Shortlex order is a method of ordering sequences, typically strings or lists, based on their length and lexicographic (dictionary) order. Here's how it works: 1. **Length Order**: Sequences are first grouped by their length. All sequences of a shorter length come before sequences of a longer length. 2. **Lexicographic Order**: Within the same length, sequences are ordered lexicographically.
An episome is a type of genetic element that can exist as a separate plasmid within a cell or integrate into the host organism's chromosomal DNA. It is a form of a plasmid, which is a small, circular piece of DNA that can replicate independently of chromosomal DNA. Episomes are particularly known for their role in certain bacteria, where they can carry genes that confer traits such as antibiotic resistance or the ability to produce virulence factors.
"SuperPrime" can refer to different concepts depending on the context in which it is used. Here are a few possible interpretations: 1. **In Mathematics**: A "super prime" is typically defined as a prime number that is also a prime index. In simpler terms, it is a prime number that appears at a position in the list of prime numbers that is also prime.
Hitori is a logic-based puzzle game that originated in Japan. The objective of Hitori is to fill in cells in a grid based on certain rules, which typically involve the numbers provided in the cells. The game is played on a rectangular grid filled with numbers. Here are the basic rules: 1. **Grid Structure**: The grid consists of a set of numbers, where each number represents how many times that number appears in its respective row and column.
PdfTeX is an extension of the TeX typesetting system designed to produce PDF (Portable Document Format) output directly.
A hardware store is a retail establishment that sells a variety of tools, building materials, home improvement supplies, and gardening products.
Gilding is a decorative technique that involves applying a thin layer of gold or a gold-like substance to a surface to create a luxurious finish. This process can be applied to various materials, including wood, metal, paper, and ceramics. There are several methods of gilding, including: 1. **Gold Leaf Gilding**: Involves applying extremely thin sheets of gold leaf to a surface, often using an adhesive or glue.
64 is a natural number that follows 63 and precedes 65. It is an important number in various contexts: 1. **Mathematics**: - It can be expressed as \(8^2\) (8 squared) or \(2^6\) (2 raised to the power of 6). - It is a perfect square as well as a perfect sixth power.
Hans Bethe by Ciro Santilli 40 Updated 2025-07-16
Head of the theoretical division at the Los Alamos Laboratory during the Manhattan Project.
Richard Feynman was working under him there, and was promoted to team lead by him because Richard impressed Hans.
He was also the person under which Freeman Dyson was originally under when he moved from the United Kingdom to the United States.
And Hans also impressed Feynman, both were problem solvers, and liked solving mental arithmetic and numerical analysis.
This relationship is what brought Feynman to Cornell University after World War II, Hans' institution, which is where Feynman did the main part of his Nobel prize winning work on quantum electrodynamics.
Hans must have been the perfect PhD advisor. He's always smiling, and he seemed so approachable. And he was incredibly capable, notably in his calculation skills, which were much more important in those pre-computer days.
In this example, posts have tags. When a post is deleted, we check to see if there are now any empty tags, and now we want to delete any empty tags that the post deletion may have created.
If we are creating and deleting posts concurrently, a naive implementation might wrongly delete the tags of a newly created post.
This could be due to a concurrency issue of the following types.
Failure case 1:
  • thread 2: delete old post
  • thread 2: find all tags with 0 posts. Finds tag0 from the deleted old post which is now empty.
  • thread 1: create new post, which we want to have tag tag0
  • thread 1: try to create a new tag tag0, but don't because it already exists, this is done using SQLite's INSERT OR IGNORE INTO or PostgreSQL's INSERT ... ON CONFLICT DO NOTHING
  • thread 1: assign tag0 to the new post by adding an entry to the join table
  • thread 2: delete all tags with 0 posts. It still sees from its previous search that tag0 is empty, and deletes it, which then cascades into the join table
which would result in the new post incorrectly not having the tag0.
