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🔗 Books 🔗 Poland

The Scottish Book (Polish: Księga Szkocka) was a thick notebook used by mathematicians of the Lwów School of Mathematics in Poland for jotting down problems meant to be solved. The notebook was named after the "Scottish Café" where it was kept.

Originally, the mathematicians who gathered at the cafe would write down the problems and equations directly on the cafe's marble table tops, but these would be erased at the end of each day, and so the record of the preceding discussions would be lost. The idea for the book was most likely originally suggested by Stefan Banach, or his wife, Łucja, who purchased a large notebook and left it with the proprietor of the cafe.

🔗 Germany 🔗 Socialism 🔗 Cold War 🔗 Germany/GDR

On 16 September 1979, eight people from two families escaped from East Germany by crossing the border into West Germany at night in a homemade hot air balloon. The unique feat was the result of over a year and a half of preparations involving three different balloons, various modifications, and a first, unsuccessful attempt. The failed attempt alerted the East German authorities to the plot, but the police were unable to identify the escapees before their second, successful flight two months later.

🔗 United States 🔗 Computing 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Iran 🔗 Computing/Software 🔗 Computing/Computer Security 🔗 Military history/Middle Eastern military history

Stuxnet is a malicious computer worm, first uncovered in 2010, thought to have been in development since at least 2005. Stuxnet targets supervisory control and data acquisition (SCADA) systems and is believed to be responsible for causing substantial damage to the nuclear program of Iran. Although neither country has openly admitted responsibility, the worm is widely understood to be a cyberweapon built jointly by the United States and Israel.

Stuxnet specifically targets programmable logic controllers (PLCs), which allow the automation of electromechanical processes such as those used to control machinery and industrial processes including gas centrifuges for separating nuclear material. Exploiting four zero-day flaws, Stuxnet functions by targeting machines using the Microsoft Windows operating system and networks, then seeking out Siemens Step7 software. Stuxnet reportedly compromised Iranian PLCs, collecting information on industrial systems and causing the fast-spinning centrifuges to tear themselves apart. Stuxnet's design and architecture are not domain-specific and it could be tailored as a platform for attacking modern supervisory control and data acquisition (SCADA) and PLC systems (e.g., in factory assembly lines or power plants), most of which are in Europe, Japan, and the US. Stuxnet reportedly ruined almost one-fifth of Iran's nuclear centrifuges. Targeting industrial control systems, the worm infected over 200,000 computers and caused 1,000 machines to physically degrade.

Stuxnet has three modules: a worm that executes all routines related to the main payload of the attack; a link file that automatically executes the propagated copies of the worm; and a rootkit component responsible for hiding all malicious files and processes, to prevent detection of Stuxnet. It is typically introduced to the target environment via an infected USB flash drive, thus crossing any air gap. The worm then propagates across the network, scanning for Siemens Step7 software on computers controlling a PLC. In the absence of either criterion, Stuxnet becomes dormant inside the computer. If both the conditions are fulfilled, Stuxnet introduces the infected rootkit onto the PLC and Step7 software, modifying the code and giving unexpected commands to the PLC while returning a loop of normal operation system values back to the users.

In 2015, Kaspersky Lab noted that the Equation Group had used two of the same zero-day attacks prior to their use in Stuxnet and commented that "the similar type of usage of both exploits together in different computer worms, at around the same time, indicates that the Equation Group and the Stuxnet developers are either the same or working closely together".

🔗 Computing 🔗 Systems 🔗 Computing/Software 🔗 Systems/Software engineering

Capability Immaturity Model (CIMM) in software engineering is a parody acronym, a semi-serious effort to provide a contrast to the Capability Maturity Model (CMM). The Capability Maturity Model is a five point scale of capability in an organization, ranging from random processes at level 1 to fully defined, managed and optimized processes at level 5. The ability of an organization to carry out its mission on time and within budget is claimed to improve as the CMM level increases.

The "Capability Im-Maturity Model" asserts that organizations can and do occupy levels below CMM level 1. An original article by Capt. Tom Schorsch USAF as part of a graduate project at the Air Force Institute of Technology provides the definitions for CIMM. He cites Prof. Anthony Finkelstein's ACM paper as an inspiration. The article describes situations that arise in dysfunctional organizations. Such situations are reportedly common in organizations of all kinds undertaking software development, i.e. they are really characterizations of the management of specific projects, since they can occur even in organizations with positive CMM levels.

Kik Piney, citing the original authors, later adapted the model to a somewhat satirical version that attracted a number of followers who felt that it was quite true to their experience.

🔗 Computing 🔗 Computer science 🔗 Software 🔗 Software/Computing

A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on Android devices is a cross compiler.

