hits leg on if on side. Tried both Kryptonite and Abus ones I have lying around. Shame. Also the Topeak MTS Trunkbag does not fit well on the pannier rack, it is not wide enough to strap: 11cm outer width, 9cm inner width, same geometry as that of the Liv bike.

Log:

2026-04-15: was hearing back wheel hit something periodically. First I separated the disk breaks with the tool but didn't solve. Then I noticed broken spoke, 9th clockwise from tube valve. I replaced it, but unfortunately spreading the disk break made me lose back breaks so I had to go into break fluid territory. Some conclusions: you can't do break fluid without the break pads and disk break in the break. This opens it up for contamination. The correct thing to do is to put a plastic protection on top of them. I spilled fluid on break at one point, it was horrible, I ended up changing the break pad which improved things a bit. Overall break felt slightly worse than before but passable.

2026-02-13: chain reched .7, changed it to new KMC X9. x9 9 speed chain 114 links. www.amazon.co.uk/dp/B07J38GX7L Started slipping like crazy on cassette when I pedaled hard, changed it to www.amazon.co.uk/dp/B073H3DST7 SHIMANO CS-HG400 9-speed cassette (11-36 teeth) which internet said was compatible and it seems to be. Didn't manage to remove it and needed help from bike shop as usual. After that it stopped slipping.

2025-09-30: kickstand broken while taking it on car. Proceeding to buy Bontrager Rear Mount Adjustable Kickstand www.trekbikes.com/gb/en_GB/equipment/bike-accessories/bike-kickstands/bontrager-rear-mount-adjustable-kickstand/p/36015/ 20 pounds + 4 delivery. The new kickstand is slightly different from the previous one, it is less slick looking, but perhaps a bit more sturdy, notably the little arm is shorter which might help prevent the previous failure mode. It came with 3 types of screws, but the two of correct diameter were a bit shorter or longer than the old ones so I just kept the old ones.

2025-09-13: chain reached 0.75, rebuying KMC X9. x9 9 speed chain 114 links. www.amazon.co.uk/dp/B07J38GX7L

2025-08: rear mudgard broke in the exact same way as last time, so I'm saying fuck this bullshit and I just fixed it up with some wire which will likely be more resistant than the shitty metal thing they had.

2025-06-26: I suddenly lost the ability to shift the front gear, cable seemed fine, upon inspection I noticed that the pedal could move sideways. Maybe linked to screeching sound that has been coming from that area for a while. As per www.youtube.com/watch?v=cPQyQnNdews leading to www.youtube.com/watch?v=QqBtB8Kyl2U this is a different system from the Kross one, two piece compression slotted rather than 3 piece. The side to side issue is mentioned precisely at: youtu.be/QqBtB8Kyl2U?t=357 Buying the standalone removal tool: www.amazon.co.uk/Professional-Extracto-Compatible-Hollowtech-Maintenance/dp/B0DP6QF11X Fixing it fixed the shift issue, but I noticed that the little plastic piece was broken. Also a few days later it became loose again during a ride, but thankfully I had the tool and put it back mid rid. TODO wanted to rebuy it but it's really hard to find... Going to try this one: www.bikeparts.co.uk/products/shimano-altus-fc-mt210-chainset-46-30-9-speed-black-170-mm-w-o-chainguard 175 mm and see if it comes with both arms. Bought it. has both arms. But I can't fit it, appears to be 1 or 2 mm short compared to the other cranck, the new arm does go on the old crank. There is a small rubber seal that is perhaps not too well inserted which might be to blame? Fuck my life! On the old one, it seems to be fully inserted into a tight hole. I didn't manage to insert the new one enough to make it fit, but if I remove it then it fits... just removing it for now then, how important could that be? Famous last words. Web says 12-14 nM torque on holding screws.

2025-06: rebuying 2x Shimano B05S brake pads, breaking is not too great and I don't want to repeat last year's episode of on-road failure. Will also be bleeding for the second time, God help me. The old pads weren't too bad, but I replaced them anyways. The bleeding was a failure and the brakes were too soft to be useful at the end, fuck. Went to two bike shops, both said bleeding not too bad, one said likely problem was contamination/friction issues. Tried cleaning rotors further, improved. Buying sandpaper and new rotors as well 2x SHIMANO SM-RT26 6-Bolt Disc Rotor and also got two more brake pads, totalling 3 new before I start putting them in with new rotor.