Failure case 2:
  • thread 2: delete old post
  • thread 2: find all tags with 0 posts
  • thread 1: create new post
  • thread 1: try to create a new tag tag0, but don't because it already exists
  • thread 2: delete all tags with 0 posts. It still sees from its previous search that tag0 is empty, and deletes it
  • thread 1: assign tag0 to the new post
which leads to a foreign key failure, because the tag does not exist anymore when the assignment happens.
Failure case 3:
  • thread 2: delete old post
  • thread 1: create new post, which we want to have tag tag0
  • thread 1: try to create a new tag tag0, and succeed because it wasn't present
  • thread 2: find all tags with 0 posts, finds the tag that was just created
  • thread 2: delete all tags with 0 posts, deleting the new tag
  • thread 1: assign tag0 to the new post
which leads to a foreign key failure, because the tag does not exist anymore when the assignment happens.
Sample executions:
  • node --unhandled-rejections=strict ./parallel_create_delete_empty_tag.js p 9 1000 'READ COMMITTED': PostgreSQL, 9 tags, DELETE/CREATE the tag0 test tag 1000 times, use READ COMMITTED
    Execution often fails, although not always. The failure is always:
    error: insert or update on table "PostTag" violates foreign key constraint "PostTag_tagId_fkey"
    because the:
    INSERT INTO "PostTag"
    tries to insert a tag that was deleted in the other thread, as it didn't have any corresponding posts, so this is the foreign key failure.
    TODO: we've never managed to observe the failure case in which tag0 is deleted. Is it truly possible? And if not, by which guarantee?
  • node --unhandled-rejections=strict ./parallel_create_delete_empty_tag.js p 9 1000 'READ COMMITTED' 'FOR UPDATE': do a SELECT ... FOR UPDATE before trying to INSERT.
    This is likely correct and the fastest correct method according to our quick benchmarking, about 20% faster than REPEATABLE READ.
    We are just now 100% sure it is corret becase we can't find out if the SELECT in the DELETE subquery could first select some rows, which are then locked by the tag creator, and only then locked by DELETE after selection. Or does it re-evaludate the SELECT even though it is in a subquery?
  • node --unhandled-rejections=strict ./parallel_create_delete_empty_tag.js p 9 1000 'REPEATABLE READ': repeatable read
    We've never observed any failures with this level. This should likely fix the foreign key issue according to the PostgreSQL docs, since:
    • the DELETE "Post" commit cannot start to be seen only in the middle of the thread 1 transaction
    • and then if DELETE happened, the thread 1 transaction will detect it, ROLLBACK, and re-run. TODO how does it detect the need rollback? Is it because of the foreign key? It is very hard to be sure about this kind of thing, just can't find the information. Related: postgreSQL serialization failure.
  • node --unhandled-rejections=strict ./parallel_create_delete_empty_tag.js p 9 1000 'SERIALIZABLE': serializable
  • node --unhandled-rejections=strict ./parallel_create_delete_empty_tag.js p 9 1000 'NONE': magic value, don't use any transaction. Can blow up of course, since even less restrictions than READ COMMITTED
All executions use 2 threads.
Some theoretical notes:
  • Failure case 3 is averted by a READ COMMITTED transaction, because thread 2 won't see the uncommitted tag that thread 1 created, and therefore won't be able to delete it
stackoverflow.com/questions/10935850/when-to-use-select-for-update from SELECT FOR UPDATE also talks about a similar example, and has relevant answers.
Unlike SARS-CoV-2 non-structural protein, these are not needed for test tube reproduction. They must therefore be for host modulation.
You need a secondary password that when used leads to an empty inbox with a setting set where message are deleted after 2 days.
This way, if the attacker sends a test email, it will still show up, but being empty is also plausible.
Of course, this means that any new emails received will be visible by the attacker, so you have to find a way to inform senders that the account has been compromised.
So you have to find a way to inform senders that the account has been compromised, e.g. a secret pre-agreed canary that must be checked each time as part of the contact protocol.

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!
We have two killer features:
  1. 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-calculus
    Articles 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/derivative
  2. 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.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    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.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
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