A **locally compact group** is a type of topological group that has the property of local compactness in addition to the group structure. Let's break down the definitions: 1. **Topological Group**: A group \( G \) is equipped with a topology such that both the group operation (multiplication) and the inverse operation are continuous.
Hodge theory is a central area in differential geometry and algebraic geometry that studies the relationship between the topology of a manifold and its differential forms. It is particularly concerned with the decomposition of differential forms on a compact, oriented Riemannian manifold and the study of their cohomology groups. The key concepts in Hodge theory are: 1. **Differential Forms**: These are generalized functions that can be integrated over manifolds.
In algebraic geometry and related fields, a **coherent sheaf** is a specific type of sheaf that combines the properties of sheaves with certain algebraic conditions that make them suitable for studying geometric objects.
The Riemann–Roch theorem is a fundamental result in algebraic geometry and complex analysis that provides a powerful tool for calculating dimensions of certain spaces of sections of line bundles on smooth projective curves.
The projective tensor product is a construction in functional analysis and tensor algebra that generalizes the notion of the tensor product of vector spaces to arbitrary topological vector spaces. It is particularly useful when dealing with dual spaces and various types of convergence in topological spaces.
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.
What poor countries have to do to get richer Pick few good bets and invest enough on them by
Ciro Santilli 40 Updated 2025-07-16
Therefore, you have to pick a few key the next big thing deep tech bets, and invest on those enough.
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:
- which poor students you will bet on educating. Since you can't give amazing education to everyone, you have to select the most promising poor students somehow, and give those free amazing learning conditions: free gifted education
- which ares to focus on. Ciro believes that molecular biology technologies and quantum computing would be good bets. Focusing on the previous next big things, e.g. classic computers, is always a losing bet on average
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.
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:
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:
- on city ride: I'm much more inclined forward than on the Kross bicycle (2017) since this is XL might be a good thing. Let's see on longer countryside ride.
- on rain: the pedal performance is terrible, very slippery!
- the breaks are good, a bit better than the Kross, but not as grippy as ones I've seen.
- It is good that it came with lights. But OMG the DUXO back light is impossible to open!!! Front battery also seemed short, to be checked
- Presta valves suck. I can't inflate it without holding it down with my feet!
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.
- www.trekbikes.com/gb/en_GB/equipment/cycling-components/bike-tyres/hybrid-bike-tyres/bontrager-h2-hard-case-ultimate-reflective-hybrid-tyre/p/31553 seems Schwalbe like, but will it fit?
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: 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: 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: 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)
- Frame: Alpha Gold Aluminium, DuoTrap S-compatible, internal cable routing, flat-mount disc, rack and mudguard mounts, 135x5 mm QR
- Mudguard/rack mounts: Alloy
- Hub front: Formula DC-20, alloy, 6-bolt, 5x100 mm QR
- Hub rear: Formula DC-22, alloy, 6-bolt, Shimano 8/9/10 freehub, 135x5 mm QR
- Rim: Bontrager Tubeless Ready Disc, 32-hole, Presta valve. TODO identify precisely. But presumably something like: www.tritoncycles.co.uk/components-c9/wheels-c126/affinity-tlr-32h-6-bolt-disc-700c-road-wheel-p25441/s79099 which says: Alloy double-wall rim with 21mm internal, 26mm external width
- Spokes: 14 g stainless steel. Not documented, but measured in store: 290mm.
- Tyre: Bontrager H2 Comp, wire bead, 30 tpi, 700x32c. Link was: www.trekbikes.com/us/en_US/equipment/cycling-components/bike-tires/hybrid-bike-tires/bontrager-h2-comp-hybrid-tire/p/31551/ but they don't sell that crap anymore? A bit weak. At shop said 35c is max recommended width.
- Shifter: Size: M, L, XL - Shimano Acera M3000, 9-speed | Size: M, L, XL - Shimano Acera M3000, 2 -speed
- Front derailleur: Shimano Acera T3000, 34.9 mm clamp, top swing, dual pull
- Rear derailleur: Shimano Alivio M3100, long cage
- Crank: Size: Shimano MT210-2, 46/30, chain guard, 175 mm length
- Cassette: Shimano HG200, 11-36, 9-speed
- Chain: KMC X9. x9 9 speed chain. Official page: www.kmcchain.com/en/product/bicycle-chain-x9-9-speed so crappy does not say link count! But presumably the 114 that is most common on most sites.
- Pedal: Bontrager City pedals. www.trekbikes.com/gb/en_GB/equipment/cycling-components/bike-pedals/platform-pedals/bontrager-city-pedal-set/p/35291/ Bontrager City Pedal Set 9/16-inch (15 mm). Installs with a 6 mm hex key or flat 15 mm pedal wrench.