2025-04: rear shift cable snapped near shifter when going over a cattle grid, was already a bit off in the previous days after last adjust I then noticed. I'll buy a SHIMANO Gear Inner Wire Y60098070 on Amazon and might pass by bike shop as well I'll see.

2025-03: rear middle metal connection broke off read mudguard. Rebuying £21.04 from: www.tritoncycles.co.uk/frames-forks-c6/frame-fork-spares-c152/eurofender-snello-700c-fenders-46mm-rear-p33330/s93941 Quite disappointed with that, didn't come with any screws, though perhaps these are frame dependant. And the drilling was a bit different, this model seems to be intended to have some wiring passing inside via some rubber tubes that I removed, and unfortunately the hole on front was too high up and didn't match up with the screw hole on frame. I just removed the broken metal piece from it and put it on the old mudguard.

2024-09: buying CHUMXINY Brake Bleed Kit: www.amazon.co.uk/dp/B0CXDQ2S1S I hope I don't regret this. But I can't find an original one on Amazon either so... £12.74. Quality is a bit crap but seems to work. The 7mm wrench however is so bad that it can't unscrew a 7mm nut.

2024-09: chain reached 0.75, rebuying KMC X9. x9 9 speed chain 114 links: www.amazon.co.uk/dp/B07J38GX7L

2024-09: when going down a hill in intense breaking, noise started coming from back disk brake. Tried to adjust, but made it worse, had to bail out on nearby bike shop. Readjusted, told me to replace back pads and likely bleed. Bought two Shimano B05S brake pads to replace the B01S that came with the bike, Internet says compatible. Brake maintenance finally caught up with me, it was a great summer and I kept putting it off. Changed just the back one for now, front still has life it seems.

2024-06: noticed a sideways lump on back tyre between spoke 23 and 24 when washing. The only sign of damage was internal near grip part, I could see some clear shearing... God those tyres are crap, or at least crap to what I've subjected them. Inner tube and outside seem perfect, so weird. If only the Schawlbe had worked! But OK now I'm forced to get something new and better, thinking:They had a Schwalbe Marathon Plus 700x35c (non-Tour, as that one didn't fit as per previous experiment) on the shop and I went for it. They said 35c was the maximum recommended for that mudgard which is a bit of a shame, but good to know. Also getting one from Amazon to match on front as shop only had one.

2024-04: micropuncture on front tube? Could not identify during ride, refilled and was OK to get home. Almost no pressure in middle of ride. Passed through some deep water which may have made things worse? Had a small pice of glass-like material stuck in tyre, but didn't seem to penetrate? One day and a half later, was full empty again after full fill without riding, so confirming micropuncture theory. Buying 2x Conti Tube Cross 28 (700C) presta inner tubes.

Tried to put a spare Schwalbe Men's Marathon Plus Tour 700x40C on the bike to get better stability. It seemed to fit the wheel quite well, but unfortunately failed to go well in the fork because it was too tall and hit the mudgard. Without mudgard it might work. Measured height was 6cm for Schwalbe vs 5.3cm for the stock one.

2024-02: another broken spoke... what crappy weak wheels!!! Bought Bavel 290 mm spokes 36pcs 14G J Bend Silver. Broken position was 22nd clockwise from inner tube valve hole.

2023-12: chain reached 0.75, rebuying KMC X9. x9 9 speed chain 114 links.

2023-12: broken spoke! Also had to replace nipple because broke inside nipple. At least learned how to change tire at last.

2023-05: buying another pair of Shimano 324 combination pedals for it: www.wiggle.com/p/shimano-m324-combination-pedals

2023-05: rebuying another Topeak Aero Wedge saddle bag for this new bike

2023-05: 2x Elite custom race cage water bottle frame cages, felt great, much better than those on the Kross! www.elite-it.com/en/products/bottle-cages/fibre-reinforced-material-frp/custom-race

2023-05: ParkTool TR1 tyre levers + GP-2 super patch kit

2023-05: Kask Rapido Medium Black/Yellow fluo helmet, got a more racy helmet too! 69 pounds, way more any previous helmet I've owned: www.kask.com/en/cycling/helmets/rapido_24_2.htm

2023-05: Lezyne hand pump, I think Sport Drive HP? ride.lezyne.com/collections/hand-pumps/products/sport-drive-hp

2023-05: Lezyne V-Pro 10 multi-tool ride.lezyne.com/products/v-pro-tool No spoke wrench unfortunately.

Initial equipment:

Annotated copypasta:Weight limit: This bike has a maximum total weight limit (combined weight of bicycle, rider and cargo) of 136 kg (300 lb)