A cross compiler is useful to compile code for multiple platforms from one development host. Direct compilation on the target platform might be infeasible, for example on embedded systems with limited computing resources.

Cross compilers are distinct from source-to-source compilers. A cross compiler is for cross-platform software generation of machine code, while a source-to-source compiler translates from one coding language to another in text code. Both are programming tools.

🔗 Computing 🔗 Computing/Computer hardware

The Honeywell 316 was a popular 16-bit minicomputer built by Honeywell starting in 1969. It is part of the Series 16, which includes the Models 116 (1965, discrete^: 4), 316 (1969), 416 (1966), 516 (1966) and DDP-716 (1969). They were commonly used for data acquisition and control, remote message concentration, clinical laboratory systems, Remote Job Entry and time-sharing. The Series-16 computers are all based on the DDP-116 designed by Gardner Hendrie at Computer Control Company, Inc. (3C) in 1964.

The 516 and later the 316 were used as Interface Message Processors (IMP) for the American ARPANET and the British NPL Network.

🔗 Mathematics

Bellard's formula is used to calculate the nth digit of π in base 16.

Bellard's formula was discovered by Fabrice Bellard in 1997. It is about 43% faster than the Bailey–Borwein–Plouffe formula (discovered in 1995). It has been used in PiHex, the now-completed distributed computing project.

One important application is verifying computations of all digits of pi performed by other means. Rather than having to compute all of the digits twice by two separate algorithms to ensure that a computation is correct, the final digits of a very long all-digits computation can be verified by the much faster Bellard's formula.

Formula:

${\displaystyle {\begin{aligned}\pi ={\frac {1}{2^{6}}}\sum _{n=0}^{\infty }{\frac {(-1)^{n}}{2^{10n}}}\,\left(-{\frac {2^{5}}{4n+1}}\right.&{}-{\frac {1}{4n+3}}+{\frac {2^{8}}{10n+1}}-{\frac {2^{6}}{10n+3}}\left.{}-{\frac {2^{2}}{10n+5}}-{\frac {2^{2}}{10n+7}}+{\frac {1}{10n+9}}\right)\end{aligned}}}$

🔗 Psychology

A cognitive distortion is an exaggerated or irrational thought pattern involved in the onset and perpetuation of psychopathological states, especially those more influenced by psychosocial factors, such as depression and anxiety. Psychiatrist Aaron T. Beck laid the groundwork for the study of these distortions, and his student David D. Burns continued research on the topic. Burns, in The Feeling Good Handbook (1989), described personal and professional anecdotes related to cognitive distortions and their elimination.

Cognitive distortions are thoughts that cause individuals to perceive reality inaccurately. According to the cognitive model of Beck, a negative outlook on reality, sometimes called negative schemas (or schemata), is a factor in symptoms of emotional dysfunction and poorer subjective well-being. Specifically, negative thinking patterns reinforce negative emotions and thoughts. During difficult circumstances, these distorted thoughts can contribute to an overall negative outlook on the world and a depressive or anxious mental state.

Challenging and changing cognitive distortions is a key element of cognitive behavioral therapy (CBT).

🔗 Mathematics

A galactic algorithm is one that runs faster than any other algorithm for problems that are sufficiently large, but where "sufficiently large" is so big that the algorithm is never used in practice. Galactic algorithms were so named by Richard Lipton and Ken Regan, as they will never be used on any of the merely terrestrial data sets we find here on Earth.

An example of a galactic algorithm is the fastest known way to multiply two numbers, which is based on a 1729-dimensional Fourier transform. This means it will not reach its stated efficiency until the numbers have at least 2¹⁷²⁹¹² bits (at least 10¹⁰³⁸ digits), which is vastly larger than the number of atoms in the known universe. So this algorithm is never used in practice.

Despite the fact that they will never be used, galactic algorithms may still contribute to computer science:

• An algorithm, even if impractical, may show new techniques that may eventually be used to create practical algorithms.
• Computer sizes may catch up to the crossover point, so that a previously impractical algorithm becomes practical.
• An impractical algorithm can still demonstrate that conjectured bounds can be achieved, or alternatively show that conjectured bounds are wrong. As Lipton says "This alone could be important and often is a great reason for finding such algorithms. For example, if tomorrow there were a discovery that showed there is a factoring algorithm with a huge but provably polynomial time bound, that would change our beliefs about factoring. The algorithm might never be used, but would certainly shape the future research into factoring." Similarly, a ${\displaystyle O\left(n^{2^{100}}\right)}$ algorithm for the Boolean satisfiability problem, although unusable in practice, would settle the P versus NP problem, the most important open problem in computer science and one of the Millennium Prize Problems.