- Saddle: Bontrager H1
- Seatpost: Bontrager alloy, 27.2 mm, 12 mm offset, 330 mm length
- Handlebar: Size: M - Bontrager Satellite Plus IsoZone, alloy, 31.8 mm, 15 mm rise, 600 mm width | Size: L, XL - Bontrager Satellite Plus IsoZone, alloy, 31.8 mm, 15 mm rise, 660 mm width
- Grips: Bontrager Satellite IsoZone Plus, lock-on, ergonomic
- Stem: Size: M, L - Bontrager Elite, 31.8 mm clamp, Blendr-compatible, 7-degree, 100 mm length | Size: XL - Bontrager Elite, 31.8 mm clamp, Blendr-compatible, 7-degree, 110 mm length
- Headset: 1-1/8" threadless, sealed cartridge bearings
- Brake: Shimano MT201 hydraulic disc, flat-mount, 160 mm rotor
- Brake rotor: Shimano RT26, 6-bolt,160 mm
- Brake pad: Brake Pad Shimano Resin Disc Pad B01S RESIN
- Light: Size: M, L, XL - Spanninga Duxo XB, battery-powered | Size: M, L, XL - AXA Greenline 35, USB rechargeable
- Kickstand: Alloy, rear-mount kickstand. More precisely looks like: Bontrager Rear Mount Adjustable Kickstand www.trekbikes.com/gb/en_GB/equipment/bike-accessories/bike-kickstands/bontrager-rear-mount-adjustable-kickstand/p/36015/
- Cargo rack: Alloy rear rack
- Mudguard: Eurofender Snello. Looks like this one: www.trekbikes.com/gb/en_GB/equipment/bike-accessories/bike-mudguards-and-accessories/bike-mudguards/eurofender-snello-700c-fender-set/p/31699/
- Approx. Weight: L - 13.17 kg / 29.04 lbs
Fatty acids are carboxylic acids with long hydrocarbon chains, which can vary in length and degree of saturation. They are essential components of lipids (fats and oils) and play crucial roles in biological processes. ### Key Features of Fatty Acids: 1. **Structure**: - **Carboxyl Group**: Each fatty acid has a carboxyl (-COOH) group at one end, which gives it acidic properties.
This shows that viewing electromagnetism as gauge theory does have experimentally observable consequences. TODO understand what that means.
In more understandable terms, it shows that the magnetic vector potential matters where the magnetic field is 0.
The idea the the wave function of a small observed system collapses "obviously" cannot be the full physical truth, only a very useful approximation of reality.
Because then are are hard pressed to determine the boundary between what collapses and what doesn't, and there isn't such a boundary, as everything is interacting, including the observer.
The many-worlds interpretation is an elegant explanation for this. Though it does feel a bit sad and superfluous.
Key exmaple: d and L amino acids. Enantiomers have identical physico-chemical properties. But their biological roles can be very different, because an enzyme might only be able to act on one of them.
Rational representation can refer to different concepts depending on the context, but it is most commonly associated with mathematics, particularly in number theory and algebra. 1. **In the context of numbers**: A rational representation usually refers to the expression of a number as a ratio of two integers.
Adds special relativity to the Schrödinger equation, and the following conclusions come basically as a direct consequence of this!
Experiments explained:
Experiments not explained: those that quantum electrodynamics explains like:See also: Dirac equation vs quantum electrodynamics.
- Lamb shift
- TODO: quantization of the electromagnetic field as photons?
The Dirac equation is a set of 4 partial differential equations on 4 complex valued wave functions. The full explicit form in Planck units is shown e.g. in Video 1. "Quantum Mechanics 12a - Dirac Equation I by ViaScience (2015)" at youtu.be/OCuaBmAzqek?t=1010:Then as done at physics.stackexchange.com/questions/32422/qm-without-complex-numbers/557600#557600 from why are complex numbers used in the Schrodinger equation?, we could further split those equations up into a system of 8 equations on 8 real-valued functions.
Equation 1.
Expanded Dirac equation in Planck units
. PHYS 485 Lecture 14: The Dirac Equation by Roger Moore (2016)
Source. A random field you add to make something transform locally the way you want. See e.g.: Video "Deriving the qED Lagrangian by Dietterich Labs (2018)".
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 3. Visual Studio Code extension installation.Figure 4. Visual Studio Code extension tree navigation.Figure 5. Web editor. You can also edit articles on the Web editor without installing anything locally.Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. - Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact





